Merge embed: export fn, --shared, -I and the two limit fixes were ported to the Finch-written compiler

The C++ sources those commits changed no longer exist on this branch; their tests (early_exit, map_add_while_looping,
shared) are in tests/ and pass.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015f73FesGZGYPkmDvUcj6QX

.github/workflows/ci.yml

@@ -1,14 +1,15 @@
 name: CI
 
+# The compiler is written in Finch. It is built from bootstrap/<system>.ll, its own LLVM IR (see bootstrap/README.md),
+# then from itself. Seeds: Linux x86-64 and ARM64 (tested here), Windows x86-64 (tested under Wine, and here),
+# macOS ARM64 and x86-64 (made with Apple's headers; only checked as IR until the macos job below passes).
+
 on:
   push:
     branches: [main, "ci/**"]
     tags: ["v*"]
   pull_request:
 
-env:
-  LLVM_VERSION: 21.1.8
-
 jobs:
   linux:
     strategy:
@@ -21,75 +22,100 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
-      - name: Install LLVM 21, libclang, tools
+      - name: Install clang 21, libclang, tools
         run: |
           wget -q https://apt.llvm.org/llvm.sh
           sudo bash llvm.sh 21
-          sudo apt-get install -y llvm-21-dev libclang-21-dev ninja-build valgrind
+          sudo apt-get install -y libclang-21-dev pkg-config valgrind
           echo "/usr/lib/llvm-21/bin" >> $GITHUB_PATH
-      - name: Build
+      - name: Build the compiler (seed, then itself, and the two must agree)
         run: |
-          cmake -S . -B build -G Ninja -DLLVM_DIR=/usr/lib/llvm-21/lib/cmake/llvm -DCMAKE_BUILD_TYPE=Release
-          ninja -C build
+          export FINCH_LIBCLANG="-L/usr/lib/llvm-21/lib -lclang-21"
+          bootstrap/build.sh
           build/finch version
-      - name: Tests
+      - name: Tests (programs, refusals, -g, a shared library, the language server)
         run: tests/run.sh
       - name: Tests under valgrind
         if: matrix.arch == 'x64'
         run: MEMCHECK=1 tests/run.sh
-      - name: Self-hosting
-        run: tests/boot.sh
-      - name: Language server
-        run: python3 tests/lsp_test.py
       - name: Package
         run: |
-          mkdir -p dist/finch && cp build/finch README.md LICENSE dist/finch/ && cp -r examples dist/finch/
+          mkdir -p dist/finch && cp build/finch README.md LICENSE dist/finch/ && cp -r runtime std examples dist/finch/
           tar -czf finch-linux-${{ matrix.arch }}.tar.gz -C dist finch
       - uses: actions/upload-artifact@v4
         with:
           name: finch-linux-${{ matrix.arch }}
           path: finch-linux-${{ matrix.arch }}.tar.gz
 
+  cross:
+    name: programs for ${{ matrix.target }}
+    runs-on: ubuntu-24.04
+    strategy:
+      fail-fast: false
+      matrix:
+        target: [windows, arm64]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install clang 21, libclang, cross compilers and emulators
+        run: |
+          wget -q https://apt.llvm.org/llvm.sh
+          sudo bash llvm.sh 21
+          sudo apt-get install -y libclang-21-dev pkg-config gcc-mingw-w64-x86-64 wine64 gcc-aarch64-linux-gnu qemu-user libc6-arm64-cross
+          echo "/usr/lib/llvm-21/bin" >> $GITHUB_PATH
+      - name: Build the compiler
+        run: |
+          export FINCH_LIBCLANG="-L/usr/lib/llvm-21/lib -lclang-21"
+          bootstrap/build.sh
+      - name: Run every test on the other system
+        run: |
+          if [ "${{ matrix.target }}" = windows ]; then
+            FINCH_CC=x86_64-w64-mingw32-gcc tests/cross.sh windows
+          else
+            FINCH_CC=aarch64-linux-gnu-gcc QEMU_LD_PREFIX=/usr/aarch64-linux-gnu tests/cross.sh arm64
+          fi
+
   macos:
     runs-on: macos-15
     steps:
       - uses: actions/checkout@v4
-      - name: Install LLVM 21
+      - name: Install LLVM 21 (libclang)
+        run: brew install llvm@21 pkg-config
+      - name: Build the compiler
         run: |
-          brew install llvm@21 ninja
-          echo "$(brew --prefix llvm@21)/bin" >> $GITHUB_PATH
-      - name: Build
-        run: |
-          cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR="$(brew --prefix llvm@21)/lib/cmake/llvm"
-          ninja -C build
+          export FINCH_CLANG="$(brew --prefix llvm@21)/bin/clang"
+          export FINCH_LIBCLANG="-L$(brew --prefix llvm@21)/lib -lclang"
+          export FINCH_LLVM_INCLUDE="$(brew --prefix llvm@21)/include"
+          bootstrap/build.sh
           build/finch version
       - name: Tests
-        run: CC=/usr/bin/clang tests/run.sh
-      - name: Self-hosting
-        run: CC=/usr/bin/clang tests/boot.sh
-      - name: Language server
-        run: python3 tests/lsp_test.py
-      - name: Apple frameworks
-        run: |
-          cat > fw.fch <<'EOF'
-          import "CoreFoundation/CoreFoundation.h"
-          link "CoreFoundation.framework"
+        run: tests/run.sh
 
-          fn main() {
-              print(CFAbsoluteTimeGetCurrent() > 0.0)
-          }
-          EOF
-          out=$(CC=/usr/bin/clang build/finch run fw.fch)
-          echo "$out"
-          test "$out" = "true"
-      - name: Package
+  windows:
+    runs-on: windows-2022
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download llvm-mingw (clang with MinGW headers) and LLVM for Windows (libclang.dll)
         run: |
-          mkdir -p dist/finch && cp build/finch README.md LICENSE dist/finch/ && cp -r examples dist/finch/
-          tar -czf finch-macos-arm64.tar.gz -C dist finch
-      - uses: actions/upload-artifact@v4
-        with:
-          name: finch-macos-arm64
-          path: finch-macos-arm64.tar.gz
+          curl -sSL -o mingw.zip https://github.com/mstorsjo/llvm-mingw/releases/download/20251216/llvm-mingw-20251216-ucrt-x86_64.zip
+          7z x -y mingw.zip -o/c/ > /dev/null
+          curl -sSL -o llvm.exe https://github.com/llvm/llvm-project/releases/download/llvmorg-21.1.8/LLVM-21.1.8-win64.exe
+          7z x -y llvm.exe -o/c/llvm > /dev/null
+      - name: Build the compiler
+        run: |
+          export PATH="/c/llvm-mingw-20251216-ucrt-x86_64/bin:$PATH"
+          export FINCH_LIBCLANG="C:/llvm/bin/libclang.dll"
+          export FINCH_LLVM_INCLUDE="C:/llvm/include"
+          export FINCH_LDFLAGS="-LC:/llvm/bin"
+          bootstrap/build.sh
+          build/finch.exe version
+      - name: Tests
+        run: |
+          export PATH="/c/llvm-mingw-20251216-ucrt-x86_64/bin:$PATH"
+          export FINCH_LDFLAGS="-LC:/llvm/bin"
+          FINCH=../build/finch.exe tests/run.sh
 
   vscode:
     runs-on: ubuntu-24.04
@@ -110,51 +136,3 @@ jobs:
         with:
           name: finch-vscode
           path: editors/vscode/finch-lang.vsix
-
-  windows:
-    runs-on: windows-2022
-    defaults:
-      run:
-        shell: bash
-    steps:
-      - uses: actions/checkout@v4
-      - uses: ilammy/msvc-dev-cmd@v1
-      - name: Cache LLVM
-        id: cache-llvm
-        uses: actions/cache@v4
-        with:
-          path: C:/llvm
-          key: llvm-${{ env.LLVM_VERSION }}-x86_64-pc-windows-msvc
-      - name: Download LLVM ${{ env.LLVM_VERSION }}
-        if: steps.cache-llvm.outputs.cache-hit != 'true'
-        run: |
-          curl -sSL -o llvm.tar.xz "https://github.com/llvm/llvm-project/releases/download/llvmorg-$LLVM_VERSION/clang+llvm-$LLVM_VERSION-x86_64-pc-windows-msvc.tar.xz"
-          mkdir -p /c/llvm
-          tar -xf llvm.tar.xz -C /c/llvm --strip-components=1
-          rm llvm.tar.xz
-      - name: Build finch.exe
-        run: |
-          echo "C:/llvm/bin" >> $GITHUB_PATH
-          export PATH="/c/llvm/bin:$PATH"
-          cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR=C:/llvm/lib/cmake/llvm \
-                -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded -DCMAKE_C_COMPILER=cl -DCMAKE_CXX_COMPILER=cl
-          ninja -C build
-          cp /c/llvm/bin/libclang.dll build/
-          build/finch.exe version
-      - name: Tests
-        run: |
-          export PATH="/c/llvm/bin:$PATH"
-          tests/run.sh
-      - name: Language server
-        run: python tests/lsp_test.py
-      - name: Package
-        run: |
-          mkdir -p dist/finch
-          cp build/finch.exe build/libclang.dll dist/finch/
-          cp README.md LICENSE dist/finch/
-          cp -r examples dist/finch/
-          cd dist && 7z a -tzip finch-windows-x64.zip finch > /dev/null
-      - uses: actions/upload-artifact@v4
-        with:
-          name: finch-windows-x64
-          path: dist/finch-windows-x64.zip

.gitignore

@@ -1,2 +1,3 @@
 build/
 *.o
+core.*

CMakeLists.txt

@@ -1,91 +0,0 @@
-cmake_minimum_required(VERSION 3.20)
-project(finch VERSION 2.4.0 LANGUAGES C CXX)  # C: LLVM's CMake config checks C headers on some systems
-
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-
-find_package(LLVM REQUIRED CONFIG)
-message(STATUS "Using LLVM ${LLVM_PACKAGE_VERSION}")
-
-add_executable(finch
-    src/main.cpp
-    src/lexer.cpp
-    src/parser.cpp
-    src/codegen.cpp
-    src/codegen_types.cpp
-    src/codegen_builtins.cpp
-    src/codegen_map.cpp
-    src/abi.cpp
-    src/cimport.cpp
-    src/target.cpp
-    src/loader.cpp
-    src/lsp.cpp
-)
-
-# The runtime (runtime/finch_rt.c) is embedded into the compiler as a string;
-# finch compiles it once into ~/.cache/finch and links it into every program.
-set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${CMAKE_SOURCE_DIR}/runtime/finch_rt.c)
-# (written as several raw string pieces: MSVC limits one literal to 16 KB)
-file(READ ${CMAKE_SOURCE_DIR}/runtime/finch_rt.c FINCH_RT_SOURCE)
-string(LENGTH "${FINCH_RT_SOURCE}" FINCH_RT_LENGTH)
-set(FINCH_RT_INC "static const char *kRuntimeSource =\n")
-set(FINCH_RT_POS 0)
-while(FINCH_RT_POS LESS FINCH_RT_LENGTH)
-    string(SUBSTRING "${FINCH_RT_SOURCE}" ${FINCH_RT_POS} 8000 FINCH_RT_PIECE)
-    string(APPEND FINCH_RT_INC "R\"FINCHRT(${FINCH_RT_PIECE})FINCHRT\"\n")
-    math(EXPR FINCH_RT_POS "${FINCH_RT_POS} + 8000")
-endwhile()
-string(APPEND FINCH_RT_INC ";\n")
-file(WRITE ${CMAKE_BINARY_DIR}/rt_source.inc "${FINCH_RT_INC}")
-target_include_directories(finch PRIVATE ${CMAKE_BINARY_DIR})
-
-# libclang reads C headers for `import "stdio.h"`
-find_path(LIBCLANG_INCLUDE clang-c/Index.h HINTS ${LLVM_INCLUDE_DIRS})
-find_library(LIBCLANG NAMES clang libclang HINTS ${LLVM_LIBRARY_DIRS})
-if(NOT LIBCLANG_INCLUDE OR NOT LIBCLANG)
-    message(FATAL_ERROR "libclang not found (on Nix: run inside nix-shell)")
-endif()
-
-target_include_directories(finch SYSTEM PRIVATE ${LLVM_INCLUDE_DIRS} ${LIBCLANG_INCLUDE})
-target_compile_definitions(finch PRIVATE ${LLVM_DEFINITIONS} FINCH_VERSION="${PROJECT_VERSION}")
-if(MSVC)
-    target_compile_options(finch PRIVATE /W3 /utf-8 /EHsc /wd4244 /wd4267 /wd4146 /wd4624)
-else()
-    target_compile_options(finch PRIVATE -Wall -Wextra)
-endif()
-
-# The official Windows LLVM package names the DIA SDK library at the path of the machine it was
-# built on (Visual Studio 2019); point it at the Visual Studio installed here.
-if(MSVC AND TARGET LLVMDebugInfoPDB AND DEFINED ENV{VSINSTALLDIR})
-    get_target_property(FINCH_PDB_LIBS LLVMDebugInfoPDB INTERFACE_LINK_LIBRARIES)
-    if(FINCH_PDB_LIBS)
-        file(TO_CMAKE_PATH "$ENV{VSINSTALLDIR}DIA SDK/lib/amd64/diaguids.lib" FINCH_DIA_LIB)
-        list(TRANSFORM FINCH_PDB_LIBS REPLACE ".*diaguids\\.lib$" "${FINCH_DIA_LIB}")
-        set_target_properties(LLVMDebugInfoPDB PROPERTIES INTERFACE_LINK_LIBRARIES "${FINCH_PDB_LIBS}")
-    endif()
-endif()
-
-# Link the one shared libLLVM when available: libclang uses it too, and two copies
-# of LLVM in one process crash on exit.
-# Finch generates code for x86-64 and ARM64; use whichever of them this LLVM was built with.
-set(FINCH_BACKENDS)
-foreach(t X86 AArch64)
-    if(t IN_LIST LLVM_TARGETS_TO_BUILD)
-        list(APPEND FINCH_BACKENDS ${t})
-        string(TOUPPER ${t} T)
-        target_compile_definitions(finch PRIVATE FINCH_TARGET_${T})
-    endif()
-endforeach()
-message(STATUS "Finch backends: ${FINCH_BACKENDS}")
-
-if(TARGET LLVM)
-    set(LLVM_LIBS LLVM)
-else()
-    set(FINCH_COMPONENTS core support passes native)
-    foreach(t ${FINCH_BACKENDS})
-        list(APPEND FINCH_COMPONENTS ${t}codegen ${t}asmparser ${t}desc ${t}info)
-    endforeach()
-    llvm_map_components_to_libnames(LLVM_LIBS ${FINCH_COMPONENTS})
-endif()
-target_link_libraries(finch PRIVATE ${LLVM_LIBS} ${LIBCLANG})

README.md

@@ -48,38 +48,33 @@ fn main() {
   ```
 - **Any C library, directly.** `import "raylib.h"` + `link "raylib"`, and you can call it, structs by value
   and callbacks included. Headers are read by libclang, so there is nothing to declare by hand.
-- **Written in itself, too.** `boot/` is a Finch compiler written in Finch that compiles itself to a
-  byte-identical result. It handles the whole language except C import and `link` (sized numbers,
-  methods, `defer`, errors as values, maps and `for k, v` all work); `tests/boot.sh` shows what is left.
+- **Written in itself.** The compiler is Finch code, and nothing else: `src/*.fch`, about 8.6k lines. It is built from a
+  seed (its own LLVM IR, `bootstrap/`) and then from itself, and the two come out identical. Its first version, in C++,
+  is kept on the `before-bootstrap` branch.
 
 ## Quick start
 
-Ready builds are in the [releases](https://github.com/Nexoniarz/Finch/releases):
-
-| System | Download | Also needs |
-|---|---|---|
-| Windows x64 | `finch-windows-x64.zip` | LLVM 21, Visual Studio Build Tools (C++); [steps](docs/en/for-technicians.md#windows) |
-| macOS (Apple Silicon) | `finch-macos-arm64.tar.gz` | `brew install llvm@21`; [steps](docs/en/for-technicians.md#macos) |
-| Linux x64 / ARM64 | `finch-linux-x64.tar.gz` / `finch-linux-arm64.tar.gz` | LLVM 21 libraries, a C compiler; [steps](docs/en/for-technicians.md#linux) |
-
-Editors: **Kate** (`editors/kate/install.sh`), **VS Code** (the `finch-lang` `.vsix` from the release), or any
-editor with LSP support (`finch lsp`).
-
-**Building it yourself** (Linux or macOS, LLVM 21):
+**Building it** (Linux x86-64 or ARM64; needs `clang` and libclang, LLVM 21):
 
 ```sh
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
-nix-shell                           # or install LLVM 21 + libclang + cmake + ninja yourself
-cmake -S . -B build -G Ninja
-ninja -C build
+nix-shell                           # or install clang + libclang (LLVM 21) + pkg-config yourself
+bootstrap/build.sh                  # the compiler is build/finch: built from the seed, then from itself
 
 ./build/finch run examples/hello.fch
 ./build/finch build examples/tour.fch -o tour && ./tour
-tests/run.sh                        # 74 passed, 0 failed
-tests/boot.sh                       # the compiler written in Finch builds itself
+tests/run.sh                        # every program, every refusal, -g, a shared library, the language server
 ```
 
+Ready builds of the compiler are in the [releases](https://github.com/Nexoniarz/Finch/releases) (Linux x64 and ARM64:
+unpack, keep `runtime/` and `std/` next to `finch`). **Programs for Windows, ARM64 and macOS** are built from Linux with
+`--target windows|arm64|macos` (see the [guide](docs/en/for-technicians.md#3-the-finch-command)); the compiler itself does not run on
+macOS or Windows yet (it needs a seed made with that system's headers: see [bootstrap/README.md](bootstrap/README.md)).
+
+Editors: **Kate** (`editors/kate/install.sh`), **VS Code** (the `finch-lang` `.vsix` from the release), or any
+editor with LSP support (`finch lsp`).
+
 ## Documentation
 
 Pick the guide that fits you:
@@ -106,7 +101,9 @@ Pick the guide that fits you:
 | Text | `"a" + "b"`, `str(42)`, `int("42")`, `s.split(",")`, `s.upper()`, `s[0]` |
 | Control | `if` / `else if` / `else`, `while`, `for i in 0..10`, `break`, `continue`, `defer` |
 | Memory | automatic for arrays, text and structs; `new(...)` / `free(...)` for your own heap structures |
-| Modules | `import shapes` → `shapes.area(b)` |
+| Enums, match | `enum Color { Red, Green }`, `match c { Red -> ... else -> ... }` (also as a value) |
+| Generics | `fn max[T](T a, T b) -> T`, `struct Stack[T]`, `Stack[int]()` |
+| Modules | `import shapes` → `shapes.area(b)`; the standard library: `json`, `path`, `time`, `proc` |
 | C interop | `import "stdio.h"`, `link "glfw"`, `link "mine.c"`, `addr(fn)` for callbacks |
 | I/O | `print(...)`, `input("? ")`, `read_file`, `write_file`, `shell` |
 | Tools | `finch run/build/ir/lsp`, `--target windows/arm64/macos`, `-g` for gdb/lldb, `-O0` |
@@ -128,7 +125,7 @@ Pick the guide that fits you:
 | [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: list the GPUs, their memory and queues, create a device |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib with C structs by value |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch building LLVM IR through the LLVM-C API |
-| [`boot/`](boot/) | the Finch compiler, written in Finch |
+| [`src/`](src/) | the compiler, written in Finch (the seed to build it is in [`bootstrap/`](bootstrap/)) |
 
 ## Roadmap
 
@@ -148,18 +145,20 @@ Pick the guide that fits you:
 - [x] Language server (`finch lsp`) and a VS Code extension
 - [x] macOS and ARM64 (Linux and Apple Silicon), with their C calling conventions; Kate support
 - [x] Methods on structs, maps, errors as values (`!`, `or`, `try`)
-- [ ] Generics, `match`, enums
-- [ ] A standard library in Finch (JSON, paths, time, processes)
+- [x] Generics (`fn max[T]`, `struct Stack[T]`), `match`, enums
+- [x] A standard library in Finch: `json`, `path`, `time`, `proc`
 
 ## Layout
 
 ```
-src/        compiler: lexer, parser, AST, codegen, C import + ABI, language server, driver (C++17, ~7k lines)
+src/        the compiler, in Finch: lexer, parser, AST, code generation (to LLVM IR as text), C import (libclang) and
+            the C calling conventions, the language server, the driver
+std/        the standard library, in Finch: json, path, time, proc
 runtime/    the small C runtime linked into every program
-boot/       the Finch compiler written in Finch (~3k lines)
+bootstrap/  build.sh and the seeds: the compiler's own LLVM IR, one per system
 examples/   example programs
 editors/    VS Code extension, Kate highlighting and LSP setup
-tests/      run/ (golden output), fail/ (expected errors), run.sh, boot.sh, cross.sh, lsp_test.py
+tests/      run/ new/ (golden output), fail/ new/fail/ (expected errors), run.sh, cross.sh, shared.sh, lsp_test.py
 docs/       en/ and pl/ guides for three audiences
 ```
 

README.pl.md

@@ -48,37 +48,33 @@ fn main() {
   ```
 - **Każda biblioteka C, bezpośrednio.** Piszesz `import "raylib.h"` i `link "raylib"`, i możesz z niej korzystać,
   także ze struktur przekazywanych przez wartość i z callbacków. Nagłówki czyta libclang, więc nie trzeba niczego deklarować ręcznie.
-- **Napisany także w sobie.** `boot/` to kompilator Fincha napisany w Finchu, który kompiluje sam siebie
-  do identycznego co do bajtu wyniku.
+- **Napisany w sobie.** Kompilator to kod w Finchu i nic więcej: `src/*.fch`, ok. 8,6 tys. linii. Buduje się go z ziarna
+  (własny kod LLVM IR, `bootstrap/`), potem z samego siebie, a oba wyniki są identyczne. Pierwsza wersja, w C++,
+  jest w gałęzi `before-bootstrap`.
 
 ## Szybki start
 
-Gotowe wersje są w [wydaniach](https://github.com/Nexoniarz/Finch/releases):
-
-| System | Plik | Potrzebuje też |
-|---|---|---|
-| Windows x64 | `finch-windows-x64.zip` | LLVM 21, Visual Studio Build Tools (C++); [kroki](docs/pl/dla-technikow.md#windows) |
-| macOS (Apple Silicon) | `finch-macos-arm64.tar.gz` | `brew install llvm@21`; [kroki](docs/pl/dla-technikow.md#macos) |
-| Linux x64 / ARM64 | `finch-linux-x64.tar.gz` / `finch-linux-arm64.tar.gz` | biblioteki LLVM 21, kompilator C; [kroki](docs/pl/dla-technikow.md#linux) |
-
-Edytory: **Kate** (`editors/kate/install.sh`), **VS Code** (plik `.vsix` `finch-lang` z wydania) albo każdy
-edytor obsługujący LSP (`finch lsp`).
-
-**Samodzielne budowanie** (Linux albo macOS, LLVM 21):
+**Budowanie** (Linux x86-64 lub ARM64; potrzebny `clang` i libclang, LLVM 21):
 
 ```sh
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
-nix-shell                           # albo zainstaluj samodzielnie LLVM 21 + libclang + cmake + ninja
-cmake -S . -B build -G Ninja
-ninja -C build
+nix-shell                           # albo zainstaluj samodzielnie clang + libclang (LLVM 21) + pkg-config
+bootstrap/build.sh                  # kompilator to build/finch: z ziarna, potem z samego siebie
 
 ./build/finch run examples/hello.fch
 ./build/finch build examples/tour.fch -o tour && ./tour
-tests/run.sh                        # 74 passed, 0 failed
-tests/boot.sh                       # kompilator napisany w Finchu buduje sam siebie
+tests/run.sh                        # każdy program, każda odmowa, -g, biblioteka współdzielona, serwer języka
 ```
 
+Gotowe kompilatory są w [wydaniach](https://github.com/Nexoniarz/Finch/releases) (Linux x64 i ARM64: rozpakuj, zostaw
+`runtime/` i `std/` obok `finch`). **Programy dla Windowsa, ARM64 i macOS** buduje się z Linuksa przez
+`--target windows|arm64|macos`; sam kompilator nie działa jeszcze na macOS ani Windowsie (potrzebuje ziarna
+zrobionego z nagłówkami tego systemu: patrz [bootstrap/README.md](bootstrap/README.md)).
+
+Edytory: **Kate** (`editors/kate/install.sh`), **VS Code** (plik `.vsix` `finch-lang` z wydania) albo dowolny
+edytor z obsługą LSP (`finch lsp`).
+
 ## Dokumentacja
 
 Wybierz przewodnik dla siebie:
@@ -105,7 +101,9 @@ Wybierz przewodnik dla siebie:
 | Tekst | `"a" + "b"`, `str(42)`, `int("42")`, `s.split(",")`, `s.upper()`, `s[0]` |
 | Sterowanie | `if` / `else if` / `else`, `while`, `for i in 0..10`, `break`, `continue`, `defer` |
 | Pamięć | automatyczna dla tablic, tekstów i struktur; `new(...)` / `free(...)` dla własnych struktur na stercie |
-| Moduły | `import ksztalty` → `ksztalty.pole(p)` |
+| Enumy, match | `enum Kolor { Czerwony, Zielony }`, `match k { Czerwony -> ... else -> ... }` (także jako wartość) |
+| Generyki | `fn max[T](T a, T b) -> T`, `struct Stos[T]`, `Stos[int]()` |
+| Moduły | `import ksztalty` → `ksztalty.pole(p)`; biblioteka standardowa: `json`, `path`, `time`, `proc` |
 | Współpraca z C | `import "stdio.h"`, `link "glfw"`, `link "moje.c"`, `addr(fn)` dla callbacków |
 | Wejście/wyjście | `print(...)`, `input("? ")`, `read_file`, `write_file`, `shell` |
 | Narzędzia | `finch run/build/ir/lsp`, `--target windows/arm64/macos`, `-g` dla gdb/lldb, `-O0` |
@@ -127,7 +125,7 @@ Wybierz przewodnik dla siebie:
 | [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: lista kart graficznych, ich pamięć i kolejki, tworzenie urządzenia |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib ze strukturami C przez wartość |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch budujący LLVM IR przez API LLVM-C |
-| [`boot/`](boot/) | kompilator Fincha napisany w Finchu |
+| [`src/`](src/) | kompilator napisany w Finchu (ziarno do jego zbudowania jest w [`bootstrap/`](bootstrap/)) |
 
 ## Plan rozwoju
 
@@ -147,18 +145,20 @@ Wybierz przewodnik dla siebie:
 - [x] Serwer języka (`finch lsp`) i rozszerzenie VS Code
 - [x] macOS i ARM64 (Linux i Apple Silicon) z ich konwencjami wywołań C; obsługa Kate
 - [x] Metody w strukturach, mapy, błędy jako wartości (`!`, `or`, `try`)
-- [ ] Typy generyczne, `match`, enumy
-- [ ] Biblioteka standardowa w Finchu (JSON, ścieżki, czas, procesy)
+- [x] Typy generyczne (`fn max[T]`, `struct Stos[T]`), `match`, enumy
+- [x] Biblioteka standardowa w Finchu: `json`, `path`, `time`, `proc`
 
 ## Struktura
 
 ```
-src/        kompilator: lekser, parser, AST, codegen, import C + ABI, serwer języka, sterownik (C++17, ok. 7 tys. linii)
+src/        kompilator, w Finchu: lekser, parser, AST, generowanie kodu (do LLVM IR jako tekst), import C (libclang)
+            i konwencje wywołań C, serwer języka, sterownik
+std/        biblioteka standardowa, w Finchu: json, path, time, proc
 runtime/    mały runtime w C dołączany do każdego programu
-boot/       kompilator Fincha napisany w Finchu (ok. 3 tys. linii)
+bootstrap/  build.sh i ziarna: własny LLVM IR kompilatora, po jednym na system
 examples/   przykładowe programy
 editors/    rozszerzenie VS Code, podświetlanie i konfiguracja LSP dla Kate
-tests/      run/ (wzorcowe wyjście), fail/ (oczekiwane błędy), run.sh, boot.sh, cross.sh, lsp_test.py
+tests/      run/ new/ (wzorcowe wyjście), fail/ new/fail/ (oczekiwane błędy), run.sh, cross.sh, shared.sh, lsp_test.py
 docs/       przewodniki en/ i pl/ dla trzech grup odbiorców
 ```
 

boot/main.fch

@@ -1,116 +0,0 @@
-// finch-boot: the Finch compiler written in Finch.
-//
-//   finch-boot build <file.fch> [-o name]    compile a program
-//   finch-boot ir    <file.fch>              print the LLVM IR
-//
-// It reads the program and the modules it imports, checks it, writes LLVM IR as text
-// and lets clang turn that into a program, linked with Finch's C runtime.
-import lexer
-import ast
-import parser
-import gen
-
-fn dirOf(str path) -> str {
-    i := path.len - 1
-    while i >= 0 && path[i] != '/' {
-        i -= 1
-    }
-    if i < 0 {
-        return "."
-    }
-    return path.sub(0, i)
-}
-
-fn stem(str path) -> str {
-    name := path.sub(dirOf(path).len + 1, path.len)
-    if dirOf(path) == "." && !path.starts_with("./") {
-        name = path
-    }
-    dot := name.find(".")
-    if dot > 0 {
-        return name.sub(0, dot)
-    }
-    return name
-}
-
-struct Loader {
-    []ast.Program progs
-    []str files
-    []str loaded
-}
-
-fn load(ptr[Loader] l, str path, str module) {
-    if !file_exists(path) {
-        if module.len > 0 {
-            print("error: can't find the module '" + module + "' (looked for " + path + ")")
-        } else {
-            print("error: can't open '" + path + "'")
-        }
-        exit(1)
-    }
-    src := read_file(path)
-    file := l.files.len
-    l.files.push(path)
-    prog := parser.parse(lexer.lex(src, path), file, path)
-    prog.module = module
-    prog.path = path
-    imports := prog.imports
-    l.progs.push(prog)
-    for name in imports {
-        if !l.loaded.contains(name) {
-            l.loaded.push(name)
-            load(l, dirOf(path) + "/" + name + ".fch", name)
-        }
-    }
-}
-
-fn usage() {
-    print("finch-boot - the Finch compiler written in Finch")
-    print("usage: finch-boot build <file.fch> [-o name]")
-    print("       finch-boot ir <file.fch>")
-    exit(1)
-}
-
-fn main([]str args) -> int {
-    if args.len < 3 {
-        usage()
-    }
-    cmd := args[1]
-    file := args[2]
-    out := stem(file)
-    if args.len == 5 && args[3] == "-o" {
-        out = args[4]
-    } else if args.len != 3 {
-        usage()
-    }
-    if cmd != "build" && cmd != "ir" {
-        usage()
-    }
-
-    loader := Loader()
-    load(addr(loader), file, "")
-    ir := gen.generate(loader.progs, loader.files)
-    if cmd == "ir" {
-        print(ir)
-        return 0
-    }
-
-    // the runtime is Finch's C file; FINCH_RT can point somewhere else
-    rt := dirOf(args[0]) + "/../runtime/finch_rt.c"
-    if file_exists("runtime/finch_rt.c") {
-        rt = "runtime/finch_rt.c"
-    }
-    if !file_exists(rt) {
-        print("error: can't find the Finch runtime (runtime/finch_rt.c)")
-        return 1
-    }
-    llPath := out + ".ll"
-    write_file(llPath, ir)
-    code := shell("clang -O2 -w '" + llPath + "' '" + rt + "' -o '" + out + "' -lm")
-    shell("rm -f '" + llPath + "'")
-    if code != 0 {
-        print("error: clang failed")
-        return 1
-    }
-    return 0
-}

bootstrap/README.md

@@ -0,0 +1,45 @@
+# The seed
+
+Finch's compiler is written in Finch. To build it you need something that already runs Finch: the **seed**, which is
+the compiler's own LLVM IR, one file per system:
+
+| File | System | Checked |
+|---|---|---|
+| `linux-x86_64.ll` | Linux x86-64 | built and tested here and in CI |
+| `linux-aarch64.ll` | Linux ARM64 | made with the ARM64 cross compiler; CI builds and tests it on an ARM64 runner |
+| `windows-x86_64.ll` | Windows x86-64 (MinGW: llvm-mingw's clang + libclang.dll) | built and run under Wine: it compiles itself, and every test program runs |
+| `macos-arm64.ll`, `macos-x86_64.ll` | macOS | made on Linux with the macOS 11.3 SDK; checked as IR only (nobody has run them yet) |
+
+`bootstrap/build.sh` compiles the seed with `clang` (and the runtime, and libclang) into `build/finch0`; `finch0` builds
+`src/` into `finch1`; `finch1` builds `src/` again into `build/finch`; the two must make the same IR, or the script stops.
+
+## Why one per system
+
+The seed includes how this system's C compiler passes structs by value, because the compiler calls libclang with
+`CXCursor`, `CXType` and `CXString` (the calling convention is different on x86-64, on ARM64 and on Windows). So a seed
+made for one system doesn't run on another, and a seed needs the target system's C headers to be made.
+
+## When to make a new one
+
+When the compiler's own source starts to use a feature that the committed seed doesn't have, `build.sh` fails at the first
+step. Make the seed from a working compiler:
+
+```sh
+bootstrap/build.sh seed            # writes bootstrap/<this system>.ll
+```
+
+For another system, from a machine that has that system's headers and a cross compiler (what `tests/cross.sh` uses):
+
+```sh
+FINCH_CC=aarch64-linux-gnu-gcc build/finch ir src/main.fch --target arm64 > bootstrap/linux-aarch64.ll
+```
+
+## Windows and macOS
+
+Windows: `windows-x86_64.ll` is made by `bootstrap/winseed.sh` on Linux (llvm-mingw's MinGW headers and the headers of an
+official LLVM for Windows); `bootstrap/winbuild.sh` turns it into `finch.exe` for trying under Wine. On a Windows machine
+`bootstrap/build.sh` does the same from Git Bash: put llvm-mingw's `bin` in PATH and set `FINCH_LIBCLANG` (the path of
+`libclang.dll`), `FINCH_LLVM_INCLUDE` (its `include` folder) and `FINCH_LDFLAGS=-L<folder of libclang.dll>`.
+
+macOS: the seeds were made with the macOS 11.3 SDK; `brew install llvm@21` gives clang and libclang; the CI job sets
+`FINCH_CLANG`, `FINCH_LIBCLANG` and `FINCH_LLVM_INCLUDE`. If the macOS build fails, that job is where it shows first.

bootstrap/build.sh

@@ -0,0 +1,57 @@
+#!/bin/sh
+# Builds the Finch compiler without a compiler for Finch: from the seed (the compiler's own LLVM IR),
+# then from itself, and checks that the two come out the same.
+#
+#   bootstrap/build.sh            build/finch
+#   bootstrap/build.sh seed       also write bootstrap/<system>.ll anew (do this when the compiler got a feature
+#                                 its own source uses, or the seed is old: the next build starts from it)
+#
+# Needs clang and libclang (the C headers are read through it). The compiler is then in build/finch. It carries the
+# runtime and the standard library inside itself (src/embedded.fch), so it runs from anywhere.
+set -eu
+cd "$(dirname "$0")/.."
+mkdir -p build
+
+case "$(uname -s)-$(uname -m)" in
+    Linux-x86_64)                 seed=linux-x86_64 ;;
+    Linux-aarch64|Linux-arm64)    seed=linux-aarch64 ;;
+    Darwin-arm64)                 seed=macos-arm64 ;;
+    Darwin-x86_64)                seed=macos-x86_64 ;;
+    MINGW*|MSYS*|CYGWIN*)         seed=windows-x86_64 ;;
+    *) echo "bootstrap: no seed for $(uname -s) $(uname -m) (see bootstrap/README.md)" >&2; exit 1 ;;
+esac
+EXE=
+case $seed in windows-*) EXE=.exe ;; esac
+[ -f "bootstrap/$seed.ll" ] || { echo "bootstrap: bootstrap/$seed.ll is missing" >&2; exit 1; }
+
+CLANG=${FINCH_CLANG:-clang}
+LIBS=${FINCH_LIBCLANG:--lclang}
+INC=
+[ -z "${FINCH_LLVM_INCLUDE:-}" ] || INC="-I $FINCH_LLVM_INCLUDE"        # where clang-c/Index.h is, if clang does not find it itself
+export FINCH_RT=$PWD/runtime/finch_rt.c
+# Windows: libclang.dll has to sit next to the programs that use it (FINCH_LIBCLANG is then the path of that dll)
+if [ -n "$EXE" ]; then cp "$LIBS" build/; fi
+
+echo "bootstrap: seed ($seed) -> build/finch0"
+$CLANG -O1 -w "bootstrap/$seed.ll" runtime/finch_rt.c -o build/finch0$EXE -lm $LIBS
+echo "bootstrap: build/finch0$EXE packs the runtime and std into src/embedded.fch"
+bootstrap/pack.sh build/finch0$EXE
+echo "bootstrap: build/finch0$EXE builds the compiler -> build/finch1"
+build/finch0$EXE build src/main.fch -o build/finch1$EXE $INC
+echo "bootstrap: build/finch1$EXE builds the compiler -> build/finch"
+build/finch1$EXE build src/main.fch -o build/finch$EXE $INC
+
+# a compiler that builds itself must come out the same however many times it does
+build/finch1$EXE ir src/main.fch $INC > build/stage1.ll
+build/finch$EXE ir src/main.fch $INC > build/stage2.ll
+if cmp -s build/stage1.ll build/stage2.ll; then
+    echo "bootstrap: build/finch1$EXE and build/finch make the same IR ($(wc -l < build/stage2.ll) lines): done"
+else
+    echo "bootstrap: the compiler does not reproduce itself (build/stage1.ll and build/stage2.ll differ)" >&2
+    exit 1
+fi
+
+if [ "${1:-}" = seed ]; then
+    cp build/stage2.ll "bootstrap/$seed.ll"
+    echo "bootstrap: wrote bootstrap/$seed.ll"
+fi

bootstrap/install.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Installs the compiler you built (bootstrap/build.sh) under a prefix:
+#   bootstrap/install.sh               /usr/local   (needs sudo)
+#   bootstrap/install.sh ~/.local
+# finch goes to <prefix>/bin; the runtime and the standard library go to <prefix>/share/finch, where finch looks for them.
+set -eu
+cd "$(dirname "$0")/.."
+prefix=${1:-/usr/local}
+[ -x build/finch ] || { echo "install: run bootstrap/build.sh first" >&2; exit 1; }
+mkdir -p "$prefix/bin" "$prefix/share/finch"
+cp build/finch "$prefix/bin/finch"
+rm -rf "$prefix/share/finch/runtime" "$prefix/share/finch/std"
+cp -r runtime std "$prefix/share/finch/"
+echo "installed: $prefix/bin/finch ($("$prefix/bin/finch" version))"

bootstrap/pack.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# Writes src/embedded.fch: the runtime and the standard library as text, so the compiler can carry them inside itself.
+#   bootstrap/pack.sh <a Finch compiler> [out.fch]
+set -eu
+cd "$(dirname "$0")/.."
+FINCH_RT=$PWD/runtime/finch_rt.c "$1" run tools/pack.fch "${2:-src/embedded.fch}" runtime/finch_rt.c std/*.fch std/*.h

bootstrap/winbuild.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+# Builds build/win/finch.exe from bootstrap/windows-x86_64.ll on Linux (to try the Windows compiler under Wine):
+#   bootstrap/winbuild.sh <llvm-mingw dir> <LLVM-for-Windows dir>
+set -eu
+cd "$(dirname "$0")/.."
+mkdir -p build/win
+"$1/bin/x86_64-w64-mingw32-clang" -O1 -w bootstrap/windows-x86_64.ll runtime/finch_rt.c -o build/win/finch.exe "$2/bin/libclang.dll"
+cp "$2/bin/libclang.dll" build/win/

bootstrap/winseed.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Makes bootstrap/windows-x86_64.ll from Linux, with a Linux-hosted llvm-mingw (MinGW headers) and the headers of an
+# official LLVM for Windows (clang-c/Index.h):
+#   bootstrap/winseed.sh <finch> <llvm-mingw dir> <LLVM-for-Windows dir>
+set -eu
+cd "$(dirname "$0")/.."
+finch=$1; mingw=$2; llvm=$3
+PATH="$mingw/bin:$PATH" FINCH_CC="$mingw/bin/x86_64-w64-mingw32-clang" "$finch" ir src/main.fch --target windows -I "$llvm/include" > bootstrap/windows-x86_64.ll
+echo "wrote bootstrap/windows-x86_64.ll"

docs/en/cheatsheet.md

@@ -12,6 +12,7 @@ Everything in Finch on one page. For explanations, see the [guides](../../README
 |---|---|
 | `finch run file.fch [args…]` | compile and run (args go to the program) |
 | `finch build file.fch [-o name]` | make a program (`name.exe` on Windows) |
+| `finch build file.fch --shared [-I dir]` | make a library (`libfile.so`, `file.dll`) that a C program loads; its `export fn`s are its C functions (numbers, bool, char, pointers) |
 | `finch ir file.fch` | print the LLVM IR |
 | `finch lsp` | the language server (editors use it) |
 | `finch version` | version |
@@ -370,7 +371,35 @@ Any LSP editor: `finch lsp`.
 
 ---
 
+## Enums and `match`
+
+```
+enum Color { Red, Green, Blue }          enum Status { Ok = 200, NotFound = 404 }
+c := Color.Green    int(c)    Color(2)    c == Color.Red      // == and != only; Color(7) is an error
+fn Color.next() -> Color { ... }                               // methods work
+
+match c { Red -> ...   Green, Blue -> { ... }   else -> ... }  // bare variant names; every variant or else
+x := match n { 1, 2 -> "few"   else -> "many" }                // an expression: every arm the same type
+```
+
+## Generics
+
+```
+fn max[T](T a, T b) -> T { ... }     max(3, 9)     max[float](1, 2.5)    // worked out, or written out
+struct Stack[T] { []T items }        fn Stack[T].push(T x) { ... }       // the type goes with it:
+s := Stack[int]()     Stack[int] t     Pair[str, int]("age", 31)         //   never just Stack()
+```
+
+## Standard library (`import name`; your own file of that name wins)
+
+| | |
+|---|---|
+| `path` | `join(a, b)` `base(p)` `dir(p)` `ext(p)` `stem(p)` `parts(p)` `clean(p)` `is_abs(p)` |
+| `time` | `now()` `millis()` `sleep(ms)` `date(t)` `local(t)` `format(t, fmt)` `days_in_month(y, m)` |
+| `proc` | `run(cmd)` `output(cmd)` (fails with its output) `env(name, fallback)` `pid()` `cwd()` |
+| `json` | `parse(text)` `stringify(v)` `pretty(v)` `new_text/number/bool/null/list/object` `v.get(k)` `v.at(i)` `v.set(k, x)` `v.push(x)` `v.has(k)` `v.str_or(d)` `v.int_or(d)` `v.float_or(d)` `v.bool_or(d)` |
+
 ## Keywords
 
-`fn return if else while for in break continue true false null import link struct defer or try`
+`fn return if else while for in break continue true false null import link struct enum match defer or try`
 (and `self` inside methods)

docs/en/for-beginners.md

@@ -63,8 +63,7 @@ these lines one by one, pressing **Enter** after each:
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
 nix-shell
-cmake -S . -B build -G Ninja
-ninja -C build
+bootstrap/build.sh
 ```
 
 If the last line finishes without the word `error`, Finch is ready.
@@ -77,7 +76,7 @@ To check it works, type:
 ./build/finch version
 ```
 
-You should see something like `finch 2.4.0`.
+You should see something like `Finch 2.4.0`.
 
 ---
 

docs/en/for-technicians.md

@@ -33,7 +33,10 @@ compiler works inside. For that, see the [guide for engineers](for-engineers.md)
 20. [Debugging](#20-debugging)
 21. [Troubleshooting](#21-troubleshooting)
 22. [Project layout and tests](#22-project-layout-and-tests)
-23. [Current limits](#23-current-limits)
+23. [Enums and match](#23-enums-and-match)
+24. [Generics](#24-generics)
+25. [The standard library](#25-the-standard-library)
+26. [Current limits](#26-current-limits)
 
 ---
 
@@ -60,78 +63,40 @@ messages that tell you how to fix the problem.
 
 ## 2. Installing
 
-Finch runs on **Linux** (x86-64 and ARM64), **macOS** (Apple Silicon and Intel) and **Windows** (x86-64),
-and is built with **LLVM 21**. Each [release](https://github.com/Nexoniarz/Finch/releases) has a ready
-`finch` for Windows, Linux x86-64, Linux ARM64 and macOS ARM64.
+The Finch compiler is written in Finch (see the [engineers' guide](for-engineers.md)). It runs on **Linux**
+(x86-64 and ARM64) and builds programs for **Linux, Windows and macOS**. It needs **clang 21** and **libclang**
+(LLVM 21) to read C headers and to compile its output.
 
-### Windows
+The compiler does not run on macOS or Windows yet; it needs a seed made with that system's headers
+([bootstrap/README.md](../../bootstrap/README.md) says why). Until then, build your Windows and macOS programs from Linux
+with `--target` (below), or use the older C++ compiler from the `before-bootstrap` branch.
 
-1. Download **`finch-windows-x64.zip`** from the [releases](https://github.com/Nexoniarz/Finch/releases)
-   and unpack it, for example to `C:\finch`. It contains `finch.exe` and `libclang.dll`.
-2. Install **LLVM 21** (`LLVM-21.x.x-win64.exe` from the
-   [LLVM releases](https://github.com/llvm/llvm-project/releases)) and tick *Add LLVM to the system PATH*.
-   Finch uses its `clang` to link programs.
-3. Install **Visual Studio Build Tools 2022** with *Desktop development with C++*: it provides the Windows
-   libraries every program is linked with.
-4. Add `C:\finch` to your PATH, open a new terminal, and run `finch version`.
+### Option A: a ready build (Linux)
 
-Programs are normal `.exe` files. To build from source on Windows instead, follow `.github/workflows/ci.yml`
-(Visual Studio 2022 + the `clang+llvm-21.x-x86_64-pc-windows-msvc` package from LLVM's releases).
+Download `finch-linux-x64.tar.gz` or `finch-linux-arm64.tar.gz` from the
+[releases](https://github.com/Nexoniarz/Finch/releases) and unpack it. Keep `runtime/` and `std/` next to the `finch` file
+(or install it, below). You also need `clang` 21 and its libclang library:
 
-### macOS
+| Distribution | Packages |
+|---|---|
+| Debian / Ubuntu | `clang-21 libclang-21-dev` from [apt.llvm.org](https://apt.llvm.org), `pkg-config` |
+| Fedora | `clang clang-devel pkgconf` |
+| Arch | `clang pkgconf` |
+| Nix | `nix-shell` in the repository gives all of it |
 
-```sh
-brew install llvm@21                # Finch's LLVM; programs are linked with Apple's clang
-```
-
-Then either unpack **`finch-macos-arm64.tar.gz`** from the releases (it uses Homebrew's `llvm@21`),
-or build it yourself (Xcode command line tools: `xcode-select --install`):
-
-```sh
-git clone https://github.com/Nexoniarz/Finch.git && cd Finch
-cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR="$(brew --prefix llvm@21)/lib/cmake/llvm"
-ninja -C build
-./build/finch version
-```
-
-Apple frameworks link with `link "Cocoa.framework"` (`-framework Cocoa`), and their headers import as usual:
-`import "OpenGL/gl.h"`.
-
-### Linux
-
-The ready `finch-linux-x64.tar.gz` / `finch-linux-arm64.tar.gz` need LLVM 21's libraries
-(Debian/Ubuntu: `libllvm21 libclang1-21` from [apt.llvm.org](https://apt.llvm.org)) and a C compiler (`cc`).
-Building it yourself works the same on x86-64 and ARM64 (Raspberry Pi 4/5, Graviton, …).
-Other LLVM versions will likely fail to compile, because LLVM's C++ API changes between releases.
-
-### Option A: Nix (recommended, nothing to install by hand)
+### Option B: build it yourself
 
 ```sh
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
-nix-shell                        # downloads LLVM, libclang, clang, cmake, ninja, pkg-config
-cmake -S . -B build -G Ninja
-ninja -C build
-./build/finch version            # finch 2.4.0 (LLVM 21.x)
+nix-shell                        # clang, libclang, pkg-config (or install them with your distribution)
+bootstrap/build.sh               # build/finch
+./build/finch version
 ```
 
-### Option B: your distribution's packages
-
-You need: a C/C++ compiler, CMake ≥ 3.20, Ninja (or Make), LLVM 21 development files,
-libclang 21 development files, and optionally `pkg-config`.
-
-| Distribution | Packages (names can differ slightly by version) |
-|---|---|
-| Debian / Ubuntu | `build-essential cmake ninja-build pkg-config llvm-21-dev libclang-21-dev` |
-| Fedora | `gcc-c++ cmake ninja-build pkgconf llvm-devel clang-devel` |
-| Arch | `base-devel cmake ninja pkgconf llvm clang` |
-
-These have not been tested; if CMake cannot find LLVM, point it there:
-
-```sh
-cmake -S . -B build -G Ninja -DLLVM_DIR=/usr/lib/llvm-21/lib/cmake/llvm
-ninja -C build
-```
+`bootstrap/build.sh` compiles the seed (`bootstrap/<system>.ll`, the compiler's own LLVM IR) into a first compiler, builds
+`src/` with it, builds `src/` again with the result and checks the two are identical. If libclang isn't where the linker
+looks, tell it: `FINCH_LIBCLANG="-L/usr/lib/llvm-21/lib -lclang-21" bootstrap/build.sh`.
 
 ### Building for another system
 
@@ -157,12 +122,13 @@ On Nix the compilers are `pkgsCross.mingwW64.buildPackages.gcc` and
 ### Putting `finch` on your PATH (optional)
 
 ```sh
-sudo cp build/finch /usr/local/bin/
+sudo bootstrap/install.sh          # /usr/local/bin/finch, and /usr/local/share/finch/{runtime,std}
+bootstrap/install.sh ~/.local      # or into your own folder
 finch version
 ```
 
-At run time Finch needs a C compiler (`cc`). It is used to link programs, and once to build
-Finch's small runtime library, which is kept in `~/.cache/finch`. Set `CC` to use a different one.
+At run time Finch needs `clang` (it compiles each program's IR and links it). The small runtime library is built once and
+kept in `~/.cache/finch`. `FINCH_CC` names a different compiler to link with; `FINCH_PATH` adds folders to look for modules in.
 
 ---
 
@@ -935,37 +901,156 @@ Visual Studio debugger and WinDbg read.
 
 ```
 Finch/
-├── src/            the compiler (C++)
-├── runtime/        finch_rt.c: the small runtime (text, arrays, input, files)
-├── boot/           the Finch compiler written in Finch (see the engineers' guide)
+├── src/            the compiler, in Finch (lexer, parser, gen: LLVM IR as text, cimport: libclang, lsp, main ...)
+├── std/            the standard library, in Finch: json, path, time, proc
+├── runtime/        finch_rt.c: the small runtime (text, arrays, maps, input, files)
+├── bootstrap/      build.sh, install.sh and the seeds (the compiler's own IR, one per system)
 ├── examples/       hello, tour, types, structs, todo, guess, c_import, window, opengl, vulkan, raylib, llvm
 ├── tests/
-│   ├── run/        programs + the exact output they must print (.out), input (.in)
-│   ├── fail/       programs that must fail, with the expected error in line 1
+│   ├── run/ new/   programs + the exact output they must print (.out), input (.in)
+│   ├── fail/ new/fail/   programs that must fail, with the expected error in line 1
 │   ├── run.sh      the test runner (MEMCHECK=1 also checks memory with valgrind)
-│   └── boot.sh     builds the self-hosted compiler with itself and compares
+│   ├── cross.sh    every test built for Windows / ARM64 and run under Wine / QEMU
+│   └── lsp_test.py the language server, talked to like an editor does
 ├── editors/        the VS Code extension (vscode/), Kate highlighting and LSP setup (kate/)
 ├── docs/           this documentation (en, pl), including the cheat sheet
-├── shell.nix       the Nix development environment
-└── CMakeLists.txt
+└── shell.nix       the Nix development environment
 ```
 
 ```sh
-tests/run.sh                 # → 74 passed, 0 failed
+tests/run.sh                 # programs, refusals, -g builds, a shared library, the language server
 MEMCHECK=1 tests/run.sh      # the same under valgrind: no leaks, no bad memory access
-tests/boot.sh                # the self-hosting check (needs clang)
 tests/cross.sh windows       # every test built for Windows and run with Wine
 tests/cross.sh arm64         # every test built for ARM64 Linux and run with QEMU
-python3 tests/lsp_test.py    # the language server
 ```
 
+### Variants that hold values
+
+A variant can carry values. Make one with `Shape.Circle(2.0)`, take them out with `match`, which names them:
+
+```c
+enum Shape {
+    Circle(float)
+    Rect(float, float)
+    Point
+}
+
+fn Shape.area() -> float {
+    return match self {
+        Circle(r) -> 3.14 * r * r
+        Rect(w, h) -> w * h
+        Point -> 0.0
+    }
+}
+```
+
+`_` ignores a value. `match` must handle every variant (or end with `else`). Printing shows `Rect(2, 3.5)`. Such an enum is
+copied and freed like a struct; it can't be compared with `==` (match on it). Variants of these enums can't have numbers.
+
 ---
 
-## 23. Current limits
+## 23. Enums and match
+
+An **enum** is a type with a short list of named values.
+
+```
+enum Color { Red, Green, Blue }
+enum Status { Ok = 200, NotFound = 404 }      // give a variant a number if it needs one
+
+c := Color.Green
+print(c)                    // Green
+print(int(Status.NotFound)) // 404
+print(Color(2))             // Blue: a number turned into the enum (checked: Color(7) is an error)
+```
+
+Variants are written `Color.Red`. They can be compared with `==` and `!=` (not with `<`), used as map keys,
+struct fields and array elements, and an enum can have methods like a struct: `fn Color.next() -> Color { ... }`.
+
+**match** picks what to do from a value, instead of a ladder of `if`:
+
+```
+match c {
+    Red -> print("warm")                  // inside a match on an enum, the bare name is enough
+    Green, Blue -> print("cool")          // several values for one arm
+}
+
+size := match n {                         // as an expression: it gives a value
+    1, 2, 3 -> "small"
+    4, 5 -> "medium"
+    else -> "large"
+}
+
+match word {
+    "quit" -> {
+        print("bye")
+        return
+    }
+    else -> print("what?")
+}
+```
+
+`match` works on enums, whole numbers, chars, text and bools. The arms are tried in order. A match on an enum has to
+handle **every variant** or end with `else` (the compiler says which are missing); any other match needs `else`.
+In an expression, every arm gives the same type.
+
+## 24. Generics
+
+Write a function or a struct once for any type, with the type as a name in square brackets:
+
+```
+fn max[T](T a, T b) -> T {
+    if a > b {
+        return a
+    }
+    return b
+}
+
+struct Stack[T] {
+    []T items
+}
+
+fn Stack[T].push(T x) {
+    self.items.push(x)
+}
+
+print(max(3, 9), max("apple", "pear"))    // T is worked out from the arguments
+print(max[float](1, 2.5))                 // or written out, where it can't be worked out
+s := Stack[int]()                         // a generic struct is always written with its type
+s.push(7)
+```
+
+Several parameters work (`struct Pair[A, B]`), and so do nested types (`Stack[Pair[int, str]]`). Each use makes its
+own copy of the code, so a generic is as fast as code written by hand. There are no constraints: if `T` can't do
+what the function does (`a > b` on a struct), the error says so and tells which version it was building, like
+`(while building bigger[Point])`.
+
+## 25. The standard library
+
+Modules that come with Finch, written in Finch. `import json` finds `json.fch` next to your file first, and the
+library's second, so your own file of the same name wins.
+
+| Module | What it does |
+|---|---|
+| `path` | `join`, `base`, `dir`, `ext`, `stem`, `parts`, `clean`, `is_abs`: paths as text, separated by `/` |
+| `time` | `now()`, `millis()` (a clock for measuring), `sleep(ms)`, `date(t)`, `local(t)`, `format(t, "%Y-%m-%d")`, `days_in_month` |
+| `proc` | `run(cmd)` (the exit code), `output(cmd)` (what it printed; an error if it failed), `env(name, fallback)`, `pid()`, `cwd()` |
+| `json` | `parse(text)`, `stringify(v)`, `pretty(v)`, and the value type `Json` with `get`, `at`, `set`, `push`, `has`, `str_or`, `int_or` ... |
+
+```
+import json
+import path
+
+doc := try json.parse(read_file("config.json"))
+name := doc.get("name").str_or("unnamed")        // a missing key is null, so chains never fail
+doc.set("name", json.new_text(name + "!"))
+write_file(path.join("out", "config.json"), json.pretty(doc))
+```
+
+## 26. Current limits
 
 Not there yet:
 
-- Generics (your own `List[T]`), interfaces, `match`, enums written in Finch.
+- Interfaces.
 - Unicode-aware text: `.len`, `s[i]` and `upper()` work on bytes / ASCII.
 - Threads.
 - Windows on ARM64, 32-bit systems, WebAssembly.

docs/pl/dla-poczatkujacych.md

@@ -63,8 +63,7 @@ i wpisz te linijki po kolei, naciskając **Enter** po każdej:
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
 nix-shell
-cmake -S . -B build -G Ninja
-ninja -C build
+bootstrap/build.sh
 ```
 
 Jeśli ostatnia linijka skończy się bez słowa `error`, Finch jest gotowy.

docs/pl/dla-technikow.md

@@ -33,7 +33,10 @@ kompilator działa w środku. Do tego służy [przewodnik dla inżynierów](dla-
 20. [Debugowanie](#20-debugowanie)
 21. [Rozwiązywanie problemów](#21-rozwiązywanie-problemów)
 22. [Struktura projektu i testy](#22-struktura-projektu-i-testy)
-23. [Obecne ograniczenia](#23-obecne-ograniczenia)
+23. [Enumy i match](#23-enumy-i-match)
+24. [Typy generyczne](#24-typy-generyczne)
+25. [Biblioteka standardowa](#25-biblioteka-standardowa)
+26. [Obecne ograniczenia](#26-obecne-ograniczenia)
 
 ---
 
@@ -60,77 +63,40 @@ i komunikaty błędów, które mówią, jak problem naprawić.
 
 ## 2. Instalacja
 
-Finch działa na **Linuksie** (x86-64 i ARM64), **macOS** (Apple Silicon i Intel) i **Windowsie** (x86-64),
-i jest budowany z **LLVM 21**. Każde [wydanie](https://github.com/Nexoniarz/Finch/releases) ma gotowy
-`finch` dla Windowsa, Linuksa x86-64, Linuksa ARM64 i macOS ARM64.
+Kompilator Fincha jest napisany w Finchu (zobacz [przewodnik dla inżynierów](dla-inzynierow.md)). Działa na **Linuksie**
+(x86-64 i ARM64) i buduje programy dla **Linuksa, Windowsa i macOS**. Potrzebuje **clanga 21** i **libclang** (LLVM 21),
+żeby czytać nagłówki C i kompilować to, co wygeneruje.
 
-### Windows
+Kompilator nie działa jeszcze na macOS ani Windowsie: potrzebuje ziarna zrobionego z nagłówkami tego systemu
+([bootstrap/README.md](../../bootstrap/README.md) tłumaczy dlaczego). Do tego czasu programy na Windows i macOS buduj z Linuksa
+przez `--target` (niżej) albo użyj starszego kompilatora w C++ z gałęzi `before-bootstrap`.
 
-1. Pobierz **`finch-windows-x64.zip`** z [wydań](https://github.com/Nexoniarz/Finch/releases) i rozpakuj,
-   np. do `C:\finch`. W środku są `finch.exe` i `libclang.dll`.
-2. Zainstaluj **LLVM 21** (`LLVM-21.x.x-win64.exe` z [wydań LLVM](https://github.com/llvm/llvm-project/releases))
-   i zaznacz *Add LLVM to the system PATH*. Finch używa jego `clang` do linkowania programów.
-3. Zainstaluj **Visual Studio Build Tools 2022** z pakietem *Desktop development with C++*: dostarcza biblioteki
-   Windowsa, z którymi linkowany jest każdy program.
-4. Dodaj `C:\finch` do PATH, otwórz nowy terminal i wpisz `finch version`.
+### Opcja A: gotowa wersja (Linux)
 
-Programy to zwykłe pliki `.exe`. Żeby zbudować Fincha ze źródeł na Windowsie, idź za `.github/workflows/ci.yml`
-(Visual Studio 2022 + pakiet `clang+llvm-21.x-x86_64-pc-windows-msvc` z wydań LLVM).
+Pobierz `finch-linux-x64.tar.gz` albo `finch-linux-arm64.tar.gz` z [wydań](https://github.com/Nexoniarz/Finch/releases)
+i rozpakuj. Zostaw `runtime/` i `std/` obok pliku `finch` (albo zainstaluj, niżej). Potrzebny jest też `clang` 21
+z biblioteką libclang:
 
-### macOS
+| Dystrybucja | Pakiety |
+|---|---|
+| Debian / Ubuntu | `clang-21 libclang-21-dev` z [apt.llvm.org](https://apt.llvm.org), `pkg-config` |
+| Fedora | `clang clang-devel pkgconf` |
+| Arch | `clang pkgconf` |
+| Nix | `nix-shell` w repozytorium daje wszystko |
 
-```sh
-brew install llvm@21                # LLVM dla Fincha; programy linkuje clang od Apple
-```
-
-Potem rozpakuj **`finch-macos-arm64.tar.gz`** z wydań (korzysta z `llvm@21` z Homebrew)
-albo zbuduj go sam (narzędzia wiersza poleceń Xcode: `xcode-select --install`):
-
-```sh
-git clone https://github.com/Nexoniarz/Finch.git && cd Finch
-cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR="$(brew --prefix llvm@21)/lib/cmake/llvm"
-ninja -C build
-./build/finch version
-```
-
-Frameworki Apple linkuje się przez `link "Cocoa.framework"` (`-framework Cocoa`), a ich nagłówki importuje
-się normalnie: `import "OpenGL/gl.h"`.
-
-### Linux
-
-Gotowe `finch-linux-x64.tar.gz` / `finch-linux-arm64.tar.gz` potrzebują bibliotek LLVM 21
-(Debian/Ubuntu: `libllvm21 libclang1-21` z [apt.llvm.org](https://apt.llvm.org)) i kompilatora C (`cc`).
-Samodzielne budowanie wygląda tak samo na x86-64 i ARM64 (Raspberry Pi 4/5, Graviton, …).
-Z innymi wersjami LLVM Finch prawdopodobnie się nie skompiluje, bo API C++ LLVM zmienia się między wydaniami.
-
-### Opcja A: Nix (zalecana, nic nie instalujesz ręcznie)
+### Opcja B: zbuduj sam
 
 ```sh
 git clone https://github.com/Nexoniarz/Finch.git
 cd Finch
-nix-shell                        # pobiera LLVM, libclang, clang, cmake, ninja, pkg-config
-cmake -S . -B build -G Ninja
-ninja -C build
-./build/finch version            # finch 2.4.0 (LLVM 21.x)
+nix-shell                        # clang, libclang, pkg-config (albo zainstaluj z dystrybucji)
+bootstrap/build.sh               # build/finch
+./build/finch version
 ```
 
-### Opcja B: pakiety z twojej dystrybucji
-
-Potrzebujesz: kompilatora C/C++, CMake ≥ 3.20, Ninja (albo Make), plików deweloperskich LLVM 21
-i libclang 21, a opcjonalnie `pkg-config`.
-
-| Dystrybucja | Pakiety (nazwy mogą się nieco różnić zależnie od wersji) |
-|---|---|
-| Debian / Ubuntu | `build-essential cmake ninja-build pkg-config llvm-21-dev libclang-21-dev` |
-| Fedora | `gcc-c++ cmake ninja-build pkgconf llvm-devel clang-devel` |
-| Arch | `base-devel cmake ninja pkgconf llvm clang` |
-
-Ta opcja nie była testowana. Jeśli CMake nie znajduje LLVM, wskaż mu katalog:
-
-```sh
-cmake -S . -B build -G Ninja -DLLVM_DIR=/usr/lib/llvm-21/lib/cmake/llvm
-ninja -C build
-```
+`bootstrap/build.sh` kompiluje ziarno (`bootstrap/<system>.ll`, własny LLVM IR kompilatora) do pierwszego kompilatora,
+buduje nim `src/`, buduje `src/` jeszcze raz wynikiem i sprawdza, że oba są identyczne. Jeśli libclang nie leży tam, gdzie
+szuka linker: `FINCH_LIBCLANG="-L/usr/lib/llvm-21/lib -lclang-21" bootstrap/build.sh`.
 
 ### Budowanie na inny system
 
@@ -156,13 +122,14 @@ Na Niksie te kompilatory to `pkgsCross.mingwW64.buildPackages.gcc` i
 ### Dodanie `finch` do PATH (opcjonalnie)
 
 ```sh
-sudo cp build/finch /usr/local/bin/
+sudo bootstrap/install.sh          # /usr/local/bin/finch oraz /usr/local/share/finch/{runtime,std}
+bootstrap/install.sh ~/.local      # albo do własnego katalogu
 finch version
 ```
 
-Podczas pracy Finch potrzebuje kompilatora C (`cc`). Używa go do linkowania programów i jednorazowo
-do zbudowania swojej małej biblioteki uruchomieniowej, którą trzyma w `~/.cache/finch`.
-Inny kompilator wskażesz zmienną `CC`.
+Podczas działania Finch potrzebuje `clanga` (kompiluje IR każdego programu i go linkuje). Mała biblioteka uruchomieniowa
+budowana jest raz i trzymana w `~/.cache/finch`. `FINCH_CC` wskazuje inny kompilator do linkowania; `FINCH_PATH` dodaje
+katalogi, w których szukać modułów.
 
 ---
 
@@ -938,37 +905,156 @@ CodeView, który czyta debugger Visual Studio i WinDbg.
 
 ```
 Finch/
-├── src/            kompilator (C++)
-├── runtime/        finch_rt.c: mała biblioteka uruchomieniowa (teksty, tablice, wejście, pliki)
-├── boot/           kompilator Fincha napisany w Finchu (zobacz przewodnik dla inżynierów)
+├── src/            kompilator, w Finchu (lekser, parser, gen: LLVM IR jako tekst, cimport: libclang, lsp, main ...)
+├── std/            biblioteka standardowa, w Finchu: json, path, time, proc
+├── runtime/        finch_rt.c: mała biblioteka uruchomieniowa (teksty, tablice, mapy, wejście, pliki)
+├── bootstrap/      build.sh, install.sh i ziarna (własny IR kompilatora, po jednym na system)
 ├── examples/       hello, tour, types, structs, todo, guess, c_import, window, opengl, vulkan, raylib, llvm
 ├── tests/
-│   ├── run/        programy + dokładny wynik (.out) i wejście (.in)
-│   ├── fail/       programy, które muszą się nie udać, z oczekiwanym błędem w 1. linijce
+│   ├── run/ new/   programy + dokładny wynik (.out) i wejście (.in)
+│   ├── fail/ new/fail/   programy, które muszą się nie udać, z oczekiwanym błędem w 1. linijce
 │   ├── run.sh      uruchamia testy (MEMCHECK=1 sprawdza też pamięć valgrindem)
-│   └── boot.sh     buduje kompilator samohostujący nim samym i porównuje
+│   ├── cross.sh    każdy test zbudowany na Windows / ARM64 i uruchomiony w Wine / QEMU
+│   └── lsp_test.py serwer języka, obsługiwany jak przez edytor
 ├── editors/        rozszerzenie VS Code (vscode/), podświetlanie i konfiguracja LSP dla Kate (kate/)
 ├── docs/           ta dokumentacja (en, pl), łącznie ze ściągą
-├── shell.nix       środowisko deweloperskie Nix
-└── CMakeLists.txt
+└── shell.nix       środowisko deweloperskie Nix
 ```
 
 ```sh
-tests/run.sh                 # → 74 passed, 0 failed
+tests/run.sh                 # programy, odmowy, buildy z -g, biblioteka współdzielona, serwer języka
 MEMCHECK=1 tests/run.sh      # to samo pod valgrindem: bez wycieków i złych dostępów do pamięci
-tests/boot.sh                # sprawdzenie samohostowania (wymaga clanga)
 tests/cross.sh windows       # każdy test zbudowany na Windowsa i uruchomiony w Wine
 tests/cross.sh arm64         # każdy test zbudowany na Linuksa ARM64 i uruchomiony w QEMU
-python3 tests/lsp_test.py    # serwer języka
 ```
 
+### Warianty z wartościami
+
+Wariant może nieść wartości. Tworzysz go przez `Shape.Circle(2.0)`, a wyciągasz `match`-em, który je nazywa:
+
+```c
+enum Shape {
+    Circle(float)
+    Rect(float, float)
+    Point
+}
+
+fn Shape.area() -> float {
+    return match self {
+        Circle(r) -> 3.14 * r * r
+        Rect(w, h) -> w * h
+        Point -> 0.0
+    }
+}
+```
+
+`_` pomija wartość. `match` musi obsłużyć każdy wariant (albo kończyć się `else`). Wypisanie pokazuje `Rect(2, 3.5)`. Taki enum
+jest kopiowany i zwalniany jak struktura; nie da się go porównać przez `==` (użyj `match`). Warianty takich enumów nie mają numerów.
+
 ---
 
-## 23. Obecne ograniczenia
+## 23. Enumy i match
+
+**Enum** to typ z krótką listą nazwanych wartości.
+
+```
+enum Kolor { Czerwony, Zielony, Niebieski }
+enum Status { Ok = 200, Brak = 404 }          // wariantowi można nadać numer
+
+k := Kolor.Zielony
+print(k)                    // Zielony
+print(int(Status.Brak))     // 404
+print(Kolor(2))             // Niebieski: liczba zamieniona na enum (sprawdzana: Kolor(7) to błąd)
+```
+
+Warianty pisze się `Kolor.Czerwony`. Można je porównywać przez `==` i `!=` (nie przez `<`), używać jako klucze map,
+pola struktur i elementy tablic, a enum może mieć metody jak struktura: `fn Kolor.nastepny() -> Kolor { ... }`.
+
+**match** wybiera, co zrobić, na podstawie wartości — zamiast drabinki `if`:
+
+```
+match k {
+    Czerwony -> print("ciepły")           // w matchu na enumie wystarczy sama nazwa
+    Zielony, Niebieski -> print("zimny")  // kilka wartości w jednej gałęzi
+}
+
+rozmiar := match n {                      // jako wyrażenie: daje wartość
+    1, 2, 3 -> "mały"
+    4, 5 -> "średni"
+    else -> "duży"
+}
+
+match slowo {
+    "koniec" -> {
+        print("pa")
+        return
+    }
+    else -> print("co?")
+}
+```
+
+`match` działa na enumach, liczbach całkowitych, znakach, tekście i bool. Gałęzie sprawdzane są po kolei. Match na
+enumie musi obsłużyć **każdy wariant** albo kończyć się `else` (kompilator wskaże brakujące); każdy inny match
+potrzebuje `else`. W wyrażeniu wszystkie gałęzie dają ten sam typ.
+
+## 24. Typy generyczne
+
+Napisz funkcję lub strukturę raz dla dowolnego typu, z typem jako nazwą w nawiasach kwadratowych:
+
+```
+fn max[T](T a, T b) -> T {
+    if a > b {
+        return a
+    }
+    return b
+}
+
+struct Stos[T] {
+    []T elementy
+}
+
+fn Stos[T].dodaj(T x) {
+    self.elementy.push(x)
+}
+
+print(max(3, 9), max("jabłko", "gruszka"))   // T wynika z argumentów
+print(max[float](1, 2.5))                    // albo zapisane wprost, gdzie nie da się go ustalić
+s := Stos[int]()                             // generyczną strukturę zawsze pisze się z typem
+s.dodaj(7)
+```
+
+Parametrów może być kilka (`struct Para[A, B]`), typy można zagnieżdżać (`Stos[Para[int, str]]`). Każde użycie tworzy
+własną kopię kodu, więc generyk jest tak szybki jak kod napisany ręcznie. Nie ma ograniczeń: jeśli `T` nie potrafi
+tego, co robi funkcja (`a > b` na strukturze), błąd mówi o tym i podaje, którą wersję budowano, np.
+`(while building wiekszy[Punkt])`.
+
+## 25. Biblioteka standardowa
+
+Moduły dołączone do Fincha, napisane w Finchu. `import json` szuka najpierw `json.fch` obok Twojego pliku, potem w
+bibliotece — więc Twój własny plik o tej nazwie ma pierwszeństwo.
+
+| Moduł | Co robi |
+|---|---|
+| `path` | `join`, `base`, `dir`, `ext`, `stem`, `parts`, `clean`, `is_abs`: ścieżki jako tekst, rozdzielone `/` |
+| `time` | `now()`, `millis()` (zegar do mierzenia), `sleep(ms)`, `date(t)`, `local(t)`, `format(t, "%Y-%m-%d")`, `days_in_month` |
+| `proc` | `run(cmd)` (kod wyjścia), `output(cmd)` (co wypisało; błąd, jeśli się nie udało), `env(nazwa, domyślna)`, `pid()`, `cwd()` |
+| `json` | `parse(tekst)`, `stringify(v)`, `pretty(v)` oraz typ wartości `Json` z `get`, `at`, `set`, `push`, `has`, `str_or`, `int_or` ... |
+
+```
+import json
+import path
+
+dok := try json.parse(read_file("config.json"))
+nazwa := dok.get("name").str_or("bez nazwy")      // brakujący klucz to null, więc łańcuch nigdy się nie psuje
+dok.set("name", json.new_text(nazwa + "!"))
+write_file(path.join("out", "config.json"), json.pretty(dok))
+```
+
+## 26. Obecne ograniczenia
 
 Jeszcze nie ma:
 
-- Typów generycznych (własnego `Lista[T]`), interfejsów, `match`, enumów pisanych w Finchu.
+- Interfejsów.
 - Tekstu świadomego Unicode: `.len`, `s[i]` i `upper()` działają na bajtach / ASCII.
 - Wątków.
 - Windowsa na ARM64, systemów 32-bitowych, WebAssembly.

docs/pl/sciaga.md

@@ -370,6 +370,34 @@ Każdy edytor z LSP: `finch lsp`.
 
 ---
 
+## Enumy i `match`
+
+```
+enum Kolor { Czerwony, Zielony }          enum Status { Ok = 200, Brak = 404 }
+k := Kolor.Zielony    int(k)    Kolor(1)    k == Kolor.Czerwony   // tylko == i !=; Kolor(7) to błąd
+fn Kolor.nastepny() -> Kolor { ... }                               // metody działają
+
+match k { Czerwony -> ...   Zielony -> { ... }   else -> ... }     // same nazwy wariantów; każdy wariant albo else
+x := match n { 1, 2 -> "mało"   else -> "dużo" }                   // wyrażenie: gałęzie tego samego typu
+```
+
+## Typy generyczne
+
+```
+fn max[T](T a, T b) -> T { ... }     max(3, 9)     max[float](1, 2.5)    // wynika z argumentów albo zapisane
+struct Stos[T] { []T elementy }      fn Stos[T].dodaj(T x) { ... }       // typ zawsze podaje się przy tworzeniu:
+s := Stos[int]()     Stos[int] t     Para[str, int]("wiek", 31)          //   nigdy samo Stos()
+```
+
+## Biblioteka standardowa (`import nazwa`; własny plik o tej nazwie ma pierwszeństwo)
+
+| | |
+|---|---|
+| `path` | `join(a, b)` `base(p)` `dir(p)` `ext(p)` `stem(p)` `parts(p)` `clean(p)` `is_abs(p)` |
+| `time` | `now()` `millis()` `sleep(ms)` `date(t)` `local(t)` `format(t, fmt)` `days_in_month(r, m)` |
+| `proc` | `run(cmd)` `output(cmd)` (błąd z jego wyjściem) `env(nazwa, domyślna)` `pid()` `cwd()` |
+| `json` | `parse(tekst)` `stringify(v)` `pretty(v)` `new_text/number/bool/null/list/object` `v.get(k)` `v.at(i)` `v.set(k, x)` `v.push(x)` `v.has(k)` `v.str_or(d)` `v.int_or(d)` `v.float_or(d)` `v.bool_or(d)` |
+
 ## Słowa kluczowe
 
 | Słowo | Po polsku |
@@ -383,6 +411,8 @@ Każdy edytor z LSP: `finch lsp`.
 | `true` / `false` / `null` | prawda / fałsz / nic |
 | `import` / `link` | zaimportuj / dolinkuj |
 | `struct` | struktura |
+| `enum` | wyliczenie |
+| `match` | dopasuj |
 | `defer` | odłóż (na koniec bloku) |
 | `or` | albo (co zrobić przy porażce) |
 | `try` | spróbuj (porażkę przekaż dalej) |

editors/kate/finch.xml

@@ -11,6 +11,8 @@
     <list name="keywords">
       <item>fn</item>
       <item>struct</item>
+      <item>enum</item>
+      <item>export</item>
     </list>
     <list name="control">
       <item>if</item>
@@ -24,6 +26,7 @@
       <item>defer</item>
       <item>or</item>
       <item>try</item>
+      <item>match</item>
     </list>
     <list name="imports">
       <item>import</item>

editors/vscode/snippets/finch.json

@@ -156,5 +156,43 @@
       "}"
     ],
     "description": "Every key and value of a map (or index and element of an array)"
+  },
+  "enum": {
+    "prefix": "enum",
+    "body": [
+      "enum ${1:Name} {",
+      "\t${2:First},",
+      "\t${3:Second}",
+      "}"
+    ],
+    "description": "An enum: a type with a few named values"
+  },
+  "match": {
+    "prefix": "match",
+    "body": [
+      "match ${1:value} {",
+      "\t${2:pattern} -> $0",
+      "\telse -> ",
+      "}"
+    ],
+    "description": "match: pick what to do from a value"
+  },
+  "generic function": {
+    "prefix": "fng",
+    "body": [
+      "fn ${1:name}[${2:T}](${3:T x}) -> ${2:T} {",
+      "\t$0",
+      "}"
+    ],
+    "description": "A function that works for any type"
+  },
+  "generic struct": {
+    "prefix": "structg",
+    "body": [
+      "struct ${1:Name}[${2:T}] {",
+      "\t$0",
+      "}"
+    ],
+    "description": "A struct that holds any type"
   }
 }

editors/vscode/syntaxes/finch.tmLanguage.json

@@ -74,7 +74,7 @@
       ]
     },
     "struct": {
-      "match": "\\b(struct)\\s+([A-Za-z_][A-Za-z0-9_]*)",
+      "match": "\\b(struct|enum)\\s+([A-Za-z_][A-Za-z0-9_]*)",
       "captures": {
         "1": {
           "name": "storage.type.struct.finch"
@@ -117,7 +117,7 @@
         },
         {
           "name": "keyword.control.finch",
-          "match": "\\b(if|else|while|for|in|break|continue|return|defer|or|try)\\b"
+          "match": "\\b(if|else|while|for|in|break|continue|return|defer|or|try|match)\\b"
         },
         {
           "name": "storage.type.function.finch",
@@ -125,7 +125,11 @@
         },
         {
           "name": "storage.type.struct.finch",
-          "match": "\\bstruct\\b"
+          "match": "\\b(struct|enum)\\b"
+        },
+        {
+          "name": "storage.modifier.finch",
+          "match": "\\bexport\\b"
         },
         {
           "name": "constant.language.finch",

notatka.txt

@@ -1 +0,0 @@
-Kupić mleko

note.txt

@@ -1 +0,0 @@
-Buy milk

runtime/finch_rt.c

@@ -37,12 +37,26 @@ static char empty[1] = "";
 
 // ---------- runtime errors ----------
 
-__attribute__((noreturn, cold)) void finch_panic(const char *file, int64_t line, const char *msg) {
+// A program that loads Finch libraries (finch build --shared) can take runtime errors over
+// instead of the process exiting: finch_module_on_fatal(handler) in each library. The handler
+// gets the message and must not return (longjmp out, or exit itself).
+static void (*fatal_hook)(const char *msg);
+void finch_on_fatal(void (*hook)(const char *msg)) { fatal_hook = hook; }
+
+static __attribute__((noreturn)) void fatal(const char *msg) {
+    if (fatal_hook) fatal_hook(msg);
     fflush(stdout);
-    fprintf(stderr, "%s:%lld: runtime error: %s\n", file, (long long)line, msg);
+    fprintf(stderr, "%s\n", msg);
     exit(1);
 }
 
+__attribute__((noreturn, cold)) void finch_panic(const char *file, int64_t line, const char *msg) {
+    char full[1024];
+    snprintf(full, sizeof full, "%s:%lld: runtime error: %s", file, (long long)line, msg);
+    fflush(stdout);
+    fatal(full);
+}
+
 __attribute__((noreturn, cold)) void finch_panic_index(const char *file, int64_t line, int64_t i, int64_t len) {
     char msg[128];
     snprintf(msg, sizeof msg, "index %lld is out of range (the length is %lld)", (long long)i, (long long)len);
@@ -52,8 +66,7 @@ __attribute__((noreturn, cold)) void finch_panic_index(const char *file, int64_t
 static void *must(void *p) {
     if (!p) {
         fflush(stdout);
-        fprintf(stderr, "runtime error: out of memory\n");
-        exit(1);
+        fatal("runtime error: out of memory");
     }
     return p;
 }

shell.nix

@@ -4,11 +4,9 @@ pkgs.mkShell {
   packages = with pkgs; [
     # building Finch (the clang wrapper first, so `clang` finds the system headers)
     llvmPackages.clang
-    llvmPackages.llvm
     llvmPackages.libclang   # reads C headers for `import "stdio.h"`
-    cmake
-    ninja
     pkg-config              # finds the right flags for `link "..."`
+    python3                 # tests/lsp_test.py
 
     # for the graphics examples (window, opengl, raylib, vulkan)
     glfw

src/abi.cpp

@@ -1,367 +0,0 @@
-// The C calling convention for structs passed and returned by value, the way clang does it:
-//   System V x86-64 (Linux, macOS): small structs split into eightbytes, INTEGER or SSE registers
-//   Microsoft x64 (Windows): 1/2/4/8 bytes in one register, everything else by address
-//   AAPCS64 (ARM64 Linux, Apple): float groups in vector registers, else up to 16 bytes in x registers
-
-#include "codegen_impl.h"
-#include "target.h"
-
-using namespace llvm;
-
-namespace finch {
-
-namespace {
-
-enum Class { None, Integer, Sse };
-
-struct Leaf {
-    uint64_t offset;
-    uint64_t size;
-    bool isFloat;
-    bool isDouble;
-};
-
-}  // namespace
-
-// Flatten a value into its scalar pieces with byte offsets.
-static void leaves(Codegen &cg, const FType &t, uint64_t base, std::vector<Leaf> &out) {
-    switch (t.kind) {
-    case FType::Struct: {
-        const StructLayout *lay = cg.dl->getStructLayout(t.info->llvm);
-        for (auto &f : t.info->fields) leaves(cg, f.type, base + lay->getElementOffset(f.llvmIndex), out);
-        break;
-    }
-    case FType::Fixed: {
-        uint64_t es = cg.dl->getTypeAllocSize(cg.ty(*t.elem));
-        for (long long i = 0; i < t.count; i++) leaves(cg, *t.elem, base + i * es, out);
-        break;
-    }
-    default:
-        out.push_back({base, cg.dl->getTypeAllocSize(cg.ty(t)), t.kind == FType::F32 || t.kind == FType::F64,
-                       t.kind == FType::F64});
-    }
-}
-
-AbiArg Codegen::classify(const FType &t) {
-    AbiArg a;
-    if (t.kind != FType::Struct) return a;  // Direct
-    uint64_t size = dl->getTypeAllocSize(ty(t));
-    if (g_target.triple.isAArch64()) {
-        // A homogeneous float aggregate (1-4 floats or 1-4 doubles) travels in vector registers.
-        std::vector<Leaf> ls;
-        leaves(*this, t, 0, ls);
-        bool hfa = !ls.empty() && ls.size() <= 4;
-        for (const Leaf &l : ls) hfa &= l.isFloat && l.isDouble == ls[0].isDouble;
-        if (hfa) {
-            llvm::Type *ft = ls[0].isDouble ? (llvm::Type *)b.getDoubleTy() : b.getFloatTy();
-            a.kind = AbiArg::Expand;
-            a.parts.push_back(ArrayType::get(ft, ls.size()));
-            a.coerced = StructType::get(ctx, std::vector<llvm::Type *>(ls.size(), ft));
-            a.stackAlign8 = !g_target.triple.isOSDarwin();
-            return a;
-        }
-        if (size > 16) {
-            a.kind = AbiArg::Indirect;  // a copy, passed by address; returned through sret
-            return a;
-        }
-        // up to 16 bytes in general registers: i64 or [2 x i64]; returned as an exact-size integer
-        uint64_t align = dl->getABITypeAlign(ty(t)).value();
-        a.kind = AbiArg::Expand;
-        if (align >= 16) {
-            a.parts.push_back(b.getInt128Ty());
-            a.coerced = b.getInt128Ty();
-        } else if (size <= 8) {
-            a.parts.push_back(b.getInt64Ty());
-            a.coerced = b.getIntNTy(size * 8);
-        } else {
-            a.parts.push_back(ArrayType::get(b.getInt64Ty(), 2));
-            a.coerced = a.parts[0];
-        }
-        return a;
-    }
-    if (g_target.windows) {
-        // Microsoft x64: 1, 2, 4 or 8 bytes travel as one integer (even if they hold floats);
-        // anything else is copied by the caller and passed by address
-        if (size == 1 || size == 2 || size == 4 || size == 8) {
-            a.kind = AbiArg::Expand;
-            a.parts.push_back(b.getIntNTy(size * 8));
-            a.coerced = a.parts[0];
-        } else {
-            a.kind = AbiArg::Indirect;
-        }
-        return a;
-    }
-    if (size > 16 || size == 0) {
-        a.kind = AbiArg::Memory;
-        return a;
-    }
-    std::vector<Leaf> ls;
-    leaves(*this, t, 0, ls);
-    unsigned n = (size + 7) / 8;
-    Class cls[2] = {None, None};
-    bool hasDouble[2] = {false, false};
-    for (const Leaf &l : ls) {
-        if (l.offset % std::min<uint64_t>(l.size, 8) != 0) {  // misaligned field (packed struct): memory
-            a.kind = AbiArg::Memory;
-            return a;
-        }
-        unsigned k = l.offset / 8;
-        cls[k] = (cls[k] == Integer || !l.isFloat) ? Integer : Sse;
-        hasDouble[k] |= l.isDouble;
-    }
-    a.kind = AbiArg::Expand;
-    for (unsigned k = 0; k < n; k++) {
-        uint64_t bytes = std::min<uint64_t>(8, size - 8 * k);
-        if (cls[k] == Sse) {
-            if (hasDouble[k]) a.parts.push_back(b.getDoubleTy());
-            else if (bytes > 4) a.parts.push_back(FixedVectorType::get(b.getFloatTy(), 2));
-            else a.parts.push_back(b.getFloatTy());
-        } else {
-            a.parts.push_back(b.getIntNTy(bytes * 8));
-        }
-    }
-    a.coerced = a.parts.size() == 1 ? a.parts[0] : StructType::get(ctx, a.parts);
-    return a;
-}
-
-namespace {
-
-struct Plan {
-    AbiArg ret;
-    std::vector<AbiArg> params;
-    llvm::FunctionType *fty = nullptr;
-};
-
-}  // namespace
-
-// Decide how every parameter travels, counting the 6 integer and 8 SSE argument registers.
-static Plan makePlan(Codegen &cg, const FType &ret, const std::vector<FType> &params, bool variadic,
-                     std::vector<llvm::Type *> *extraTypes = nullptr) {
-    Plan pl;
-    int intRegs = 6, sseRegs = 8;
-    std::vector<llvm::Type *> types;
-    llvm::Type *retTy = cg.ty(ret);
-    if (ret.kind == FType::Str) retTy = cg.b.getPtrTy();
-    pl.ret = cg.classify(ret);
-    if (pl.ret.kind == AbiArg::Indirect) pl.ret.kind = AbiArg::Memory;  // returned through a hidden pointer
-    if (pl.ret.kind == AbiArg::Memory) {
-        types.push_back(cg.b.getPtrTy());  // sret
-        retTy = cg.b.getVoidTy();
-        intRegs--;
-    } else if (pl.ret.kind == AbiArg::Expand) {
-        retTy = pl.ret.coerced;
-    }
-    for (const FType &t : params) {
-        AbiArg a = cg.classify(t);
-        if (a.kind == AbiArg::Expand) {
-            int ni = 0, ns = 0;
-            for (llvm::Type *p : a.parts) (p->isIntegerTy() ? ni : ns)++;
-            // only System V counts registers here; elsewhere the backend places each part
-            if (g_target.windows || g_target.triple.isAArch64() || (ni <= intRegs && ns <= sseRegs)) {
-                intRegs -= ni;
-                sseRegs -= ns;
-                for (llvm::Type *p : a.parts) types.push_back(p);
-            } else {
-                a.kind = AbiArg::Memory;  // out of registers: the whole struct goes on the stack
-            }
-        }
-        if (a.kind == AbiArg::Memory || a.kind == AbiArg::Indirect) types.push_back(cg.b.getPtrTy());
-        if (a.kind == AbiArg::Direct) {
-            if (t.isFloat()) sseRegs--;
-            else intRegs--;
-            types.push_back(t.kind == FType::Str ? cg.b.getPtrTy() : cg.ty(t));
-        }
-        pl.params.push_back(a);
-    }
-    (void)extraTypes;
-    pl.fty = FunctionType::get(retTy, types, variadic);
-    return pl;
-}
-
-// Is C's plain `char` signed? Yes on x86 and Apple; no on ARM64 Linux.
-static bool charIsSigned() {
-    return !g_target.triple.isAArch64() || g_target.triple.isOSDarwin() || g_target.triple.isOSWindows();
-}
-
-static Attribute::AttrKind extAttr(const FType &t) {
-    if (t.bits() >= 32 || !(t.isInt() || t.kind == FType::Bool || t.kind == FType::Char)) return Attribute::None;
-    if (t.kind == FType::Char) return charIsSigned() ? Attribute::SExt : Attribute::ZExt;
-    return t.isSigned() ? Attribute::SExt : Attribute::ZExt;
-}
-
-// Attributes that tell LLVM how C passes each piece: sret, byval, signext/zeroext.
-static AttributeList attrsFor(Codegen &cg, const Plan &pl, const FType &ret, const std::vector<FType> &params) {
-    LLVMContext &ctx = cg.ctx;
-    AttributeList al;
-    unsigned idx = 0;
-    if (pl.ret.kind == AbiArg::Memory) {
-        al = al.addParamAttribute(ctx, idx, Attribute::getWithStructRetType(ctx, cg.ty(ret)));
-        idx++;
-    } else if (Attribute::AttrKind k = extAttr(ret); k != Attribute::None) {
-        al = al.addRetAttribute(ctx, k);
-    }
-    for (size_t i = 0; i < params.size(); i++) {
-        const AbiArg &a = pl.params[i];
-        if (a.kind == AbiArg::Memory) {
-            uint64_t align = std::max<uint64_t>(8, params[i].info->isC ? params[i].info->cstruct->align : 8);
-            al = al.addParamAttribute(ctx, idx, Attribute::getWithByValType(ctx, cg.ty(params[i])));
-            al = al.addParamAttribute(ctx, idx, Attribute::getWithAlignment(ctx, Align(align)));
-            idx++;
-        } else if (a.kind == AbiArg::Indirect) {
-            idx++;
-        } else if (a.kind == AbiArg::Expand) {
-            if (a.stackAlign8) al = al.addParamAttribute(ctx, idx, Attribute::getWithStackAlignment(ctx, Align(8)));
-            idx += a.parts.size();
-        } else {
-            if (Attribute::AttrKind k = extAttr(params[i]); k != Attribute::None) al = al.addParamAttribute(ctx, idx, k);
-            idx++;
-        }
-    }
-    return al;
-}
-
-static std::vector<FType> resolvedParams(Codegen &cg, const CFunc &f) {
-    std::vector<FType> ps;
-    for (const FType &t : f.params) ps.push_back(cg.resolve(t, Pos{}));
-    return ps;
-}
-
-Function *Codegen::declareC(const CFunc &f) {
-    if (Function *fn = mod->getFunction(f.name)) return fn;
-    FType ret = resolve(f.ret, Pos{});
-    std::vector<FType> ps = resolvedParams(*this, f);
-    for (const FType &t : ps)
-        if (t.kind == FType::Struct && !t.info->unsupported.empty()) return nullptr;
-    Plan pl = makePlan(*this, ret, ps, f.variadic);
-    Function *fn = Function::Create(pl.fty, Function::ExternalLinkage, f.name, mod.get());
-    fn->setAttributes(attrsFor(*this, pl, ret, ps));
-    return fn;
-}
-
-// A stack slot big enough for both the struct and its register form.
-static Value *abiSlot(Codegen &cg, const FType &t, const AbiArg &a) {
-    llvm::Type *st = cg.ty(t);
-    llvm::Type *big = a.coerced && cg.dl->getTypeAllocSize(a.coerced) > cg.dl->getTypeAllocSize(st) ? a.coerced : st;
-    return cg.tmpOf(big);
-}
-
-Value_ Codegen::emitCCall(const CFunc &f, Function *fn, std::vector<Value_> args, Pos p) {
-    FType ret = resolve(f.ret, p);
-    std::vector<FType> ps = resolvedParams(*this, f);
-    for (const FType &t : ps)
-        if (t.kind == FType::Struct && !t.info->unsupported.empty())
-            failAt(p.file, p.line, p.col, "the C function '" + f.name + "' takes the struct " + t.info->name +
-                                              " by value, which Finch can't pass yet: it " + t.info->unsupported);
-    if (ret.kind == FType::Struct && !ret.info->unsupported.empty())
-        failAt(p.file, p.line, p.col, "the C function '" + f.name + "' returns the struct " + ret.info->name +
-                                          " by value, which Finch can't receive yet: it " + ret.info->unsupported);
-    Plan pl = makePlan(*this, ret, ps, f.variadic);
-
-    std::vector<Value *> ll;
-    Value *sret = nullptr;
-    if (pl.ret.kind == AbiArg::Memory) {
-        sret = tmpOf(ty(ret));
-        cast<AllocaInst>(sret)->setAlignment(Align(16));
-        ll.push_back(sret);
-    }
-    for (size_t i = 0; i < args.size(); i++) {
-        const Value_ &v = args[i];
-        if (i >= ps.size()) {  // the '...' part: C's default promotions
-            const FType &t = v.type;
-            Value *x = v.v;
-            if (t.kind == FType::F32) x = b.CreateFPExt(x, b.getDoubleTy());
-            else if (t.kind == FType::Str) x = cstr(x);
-            else if (t.kind == FType::Bool || ((t.isInt() || t.kind == FType::Char) && t.bits() < 32))
-                x = b.CreateIntCast(x, b.getInt32Ty(), t.isSigned() || (t.kind == FType::Char && charIsSigned()));
-            ll.push_back(x);
-            continue;
-        }
-        const AbiArg &a = pl.params[i];
-        if (ps[i].kind == FType::Str) {
-            ll.push_back(cstr(v.v));
-        } else if (a.kind == AbiArg::Memory || a.kind == AbiArg::Indirect) {
-            Value *s = tmpOf(ty(ps[i]));  // a copy the callee may change
-            cast<AllocaInst>(s)->setAlignment(Align(16));
-            b.CreateStore(v.v, s);
-            ll.push_back(s);
-        } else if (a.kind == AbiArg::Expand) {
-            Value *s = abiSlot(*this, ps[i], a);
-            b.CreateStore(v.v, s);
-            for (size_t k = 0; k < a.parts.size(); k++)
-                ll.push_back(b.CreateLoad(a.parts[k], b.CreateConstInBoundsGEP1_64(b.getInt8Ty(), s, 8 * k)));
-        } else {
-            ll.push_back(v.v);
-        }
-    }
-    CallInst *call = b.CreateCall(pl.fty, fn, ll);
-    AttributeList al = attrsFor(*this, pl, ret, ps);
-    call->setAttributes(al);
-
-    if (ret.kind == FType::Void) return {nullptr, FType::Void};
-    if (pl.ret.kind == AbiArg::Memory) return {b.CreateLoad(ty(ret), sret), ret};
-    if (pl.ret.kind == AbiArg::Expand) {
-        Value *s = abiSlot(*this, ret, pl.ret);
-        b.CreateStore(call, s);
-        return {b.CreateLoad(ty(ret), s), ret};
-    }
-    if (ret.kind == FType::Str) return strFromC(call);  // borrowed: copied if it is kept
-    return {call, ret};
-}
-
-// A C-callable door into a Finch function, for addr(fn) (callbacks like qsort's or libclang's).
-Function *Codegen::cThunk(Fn &fn, Pos p) {
-    if (fn.cThunk) return fn.cThunk;
-    auto cOk = [](const FType &t) {
-        return t.isNumber() || t.kind == FType::Bool || t.kind == FType::Char || t.isPtr() || t.kind == FType::Void ||
-               (t.kind == FType::Struct && t.info->isC);
-    };
-    for (const FType &t : fn.params)
-        if (!cOk(t))
-            failAt(p.file, p.line, p.col, "addr(" + fn.decl->name + ") gives C a function pointer, so its parameters must be C types (numbers, ptr, C structs), not " + t.show());
-    if (!cOk(fn.ret)) failAt(p.file, p.line, p.col, "addr(" + fn.decl->name + "): a function given to C can't return " + fn.ret.show());
-
-    Plan pl = makePlan(*this, fn.ret, fn.params, false);
-    Function *th = Function::Create(pl.fty, Function::InternalLinkage, "finch.c." + fn.decl->name, mod.get());
-    th->setAttributes(attrsFor(*this, pl, fn.ret, fn.params));
-    fn.cThunk = th;
-
-    IRBuilderBase::InsertPointGuard guard(b);
-    DISubprogram *savedFn = diFn;
-    diFn = nullptr;
-    b.SetInsertPoint(BasicBlock::Create(ctx, "entry", th));
-    b.SetCurrentDebugLocation(DebugLoc());
-    unsigned ai = 0;
-    Value *sret = nullptr;
-    if (pl.ret.kind == AbiArg::Memory) sret = th->getArg(ai++);
-    std::vector<Value *> args;
-    for (size_t i = 0; i < fn.params.size(); i++) {
-        const AbiArg &a = pl.params[i];
-        if (a.kind == AbiArg::Memory || a.kind == AbiArg::Indirect) {
-            args.push_back(b.CreateLoad(ty(fn.params[i]), th->getArg(ai++)));
-        } else if (a.kind == AbiArg::Expand) {
-            Value *s = abiSlot(*this, fn.params[i], a);
-            for (size_t k = 0; k < a.parts.size(); k++)
-                b.CreateStore(th->getArg(ai++), b.CreateConstInBoundsGEP1_64(b.getInt8Ty(), s, 8 * k));
-            args.push_back(b.CreateLoad(ty(fn.params[i]), s));
-        } else {
-            args.push_back(th->getArg(ai++));
-        }
-    }
-    Value *r = b.CreateCall(fn.llvm, args);
-    if (fn.ret.kind == FType::Void) {
-        b.CreateRetVoid();
-    } else if (pl.ret.kind == AbiArg::Memory) {
-        b.CreateStore(r, sret);
-        b.CreateRetVoid();
-    } else if (pl.ret.kind == AbiArg::Expand) {
-        Value *s = abiSlot(*this, fn.ret, pl.ret);
-        b.CreateStore(r, s);
-        b.CreateRet(b.CreateLoad(pl.ret.coerced, s));
-    } else {
-        b.CreateRet(r);
-    }
-    diFn = savedFn;
-    return th;
-}
-
-}  // namespace finch

src/ast.fch

@@ -9,6 +9,7 @@ struct Type {
     []Type elem
     str name
     str module
+    int count       // "fixed": [N]T, only inside C structs
 }
 
 fn simple(str kind) -> Type {
@@ -39,10 +40,13 @@ fn same(Type a, Type b) -> bool {
     if a.kind != b.kind {
         return false
     }
-    if a.kind == "struct" || a.kind == "named" {
+    if a.kind == "struct" || a.kind == "named" || a.kind == "enum" {
         return a.name == b.name && a.module == b.module
     }
-    if a.kind == "array" || a.kind == "ptr" || a.kind == "map" {
+    if a.kind == "fixed" && a.count != b.count {
+        return false
+    }
+    if a.kind == "array" || a.kind == "ptr" || a.kind == "map" || a.kind == "fixed" {
         if a.elem.len != b.elem.len {
             return false
         }
@@ -60,6 +64,9 @@ fn show(Type t) -> str {
     if t.kind == "array" {
         return "[]" + show(t.elem[0])
     }
+    if t.kind == "fixed" {
+        return "[" + str(t.count) + "]" + show(t.elem[0])
+    }
     if t.kind == "map" {
         return "map[" + show(t.elem[0]) + "]" + show(t.elem[1])
     }
@@ -69,7 +76,7 @@ fn show(Type t) -> str {
         }
         return "ptr[" + show(t.elem[0]) + "]"
     }
-    if t.kind == "struct" || t.kind == "named" {
+    if t.kind == "struct" || t.kind == "named" || t.kind == "enum" {
         if t.module.len > 0 {
             return t.module + "." + t.name
         }
@@ -84,26 +91,34 @@ fn show(Type t) -> str {
 // One node of the tree, for expressions, statements, functions and structs alike.
 //   expressions: int float str char bool null var unary binary call member index array method
 //   statements:  decl assign expr if while for each return break continue block
-//   top level:   fn param struct field
+//   top level:   fn param struct field enum variant
+//   match:       match (kids: subject, arms...), arm (kids: patterns node, body; flag: the else arm), patterns
 struct Node {
     str kind
     str name      // identifier, operator, callee, field or method name
     str recv      // fn Point.move(...): "Point"; empty for a plain function
+    []str tparams // fn max[T](...), struct Stack[T], fn Stack[T].push: the type parameters
     str text      // literal text
     Type ty       // declared type (decl, param, field, fn result)
     bool flag     // decl: has a type; or: the right side is a { block }
     bool fallible // fn: -> T!  or  -> !
+    bool exported // export fn: a C function of a library (finch build --shared)
     []Node kids
     []str names   // named arguments: Point(x: 1)
     int line
     int col
     int file
+    int endLine   // block, fn: the line of the closing }
 }
 
 struct Program {
     str module
     str path
     []str imports   // Finch modules
+    []str cimports  // C headers: import "stdio.h"
+    []str cwhere    // where each was written, for error messages
+    []str links     // link "glfw", link "mine.c"
     []Node structs
+    []Node enums
     []Node fns
 }

src/ast.h

@@ -1,356 +0,0 @@
-#pragma once
-
-#include <memory>
-#include <string>
-#include <vector>
-
-struct StructInfo;  // filled in by codegen: fields, LLVM type, ownership
-
-struct Type {
-    enum Kind {
-        Void, Bool, Char, I8, I16, I32, I64, U8, U16, U32, U64, F32, F64,
-        Str, Ptr, Null,
-        Array,   // []T: growable, owns its elements
-        Map,     // map[K]V: a hash map that keeps insertion order, owns its keys and values
-        Fixed,   // [N]T: only inside C structs
-        Struct,  // a resolved struct
-        Named,   // a struct name as written, before codegen resolves it
-    };
-    Kind kind = Void;
-    std::shared_ptr<Type> elem;  // Ptr (null = untyped `ptr`), Array, Fixed; Map: the value
-    std::shared_ptr<Type> key;   // Map
-    long long count = 0;         // Fixed
-    std::string name;            // Named / Struct
-    std::string module;          // Named: written qualifier ("" = none); Struct: defining module
-    StructInfo *info = nullptr;  // Struct
-
-    Type() = default;
-    Type(Kind k) : kind(k) {}
-    static Type ptrTo(const Type &t) {
-        Type p(Ptr);
-        p.elem = std::make_shared<Type>(t);
-        return p;
-    }
-    static Type arrayOf(const Type &t) {
-        Type a(Array);
-        a.elem = std::make_shared<Type>(t);
-        return a;
-    }
-    static Type mapOf(const Type &k, const Type &v) {
-        Type m(Map);
-        m.key = std::make_shared<Type>(k);
-        m.elem = std::make_shared<Type>(v);
-        return m;
-    }
-
-    bool isInt() const { return kind >= I8 && kind <= U64; }
-    bool isSigned() const { return kind >= I8 && kind <= I64; }
-    bool isUnsigned() const { return kind >= U8 && kind <= U64; }
-    bool isFloat() const { return kind == F32 || kind == F64; }
-    bool isNumber() const { return isInt() || isFloat(); }
-    bool isPtr() const { return kind == Ptr; }
-    int bits() const {
-        switch (kind) {
-        case Bool: return 1;
-        case Char: case I8: case U8: return 8;
-        case I16: case U16: return 16;
-        case I32: case U32: case F32: return 32;
-        default: return 64;
-        }
-    }
-
-    bool operator==(const Type &o) const {
-        if (kind != o.kind) return false;
-        switch (kind) {
-        case Ptr:
-            if (!elem || !o.elem) return !elem && !o.elem;
-            return *elem == *o.elem;
-        case Array: return *elem == *o.elem;
-        case Map: return *key == *o.key && *elem == *o.elem;
-        case Fixed: return count == o.count && *elem == *o.elem;
-        case Struct: return info == o.info;
-        case Named: return name == o.name && module == o.module;
-        default: return true;
-        }
-    }
-    bool operator!=(const Type &o) const { return !(*this == o); }
-
-    // How the type is written in Finch, for error messages.
-    std::string show() const {
-        switch (kind) {
-        case Void: return "nothing";
-        case Bool: return "bool";
-        case Char: return "char";
-        case I8: return "i8";
-        case I16: return "i16";
-        case I32: return "i32";
-        case I64: return "int";
-        case U8: return "u8";
-        case U16: return "u16";
-        case U32: return "u32";
-        case U64: return "u64";
-        case F32: return "f32";
-        case F64: return "float";
-        case Str: return "str";
-        case Ptr: return elem ? "ptr[" + elem->show() + "]" : "ptr";
-        case Null: return "null";
-        case Array: return "[]" + elem->show();
-        case Map: return "map[" + key->show() + "]" + elem->show();
-        case Fixed: return "[" + std::to_string(count) + "]" + elem->show();
-        case Struct:
-        case Named: return module.empty() ? name : module + "." + name;
-        }
-        return "?";
-    }
-};
-
-// Built-in type names. `int` is i64 and `float` is f64: the everyday defaults.
-bool typeFromName(const std::string &name, Type &out);
-
-struct Pos {
-    int line = 0, col = 0;
-    int file = 0;  // index into the list of source files (see error.h)
-};
-
-// ---------- expressions ----------
-
-enum class ExprKind { Int, Float, Bool, Char, Str, Null, Var, Unary, Binary, Call, Member, Index, ArrayLit, Method,
-                      MapLit, Try, OrElse };
-
-struct Expr {
-    ExprKind kind;
-    Pos pos;
-    Expr(ExprKind k, Pos p) : kind(k), pos(p) {}
-    virtual ~Expr() = default;
-};
-using ExprPtr = std::unique_ptr<Expr>;
-
-struct IntExpr : Expr {
-    long long value;
-    IntExpr(Pos p, long long v) : Expr(ExprKind::Int, p), value(v) {}
-};
-struct FloatExpr : Expr {
-    double value;
-    FloatExpr(Pos p, double v) : Expr(ExprKind::Float, p), value(v) {}
-};
-struct BoolExpr : Expr {
-    bool value;
-    BoolExpr(Pos p, bool v) : Expr(ExprKind::Bool, p), value(v) {}
-};
-struct CharExpr : Expr {
-    char value;
-    CharExpr(Pos p, char v) : Expr(ExprKind::Char, p), value(v) {}
-};
-struct StrExpr : Expr {
-    std::string value;
-    StrExpr(Pos p, std::string v) : Expr(ExprKind::Str, p), value(std::move(v)) {}
-};
-struct NullExpr : Expr {
-    explicit NullExpr(Pos p) : Expr(ExprKind::Null, p) {}
-};
-struct VarExpr : Expr {
-    std::string name;
-    VarExpr(Pos p, std::string n) : Expr(ExprKind::Var, p), name(std::move(n)) {}
-};
-struct UnaryExpr : Expr {
-    char op;  // '-', '!' or '~'
-    ExprPtr operand;
-    UnaryExpr(Pos p, char o, ExprPtr e) : Expr(ExprKind::Unary, p), op(o), operand(std::move(e)) {}
-};
-enum class BinOp {
-    Add, Sub, Mul, Div, Mod,
-    BitAnd, BitOr, BitXor, Shl, Shr,
-    Eq, NotEq, Less, LessEq, Greater, GreaterEq,
-    And, Or,
-};
-struct BinaryExpr : Expr {
-    BinOp op;
-    ExprPtr lhs, rhs;
-    BinaryExpr(Pos p, BinOp o, ExprPtr l, ExprPtr r)
-        : Expr(ExprKind::Binary, p), op(o), lhs(std::move(l)), rhs(std::move(r)) {}
-};
-// name(args): a function, a built-in, a conversion or a struct constructor.
-struct CallExpr : Expr {
-    std::string callee;
-    std::vector<ExprPtr> args;
-    std::vector<std::string> argNames;  // "" for positional; Point(x: 1, y: 2)
-    CallExpr(Pos p, std::string c) : Expr(ExprKind::Call, p), callee(std::move(c)) {}
-};
-struct MemberExpr : Expr {  // obj.field, p.value, a.len
-    ExprPtr obj;
-    std::string field;
-    MemberExpr(Pos p, ExprPtr o, std::string f)
-        : Expr(ExprKind::Member, p), obj(std::move(o)), field(std::move(f)) {}
-};
-struct IndexExpr : Expr {  // a[i]
-    ExprPtr obj, index;
-    IndexExpr(Pos p, ExprPtr o, ExprPtr i) : Expr(ExprKind::Index, p), obj(std::move(o)), index(std::move(i)) {}
-};
-struct ArrayLitExpr : Expr {  // [1, 2, 3]
-    std::vector<ExprPtr> elems;
-    explicit ArrayLitExpr(Pos p) : Expr(ExprKind::ArrayLit, p) {}
-};
-struct MapLitExpr : Expr {  // ["a": 1, "b": 2], or [:] for an empty map
-    std::vector<ExprPtr> keys, values;
-    explicit MapLitExpr(Pos p) : Expr(ExprKind::MapLit, p) {}
-};
-// obj.name(args): a.push(x), s.find("x"), p.move(1, 2), and math.sqrt(2) / math.Vec(1, 2) for modules
-struct MethodExpr : Expr {
-    ExprPtr obj;
-    std::string name;
-    std::vector<ExprPtr> args;
-    std::vector<std::string> argNames;
-    MethodExpr(Pos p, ExprPtr o, std::string n) : Expr(ExprKind::Method, p), obj(std::move(o)), name(std::move(n)) {}
-};
-
-struct BlockStmt;
-// try f(x): if f fails, the current function fails with the same error
-struct TryExpr : Expr {
-    ExprPtr call;
-    TryExpr(Pos p, ExprPtr c) : Expr(ExprKind::Try, p), call(std::move(c)) {}
-};
-// f(x) or fallback,  f(x) or { ...err... }
-struct OrElseExpr : Expr {
-    ExprPtr call;
-    ExprPtr fallback;                   // or a value
-    std::unique_ptr<BlockStmt> block;   // or a block that sees `err`
-    OrElseExpr(Pos p, ExprPtr c) : Expr(ExprKind::OrElse, p), call(std::move(c)) {}
-    ~OrElseExpr() override;
-};
-
-// ---------- statements ----------
-
-enum class StmtKind { VarDecl, Assign, Expr, If, While, For, ForEach, Return, Break, Continue, Block, Defer };
-
-struct Stmt {
-    StmtKind kind;
-    Pos pos;
-    Stmt(StmtKind k, Pos p) : kind(k), pos(p) {}
-    virtual ~Stmt() = default;
-};
-using StmtPtr = std::unique_ptr<Stmt>;
-
-struct BlockStmt : Stmt {
-    std::vector<StmtPtr> body;
-    Pos end;  // the closing '}' 
-    explicit BlockStmt(Pos p) : Stmt(StmtKind::Block, p) {}
-};
-using BlockPtr = std::unique_ptr<BlockStmt>;
-inline OrElseExpr::~OrElseExpr() = default;
-
-struct VarDeclStmt : Stmt {
-    bool hasType;  // `int x = 5` vs `x := 5`
-    Type type;
-    std::string name;
-    Pos namePos;
-    ExprPtr init;  // may be null only when hasType
-    VarDeclStmt(Pos p) : Stmt(StmtKind::VarDecl, p) {}
-};
-struct AssignStmt : Stmt {
-    ExprPtr target;  // a variable, field, element or p.value
-    char op;         // '=', '+', '-', '*', '/', '%'
-    ExprPtr value;
-    AssignStmt(Pos p) : Stmt(StmtKind::Assign, p) {}
-};
-struct ExprStmt : Stmt {
-    ExprPtr expr;
-    ExprStmt(Pos p, ExprPtr e) : Stmt(StmtKind::Expr, p), expr(std::move(e)) {}
-};
-struct IfStmt : Stmt {
-    ExprPtr cond;
-    BlockPtr then;
-    StmtPtr otherwise;  // null, BlockStmt, or IfStmt (else if)
-    IfStmt(Pos p) : Stmt(StmtKind::If, p) {}
-};
-struct WhileStmt : Stmt {
-    ExprPtr cond;
-    BlockPtr body;
-    WhileStmt(Pos p) : Stmt(StmtKind::While, p) {}
-};
-struct ForStmt : Stmt {
-    std::string var;
-    Pos varPos;
-    ExprPtr from, to;  // for var in from..to  (to is exclusive)
-    BlockPtr body;
-    ForStmt(Pos p) : Stmt(StmtKind::For, p) {}
-};
-struct ForEachStmt : Stmt {
-    std::string var;
-    Pos varPos;
-    std::string var2;  // for i, x in list  /  for k, v in map  ("" = one variable)
-    Pos var2Pos;
-    ExprPtr list;  // for var in list  (an array, a str or a map)
-    BlockPtr body;
-    ForEachStmt(Pos p) : Stmt(StmtKind::ForEach, p) {}
-};
-struct ReturnStmt : Stmt {
-    ExprPtr value;  // may be null
-    ReturnStmt(Pos p) : Stmt(StmtKind::Return, p) {}
-};
-struct BreakStmt : Stmt {
-    explicit BreakStmt(Pos p) : Stmt(StmtKind::Break, p) {}
-};
-struct ContinueStmt : Stmt {
-    explicit ContinueStmt(Pos p) : Stmt(StmtKind::Continue, p) {}
-};
-struct DeferStmt : Stmt {  // defer <statement>: runs when the block ends
-    StmtPtr body;
-    DeferStmt(Pos p, StmtPtr s) : Stmt(StmtKind::Defer, p), body(std::move(s)) {}
-};
-
-// ---------- top level ----------
-
-struct Param {
-    Type type;
-    std::string name;
-    Pos pos;      // the type
-    Pos namePos;  // the name
-};
-
-struct FnDecl {
-    Pos pos;
-    Pos namePos;
-    std::string name;
-    std::string recv;  // fn Point.move(...): "Point" (a method; `self` is the Point it is called on)
-    Pos recvPos;
-    Type ret;  // Void when there is no `-> type`
-    bool fallible = false;  // -> int!  /  -> !  : can fail with an error
-    std::vector<Param> params;
-    BlockPtr body;
-};
-
-struct Field {
-    Type type;
-    std::string name;
-    ExprPtr init;  // default value, may be null
-    Pos pos;
-    Pos namePos;
-};
-
-struct StructDecl {
-    Pos pos;
-    Pos namePos;
-    std::string name;
-    std::vector<Field> fields;
-};
-
-struct Import {
-    Pos pos;
-    std::string path;  // "stdio.h" (C header, isC) or "math" (Finch module)
-    bool isC = true;
-};
-
-struct Link {
-    Pos pos;
-    std::string lib;  // "glfw" -> libglfw.so; "helpers.c" / ".o" / ".a" -> a file next to the .fch file
-};
-
-// One .fch file.
-struct Program {
-    std::string module;  // "" for the main file, else the module's name
-    std::string path;
-    std::vector<Import> imports;
-    std::vector<Link> links;
-    std::vector<StructDecl> structs;
-    std::vector<FnDecl> fns;
-};

src/builtins_doc.h

@@ -1,80 +0,0 @@
-#pragma once
-// One description of every built-in function and method, shared by the language server
-// (hover, completion, signature help).
-
-struct BuiltinDoc {
-    const char *name;
-    const char *signature;
-    const char *doc;
-};
-
-inline const BuiltinDoc kBuiltins[] = {
-    {"print", "print(a, b, ...)", "Prints the values separated by spaces, then a new line. Works with every type."},
-    {"input", "input(str question = \"\") -> str", "Shows the question and reads one line typed by the user, without the newline."},
-    {"read_file", "read_file(str path) -> str", "The whole file as text. Stops the program if it can't be read, unless handled: read_file(p) or { ... }, try read_file(p)."},
-    {"write_file", "write_file(str path, str text) -> bool", "Writes (replaces) the file. true if it worked; with or / try, the reason it didn't."},
-    {"file_exists", "file_exists(str path) -> bool", "Is there a file at this path?"},
-    {"delete_file", "delete_file(str path) -> bool", "Deletes the file. true if it worked; with or / try, the reason it didn't."},
-    {"error", "error(str message)", "The failure a fallible function returns: return error(\"...\"). The caller handles it with or / try."},
-    {"shell", "shell(str command) -> int", "Runs a command in the system's shell and gives back its exit code."},
-    {"exit", "exit(int code)", "Ends the program right away with this exit code."},
-    {"addr", "addr(x) -> ptr[T]", "A pointer to a variable, field or element. addr(function) gives C a callback."},
-    {"new", "new(value) -> ptr[T]", "Puts a copy of the value on the heap. Give it back with free(...)."},
-    {"free", "free(ptr p)", "Gives back memory from new(...) (or from C), freeing what the value owns."},
-    {"str", "str(x) -> str", "Turns a number, bool, char, []u8 or C char pointer into text."},
-    {"int", "int(x) -> int", "Converts to a whole number: cuts off fractions, parses text (stops the program if it isn't a number, unless handled: int(s) or 0)."},
-    {"float", "float(x) -> float", "Converts to a decimal number; parses text (int(s) or 0.0 handles bad text)."},
-    {"char", "char(int n) -> char", "The character with this code."},
-    {"bool", "bool(int n) -> bool", "true for any number but 0."},
-    {"ptr", "ptr(x) -> ptr", "An untyped pointer: from a typed pointer, or from a number (an address or offset for C)."},
-};
-
-inline const BuiltinDoc kArrayMethods[] = {
-    {"len", ".len -> int", "The number of elements."},
-    {"ptr", ".ptr -> ptr[T]", "The address of the first element, for C."},
-    {"push", "push(T x)", "Adds x at the end."},
-    {"pop", "pop() -> T", "Removes the last element and gives it back."},
-    {"insert", "insert(int i, T x)", "Puts x at position i, moving the rest."},
-    {"remove", "remove(int i) -> T", "Removes position i and gives it back."},
-    {"clear", "clear()", "Removes everything."},
-    {"resize", "resize(int n)", "Makes the array n long; new elements are zero."},
-    {"find", "find(T x) -> int", "The index of x, or -1."},
-    {"contains", "contains(T x) -> bool", "Is x in the array?"},
-    {"sort", "sort()", "Sorts in place (numbers, chars, str)."},
-    {"reverse", "reverse()", "Reverses in place."},
-    {"slice", "slice(int start, int end) -> []T", "A new array with the elements start to end-1."},
-    {"join", "join(str sep) -> str", "For []str: one text with sep between the parts."},
-};
-
-inline const BuiltinDoc kStrMethods[] = {
-    {"len", ".len -> int", "The number of bytes."},
-    {"ptr", ".ptr -> ptr[char]", "The address of the text, for C (valid while the str lives)."},
-    {"sub", "sub(int start, int end) -> str", "The part from start to end-1."},
-    {"find", "find(str t) -> int", "Where t starts, or -1."},
-    {"contains", "contains(str t) -> bool", "Does the text contain t?"},
-    {"starts_with", "starts_with(str t) -> bool", "Does the text start with t?"},
-    {"ends_with", "ends_with(str t) -> bool", "Does the text end with t?"},
-    {"split", "split(str sep) -> []str", "The parts between each sep; split(\"\") gives single characters."},
-    {"trim", "trim() -> str", "Without spaces and newlines at both ends."},
-    {"upper", "upper() -> str", "With a-z changed to A-Z."},
-    {"lower", "lower() -> str", "With A-Z changed to a-z."},
-    {"replace", "replace(str from, str to) -> str", "Every from replaced by to."},
-    {"repeat", "repeat(int n) -> str", "The text n times."},
-    {"bytes", "bytes() -> []u8", "The bytes of the text."},
-};
-
-inline const BuiltinDoc kMapMethods[] = {
-    {"len", ".len -> int", "The number of keys."},
-    {"has", "has(K key) -> bool", "Is the key in the map?"},
-    {"get", "get(K key, V default) -> V", "The value for key, or default if the key isn't there."},
-    {"remove", "remove(K key) -> bool", "Removes the key and its value; true if it was there."},
-    {"clear", "clear()", "Removes everything."},
-    {"keys", "keys() -> []K", "The keys, in the order they were added."},
-    {"values", "values() -> []V", "The values, in the order their keys were added."},
-};
-
-inline const char *kKeywords[] = {"fn", "return", "if", "else", "while", "for", "in", "break", "continue", "true",
-                                  "false", "null", "import", "link", "struct", "defer", "or", "try", "self"};
-
-inline const char *kTypeNames[] = {"int", "float", "bool", "char", "str", "ptr", "map", "i8", "i16", "i32", "i64",
-                                   "u8", "u16", "u32", "u64", "f32", "f64"};

src/cimport.cpp

@@ -1,373 +0,0 @@
-#include "cimport.h"
-#include "error.h"
-#include "target.h"
-
-#include <clang-c/Index.h>
-
-#include <cctype>
-#include <cstdio>
-#include <cstdlib>
-#include <cstring>
-#include <sstream>
-
-namespace {
-
-// Ask the system C compiler where it looks for headers (and, on macOS, frameworks), so we find
-// the same stdio.h it would. Returns ready -isystem / -iframework arguments.
-std::vector<std::string> systemIncludeArgs() {
-    std::string output;
-    capture(g_target.cc + " -E -v -x c " + nullDevice(), output);
-    std::vector<std::string> dirs;
-    std::stringstream lines(output);
-    bool inList = false;
-    for (std::string l; std::getline(lines, l);) {
-        if (!l.empty() && l.back() == '\r') l.pop_back();
-        l += "\n";
-        if (l.rfind("#include <...> search starts here:", 0) == 0) { inList = true; continue; }
-        if (l.rfind("End of search list.", 0) == 0) break;
-        if (!inList) continue;
-        size_t a = l.find_first_not_of(' ');
-        size_t z = l.find_last_not_of(" \n");
-        if (a == std::string::npos) continue;
-        std::string d = l.substr(a, z - a + 1);
-        // macOS: "/…/System/Library/Frameworks (framework directory)" holds <OpenGL/gl.h> and friends
-        if (d.size() > 22 && d.compare(d.size() - 22, 22, " (framework directory)") == 0)
-            dirs.push_back("-iframework" + d.substr(0, d.size() - 22));
-        else
-            dirs.push_back("-isystem" + d);
-    }
-    return dirs;
-}
-
-std::string str(CXString s) {
-    std::string out = clang_getCString(s) ? clang_getCString(s) : "";
-    clang_disposeString(s);
-    return out;
-}
-
-// Where a C type is used decides how `char *` looks in Finch: in function signatures it is
-// a `str`; inside structs, globals and behind pointers it stays a raw `ptr[char]`.
-enum class Ctx { Signature, Data };
-
-struct Importer {
-    CImports &out;
-    CXTranslationUnit tu = nullptr;
-    std::string header;
-    std::map<std::string, std::string> recordNames;  // record USR -> Finch name (typedef wins)
-    std::map<std::string, int> defining;             // USR -> 1 while its fields are being mapped
-    int anon = 0;
-
-    explicit Importer(CImports &o) : out(o) {}
-
-    // The Finch name of a C record: its typedef name, its tag, or a made-up one.
-    std::string recordName(CXType t) {
-        CXCursor decl = clang_getTypeDeclaration(t);
-        std::string usr = str(clang_getCursorUSR(decl));
-        auto it = recordNames.find(usr);
-        if (it != recordNames.end()) return it->second;
-        std::string name = str(clang_getCursorSpelling(decl));
-        if (name.empty() || name.find(' ') != std::string::npos) name = "anon_struct_" + std::to_string(++anon);
-        recordNames[usr] = name;
-        return name;
-    }
-
-    // Fill out.structs[name] for a complete record; returns its name, or "" if it can't be one.
-    std::string defineRecord(CXType t) {
-        t = clang_getCanonicalType(t);
-        CXCursor decl = clang_getTypeDeclaration(t);
-        std::string usr = str(clang_getCursorUSR(decl));
-        std::string name = recordName(t);
-        if (out.structs.count(name) || defining.count(usr)) return name;
-        long long size = clang_Type_getSizeOf(t);
-        if (size < 0) return "";  // incomplete (opaque) struct
-        defining[usr] = 1;
-
-        CStruct s;
-        s.name = name;
-        s.size = size;
-        s.align = clang_Type_getAlignOf(t);
-        if (clang_getCursorKind(decl) == CXCursor_UnionDecl) s.unsupported = "is a C union";
-        struct Ctx2 { Importer *self; CStruct *s; } c2{this, &s};
-        clang_Type_visitFields(t, [](CXCursor field, CXClientData data) -> CXVisitorResult {
-            auto &c = *static_cast<Ctx2 *>(data);
-            CField f;
-            f.name = str(clang_getCursorSpelling(field));
-            CXType ft = clang_getCanonicalType(clang_getCursorType(field));
-            f.offset = clang_Cursor_getOffsetOfField(field) / 8;
-            f.size = clang_Type_getSizeOf(ft);
-            f.align = clang_Type_getAlignOf(ft);
-            std::string why;
-            if (clang_Cursor_isBitField(field)) {
-                c.s->unsupported = "has bit fields";
-                f.hidden = true;
-            } else if (ft.kind == CXType_Record &&
-                       clang_getCursorKind(clang_getTypeDeclaration(ft)) == CXCursor_UnionDecl) {
-                f.hidden = true;  // unions are kept as opaque bytes
-            } else if (!c.self->mapType(ft, f.type, why, Ctx::Data)) {
-                f.hidden = true;
-            }
-            if (f.hidden) c.s->hasHidden = true;
-            if (f.name.empty()) f.hidden = true;
-            c.s->fields.push_back(f);
-            return CXVisit_Continue;
-        }, &c2);
-        defining.erase(usr);
-        out.structs[name] = s;
-        return name;
-    }
-
-    // C type -> Finch type. Returns false (with a reason) if Finch can't express it.
-    bool mapType(CXType t, Type &res, std::string &why, Ctx ctx) {
-        t = clang_getCanonicalType(t);
-        long long size = clang_Type_getSizeOf(t);
-        auto sized = [&](bool isSigned) {
-            switch (size) {
-            case 1: res = isSigned ? Type::I8 : Type::U8; return true;
-            case 2: res = isSigned ? Type::I16 : Type::U16; return true;
-            case 4: res = isSigned ? Type::I32 : Type::U32; return true;
-            case 8: res = isSigned ? Type::I64 : Type::U64; return true;
-            }
-            why = "uses a " + std::to_string(size * 8) + "-bit number";
-            return false;
-        };
-
-        switch (t.kind) {
-        case CXType_Void: res = Type::Void; return true;
-        case CXType_Bool: res = Type::Bool; return true;
-        case CXType_Char_S:
-        case CXType_Char_U: res = Type::Char; return true;
-        case CXType_SChar:
-        case CXType_Short:
-        case CXType_Int:
-        case CXType_Long:
-        case CXType_LongLong: return sized(true);
-        case CXType_UChar:
-        case CXType_UShort:
-        case CXType_UInt:
-        case CXType_ULong:
-        case CXType_ULongLong: return sized(false);
-        case CXType_Enum: return sized(true);
-        case CXType_Float: res = Type::F32; return true;
-        case CXType_Double: res = Type::F64; return true;
-        case CXType_Pointer: {
-            CXType pointee = clang_getCanonicalType(clang_getPointeeType(t));
-            if ((pointee.kind == CXType_Char_S || pointee.kind == CXType_Char_U) && ctx == Ctx::Signature) {
-                res = Type::Str;  // char* in a signature is a C string
-                return true;
-            }
-            Type inner;
-            std::string ignored;
-            if (pointee.kind == CXType_Void || pointee.kind == CXType_FunctionProto ||
-                pointee.kind == CXType_FunctionNoProto || !mapType(pointee, inner, ignored, Ctx::Data) ||
-                inner.kind == Type::Void || inner.kind == Type::Fixed)
-                res = Type::Ptr;  // an opaque `ptr` you can pass around
-            else
-                res = Type::ptrTo(inner);
-            return true;
-        }
-        case CXType_Record: {
-            if (clang_getCursorKind(clang_getTypeDeclaration(t)) == CXCursor_UnionDecl) {
-                why = "uses a C union by value";
-                return false;
-            }
-            std::string name = defineRecord(t);
-            if (name.empty()) {
-                why = "uses an incomplete C struct by value";
-                return false;
-            }
-            res = Type(Type::Named);
-            res.name = name;
-            res.module = "C";
-            return true;
-        }
-        case CXType_ConstantArray: {
-            Type inner;
-            if (!mapType(clang_getArrayElementType(t), inner, why, Ctx::Data)) return false;
-            res = Type(Type::Fixed);
-            res.elem = std::make_shared<Type>(inner);
-            res.count = clang_getArraySize(t);
-            return true;
-        }
-        case CXType_LongDouble: why = "uses long double"; return false;
-        default: why = "uses the C type '" + str(clang_getTypeSpelling(t)) + "'"; return false;
-        }
-    }
-
-    // Simple #defines: a single number, maybe negative, maybe in parentheses.
-    bool macroValue(CXCursor c, CConst &res) {
-        CXToken *toks;
-        unsigned n;
-        clang_tokenize(tu, clang_getCursorExtent(c), &toks, &n);
-        std::vector<std::string> parts;
-        for (unsigned k = 1; k < n; k++) {  // token 0 is the macro's name
-            if (clang_getTokenKind(toks[k]) == CXToken_Comment) continue;
-            parts.push_back(str(clang_getTokenSpelling(tu, toks[k])));
-        }
-        clang_disposeTokens(tu, toks, n);
-
-        while (parts.size() >= 2 && parts.front() == "(" && parts.back() == ")") {
-            parts.erase(parts.begin());
-            parts.pop_back();
-        }
-        bool neg = false;
-        if (parts.size() == 2 && parts[0] == "-") {
-            neg = true;
-            parts.erase(parts.begin());
-        }
-        if (parts.size() != 1) return false;
-        const std::string &lit = parts[0];
-        if (lit.empty() || !(std::isdigit((unsigned char)lit[0]) || lit[0] == '.')) return false;
-
-        bool isFloat = lit.find_first_of(".eE") != std::string::npos && lit.rfind("0x", 0) != 0;
-        char *end;
-        if (isFloat) {
-            res.type = Type::F64;
-            res.f = std::strtod(lit.c_str(), &end);
-            if (neg) res.f = -res.f;
-        } else {
-            res.type = Type::I64;
-            res.i = (long long)std::strtoull(lit.c_str(), &end, 0);  // C rules: 0x.., 0755
-            if (neg) res.i = -res.i;
-        }
-        for (; *end; end++)  // allow suffixes: 10UL, 1.0f
-            if (!std::strchr("uUlLfF", *end)) return false;
-        return true;
-    }
-
-    void visitTop(CXCursor c) {
-        std::string name = str(clang_getCursorSpelling(c));
-        switch (clang_getCursorKind(c)) {
-        case CXCursor_TypedefDecl: {
-            // typedef struct {...} Name;  ->  the struct is called Name in Finch
-            CXType u = clang_getCanonicalType(clang_getTypedefDeclUnderlyingType(c));
-            if (u.kind == CXType_Record) {
-                std::string usr = str(clang_getCursorUSR(clang_getTypeDeclaration(u)));
-                // prefer the typedef name, unless the struct is already known under its tag
-                auto it = recordNames.find(usr);
-                bool used = it != recordNames.end() && out.structs.count(it->second);
-                if (!used && !out.structs.count(name)) recordNames[usr] = name;
-            }
-            break;
-        }
-        case CXCursor_FunctionDecl: {
-            if (out.fns.count(name)) break;
-            CFunc f;
-            f.name = name;
-            f.header = header;
-            if (clang_Cursor_getStorageClass(c) == CX_SC_Static) {
-                f.unsupported = "is a static inline C function (it has no code to link against)";
-                out.fns[name] = f;
-                break;
-            }
-            CXType ft = clang_getCanonicalType(clang_getCursorType(c));
-            if (ft.kind == CXType_FunctionNoProto) {
-                f.unsupported = "has no parameter list in its C declaration";
-                out.fns[name] = f;
-                break;
-            }
-            std::string why;
-            if (!mapType(clang_getResultType(ft), f.ret, why, Ctx::Signature)) f.unsupported = why;
-            int n = clang_getNumArgTypes(ft);
-            for (int k = 0; k < n && f.unsupported.empty(); k++) {
-                Type t;
-                if (!mapType(clang_getArgType(ft, k), t, why, Ctx::Signature)) f.unsupported = why;
-                f.params.push_back(t);
-            }
-            f.variadic = clang_isFunctionTypeVariadic(ft);
-            out.fns[name] = f;
-            break;
-        }
-        case CXCursor_VarDecl: {
-            if (clang_Cursor_getStorageClass(c) != CX_SC_Extern || out.globals.count(name)) break;
-            CGlobal g;
-            std::string why;
-            if (mapType(clang_getCursorType(c), g.type, why, Ctx::Data)) out.globals[name] = g;
-            break;
-        }
-        case CXCursor_StructDecl:
-            if (clang_isCursorDefinition(c) && !name.empty() && name.find(' ') == std::string::npos) {
-                std::string usr = str(clang_getCursorUSR(c));
-                if (!recordNames.count(usr)) recordNames[usr] = name;
-            }
-            break;
-        case CXCursor_EnumDecl:
-            clang_visitChildren(c, [](CXCursor k, CXCursor, CXClientData d) {
-                static_cast<Importer *>(d)->visitTop(k);
-                return CXChildVisit_Continue;
-            }, this);
-            break;
-        case CXCursor_EnumConstantDecl: {
-            CConst k;
-            k.type = Type::I64;
-            k.i = clang_getEnumConstantDeclValue(c);
-            out.consts.emplace(name, k);
-            break;
-        }
-        case CXCursor_MacroDefinition: {
-            if (clang_Cursor_isMacroBuiltin(c) || clang_Cursor_isMacroFunctionLike(c)) break;
-            CConst k;
-            if (macroValue(c, k)) out.consts.emplace(name, k);
-            break;
-        }
-        default: break;
-        }
-    }
-};
-
-}  // namespace
-
-CImports importHeaders(const std::vector<Import> &imports, const std::vector<std::string> &dirs) {
-    CImports out;
-    bool any = false;
-    for (const Import &im : imports) any |= im.isC;
-    if (!any) return out;
-
-    // parse for the target system: sizes (long is 32 bits on Windows) and headers differ
-    std::vector<std::string> args = {"-x", "c", "-std=gnu11", "--target=" + g_target.triple.str()};
-    if (g_target.windows) args.push_back("-D_USE_MATH_DEFINES");  // M_PI and friends, as on Linux
-    for (const std::string &d : dirs) args.push_back("-I" + d);
-    for (const std::string &d : systemIncludeArgs()) args.push_back(d);
-    std::vector<const char *> argv;
-    for (const std::string &a : args) argv.push_back(a.c_str());
-
-    Importer imp(out);
-    CXIndex index = clang_createIndex(0, 0);
-    for (const Import &im : imports) {
-        if (!im.isC) continue;
-        std::string src = "#include \"" + im.path + "\"\n";
-        CXUnsavedFile file = {"finch_import.c", src.c_str(), (unsigned long)src.size()};
-        CXTranslationUnit tu = nullptr;
-        CXErrorCode err = clang_parseTranslationUnit2(
-            index, "finch_import.c", argv.data(), (int)argv.size(), &file, 1,
-            CXTranslationUnit_DetailedPreprocessingRecord | CXTranslationUnit_SkipFunctionBodies, &tu);
-        if (err != CXError_Success || !tu) failAt(im.pos.file, im.pos.line, im.pos.col, "couldn't read C header '" + im.path + "'");
-
-        for (unsigned k = 0; k < clang_getNumDiagnostics(tu); k++) {
-            CXDiagnostic d = clang_getDiagnostic(tu, k);
-            if (clang_getDiagnosticSeverity(d) >= CXDiagnostic_Error) {
-                std::string msg = str(clang_getDiagnosticSpelling(d));
-                clang_disposeDiagnostic(d);
-                if (msg.find("file not found") != std::string::npos) {
-                    // "'GL/gl.h' file not found": it may be a header that this one includes
-                    std::string missing = msg.substr(1, msg.find('\'', 1) - 1);
-                    if (missing == im.path)
-                        failAt(im.pos.file, im.pos.line, im.pos.col, "can't find the C header '" + im.path + "'");
-                    failAt(im.pos.file, im.pos.line, im.pos.col, "can't find the C header '" + missing + "', which '" + im.path +
-                                                                     "' includes (is its library's development package installed?)");
-                }
-                failAt(im.pos.file, im.pos.line, im.pos.col, "C header '" + im.path + "' has an error: " + msg);
-            }
-            clang_disposeDiagnostic(d);
-        }
-
-        imp.tu = tu;
-        imp.header = im.path;
-        clang_visitChildren(clang_getTranslationUnitCursor(tu), [](CXCursor c, CXCursor, CXClientData d) {
-            static_cast<Importer *>(d)->visitTop(c);
-            return CXChildVisit_Continue;
-        }, &imp);
-        clang_disposeTranslationUnit(tu);
-    }
-    clang_disposeIndex(index);
-    return out;
-}

src/cimport.fch

@@ -0,0 +1,569 @@
+// C headers, read through libclang, written in Finch.
+//
+// What `import "stdio.h"` teaches the compiler: the C functions, the constants (enum values and
+// plain #define numbers), the extern variables (stdout) and the structs. The same job as
+// src/cimport.cpp, done by calling libclang's C API through Finch's own C import -- which is
+// what makes this the part that closes the bootstrap: to compile this file the self-hosted
+// compiler has to read libclang's headers with this very code.
+//
+// C structs by value appear in types as the named type `module "C"`.
+import ast
+import host
+import "clang-c/Index.h"
+link "clang"
+
+struct CFunc {
+    str name
+    str header          // the import it came from
+    ast.Type ret
+    []ast.Type params
+    bool variadic
+    str unsupported     // non-empty: why Finch can't call it (yet)
+}
+
+struct CConst {         // enum values and simple #define numbers
+    bool isFloat
+    int i
+    float f
+    str text            // a float as written, so no digits are lost: 3.14159265358979323846
+}
+
+struct CField {
+    str name
+    ast.Type ty
+    int offset          // bytes
+    int size
+    int align
+    bool hidden         // unions, bit fields, unmappable types: kept for layout only
+}
+
+struct CStruct {
+    str name
+    []CField fields
+    int size
+    int align
+    str unsupported     // why it can't be used by value (pointers to it still work)
+    bool hasHidden
+}
+
+struct CImports {
+    map[str]CFunc fns
+    map[str]CConst consts
+    map[str]ast.Type globals
+    map[str]CStruct structs
+    []str structOrder   // the order they were defined in
+}
+
+// A header to read: the path as written, and where it was written, for error messages.
+struct Header {
+    str path
+    str where
+}
+
+// Where a C type is used decides how `char *` looks in Finch: in function signatures it is a
+// `str`; inside structs, globals and behind pointers it stays a raw `ptr[char]`.
+struct Mapped {
+    ast.Type ty
+    str why
+    bool ok
+}
+
+struct Importer {
+    CImports out
+    ptr tu
+    str header
+    map[str]str recordNames     // record USR -> Finch name (a typedef name wins)
+    map[str]bool defining       // USR -> true while its fields are being mapped
+    int anon
+}
+
+fn text(CXString s) -> str {
+    out := clang_getCString(s)
+    clang_disposeString(s)
+    return out
+}
+
+fn ok(ast.Type t) -> Mapped {
+    return Mapped(ty: t, ok: true)
+}
+
+fn no(str why) -> Mapped {
+    return Mapped(why: why, ok: false)
+}
+
+fn fixed(ast.Type elem, int count) -> ast.Type {
+    t := ast.Type(kind: "fixed", count: count)
+    t.elem.push(elem)
+    return t
+}
+
+// ---------- the system's header folders ----------
+
+// Ask the system C compiler where it looks for headers, so we find the same stdio.h it would.
+fn systemIncludeArgs(str cc) -> []str {
+    []str dirs
+    tmp := host.tempDir() + "/finch_cc_dirs_" + str(host.pid()) + ".txt"
+    empty := host.tempDir() + "/finch_empty_" + str(host.pid()) + ".c"
+    write_file(empty, "")
+    host.run(cc + " -E -v -x c " + host.quote(empty) + " 2> " + host.quote(tmp) + " > " + host.nullDevice())
+    host.remove(empty)
+    if !file_exists(tmp) {
+        return dirs
+    }
+    inList := false
+    for line in read_file(tmp).split("\n") {
+        l := line.trim()
+        if l.starts_with("#include <...> search starts here:") {
+            inList = true
+            continue
+        }
+        if l.starts_with("End of search list.") {
+            break
+        }
+        if !inList || l.len == 0 {
+            continue
+        }
+        // macOS: "/.../Frameworks (framework directory)"
+        if l.ends_with(" (framework directory)") {
+            dirs.push("-iframework" + l.sub(0, l.len - 22))
+        } else {
+            dirs.push("-isystem" + l)
+        }
+    }
+    host.remove(tmp)
+    return dirs
+}
+
+// ---------- records ----------
+
+// The Finch name of a C record: its typedef name, its tag, or a made-up one.
+fn recordName(ptr[Importer] imp, CXType t) -> str {
+    decl := clang_getTypeDeclaration(t)
+    usr := text(clang_getCursorUSR(decl))
+    if imp.recordNames.has(usr) {
+        return imp.recordNames[usr]
+    }
+    name := text(clang_getCursorSpelling(decl))
+    if name.len == 0 || name.contains(" ") {
+        imp.anon += 1
+        name = "anon_struct_" + str(imp.anon)
+    }
+    imp.recordNames[usr] = name
+    return name
+}
+
+// Fill out.structs[name] for a complete record; returns its name, or "" if it can't be one.
+fn defineRecord(ptr[Importer] imp, CXType type) -> str {
+    t := clang_getCanonicalType(type)
+    decl := clang_getTypeDeclaration(t)
+    usr := text(clang_getCursorUSR(decl))
+    name := recordName(imp, t)
+    if imp.out.structs.has(name) || imp.defining.has(usr) {
+        return name
+    }
+    size := int(clang_Type_getSizeOf(t))
+    if size < 0 {
+        return ""           // incomplete (opaque) struct
+    }
+    imp.defining[usr] = true
+    s := CStruct(name: name, size: size, align: int(clang_Type_getAlignOf(t)))
+    if clang_getCursorKind(decl) == CXCursor_UnionDecl {
+        s.unsupported = "is a C union"
+    }
+    // the fields are collected by a callback that gets the importer and the struct through one pointer
+    ctx := FieldCtx(imp: imp, s: addr(s))
+    clang_Type_visitFields(t, addr(visitField), addr(ctx))
+    imp.defining.remove(usr)
+    imp.out.structs[name] = s
+    imp.out.structOrder.push(name)
+    return name
+}
+
+struct FieldCtx {
+    ptr[Importer] imp
+    ptr[CStruct] s
+}
+
+fn visitField(CXCursor field, ptr data) -> i32 {
+    ptr[FieldCtx] c = data
+    f := CField(name: text(clang_getCursorSpelling(field)))
+    ft := clang_getCanonicalType(clang_getCursorType(field))
+    f.offset = int(clang_Cursor_getOffsetOfField(field)) / 8
+    f.size = int(clang_Type_getSizeOf(ft))
+    f.align = int(clang_Type_getAlignOf(ft))
+    if clang_Cursor_isBitField(field) != 0 {
+        c.s.unsupported = "has bit fields"
+        f.hidden = true
+    } else if ft.kind == CXType_Record && clang_getCursorKind(clang_getTypeDeclaration(ft)) == CXCursor_UnionDecl {
+        f.hidden = true     // unions are kept as opaque bytes
+    } else {
+        m := mapType(c.imp, ft, false, false)
+        if m.ok {
+            f.ty = m.ty
+        } else {
+            f.hidden = true
+        }
+    }
+    if f.hidden {
+        c.s.hasHidden = true
+    }
+    if f.name.len == 0 {
+        f.hidden = true
+    }
+    c.s.fields.push(f)
+    return CXVisit_Continue
+}
+
+// ---------- types ----------
+
+fn sized(int size, bool signed) -> Mapped {
+    if size == 1 {
+        if signed {
+            return ok(ast.simple("i8"))
+        }
+        return ok(ast.simple("u8"))
+    }
+    if size == 2 {
+        if signed {
+            return ok(ast.simple("i16"))
+        }
+        return ok(ast.simple("u16"))
+    }
+    if size == 4 {
+        if signed {
+            return ok(ast.simple("i32"))
+        }
+        return ok(ast.simple("u32"))
+    }
+    if size == 8 {
+        if signed {
+            return ok(ast.simple("int"))
+        }
+        return ok(ast.simple("u64"))
+    }
+    return no("uses a " + str(size * 8) + "-bit number")
+}
+
+// C type -> Finch type. Not ok (with a reason) if Finch can't express it.
+// `signature`: a char * is a str (a function's parameters and result); anywhere else it stays a ptr[char].
+// A parameter that is a plain `char *` (not const) is a buffer C writes into, and stays a ptr[char];
+// only `const char *` is text going in. A result that is a char * is always text coming out.
+fn mapType(ptr[Importer] imp, CXType type, bool signature, bool param) -> Mapped {
+    t := clang_getCanonicalType(type)
+    size := int(clang_Type_getSizeOf(t))
+    k := t.kind
+    if k == CXType_Void {
+        return ok(ast.simple("void"))
+    }
+    if k == CXType_Bool {
+        return ok(ast.simple("bool"))
+    }
+    if k == CXType_Char_S || k == CXType_Char_U {
+        return ok(ast.simple("char"))
+    }
+    if k == CXType_SChar || k == CXType_Short || k == CXType_Int || k == CXType_Long || k == CXType_LongLong {
+        return sized(size, true)
+    }
+    if k == CXType_UChar || k == CXType_UShort || k == CXType_UInt || k == CXType_ULong || k == CXType_ULongLong {
+        return sized(size, false)
+    }
+    if k == CXType_Enum {
+        return sized(size, true)
+    }
+    if k == CXType_Float {
+        return ok(ast.simple("f32"))
+    }
+    if k == CXType_Double {
+        return ok(ast.simple("float"))
+    }
+    if k == CXType_Pointer {
+        pointee := clang_getCanonicalType(clang_getPointeeType(t))
+        if (pointee.kind == CXType_Char_S || pointee.kind == CXType_Char_U) && signature {
+            if !param || clang_isConstQualifiedType(pointee) != 0 {
+                return ok(ast.simple("str"))    // a C string
+            }
+        }
+        if pointee.kind == CXType_Void || pointee.kind == CXType_FunctionProto || pointee.kind == CXType_FunctionNoProto {
+            return ok(ast.simple("ptr"))        // an opaque `ptr` you can pass around
+        }
+        inner := mapType(imp, pointee, false, false)
+        if !inner.ok || inner.ty.kind == "void" || inner.ty.kind == "fixed" {
+            return ok(ast.simple("ptr"))
+        }
+        return ok(ast.ptrTo(inner.ty))
+    }
+    if k == CXType_Record {
+        if clang_getCursorKind(clang_getTypeDeclaration(t)) == CXCursor_UnionDecl {
+            return no("uses a C union by value")
+        }
+        name := defineRecord(imp, t)
+        if name.len == 0 {
+            return no("uses an incomplete C struct by value")
+        }
+        return ok(ast.Type(kind: "named", name: name, module: "C"))
+    }
+    if k == CXType_ConstantArray {
+        inner := mapType(imp, clang_getArrayElementType(t), false, false)
+        if !inner.ok {
+            return inner
+        }
+        return ok(fixed(inner.ty, int(clang_getArraySize(t))))
+    }
+    if k == CXType_LongDouble {
+        return no("uses long double")
+    }
+    return no("uses the C type '" + text(clang_getTypeSpelling(t)) + "'")
+}
+
+// ---------- #define numbers ----------
+
+struct Number {
+    CConst c
+    bool ok
+}
+
+// "0x1F", "010", "10UL" -> the value, and whether the text was a whole number
+fn parseInt(str lit) -> Number {
+    s := lit
+    base := 10
+    if s.starts_with("0x") || s.starts_with("0X") {
+        base = 16
+        s = s.sub(2, s.len)
+    } else if s.len > 1 && s[0] == '0' {
+        base = 8
+        s = s.sub(1, s.len)
+    }
+    n := 0
+    seen := false
+    i := 0
+    while i < s.len {
+        c := s[i]
+        d := 99
+        if c >= '0' && c <= '9' {
+            d = int(c) - int('0')
+        } else if c >= 'a' && c <= 'f' {
+            d = int(c) - int('a') + 10
+        } else if c >= 'A' && c <= 'F' {
+            d = int(c) - int('A') + 10
+        }
+        if d >= base {
+            break
+        }
+        n = n * base + d
+        seen = true
+        i += 1
+    }
+    // what is left may only be suffixes: 10UL
+    while i < s.len {
+        if !"uUlL".contains(str(s[i])) {
+            return Number()
+        }
+        i += 1
+    }
+    if !seen && base != 8 {
+        return Number()
+    }
+    return Number(c: CConst(i: n), ok: true)
+}
+
+// Simple #defines: a single number, maybe negative, maybe in parentheses.
+fn macroValue(ptr[Importer] imp, CXCursor c) -> Number {
+    ptr[CXToken] tokens = null
+    u32 n = 0
+    clang_tokenize(imp.tu, clang_getCursorExtent(c), addr(tokens), addr(n))
+    []str parts
+    for k in 1..int(n) {            // token 0 is the macro's name
+        if clang_getTokenKind(tokens[k]) == CXToken_Comment {
+            continue
+        }
+        parts.push(text(clang_getTokenSpelling(imp.tu, tokens[k])))
+    }
+    clang_disposeTokens(imp.tu, tokens, n)
+
+    while parts.len >= 2 && parts[0] == "(" && parts[parts.len - 1] == ")" {
+        parts.remove(0)
+        parts.pop()
+    }
+    neg := false
+    if parts.len == 2 && parts[0] == "-" {
+        neg = true
+        parts.remove(0)
+    }
+    if parts.len != 1 {
+        return Number()
+    }
+    lit := parts[0]
+    if lit.len == 0 || !((lit[0] >= '0' && lit[0] <= '9') || lit[0] == '.') {
+        return Number()
+    }
+    isFloat := (lit.contains(".") || lit.contains("e") || lit.contains("E")) && !lit.starts_with("0x")
+    if isFloat {
+        body := lit
+        while body.len > 0 && "fFlL".contains(str(body[body.len - 1])) {
+            body = body.sub(0, body.len - 1)
+        }
+        v := float(body) or {
+            return Number()
+        }
+        if neg {
+            v = 0.0 - v
+        }
+        return Number(c: CConst(isFloat: true, f: v, text: body), ok: true)
+    }
+    r := parseInt(lit)
+    if r.ok && neg {
+        r.c.i = 0 - r.c.i
+    }
+    return r
+}
+
+// ---------- the top level ----------
+
+fn visitTop(CXCursor c, CXCursor parent, ptr data) -> i32 {
+    ptr[Importer] imp = data
+    visit(imp, c)
+    return CXChildVisit_Continue
+}
+
+fn visit(ptr[Importer] imp, CXCursor c) {
+    name := text(clang_getCursorSpelling(c))
+    kind := clang_getCursorKind(c)
+    if kind == CXCursor_TypedefDecl {
+        // typedef struct {...} Name;  ->  the struct is called Name in Finch
+        u := clang_getCanonicalType(clang_getTypedefDeclUnderlyingType(c))
+        if u.kind == CXType_Record {
+            usr := text(clang_getCursorUSR(clang_getTypeDeclaration(u)))
+            // prefer the typedef name, unless the struct is already known under its tag
+            used := imp.recordNames.has(usr) && imp.out.structs.has(imp.recordNames[usr])
+            if !used && !imp.out.structs.has(name) {
+                imp.recordNames[usr] = name
+            }
+        }
+    } else if kind == CXCursor_FunctionDecl {
+        if imp.out.fns.has(name) {
+            return
+        }
+        f := CFunc(name: name, header: imp.header)
+        if clang_Cursor_getStorageClass(c) == CX_SC_Static {
+            f.unsupported = "is a static inline C function (it has no code to link against)"
+            imp.out.fns[name] = f
+            return
+        }
+        ft := clang_getCanonicalType(clang_getCursorType(c))
+        if ft.kind == CXType_FunctionNoProto {
+            f.unsupported = "has no parameter list in its C declaration"
+            imp.out.fns[name] = f
+            return
+        }
+        r := mapType(imp, clang_getResultType(ft), true, false)
+        if r.ok {
+            f.ret = r.ty
+        } else {
+            f.unsupported = r.why
+        }
+        n := int(clang_getNumArgTypes(ft))
+        for k in 0..n {
+            if f.unsupported.len > 0 {
+                break
+            }
+            p := mapType(imp, clang_getArgType(ft, u32(k)), true, true)
+            if p.ok {
+                f.params.push(p.ty)
+            } else {
+                f.unsupported = p.why
+            }
+        }
+        f.variadic = clang_isFunctionTypeVariadic(ft) != 0
+        imp.out.fns[name] = f
+    } else if kind == CXCursor_VarDecl {
+        if clang_Cursor_getStorageClass(c) != CX_SC_Extern || imp.out.globals.has(name) {
+            return
+        }
+        g := mapType(imp, clang_getCursorType(c), false, false)
+        if g.ok {
+            imp.out.globals[name] = g.ty
+        }
+    } else if kind == CXCursor_StructDecl {
+        if clang_isCursorDefinition(c) != 0 && name.len > 0 && !name.contains(" ") {
+            usr := text(clang_getCursorUSR(c))
+            if !imp.recordNames.has(usr) {
+                imp.recordNames[usr] = name
+            }
+        }
+    } else if kind == CXCursor_EnumDecl {
+        clang_visitChildren(c, addr(visitTop), imp)
+    } else if kind == CXCursor_EnumConstantDecl {
+        if !imp.out.consts.has(name) {
+            imp.out.consts[name] = CConst(i: int(clang_getEnumConstantDeclValue(c)))
+        }
+    } else if kind == CXCursor_MacroDefinition {
+        if clang_Cursor_isMacroBuiltin(c) != 0 || clang_Cursor_isMacroFunctionLike(c) != 0 {
+            return
+        }
+        v := macroValue(imp, c)
+        if v.ok && !imp.out.consts.has(name) {
+            imp.out.consts[name] = v.c
+        }
+    }
+}
+
+// Read every header in `headers`; `dirs` are searched first for "local.h" headers.
+// `target` is the LLVM triple the program is built for ("" = this system): sizes and headers depend on it.
+fn importHeaders([]Header headers, []str dirs, str target, bool windows, str ccFor) -> CImports! {
+    imp := Importer()
+    if headers.len == 0 {
+        return imp.out
+    }
+    []str args = ["-x", "c", "-std=gnu11"]
+    if target.len > 0 {
+        args.push("--target=" + target)
+    }
+    if windows {
+        args.push("-D_USE_MATH_DEFINES")       // M_PI and friends, as on Linux
+    }
+    for d in dirs {
+        args.push("-I" + d)
+    }
+    for d in systemIncludeArgs(ccFor) {
+        args.push(d)
+    }
+    []ptr[char] argv
+    for i in 0..args.len {
+        argv.push(args[i].ptr)
+    }
+    index := clang_createIndex(0, 0)
+    for h in headers {
+        src := "#include \"" + h.path + "\"\n"
+        file := host.unsavedFile("finch_import.c", src)
+        ptr tu = null
+        flags := CXTranslationUnit_DetailedPreprocessingRecord | CXTranslationUnit_SkipFunctionBodies
+        err := clang_parseTranslationUnit2(index, "finch_import.c", argv.ptr, i32(argv.len), addr(file), 1, u32(flags), addr(tu))
+        if err != CXError_Success || tu == null {
+            return error(h.where + ": error: couldn't read C header '" + h.path + "'")
+        }
+        nd := int(clang_getNumDiagnostics(tu))
+        for k in 0..nd {
+            d := clang_getDiagnostic(tu, u32(k))
+            if clang_getDiagnosticSeverity(d) >= CXDiagnostic_Error {
+                msg := text(clang_getDiagnosticSpelling(d))
+                clang_disposeDiagnostic(d)
+                if msg.contains("file not found") {
+                    // "'GL/gl.h' file not found": it may be a header that this one includes
+                    missing := msg.sub(1, msg.sub(1, msg.len).find("'") + 1)
+                    if missing == h.path {
+                        return error(h.where + ": error: can't find the C header '" + h.path + "'")
+                    }
+                    return error(h.where + ": error: can't find the C header '" + missing + "', which '" + h.path + "' includes (is its library's development package installed?)")
+                }
+                return error(h.where + ": error: C header '" + h.path + "' has an error: " + msg)
+            }
+            clang_disposeDiagnostic(d)
+        }
+        imp.tu = tu
+        imp.header = h.path
+        clang_visitChildren(clang_getTranslationUnitCursor(tu), addr(visitTop), addr(imp))
+        clang_disposeTranslationUnit(tu)
+    }
+    clang_disposeIndex(index)
+    return imp.out
+}

src/cimport.h

@@ -1,56 +0,0 @@
-#pragma once
-
-#include "ast.h"
-
-#include <map>
-#include <string>
-#include <unordered_map>
-#include <vector>
-
-// What Finch learned from `import "something.h"`.
-// C structs by value appear in types as Named{name, module "C"}.
-
-struct CFunc {
-    std::string name;
-    std::string header;  // the import it came from
-    Type ret;
-    std::vector<Type> params;
-    bool variadic = false;
-    std::string unsupported;  // non-empty: why Finch can't call it (yet)
-};
-
-struct CConst {  // enum values and simple #define numbers
-    Type type;
-    long long i = 0;
-    double f = 0;
-};
-
-struct CGlobal {  // extern variables like stdout
-    Type type;
-};
-
-struct CField {
-    std::string name;
-    Type type;
-    long long offset = 0;  // bytes
-    long long size = 0, align = 1;
-    bool hidden = false;   // unions, bitfields, unmappable types: kept for layout only
-};
-
-struct CStruct {
-    std::string name;
-    std::vector<CField> fields;
-    long long size = 0, align = 1;
-    std::string unsupported;  // why it can't be used by value (pointers to it still work)
-    bool hasHidden = false;
-};
-
-struct CImports {
-    std::unordered_map<std::string, CFunc> fns;
-    std::unordered_map<std::string, CConst> consts;
-    std::unordered_map<std::string, CGlobal> globals;
-    std::map<std::string, CStruct> structs;
-};
-
-// `dirs`: folders searched first for "local.h" headers (the .fch files' folders).
-CImports importHeaders(const std::vector<Import> &imports, const std::vector<std::string> &dirs);

src/codegen.h

@@ -1,15 +0,0 @@
-#pragma once
-
-#include "ast.h"
-#include "cimport.h"
-
-#include <llvm/IR/LLVMContext.h>
-#include <llvm/IR/Module.h>
-#include <llvm/Target/TargetMachine.h>
-
-#include <memory>
-
-// All files of the program (the main file first, then its modules) become one LLVM module.
-// `tm` describes the machine we compile for (sizes, alignment), which shapes the IR.
-std::unique_ptr<llvm::Module> generate(const std::vector<Program> &progs, const CImports &c, llvm::LLVMContext &ctx,
-                                       llvm::TargetMachine &tm, bool debug);

src/codegen_builtins.cpp

@@ -1,905 +0,0 @@
-// Code generation, part 3: calls, built-in functions, conversions and methods.
-
-#include "codegen_impl.h"
-#include "builtins_doc.h"
-
-using namespace llvm;
-
-namespace finch {
-
-bool Codegen::isBuiltin(const std::string &n) {
-    static const std::set<std::string> names = {"print", "addr", "input", "new", "free", "read_file", "write_file",
-                                                "file_exists", "delete_file", "exit", "shell", "error"};
-    FType t;
-    return names.count(n) || typeFromName(n, t);
-}
-
-// Help people who forgot an import.
-std::string Codegen::headerHint(const std::string &name) {
-    static const std::unordered_map<std::string, const char *> known = {
-        {"printf", "stdio.h"},  {"puts", "stdio.h"},   {"putchar", "stdio.h"}, {"scanf", "stdio.h"},
-        {"fopen", "stdio.h"},   {"getchar", "stdio.h"}, {"sqrt", "math.h"},     {"pow", "math.h"},
-        {"sin", "math.h"},      {"cos", "math.h"},     {"floor", "math.h"},    {"fabs", "math.h"},
-        {"malloc", "stdlib.h"}, {"rand", "stdlib.h"},  {"srand", "stdlib.h"},  {"abs", "stdlib.h"},
-        {"atoi", "stdlib.h"},   {"strlen", "string.h"}, {"strcpy", "string.h"}, {"memcpy", "string.h"},
-        {"time", "time.h"},     {"sleep", "unistd.h"}, {"usleep", "unistd.h"},
-    };
-    auto it = known.find(name);
-    return it == known.end() ? "" : std::string(" (it's from C: add  import \"") + it->second + "\"  at the top)";
-}
-
-void Codegen::checkArgs(const std::vector<ExprPtr> &args, const std::vector<std::string> &names, size_t want, Pos p,
-                        const std::string &name, bool variadic) {
-    for (size_t i = 0; i < names.size(); i++)
-        if (!names[i].empty())
-            failAt(args[i]->pos.file, args[i]->pos.line, args[i]->pos.col, "named arguments (" + names[i] + ": ...) are only for creating structs");
-    if (args.size() == want || (variadic && args.size() > want)) return;
-    failAt(p.file, p.line, p.col, "'" + name + "' takes " + (variadic ? "at least " : "") + std::to_string(want) +
-                                      " argument(s), but got " + std::to_string(args.size()));
-}
-
-Function *Codegen::libc(const char *name, llvm::Type *ret, std::vector<llvm::Type *> params, bool vararg) {
-    FunctionCallee c = mod->getOrInsertFunction(name, FunctionType::get(ret, params, vararg));
-    return cast<Function>(c.getCallee());
-}
-
-// The runtime (runtime/finch_rt.c), declared on first use.
-Function *Codegen::rt(const std::string &name) {
-    if (Function *f = mod->getFunction(name)) return f;
-    llvm::Type *P = b.getPtrTy(), *I = b.getInt64Ty(), *I32 = b.getInt32Ty(), *D = b.getDoubleTy(), *V = b.getVoidTy();
-    struct Sig { llvm::Type *ret; std::vector<llvm::Type *> params; };
-    std::map<std::string, Sig> sigs = {
-        {"finch_panic", {V, {P, I, P}}},
-        {"finch_panic_index", {V, {P, I, I, I}}},
-        {"finch_alloc", {P, {I}}},
-        {"finch_zalloc", {P, {I}}},
-        {"finch_str_copy", {V, {P, P}}},
-        {"finch_str_own", {V, {P}}},
-        {"finch_str_drop", {V, {P}}},
-        {"finch_str_from_c", {V, {P, P}}},
-        {"finch_str_concat", {V, {P, P, P}}},
-        {"finch_str_eq", {I32, {P, P}}},
-        {"finch_str_cmp", {I, {P, P}}},
-        {"finch_str_from_int", {V, {P, I}}},
-        {"finch_str_from_uint", {V, {P, I}}},
-        {"finch_str_from_float", {V, {P, D}}},
-        {"finch_str_from_char", {V, {P, b.getInt8Ty()}}},
-        {"finch_str_from_bool", {V, {P, I32}}},
-        {"finch_str_to_int", {I, {P, P, I}}},
-        {"finch_str_to_float", {D, {P, P, I}}},
-        {"finch_str_sub", {V, {P, P, I, I, P, I}}},
-        {"finch_str_find", {I, {P, P}}},
-        {"finch_str_starts", {I32, {P, P}}},
-        {"finch_str_ends", {I32, {P, P}}},
-        {"finch_str_trim", {V, {P, P}}},
-        {"finch_str_upper", {V, {P, P}}},
-        {"finch_str_lower", {V, {P, P}}},
-        {"finch_str_replace", {V, {P, P, P, P}}},
-        {"finch_str_split", {V, {P, P, P}}},
-        {"finch_str_join", {V, {P, P, P}}},
-        {"finch_str_repeat", {V, {P, P, I}}},
-        {"finch_str_from_bytes", {V, {P, P}}},
-        {"finch_arr_reserve", {V, {P, I, I}}},
-        {"finch_arr_make", {V, {P, I, I}}},
-        {"finch_arr_resize", {V, {P, I, I}}},
-        {"finch_arr_clone_raw", {V, {P, P, I}}},
-        {"finch_arr_free", {V, {P}}},
-        {"finch_arr_insert_gap", {V, {P, I, I, P, I}}},
-        {"finch_arr_remove_gap", {V, {P, I, I}}},
-        {"finch_bytes_from_str", {V, {P, P}}},
-        {"finch_args", {V, {P, I32, P}}},
-        {"finch_input", {V, {P, P}}},
-        {"finch_file_exists", {I32, {P}}},
-        {"finch_read_file", {V, {P, P, P, I}}},
-        {"finch_write_file", {I32, {P, P}}},
-        {"finch_shell", {I, {P}}},
-        {"finch_delete_file", {I32, {P}}},
-        {"finch_std_stream", {P, {I32}}},
-        {"finch_str_try_int", {I32, {P, P, P}}},
-        {"finch_str_try_float", {I32, {P, P, P}}},
-        {"finch_try_read_file", {I32, {P, P, P}}},
-        {"finch_try_write_file", {I32, {P, P, P}}},
-        {"finch_try_delete_file", {I32, {P, P}}},
-        {"finch_report_error", {V, {P}}},
-        {"finch_map_find", {I, {P, P, I, I, I32}}},
-        {"finch_map_slot", {I, {P, P, I, I, I32, P}}},
-        {"finch_map_remove_at", {V, {P, I, I}}},
-        {"finch_map_clear", {V, {P}}},
-        {"finch_map_free", {V, {P}}},
-        {"finch_map_clone_raw", {V, {P, P, I}}},
-        {"finch_map_missing", {V, {P, I, P}}},
-        {"finch_map_changed", {V, {P, I}}},
-        {"finch_buf_add", {V, {P, P, I}}},
-        {"finch_buf_int", {V, {P, I}}},
-        {"finch_buf_uint", {V, {P, I}}},
-        {"finch_buf_float", {V, {P, D}}},
-        {"finch_buf_bool", {V, {P, I32}}},
-        {"finch_buf_ptr", {V, {P, P}}},
-        {"finch_buf_char", {V, {P, b.getInt8Ty(), I32}}},
-        {"finch_buf_str", {V, {P, P, I32}}},
-        {"finch_buf_print", {V, {P}}},
-    };
-    auto it = sigs.find(name);
-    if (it == sigs.end()) {
-        std::fprintf(stderr, "internal compiler error: unknown runtime function %s\n", name.c_str());
-        std::exit(2);
-    }
-    Function *f = Function::Create(FunctionType::get(it->second.ret, it->second.params, false), Function::ExternalLinkage,
-                                   name, mod.get());
-    if (name == "finch_panic" || name == "finch_panic_index" || name == "finch_map_missing" || name == "finch_map_changed") {
-        f->addFnAttr(Attribute::NoReturn);
-        f->addFnAttr(Attribute::Cold);
-    }
-    if (name == "finch_str_from_char" || name == "finch_buf_char") f->addParamAttr(1, Attribute::SExt);
-    return f;
-}
-
-// ---------- runtime errors ----------
-
-Value *Codegen::fileName(Pos p) {
-    std::string key = "file." + std::to_string(p.file);
-    if (GlobalVariable *g = mod->getNamedGlobal("finch." + key)) return g;
-    GlobalVariable *g = b.CreateGlobalString(g_files[p.file].path, "finch." + key);
-    return g;
-}
-
-void Codegen::panicIf(Value *cond, const std::string &msg, Pos p) {
-    BasicBlock *bad = newBlock("panic");
-    BasicBlock *ok = newBlock("ok");
-    b.CreateCondBr(cond, bad, ok);
-    b.SetInsertPoint(bad);
-    b.CreateCall(rt("finch_panic"), {fileName(p), b.getInt64(p.line), b.CreateGlobalString(msg, "panic.msg")});
-    b.CreateUnreachable();
-    b.SetInsertPoint(ok);
-}
-
-void Codegen::boundsCheck(Value *i, Value *len, Pos p) {
-    BasicBlock *bad = newBlock("out.of.range");
-    BasicBlock *ok = newBlock("in.range");
-    b.CreateCondBr(b.CreateICmpUGE(i, len), bad, ok);  // unsigned: catches negative indexes too
-    b.SetInsertPoint(bad);
-    b.CreateCall(rt("finch_panic_index"), {fileName(p), b.getInt64(p.line), i, len});
-    b.CreateUnreachable();
-    b.SetInsertPoint(ok);
-}
-
-// Dividing by zero is undefined in C; in Finch it is a clear error.
-void Codegen::checkDivisor(const Value_ &l, const Value_ &r, Pos p) {
-    auto *c = dyn_cast<ConstantInt>(r.v);
-    if (c && c->isZero()) failAt(p.file, p.line, p.col, "division by zero");
-    if (!c) panicIf(b.CreateICmpEQ(r.v, ConstantInt::get(r.v->getType(), 0)), "division by zero", p);
-    // the smallest signed number divided by -1 doesn't fit anywhere
-    if (l.type.isSigned() && (!c || c->isMinusOne())) {
-        Value *min = ConstantInt::get(l.v->getType(), APInt::getSignedMinValue(l.type.bits()));
-        Value *minusOne = ConstantInt::get(r.v->getType(), -1, true);
-        panicIf(b.CreateAnd(b.CreateICmpEQ(l.v, min), b.CreateICmpEQ(r.v, minusOne)),
-                "division overflows (the smallest number divided by -1)", p);
-    }
-}
-
-Value *Codegen::cGlobal(const std::string &name) {
-    if (GlobalVariable *gv = mod->getNamedGlobal(name)) return gv;
-    FType t = resolve(cimports.globals.at(name).type, Pos{});
-    return new GlobalVariable(*mod, ty(t), false, GlobalValue::ExternalLinkage, nullptr, name);
-}
-
-// ---------- calls ----------
-
-static std::string docHover(const BuiltinDoc &d) {
-    return "```finch\n" + std::string(d.signature) + "\n```\n" + d.doc;
-}
-
-static std::string cSignature(const CFunc &f) {
-    std::string s = f.ret.show() + " " + f.name + "(";
-    for (size_t i = 0; i < f.params.size(); i++) s += (i ? ", " : "") + f.params[i].show();
-    if (f.variadic) s += f.params.empty() ? "..." : ", ...";
-    return s + ")";
-}
-
-Value_ Codegen::call(const CallExpr &c) {
-    const std::string &n = c.callee;
-    Pos p = c.pos;
-    if (g_index)
-        for (const BuiltinDoc &d : kBuiltins)
-            if (n == d.name) note(p, n.size(), docHover(d));
-    auto one = [&](const char *what) -> const Expr & {
-        checkArgs(c.args, c.argNames, 1, p, n);
-        (void)what;
-        return *c.args[0];
-    };
-
-    bool canFail = &c == fallibleTarget;  // inside `... or ...` / `try ...`: report failures instead of stopping
-    // a failure: set the flag and message that `or` / `try` look at
-    auto failedIf = [&](Value *ok, Value *errSlot) {
-        fallibleFailed = b.CreateICmpEQ(ok, b.getInt32(0));
-        fallibleMsg = b.CreateLoad(ty(FType::Str), errSlot);
-    };
-    if (n == "error")
-        failAt(p.file, p.line, p.col, "error(...) makes an error to return from a function that can fail: return error(\"...\")");
-    if (n == "print") {
-        checkArgs(c.args, c.argNames, 0, p, n, true);
-        return print(c.args, p);
-    }
-    if (n == "addr") {
-        checkArgs(c.args, c.argNames, 1, p, n);
-        return addrOf(c.args, p);
-    }
-    if (n == "input") {
-        if (c.args.size() > 1) checkArgs(c.args, c.argNames, 1, p, n);
-        Value_ prompt = c.args.empty() ? Value_{strConst(""), FType::Str, false, true}
-                                       : coerce(expr(*c.args[0]), FType::Str, c.args[0]->pos, "the question");
-        Value *out = tmpOf(ty(FType::Str));
-        b.CreateCall(rt("finch_input"), {out, tmp(prompt.v)});
-        release(prompt);
-        return {b.CreateLoad(ty(FType::Str), out), FType::Str, false, true};
-    }
-    if (n == "new") {
-        const Expr &a = one("value");
-        Value_ v = expr(a);
-        if (v.type.kind == FType::Void || v.type.kind == FType::Null)
-            failAt(a.pos.file, a.pos.line, a.pos.col, "new(...) needs a value to put in memory, like new(Point(x: 1, y: 2))");
-        Value *mem = b.CreateCall(rt("finch_alloc"), {elemSize(v.type)});
-        b.CreateStore(own(v), mem);
-        return {mem, FType::ptrTo(v.type)};
-    }
-    if (n == "free") {
-        const Expr &a = one("pointer");
-        Value_ v = expr(a);
-        if (!v.type.isPtr())
-            failAt(a.pos.file, a.pos.line, a.pos.col, "free(...) is only for pointers from new(...) or C; arrays, str and structs are freed by Finch at the end of their block");
-        if (v.type.elem && owning(*v.type.elem)) {
-            BasicBlock *drop = newBlock("free.drop"), *done = newBlock("free.done");
-            b.CreateCondBr(b.CreateIsNull(v.v), done, drop);
-            b.SetInsertPoint(drop);
-            dropAt(v.v, *v.type.elem);
-            b.CreateBr(done);
-            b.SetInsertPoint(done);
-        }
-        b.CreateCall(libc("free", b.getVoidTy(), {b.getPtrTy()}), {v.v});
-        return {nullptr, FType::Void};
-    }
-    if (n == "exit") {
-        Value *code = coerce(expr(one("code")), FType::I32, c.args[0]->pos, "the exit code").v;
-        b.CreateCall(libc("fflush", b.getInt32Ty(), {b.getPtrTy()}), {ConstantPointerNull::get(b.getPtrTy())});
-        b.CreateCall(libc("exit", b.getVoidTy(), {b.getInt32Ty()}), {code});
-        return {nullptr, FType::Void};
-    }
-    if (n == "delete_file") {
-        Value_ path = coerce(expr(one("path")), FType::Str, c.args[0]->pos, "the file name");
-        Value *ss = tmpOf(ty(FType::Str));
-        b.CreateCall(rt("finch_str_copy"), {ss, tmp(path.v)});  // NUL-terminated copy
-        if (canFail) {
-            Value *err = tmp(zero(FType::Str));
-            failedIf(b.CreateCall(rt("finch_try_delete_file"), {ss, err}), err);
-            dropAt(ss, FType::Str);
-            release(path);
-            return {nullptr, FType::Void};
-        }
-        Value *r = b.CreateCall(rt("finch_delete_file"), {ss});
-        dropAt(ss, FType::Str);
-        release(path);
-        return {b.CreateICmpNE(r, b.getInt32(0)), FType::Bool};
-    }
-    if (n == "read_file" || n == "file_exists") {
-        Value_ path = coerce(expr(one("path")), FType::Str, c.args[0]->pos, "the file name");
-        Value *pp = tmp(path.v);
-        Value_ res;
-        if (n == "file_exists") {
-            res = {b.CreateICmpNE(b.CreateCall(rt("finch_file_exists"), {pp}), b.getInt32(0)), FType::Bool};
-        } else if (canFail) {
-            Value *out = tmp(zero(FType::Str)), *err = tmp(zero(FType::Str));
-            failedIf(b.CreateCall(rt("finch_try_read_file"), {out, pp, err}), err);
-            res = {b.CreateLoad(ty(FType::Str), out), FType::Str, false, true};
-        } else {
-            Value *out = tmpOf(ty(FType::Str));
-            b.CreateCall(rt("finch_read_file"), {out, pp, fileName(p), b.getInt64(p.line)});
-            res = {b.CreateLoad(ty(FType::Str), out), FType::Str, false, true};
-        }
-        release(path);
-        return res;
-    }
-    if (n == "shell") {
-        Value_ cmd = coerce(expr(one("command")), FType::Str, c.args[0]->pos, "the command");
-        Value *ss = tmpOf(ty(FType::Str));
-        b.CreateCall(rt("finch_str_copy"), {ss, tmp(cmd.v)});  // a heap copy is always NUL-terminated
-        Value *r = b.CreateCall(rt("finch_shell"), {ss});
-        dropAt(ss, FType::Str);
-        release(cmd);
-        return {r, FType::I64};
-    }
-    if (n == "write_file") {
-        checkArgs(c.args, c.argNames, 2, p, n);
-        Value_ path = coerce(expr(*c.args[0]), FType::Str, c.args[0]->pos, "the file name");
-        Held held(*this);
-        hold(path);
-        Value_ text = coerce(expr(*c.args[1]), FType::Str, c.args[1]->pos, "the text");
-        if (canFail) {
-            Value *err = tmp(zero(FType::Str));
-            failedIf(b.CreateCall(rt("finch_try_write_file"), {tmp(path.v), tmp(text.v), err}), err);
-            release(path);
-            release(text);
-            return {nullptr, FType::Void};
-        }
-        Value *ok = b.CreateCall(rt("finch_write_file"), {tmp(path.v), tmp(text.v)});
-        release(path);
-        release(text);
-        return {b.CreateICmpNE(ok, b.getInt32(0)), FType::Bool};
-    }
-    FType target;
-    if (typeFromName(n, target)) {
-        checkArgs(c.args, c.argNames, 1, p, n);
-        return convert(target, c.args, p, n, canFail);
-    }
-
-    ModuleScope &m = modules[curModule];
-    if (auto it = m.fns.find(n); it != m.fns.end()) {
-        note(p, n.size(), "```finch\n" + signature(it->second) + "\n```", it->second.decl->namePos);
-        return callFinch(it->second, c.args, c.argNames, p, n, &c);
-    }
-    if (StructInfo *s = findStruct("", n, false)) {
-        note(p, n.size(), structHover(s), s->decl ? s->decl->namePos : Pos{});
-        return construct(s, c.args, c.argNames, p);
-    }
-    if (auto cf = cimports.fns.find(n); cf != cimports.fns.end()) {
-        note(p, n.size(), "C function from `" + cf->second.header + "`\n```c\n" + cSignature(cf->second) + "\n```");
-        checkArgs(c.args, c.argNames, cf->second.params.size(), p, n, cf->second.variadic);
-        return callC(cf->second, c.args, p);
-    }
-    if (lookup(n)) failAt(p.file, p.line, p.col, "'" + n + "' is a variable, not a function");
-    for (auto &[mname, ms] : modules)
-        if (ms.fns.count(n) && mname != curModule && !mname.empty())
-            failAt(p.file, p.line, p.col, "there is no function named '" + n + "' here; it is in the module " + mname +
-                                              " (write " + mname + "." + n + "(...)" + (m.imports.count(mname) ? "" : " and add: import " + mname) + ")");
-    failAt(p.file, p.line, p.col, "there is no function named '" + n + "'" + headerHint(n));
-}
-
-Value_ Codegen::callFinch(const Fn &fn, const std::vector<ExprPtr> &args, const std::vector<std::string> &names, Pos p,
-                          const std::string &shown, const Expr *site, Value *self, const std::string &selfRoot) {
-    const FnDecl &d = *fn.decl;
-    if (fn.module.empty() && d.name == "main" && !fn.recv) failAt(p.file, p.line, p.col, "main can't be called, it is where the program starts");
-    if (fn.fallible && site != fallibleTarget)
-        failAt(p.file, p.line, p.col, "'" + shown + "' can fail, so say what happens then:  " + shown + "(...) or <value>,  " + shown +
-                                          "(...) or { ... },  or  try " + shown + "(...)");
-    checkArgs(args, names, fn.params.size(), p, shown);
-    std::vector<Value *> vals;
-    std::vector<Value_> fresh;
-    Held held(*this);
-    if (self) vals.push_back(self);
-    for (size_t i = 0; i < args.size(); i++) {
-        Value_ v = coerce(exprWant(*args[i], fn.params[i]), fn.params[i], args[i]->pos, "argument '" + d.params[i].name + "'");
-        // a method that changes self gets its own copy of anything that lives inside self (p.add(p.items))
-        if (fn.mutatesSelf && !selfRoot.empty() && owning(v.type) && !v.fresh && rootVar(*args[i]) == selfRoot)
-            v = {copyValue(v.v, v.type), v.type, false, true};
-        vals.push_back(v.v);  // owning values are lent: the function never drops them
-        if (v.fresh) fresh.push_back(v);
-        hold(v);
-    }
-    setLoc(p);
-    Value *r = b.CreateCall(fn.llvm, vals);
-    for (auto &v : fresh) release(v);
-    if (fn.fallible) {
-        fallibleFailed = b.CreateNot(b.CreateExtractValue(r, 0));
-        fallibleMsg = b.CreateExtractValue(r, 2);
-        if (fn.ret.kind == FType::Void) return {nullptr, FType::Void};
-        return {b.CreateExtractValue(r, 1), fn.ret, false, owning(fn.ret)};
-    }
-    if (fn.ret.kind == FType::Void) return {nullptr, FType::Void};
-    return {r, fn.ret, false, owning(fn.ret)};
-}
-
-Value_ Codegen::construct(StructInfo *s, const std::vector<ExprPtr> &args, const std::vector<std::string> &names, Pos p) {
-    resolveStruct(s);
-    FType t(FType::Struct);
-    t.info = s;
-    t.name = s->name;
-    t.module = s->module == "C" ? "" : s->module;
-    std::vector<const StructInfo::F *> fields;
-    for (auto &f : s->fields) fields.push_back(&f);
-
-    bool named = !names.empty() && !names[0].empty();
-    std::vector<const Expr *> given(fields.size(), nullptr);
-    for (size_t i = 0; i < args.size(); i++) {
-        Pos ap = args[i]->pos;
-        if (names[i].empty() == named)
-            failAt(ap.file, ap.line, ap.col, "give either all fields by name (x: 1, y: 2) or none (1, 2), not a mix");
-        if (!named) {
-            if (args.size() != fields.size())
-                failAt(p.file, p.line, p.col, s->name + " has " + std::to_string(fields.size()) + " fields, but got " +
-                                                  std::to_string(args.size()) + " values (or name them: " + s->name + "(field: value))");
-            given[i] = args[i].get();
-            continue;
-        }
-        size_t k = 0;
-        while (k < fields.size() && fields[k]->name != names[i]) k++;
-        if (k == fields.size()) failAt(ap.file, ap.line, ap.col, s->name + " has no field '" + names[i] + "'");
-        if (given[k]) failAt(ap.file, ap.line, ap.col, "the field '" + names[i] + "' is given twice");
-        given[k] = args[i].get();
-    }
-
-    Value *v = zero(t);
-    Held held(*this);
-    for (size_t k = 0; k < fields.size(); k++) {
-        const StructInfo::F &f = *fields[k];
-        Value_ fv;
-        if (given[k]) {
-            fv = coerce(exprWant(*given[k], f.type), f.type, given[k]->pos, "the field '" + f.name + "'");
-        } else if (f.init) {
-            // a default value is evaluated where the struct is defined, without the caller's variables
-            std::vector<Scope> saved;
-            std::swap(saved, scopes);
-            scopes.reserve(256);
-            pushScope();
-            std::string savedModule = curModule;
-            curModule = s->module;
-            fv = coerce(exprWant(*f.init, f.type), f.type, f.init->pos, "the default of '" + f.name + "'");
-            curModule = savedModule;
-            scopes.pop_back();
-            std::swap(saved, scopes);
-        } else {
-            continue;  // zero
-        }
-        Value *fo = own(fv);
-        hold({fo, f.type, false, true});
-        v = b.CreateInsertValue(v, fo, f.llvmIndex);
-    }
-    return {v, t, false, owning(t)};
-}
-
-Value_ Codegen::callC(const CFunc &f, const std::vector<ExprPtr> &args, Pos p) {
-    if (!f.unsupported.empty())
-        failAt(p.file, p.line, p.col, "the C function '" + f.name + "' can't be used from Finch yet: it " + f.unsupported);
-    std::vector<Value_> vals;
-    Held held(*this);
-    for (size_t i = 0; i < args.size(); i++) {
-        if (!vals.empty()) hold(vals.back());
-        if (i < f.params.size()) {
-            FType pt = resolve(f.params[i], p);
-            vals.push_back(coerce(exprWant(*args[i], pt), pt, args[i]->pos, "argument " + std::to_string(i + 1) + " of " + f.name));
-        } else {
-            Value_ v = expr(*args[i]);
-            if (v.type.kind == FType::Void) failAt(args[i]->pos.file, args[i]->pos.line, args[i]->pos.col, "this gives back nothing");
-            if (v.type.kind == FType::Struct || v.type.kind == FType::Array)
-                failAt(args[i]->pos.file, args[i]->pos.line, args[i]->pos.col, "structs and arrays can't be passed to the '...' part of a C function");
-            vals.push_back(v);
-        }
-    }
-    setLoc(p);
-    Value_ r = emitCCall(f, declareC(f), vals, p);
-    for (auto &v : vals) release(v);
-    return r;
-}
-
-// ---------- built-ins ----------
-
-// print(a, b, c) prints the values separated by spaces, then a newline.
-Value_ Codegen::print(const std::vector<ExprPtr> &args, Pos) {
-    for (size_t i = 0; i < args.size(); i++) {
-        Value_ v = expr(*args[i]);
-        if (v.type.kind == FType::Void)
-            failAt(args[i]->pos.file, args[i]->pos.line, args[i]->pos.col, "this gives back nothing, so there is nothing to print");
-        if (i) printf_(" ", {});
-        emitPrint(v.v, v.type, false);
-        release(v);
-    }
-    printf_("\n", {});
-    return {nullptr, FType::Void};
-}
-
-// addr(x) gives a pointer to x; addr(function) gives a C-callable function pointer.
-Value_ Codegen::addrOf(const std::vector<ExprPtr> &args, Pos p) {
-    const Expr &e = *args[0];
-    if (e.kind == ExprKind::Var) {
-        const std::string &n = static_cast<const VarExpr &>(e).name;
-        Var *v = lookup(n);
-        if (!v) {
-            auto &fns = modules[curModule].fns;
-            if (auto it = fns.find(n); it != fns.end()) return {cThunk(it->second, p), FType::Ptr};
-        }
-        if (v && v->readonly) failAt(e.pos.file, e.pos.line, e.pos.col, "can't take the address of a loop variable");
-    }
-    if (e.kind != ExprKind::Var && e.kind != ExprKind::Member && e.kind != ExprKind::Index)
-        failAt(e.pos.file, e.pos.line, e.pos.col, "addr(...) needs a variable, a field or an element, like addr(x)");
-    Place pl = place(e, true);
-    return {pl.addr, FType::ptrTo(pl.type)};
-}
-
-// Explicit conversions: int(x), u8(x), float(x), char(x), bool(x), str(x), ptr(x) ...
-Value_ Codegen::convert(const FType &to, const std::vector<ExprPtr> &args, Pos, const std::string &name, bool canFail) {
-    Value_ v = expr(*args[0]);
-    const FType &from = v.type;
-    Pos p = args[0]->pos;
-    if (to.kind == FType::Str) {
-        Value *out = tmpOf(ty(FType::Str));
-        if (from.kind == FType::Str) return {copyValue(v.v, FType::Str), FType::Str, false, true};
-        if (from.isPtr()) return strFromC(v.v);
-        if (from.isSigned()) b.CreateCall(rt("finch_str_from_int"), {out, b.CreateSExt(v.v, b.getInt64Ty())});
-        else if (from.isUnsigned()) b.CreateCall(rt("finch_str_from_uint"), {out, b.CreateZExt(v.v, b.getInt64Ty())});
-        else if (from.isFloat()) b.CreateCall(rt("finch_str_from_float"), {out, b.CreateFPExt(v.v, b.getDoubleTy())});
-        else if (from.kind == FType::Char) b.CreateCall(rt("finch_str_from_char"), {out, v.v});
-        else if (from.kind == FType::Bool) b.CreateCall(rt("finch_str_from_bool"), {out, b.CreateZExt(v.v, b.getInt32Ty())});
-        else if (from.kind == FType::Array && (from.elem->kind == FType::U8 || from.elem->kind == FType::Char)) {
-            b.CreateCall(rt("finch_str_from_bytes"), {out, tmp(v.v)});
-            release(v);
-        } else if (from.kind == FType::Array || from.kind == FType::Fixed || from.kind == FType::Map || from.kind == FType::Struct) {
-            b.CreateStore(zero(FType::Str), out);  // the same text print(...) shows
-            emitFormat(out, v.v, from, false);
-            release(v);
-        } else {
-            failAt(p.file, p.line, p.col, "can't turn " + from.show() + " into str");
-        }
-        return {b.CreateLoad(ty(FType::Str), out), FType::Str, false, true};
-    }
-    if (from == to) return v;
-    if (from.kind == FType::Str && (to.isInt() || to.isFloat()) && canFail) {  // int(text) or 0
-        Value *sp = tmp(v.v), *err = tmp(zero(FType::Str));
-        Value *out = tmp(to.isInt() ? (Value *)b.getInt64(0) : ConstantFP::get(b.getDoubleTy(), 0));
-        Value *ok = b.CreateCall(rt(to.isInt() ? "finch_str_try_int" : "finch_str_try_float"), {sp, out, err});
-        fallibleFailed = b.CreateICmpEQ(ok, b.getInt32(0));
-        fallibleMsg = b.CreateLoad(ty(FType::Str), err);
-        Value_ r;
-        if (to.isInt()) r = {intCast(b.CreateLoad(b.getInt64Ty(), out), FType::I64, to), to};
-        else r = {b.CreateFPCast(b.CreateLoad(b.getDoubleTy(), out), ty(to)), to};
-        release(v);
-        return r;
-    }
-    if (from.kind == FType::Str && (to.isInt() || to.isFloat())) {
-        Value *sp = tmp(v.v);
-        Value_ r;
-        if (to.isInt()) r = {intCast(b.CreateCall(rt("finch_str_to_int"), {sp, fileName(p), b.getInt64(p.line)}), FType::I64, to), to};
-        else r = {b.CreateFPCast(b.CreateCall(rt("finch_str_to_float"), {sp, fileName(p), b.getInt64(p.line)}), ty(to)), to};
-        release(v);
-        return r;
-    }
-    if (to.isInt() || to.kind == FType::Char) {
-        if (from.isInt() || from.kind == FType::Char) return {b.CreateIntCast(v.v, ty(to), from.isSigned()), to};
-        if (from.kind == FType::Bool) return {b.CreateZExt(v.v, ty(to)), to};
-        if (from.isFloat() && to.isInt()) return {to.isSigned() ? b.CreateFPToSI(v.v, ty(to)) : b.CreateFPToUI(v.v, ty(to)), to};
-    }
-    if (to.isFloat()) {
-        if (from.isInt()) return {intToFloat(v.v, from, to), to};
-        if (from.isFloat()) return {b.CreateFPCast(v.v, ty(to)), to};
-    }
-    if (to.kind == FType::Bool && from.isInt()) return {b.CreateICmpNE(v.v, ConstantInt::get(ty(from), 0)), to};
-    if (to.isPtr() && (from.isPtr() || from.kind == FType::Null)) return {v.v, to};
-    if (to.isPtr() && from.isInt()) return {b.CreateIntToPtr(intCast(v.v, from, FType::U64), b.getPtrTy()), to};  // an address or offset for C
-    if (to.isInt() && from.isPtr()) return {b.CreatePtrToInt(v.v, ty(to)), to};
-    if (to.isPtr() && from.kind == FType::Str) failAt(p.file, p.line, p.col, "use .ptr to get a str's address (it is only valid while the str lives)");
-    failAt(p.file, p.line, p.col, "can't turn " + from.show() + " into " + name);
-}
-
-// ---------- methods ----------
-
-Value_ Codegen::method(const MethodExpr &m) {
-    Pos p = m.pos;
-    // math.sqrt(x), math.Vec(1, 2)
-    if (m.obj->kind == ExprKind::Var) {
-        const std::string &mn = static_cast<const VarExpr &>(*m.obj).name;
-        if (!lookup(mn) && modules[curModule].imports.count(mn)) {
-            auto mi = modules.find(mn);
-            if (mi == modules.end()) failAt(p.file, p.line, p.col, "the module '" + mn + "' was not found");
-            note(m.obj->pos, mn.size(), "module `" + mn + "`");
-            Pos namePos{p.line, p.col + 1, p.file};
-            if (auto it = mi->second.fns.find(m.name); it != mi->second.fns.end()) {
-                note(namePos, m.name.size(), "```finch\n" + signature(it->second) + "\n```", it->second.decl->namePos);
-                return callFinch(it->second, m.args, m.argNames, p, mn + "." + m.name, &m);
-            }
-            if (auto it = mi->second.structs.find(m.name); it != mi->second.structs.end()) {
-                note(namePos, m.name.size(), structHover(it->second), it->second->decl->namePos);
-                return construct(it->second, m.args, m.argNames, p);
-            }
-            failAt(p.file, p.line, p.col, "the module '" + mn + "' has no function or struct named '" + m.name + "'");
-        }
-        if (!lookup(mn) && !cimports.globals.count(mn) && !cimports.consts.count(mn))
-            failAt(m.obj->pos.file, m.obj->pos.line, m.obj->pos.col,
-                   "there is no variable or module named '" + mn + "' (to use a module, add  import " + mn + "  at the top)");
-    }
-    static const std::set<std::string> changing = {"push", "pop", "insert", "remove", "clear", "resize", "sort", "reverse"};
-    // writing through a map's m[key] adds the key if it's missing: groups[k].push(x)
-    LRef r = ref(*m.obj, changing.count(m.name) > 0 || mutatingMethods.count(m.name) > 0);
-    FType t = r.isPlace ? r.pl.type : r.val.type;
-    if (t.kind == FType::Struct || (t.isPtr() && t.elem && t.elem->kind == FType::Struct)) return structMethod(m, r, t);
-    if (changing.count(m.name) && (t.kind == FType::Array || t.kind == FType::Map)) {
-        std::string root = rootVar(*m.obj);
-        if (Var *v = root.empty() ? nullptr : lookup(root); v && v->readonly) failAt(p.file, p.line, p.col, v->readonlyWhy);
-    }
-    Held held(*this);
-    if (t.kind == FType::Map) {
-        Value_ recv = r.isPlace ? Value_{r.pl.addr, t} : Value_{tmp(r.val.v), t, false, r.val.fresh};
-        if (!r.isPlace && r.val.fresh) holdAddr(recv.v, t);
-        Value_ out = mapMethod(m, &recv);
-        if (!r.isPlace && r.val.fresh) dropAt(recv.v, t);
-        return out;
-    }
-    if (g_index && (t.kind == FType::Array || t.kind == FType::Str)) {
-        auto look = [&](const BuiltinDoc *first, const BuiltinDoc *last) {
-            for (; first != last; ++first)
-                if (m.name == first->name) note(Pos{p.line, p.col + 1, p.file}, m.name.size(), docHover(*first));
-        };
-        if (t.kind == FType::Str) look(std::begin(kStrMethods), std::end(kStrMethods));
-        else look(std::begin(kArrayMethods), std::end(kArrayMethods));
-    }
-    if (t.kind == FType::Array) {
-        Value_ recv = r.isPlace ? Value_{r.pl.addr, t} : r.val;
-        if (!r.isPlace) {
-            if (changing.count(m.name)) failAt(p.file, p.line, p.col, m.name + "() would change a temporary array; store it in a variable first");
-            recv = {tmp(r.val.v), t, false, r.val.fresh};
-            if (r.val.fresh) holdAddr(recv.v, t);
-        }
-        Value_ out = arrayMethod(m, &recv);
-        if (!r.isPlace && r.val.fresh) dropAt(recv.v, t);
-        return out;
-    }
-    if (t.kind == FType::Str) {
-        Value_ sv = r.isPlace ? Value_{b.CreateLoad(ty(t), r.pl.addr), t} : r.val;
-        Value *addr = tmp(sv.v);  // the runtime takes strings by address
-        if (!r.isPlace) hold(sv);
-        auto argStr = [&](size_t i, const char *what) {
-            Value_ a = coerce(expr(*m.args[i]), FType::Str, m.args[i]->pos, what);
-            hold(a);
-            return a;
-        };
-        auto argInt = [&](size_t i, const char *what) {
-            return coerce(expr(*m.args[i]), FType::I64, m.args[i]->pos, what).v;
-        };
-        auto need = [&](size_t n) { checkArgs(m.args, m.argNames, n, p, m.name); };
-        Value *out = tmpOf(ty(FType::Str));
-        Value_ res;
-        const std::string &n = m.name;
-        auto strRes = [&]() { return Value_{b.CreateLoad(ty(FType::Str), out), FType::Str, false, true}; };
-        if (n == "sub") {
-            need(2);
-            Value *a = argInt(0, "the start"), *e = argInt(1, "the end");
-            b.CreateCall(rt("finch_str_sub"), {out, addr, a, e, fileName(p), b.getInt64(p.line)});
-            res = strRes();
-        } else if (n == "find" || n == "contains" || n == "starts_with" || n == "ends_with") {
-            need(1);
-            Value_ t2 = argStr(0, "the text to look for");
-            Value *tp = tmp(t2.v);
-            if (n == "find") res = {b.CreateCall(rt("finch_str_find"), {addr, tp}), FType::I64};
-            else if (n == "contains") res = {b.CreateICmpSGE(b.CreateCall(rt("finch_str_find"), {addr, tp}), b.getInt64(0)), FType::Bool};
-            else res = {b.CreateICmpNE(b.CreateCall(rt(n == "starts_with" ? "finch_str_starts" : "finch_str_ends"), {addr, tp}), b.getInt32(0)), FType::Bool};
-            release(t2);
-        } else if (n == "trim" || n == "upper" || n == "lower") {
-            need(0);
-            b.CreateCall(rt("finch_str_" + n), {out, addr});
-            res = strRes();
-        } else if (n == "replace") {
-            need(2);
-            Value_ a = argStr(0, "the text to replace"), c = argStr(1, "the new text");
-            b.CreateCall(rt("finch_str_replace"), {out, addr, tmp(a.v), tmp(c.v)});
-            release(a);
-            release(c);
-            res = strRes();
-        } else if (n == "split") {
-            need(1);
-            Value_ sep = argStr(0, "the separator");
-            FType at = FType::arrayOf(FType::Str);
-            Value *ao = tmpOf(ty(at));
-            b.CreateCall(rt("finch_str_split"), {ao, addr, tmp(sep.v)});
-            release(sep);
-            res = {b.CreateLoad(ty(at), ao), at, false, true};
-        } else if (n == "repeat") {
-            need(1);
-            b.CreateCall(rt("finch_str_repeat"), {out, addr, argInt(0, "the count")});
-            res = strRes();
-        } else if (n == "bytes") {
-            need(0);
-            FType at = FType::arrayOf(FType::U8);
-            Value *ao = tmpOf(ty(at));
-            b.CreateCall(rt("finch_bytes_from_str"), {ao, addr});
-            res = {b.CreateLoad(ty(at), ao), at, false, true};
-        } else {
-            failAt(p.file, p.line, p.col, "a str has no method '" + n + "' (it has: sub, find, contains, starts_with, ends_with, split, trim, upper, lower, replace, repeat, bytes)");
-        }
-        if (!r.isPlace) release(sv);
-        return res;
-    }
-    failAt(p.file, p.line, p.col, t.show() + " has no methods");
-}
-
-// p.move(1, 2): a method of a struct (also through a ptr[Struct]); self is passed by address
-Value_ Codegen::structMethod(const MethodExpr &m, LRef &r, const FType &t) {
-    Pos p = m.pos;
-    FType st = t.isPtr() ? *t.elem : t;
-    auto ms = methods.find(st.info);
-    const Fn *fn = nullptr;
-    if (ms != methods.end())
-        if (auto it = ms->second.find(m.name); it != ms->second.end()) fn = &it->second;
-    if (!fn) {
-        std::string names;
-        if (ms != methods.end())
-            for (auto &[n, f] : ms->second) names += (names.empty() ? "" : ", ") + n;
-        if (names.empty())
-            failAt(p.file, p.line, p.col, "the struct " + st.show() + " has no methods; add one with  fn " + st.name + "." + m.name + "(...) { ... }");
-        failAt(p.file, p.line, p.col, "the struct " + st.show() + " has no method '" + m.name + "' (it has: " + names + ")");
-    }
-    note(Pos{p.line, p.col + 1, p.file}, m.name.size(), "```finch\n" + signature(*fn) + "\n```", fn->decl->namePos);
-    std::string root = rootVar(*m.obj);
-    if (fn->mutatesSelf && !root.empty() && !t.isPtr())
-        if (Var *v = lookup(root); v && v->readonly) failAt(p.file, p.line, p.col, v->readonlyWhy);
-
-    Value *self;
-    bool temp = false;
-    if (t.isPtr()) {
-        self = r.isPlace ? b.CreateLoad(b.getPtrTy(), r.pl.addr) : r.val.v;
-        panicIf(b.CreateIsNull(self), "called ." + m.name + "() on a null pointer", p);
-        root.clear();  // self lives somewhere else
-    } else if (r.isPlace) {
-        self = r.pl.addr;
-    } else {
-        self = tmp(r.val.v);  // a temporary struct: Point(1, 2).length()
-        temp = true;
-    }
-    Held held(*this);
-    if (temp && r.val.fresh) holdAddr(self, st);
-    Value_ out = callFinch(*fn, m.args, m.argNames, p, st.name + "." + m.name, &m, self, root);
-    if (temp && r.val.fresh && owning(st)) dropAt(self, st);
-    return out;
-}
-
-// An element compare for find/contains/sort: -1, 0, 1 (only numbers, chars, bools and str)
-static bool comparable(const FType &t) {
-    return t.isNumber() || t.kind == FType::Char || t.kind == FType::Bool || t.kind == FType::Str;
-}
-
-Value_ Codegen::arrayMethod(const MethodExpr &m, Value_ *recv) {
-    Pos p = m.pos;
-    const std::string &n = m.name;
-    FType at = recv->type, et = *at.elem;
-    llvm::Type *AT = ty(at), *ET = ty(et);
-    Value *a = recv->v;  // the array's address
-    auto need = [&](size_t k) { checkArgs(m.args, m.argNames, k, p, n); };
-    auto lenAddr = [&]() { return b.CreateStructGEP(AT, a, 1); };
-    auto len = [&]() { return b.CreateLoad(b.getInt64Ty(), lenAddr()); };
-    auto data = [&]() { return b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(AT, a, 0)); };
-    auto elemValue = [&](size_t i) { return own(coerce(exprWant(*m.args[i], et), et, m.args[i]->pos, "the element")); };
-
-    if (n == "push") {
-        need(1);
-        Value *v = elemValue(0);
-        Value *l = len();
-        b.CreateCall(rt("finch_arr_reserve"), {a, b.CreateAdd(l, b.getInt64(1)), elemSize(et)});
-        b.CreateStore(v, b.CreateInBoundsGEP(ET, data(), l));
-        b.CreateStore(b.CreateAdd(l, b.getInt64(1)), lenAddr());
-        return {nullptr, FType::Void};
-    }
-    if (n == "pop") {
-        need(0);
-        Value *l = len();
-        panicIf(b.CreateICmpEQ(l, b.getInt64(0)), "pop() on an empty array", p);
-        Value *last = b.CreateSub(l, b.getInt64(1));
-        Value *v = b.CreateLoad(ET, b.CreateInBoundsGEP(ET, data(), last));
-        b.CreateStore(last, lenAddr());
-        return {v, et, false, owning(et)};
-    }
-    if (n == "insert") {
-        need(2);
-        Value *i = coerce(expr(*m.args[0]), FType::I64, m.args[0]->pos, "the position").v;
-        Value *v = elemValue(1);
-        b.CreateCall(rt("finch_arr_insert_gap"), {a, i, elemSize(et), fileName(p), b.getInt64(p.line)});
-        b.CreateStore(v, b.CreateInBoundsGEP(ET, data(), i));
-        return {nullptr, FType::Void};
-    }
-    if (n == "remove") {
-        need(1);
-        Value *i = coerce(expr(*m.args[0]), FType::I64, m.args[0]->pos, "the position").v;
-        boundsCheck(i, len(), p);
-        Value *v = b.CreateLoad(ET, b.CreateInBoundsGEP(ET, data(), i));
-        b.CreateCall(rt("finch_arr_remove_gap"), {a, i, elemSize(et)});
-        return {v, et, false, owning(et)};
-    }
-    if (n == "clear" || n == "resize") {
-        need(n == "clear" ? 0 : 1);
-        Value *nl = n == "clear" ? (Value *)b.getInt64(0) : coerce(expr(*m.args[0]), FType::I64, m.args[0]->pos, "the new length").v;
-        if (owning(et)) {  // drop the elements that go away
-            Value *l = len(), *d = data();
-            Value *from = b.CreateSelect(b.CreateICmpSLT(nl, l), b.CreateSelect(b.CreateICmpSLT(nl, b.getInt64(0)), b.getInt64(0), nl), l);
-            forN(b.CreateSub(l, from), [&](Value *k) { dropAt(b.CreateInBoundsGEP(ET, d, b.CreateAdd(from, k)), et); });
-        }
-        b.CreateCall(rt("finch_arr_resize"), {a, nl, elemSize(et)});
-        return {nullptr, FType::Void};
-    }
-    if (n == "find" || n == "contains") {
-        need(1);
-        if (!comparable(et)) failAt(p.file, p.line, p.col, n + "() works on arrays of numbers, chars, bools or str");
-        Value_ x = coerce(exprWant(*m.args[0], et), et, m.args[0]->pos, "the value to look for");
-        Value *xv = x.v;
-        Value *res = tmpOf(b.getInt64Ty());
-        b.CreateStore(b.getInt64(-1), res);
-        Value *l = len(), *d = data();
-        Value *i = tmpOf(b.getInt64Ty());
-        b.CreateStore(b.getInt64(0), i);
-        BasicBlock *cond = newBlock("find.cond"), *body = newBlock("find.body"), *hit = newBlock("find.hit"),
-                   *next = newBlock("find.next"), *end = newBlock("find.end");
-        b.CreateBr(cond);
-        b.SetInsertPoint(cond);
-        Value *iv = b.CreateLoad(b.getInt64Ty(), i);
-        b.CreateCondBr(b.CreateICmpSLT(iv, l), body, end);
-        b.SetInsertPoint(body);
-        Value_ ev{b.CreateLoad(ET, b.CreateInBoundsGEP(ET, d, iv)), et};
-        Value *eq = compare(BinOp::Eq, ev, {xv, et}, p).v;
-        b.CreateCondBr(eq, hit, next);
-        b.SetInsertPoint(hit);
-        b.CreateStore(iv, res);
-        b.CreateBr(end);
-        b.SetInsertPoint(next);
-        b.CreateStore(b.CreateAdd(iv, b.getInt64(1)), i);
-        b.CreateBr(cond);
-        b.SetInsertPoint(end);
-        release(x);
-        Value *r = b.CreateLoad(b.getInt64Ty(), res);
-        if (n == "find") return {r, FType::I64};
-        return {b.CreateICmpSGE(r, b.getInt64(0)), FType::Bool};
-    }
-    if (n == "join") {
-        need(1);
-        if (et.kind != FType::Str) failAt(p.file, p.line, p.col, "join() works on an array of str");
-        Value_ sep = coerce(expr(*m.args[0]), FType::Str, m.args[0]->pos, "the separator");
-        Value *out = tmpOf(ty(FType::Str));
-        b.CreateCall(rt("finch_str_join"), {out, a, tmp(sep.v)});
-        release(sep);
-        return {b.CreateLoad(ty(FType::Str), out), FType::Str, false, true};
-    }
-    if (n == "slice") {
-        need(2);
-        Value *s = coerce(expr(*m.args[0]), FType::I64, m.args[0]->pos, "the start").v;
-        Value *e = coerce(expr(*m.args[1]), FType::I64, m.args[1]->pos, "the end").v;
-        Value *l = len();
-        panicIf(b.CreateOr(b.CreateOr(b.CreateICmpSLT(s, b.getInt64(0)), b.CreateICmpSGT(e, l)), b.CreateICmpSGT(s, e)),
-                "slice(start, end) is out of range", p);
-        Value *cnt = b.CreateSub(e, s);
-        Value *out = tmpOf(AT);
-        b.CreateCall(rt("finch_arr_make"), {out, cnt, elemSize(et)});
-        Value *src = data();
-        Value *dst = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(AT, out, 0));
-        forN(cnt, [&](Value *k) {
-            copyAt(b.CreateInBoundsGEP(ET, dst, k), b.CreateInBoundsGEP(ET, src, b.CreateAdd(s, k)), et);
-        });
-        return {b.CreateLoad(AT, out), at, false, true};
-    }
-    if (n == "reverse") {
-        need(0);
-        Value *l = len(), *d = data();
-        forN(b.CreateSDiv(l, b.getInt64(2)), [&](Value *k) {
-            Value *x = b.CreateInBoundsGEP(ET, d, k);
-            Value *y = b.CreateInBoundsGEP(ET, d, b.CreateSub(b.CreateSub(l, b.getInt64(1)), k));
-            Value *xv = b.CreateLoad(ET, x), *yv = b.CreateLoad(ET, y);
-            b.CreateStore(yv, x);
-            b.CreateStore(xv, y);
-        });
-        return {nullptr, FType::Void};
-    }
-    if (n == "sort") {
-        need(0);
-        if (!comparable(et) || et.kind == FType::Bool) failAt(p.file, p.line, p.col, "sort() works on arrays of numbers, chars or str");
-        std::string key = "cmp." + typeKey(et);
-        Function *cmp = helpers[key];
-        if (!cmp) {
-            cmp = Function::Create(FunctionType::get(b.getInt32Ty(), {b.getPtrTy(), b.getPtrTy()}, false),
-                                   Function::InternalLinkage, "finch." + key, mod.get());
-            helpers[key] = cmp;
-            IRBuilderBase::InsertPointGuard g(b);
-            DISubprogram *savedFn = diFn;
-            diFn = nullptr;
-            b.SetInsertPoint(BasicBlock::Create(ctx, "entry", cmp));
-            b.SetCurrentDebugLocation(DebugLoc());
-            Value *x = cmp->getArg(0), *y = cmp->getArg(1);
-            Value *r;
-            if (et.kind == FType::Str) {
-                r = b.CreateTrunc(b.CreateCall(rt("finch_str_cmp"), {x, y}), b.getInt32Ty());
-            } else {
-                Value_ xv{b.CreateLoad(ET, x), et}, yv{b.CreateLoad(ET, y), et};
-                Value *lt = compare(BinOp::Less, xv, yv, p).v, *gt = compare(BinOp::Greater, xv, yv, p).v;
-                r = b.CreateSub(b.CreateZExt(gt, b.getInt32Ty()), b.CreateZExt(lt, b.getInt32Ty()));
-            }
-            b.CreateRet(r);
-            diFn = savedFn;
-        }
-        b.CreateCall(libc("qsort", b.getVoidTy(), {b.getPtrTy(), b.getInt64Ty(), b.getInt64Ty(), b.getPtrTy()}),
-                     {data(), len(), elemSize(et), cmp});
-        return {nullptr, FType::Void};
-    }
-    failAt(p.file, p.line, p.col, "an array has no method '" + n + "' (it has: push, pop, insert, remove, clear, resize, find, contains, join, slice, reverse, sort)");
-}
-
-}  // namespace finch

src/codegen_impl.h

@@ -1,327 +0,0 @@
-#pragma once
-// Internal to the code generator: the Codegen class, shared by codegen*.cpp and abi.cpp.
-
-#include "codegen.h"
-#include "error.h"
-#include "index.h"
-
-#include <llvm/IR/Constants.h>
-#include <llvm/IR/DIBuilder.h>
-#include <llvm/IR/IRBuilder.h>
-#include <llvm/IR/Verifier.h>
-#include <llvm/Support/raw_ostream.h>
-
-#include <functional>
-#include <map>
-#include <set>
-#include <unordered_map>
-
-using FType = ::Type;  // Finch types (llvm::Type is the LLVM one)
-
-struct StructInfo {
-    std::string name;
-    std::string module;  // "" main file, a module name, or "C" for imported C structs
-    bool isC = false;
-    const StructDecl *decl = nullptr;  // Finch structs
-    const CStruct *cstruct = nullptr;    // C structs
-    struct F {
-        std::string name;
-        FType type;
-        const Expr *init = nullptr;  // default value
-        bool hidden = false;         // C union/bitfield padding: has no name in Finch
-        unsigned llvmIndex = 0;      // C structs carry explicit padding between fields
-        Pos pos;                     // Finch structs: where the field is declared
-    };
-    std::vector<F> fields;
-    llvm::StructType *llvm = nullptr;
-    int state = 0;  // 0 = not resolved, 1 = resolving (cycle check), 2 = done
-    bool owning = false;
-    std::string unsupported;  // C structs Finch can't lay out
-    Pos pos;
-};
-
-namespace finch {
-
-struct Value_ {
-    llvm::Value *v;
-    FType type;
-    bool literal = false;  // a number written in the code (or a C constant): adapts to the type around it
-    bool fresh = false;    // an owning value nobody holds yet: it must be stored (moved) or released
-};
-
-struct Var {
-    llvm::Value *slot;
-    FType type;
-    bool readonly = false;  // loop variables
-    std::string readonlyWhy;
-    bool owned = false;     // dropped when its scope ends
-    int order = 0;          // declaration order, for defer
-    bool moved = false;     // returned out of the function: not dropped on that path
-    Pos pos;                // where it was declared
-};
-
-struct Cleanup {
-    bool isDefer;
-    std::string var;            // Drop: the variable
-    const Stmt *body = nullptr; // Defer: the statement
-    int order = 0;              // Defer: variables declared after it are not visible
-};
-
-struct Scope {
-    std::unordered_map<std::string, Var> vars;
-    std::vector<Cleanup> cleanups;
-};
-
-struct Fn {
-    llvm::Function *llvm = nullptr;
-    const FnDecl *decl = nullptr;
-    std::string module;
-    std::vector<bool> borrowParam;  // owning params the function never changes: no copy
-    llvm::Function *cThunk = nullptr;
-    FType ret;                      // resolved types
-    std::vector<FType> params;
-    StructInfo *recv = nullptr;     // a method of this struct: the first LLVM parameter is `self`'s address
-    bool mutatesSelf = false;       // the method changes `self`
-    bool fallible = false;          // -> T!: returns { i1 ok, T value, str error }
-};
-
-struct Loop {
-    llvm::BasicBlock *continueTo, *breakTo;
-    size_t scopeDepth;    // scopes opened inside the loop are cleaned up by break/continue
-    size_t pendingDepth;  // and so are temporaries held by expressions around it (see Codegen::pending)
-};
-
-// A fresh value an expression is holding while it computes another part (f(a + b, try g())): if that
-// part leaves early (try, or a return/break/continue in an `or { }` block), it must be dropped.
-struct Pending {
-    llvm::Value *v;
-    FType type;
-    bool isAddr;  // v is the value's address
-};
-
-struct Place {  // something that can be assigned to
-    llvm::Value *addr;
-    FType type;
-};
-
-struct LRef {
-    bool isPlace;
-    Place pl;
-    Value_ val;
-};
-
-struct ModuleScope {
-    std::map<std::string, Fn> fns;
-    std::map<std::string, StructInfo *> structs;
-    std::set<std::string> imports;  // Finch modules visible here
-};
-
-// How a C struct travels: System V x86-64 (Linux) or Microsoft x64 (Windows).
-struct AbiArg {
-    // Direct: as is. Expand: split into register-sized parts. Memory: on the stack (byval), or
-    // returned through a hidden pointer (sret). Indirect (Windows): a pointer to a copy the caller made.
-    enum Kind { Direct, Expand, Memory, Indirect } kind = Direct;
-    std::vector<llvm::Type *> parts;  // Expand: one value per eightbyte
-    llvm::Type *coerced = nullptr;    // Expand: { parts... } for returns
-    bool stackAlign8 = false;         // AArch64 Linux: HFA arguments that end up on the stack
-};
-
-class Codegen {
-public:
-    Codegen(llvm::LLVMContext &c, const std::vector<Program> &progs, const CImports &ci, llvm::TargetMachine &tm,
-            bool debug);
-    std::unique_ptr<llvm::Module> run();
-
-    // ---------- state ----------
-    llvm::LLVMContext &ctx;
-    llvm::IRBuilder<> b;
-    std::unique_ptr<llvm::Module> mod;
-    const std::vector<Program> &progs;
-    const CImports &cimports;
-    const llvm::DataLayout *dl;
-
-    std::map<std::string, ModuleScope> modules;
-    std::map<std::string, StructInfo *> cStructs;
-    std::vector<std::unique_ptr<StructInfo>> structStore;
-    std::vector<Scope> scopes;
-    std::vector<Loop> loops;
-    std::vector<Pending> pending;
-    const Fn *curFn = nullptr;
-    std::string curModule;
-    int varOrder = 0;
-    int deferLimit = -1;  // while emitting a defer: hide variables declared after it
-    int inDefer = 0;
-    std::map<std::string, llvm::Function *> helpers;  // drop/copy/print per type
-    std::map<StructInfo *, std::map<std::string, Fn>> methods;
-    std::set<std::string> mutatingMethods;  // names of methods that change self (for the mutation analysis)
-
-    // errors as values: the call that `or` / `try` is handling reports here whether it failed
-    const Expr *fallibleTarget = nullptr;
-    llvm::Value *fallibleFailed = nullptr;  // i1
-    llvm::Value *fallibleMsg = nullptr;     // str
-
-    // debug info (-g)
-    bool debug;
-    std::unique_ptr<llvm::DIBuilder> di;
-    std::vector<llvm::DIFile *> diFiles;
-    llvm::DICompileUnit *diUnit = nullptr;
-    llvm::DISubprogram *diFn = nullptr;
-    std::map<std::string, llvm::DIType *> diTypes;
-
-    // ---------- codegen.cpp: program, statements, expressions ----------
-    void declareStructs();
-    void declareFns();
-    void declare(const Program &p, const FnDecl &fn);
-    void define(Fn &fn);
-    void defineMainWrapper();
-    void block(const BlockStmt &blk);
-    void blockBody(const BlockStmt &blk);
-    void stmt(const Stmt &s);
-    void varDecl(const VarDeclStmt &s);
-    void assign(const AssignStmt &s);
-    void ifStmt(const IfStmt &s);
-    void whileStmt(const WhileStmt &s);
-    void forStmt(const ForStmt &s);
-    void forEachStmt(const ForEachStmt &s);
-    void returnStmt(const ReturnStmt &s);
-    llvm::Type *retType(const Fn &f);
-    void retValue(llvm::Value *v);    // return from the current function (wrapped as success if it can fail)
-    void retError(llvm::Value *msg);  // fail the current function with the str `msg`
-    void jump(bool isBreak, Pos p);
-    llvm::Value *condition(const Expr &e);
-    void continueAt(llvm::BasicBlock *bb, llvm::BasicBlock *deadEnd);
-    bool terminated();
-    llvm::BasicBlock *newBlock(const char *name);
-
-    void hold(const Value_ &v);                   // see Pending
-    void holdAddr(llvm::Value *addr, const FType &t);
-    void dropPending(size_t downTo);               // emit drops for pending[downTo..]
-    struct Held {                                  // forgets what was held when the expression is done
-        Codegen &cg;
-        size_t mark;
-        explicit Held(Codegen &c) : cg(c), mark(c.pending.size()) {}
-        ~Held() { cg.pending.erase(cg.pending.begin() + mark, cg.pending.end()); }
-    };
-    void pushScope();
-    void popScope();                      // emits the scope's cleanups if reachable
-    void emitCleanups(size_t downTo);     // run cleanups of scopes [downTo, end) without popping
-    void emitScopeCleanups(size_t idx);
-    llvm::AllocaInst *slot(const FType &t, const std::string &name);
-    Var *lookup(const std::string &name);
-    Var &addVar(Pos p, const std::string &name, const FType &t, llvm::Value *init, bool owned, bool readonly = false,
-                unsigned argNo = 0);
-
-    Value_ expr(const Expr &e);
-    Value_ exprWant(const Expr &e, const FType &want);
-    Value_ binary(const BinaryExpr &e);
-    Value_ unary(const UnaryExpr &e);
-    Value_ logic(const BinaryExpr &e);
-    Value_ arith(BinOp op, Value_ l, Value_ r, Pos p);
-    Value_ arithOp(BinOp op, Value_ l, Value_ r, Pos p);
-    Value_ compare(BinOp op, Value_ l, Value_ r, Pos p);
-    bool unify(Value_ &l, Value_ &r);
-    [[noreturn]] void badOperands(BinOp op, const Value_ &l, const Value_ &r, Pos p);
-    LRef ref(const Expr &e, bool forWrite = false);  // an address if `e` has one, else a value
-    Place place(const Expr &e, bool forWrite = false);
-    LRef member(const MemberExpr &m, bool forWrite);
-    LRef index(const IndexExpr &e, bool forWrite);
-    Value_ arrayLit(const ArrayLitExpr &a, const FType *want);
-    Value_ fallible(const Expr &call, llvm::Value *&failed, llvm::Value *&msg);
-    Value_ tryExpr(const TryExpr &t);
-    Value_ orElse(const OrElseExpr &e, bool discard = false);  // discard: a statement, the value isn't used
-    FType structType(StructInfo *s);
-    std::string rootVar(const Expr &e);
-    bool mutates(const std::string &name, const Stmt &s);
-    bool mutatesExpr(const std::string &name, const Expr &e);
-
-    // ---------- codegen_types.cpp: types, conversions, ownership, printing ----------
-    llvm::Type *ty(const FType &t);
-    FType resolve(const FType &t, Pos p);
-    FType resolveT(const FType &t, Pos p, bool deep);  // deep: structs by value must be complete
-    void forN(llvm::Value *n, const std::function<void(llvm::Value *)> &body);  // for i in 0..n
-    llvm::Value *tmpOf(llvm::Type *t);  // an uninitialised stack slot
-    void resolveStruct(StructInfo *s);
-    StructInfo *findStruct(const std::string &module, const std::string &name, bool qualified);
-    bool owning(const FType &t);
-    llvm::Constant *zero(const FType &t);
-    Value_ defaultValue(const FType &t, Pos p);
-    static bool widens(const FType &from, const FType &to);
-    static bool fits(llvm::ConstantInt *c, const FType &from, const FType &to);
-    llvm::Value *intCast(llvm::Value *v, const FType &from, const FType &to);
-    llvm::Value *intToFloat(llvm::Value *v, const FType &from, const FType &to);
-    Value_ coerce(Value_ v, const FType &want, Pos p, const std::string &what);
-    llvm::Value *own(const Value_ &v);  // something that can be stored: moved if fresh, else copied
-    void release(const Value_ &v);      // drop a fresh value nobody kept
-    llvm::Value *copyValue(llvm::Value *v, const FType &t);
-    void dropValue(llvm::Value *v, const FType &t);
-    void dropAt(llvm::Value *addr, const FType &t);
-    void copyAt(llvm::Value *dst, llvm::Value *src, const FType &t);
-    llvm::Function *dropFn(const FType &t);
-    llvm::Function *copyFn(const FType &t);
-    std::string typeKey(const FType &t);
-    llvm::Value *tmp(llvm::Value *v);  // a stack copy of v, to pass by address
-    void emitPrint(llvm::Value *v, const FType &t, bool quoted);
-    void emitFormat(llvm::Value *buf, llvm::Value *v, const FType &t, bool quoted);  // append v as text to the str at buf
-    void bufText(llvm::Value *buf, const std::string &text);
-    llvm::Function *formatFn(const FType &t);
-    void printf_(const std::string &fmt, std::vector<llvm::Value *> args);
-    llvm::Value *strConst(const std::string &s);
-    llvm::Value *cstr(llvm::Value *strValue);  // str -> char* for C
-    Value_ strFromC(llvm::Value *p);            // char* -> borrowed str
-    llvm::Value *elemSize(const FType &t);
-
-    // ---------- codegen_builtins.cpp: calls, built-ins, methods ----------
-    Value_ call(const CallExpr &c);
-    Value_ method(const MethodExpr &m);
-    Value_ callFinch(const Fn &fn, const std::vector<ExprPtr> &args, const std::vector<std::string> &names, Pos p,
-                     const std::string &shownName, const Expr *site, llvm::Value *self = nullptr,
-                     const std::string &selfRoot = "");
-    Value_ construct(StructInfo *s, const std::vector<ExprPtr> &args, const std::vector<std::string> &names, Pos p);
-    Value_ callC(const CFunc &f, const std::vector<ExprPtr> &args, Pos p);
-    Value_ convert(const FType &to, const std::vector<ExprPtr> &args, Pos p, const std::string &name, bool canFail = false);
-    Value_ print(const std::vector<ExprPtr> &args, Pos p);
-    Value_ addrOf(const std::vector<ExprPtr> &args, Pos p);
-    Value_ arrayMethod(const MethodExpr &m, Value_ *recv);
-    Value_ structMethod(const MethodExpr &m, LRef &r, const FType &t);
-
-    // ---------- codegen_map.cpp: maps ----------
-    llvm::StructType *mapEntryTy(const FType &t);
-    Value_ mapLit(const MapLitExpr &e, const FType *want);
-    LRef mapIndex(const IndexExpr &e, LRef &obj, const FType &t, bool forWrite);
-    Value_ mapMethod(const MethodExpr &m, Value_ *recv);
-    std::vector<llvm::Value *> mapArgs(llvm::Value *map, llvm::Value *keyAddr, const FType &t);
-    llvm::Value *mapSlot(llvm::Value *map, const FType &t, const Value_ &key, Pos p, bool fill);
-    llvm::Value *mapEntry(llvm::Value *map, const FType &t, llvm::Value *i);
-    void forEachEntry(llvm::Value *map, const FType &t, const std::function<void(llvm::Value *i, llvm::Value *entry)> &body);
-    llvm::Value *keyText(const Value_ &key);
-    bool isBuiltin(const std::string &n);
-    std::string headerHint(const std::string &name);
-    void checkArgs(const std::vector<ExprPtr> &args, const std::vector<std::string> &names, size_t want, Pos p,
-                   const std::string &name, bool variadic = false);
-    llvm::Value *cGlobal(const std::string &name);
-    llvm::Function *rt(const std::string &name);  // a runtime function by name
-
-    // runtime errors
-    llvm::Value *fileName(Pos p);
-    void panicIf(llvm::Value *cond, const std::string &msg, Pos p);
-    void boundsCheck(llvm::Value *i, llvm::Value *len, Pos p);
-    void checkDivisor(const Value_ &l, const Value_ &r, Pos p);
-    llvm::Function *libc(const char *name, llvm::Type *ret, std::vector<llvm::Type *> params, bool vararg = false);
-
-    // ---------- abi.cpp: C calling convention for structs by value ----------
-    AbiArg classify(const FType &t);
-    llvm::Function *declareC(const CFunc &f);
-    Value_ emitCCall(const CFunc &f, llvm::Function *fn, std::vector<Value_> args, Pos p);
-    llvm::Function *cThunk(Fn &fn, Pos p);
-
-    // ---------- language server index ----------
-    void note(Pos at, size_t len, const std::string &hover, Pos def = Pos{});
-    std::string signature(const Fn &fn);
-    std::string structHover(StructInfo *s);
-
-    // ---------- debug info ----------
-    void setLoc(Pos p);
-    llvm::DIType *diType(const FType &t);
-};
-
-}  // namespace finch

src/codegen_map.cpp

@@ -1,246 +0,0 @@
-// Code generation, part 4: maps.
-//
-// map[K]V is { entries, len, used, cap, index, icap } (see runtime/finch_rt.c). The runtime finds and
-// places entries; the compiler stores, copies and drops the keys and values in them, like it does
-// for array elements. An entry is { i64 hash, K key, V value }; hash 0 marks a removed entry.
-
-#include "codegen_impl.h"
-#include "builtins_doc.h"
-
-using namespace llvm;
-
-namespace finch {
-
-StructType *Codegen::mapEntryTy(const FType &t) {
-    return StructType::get(ctx, {b.getInt64Ty(), ty(*t.key), ty(*t.elem)});
-}
-
-// The runtime's (map, key, entry size, key size, key is str) arguments.
-std::vector<Value *> Codegen::mapArgs(Value *map, Value *keyAddr, const FType &t) {
-    return {map, keyAddr, b.getInt64(dl->getTypeAllocSize(mapEntryTy(t))), elemSize(*t.key),
-            b.getInt32(t.key->kind == FType::Str ? 1 : 0)};
-}
-
-Value *Codegen::mapEntry(Value *map, const FType &t, Value *i) {
-    Value *entries = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(t), map, 0));
-    return b.CreateInBoundsGEP(mapEntryTy(t), entries, i);
-}
-
-// The entry for `key`, added if it's missing: the key is copied in, and the value is its type's
-// default when `fill` (m[k] += 1 starts from 0).
-Value *Codegen::mapSlot(Value *map, const FType &t, const Value_ &key, Pos p, bool fill) {
-    StructType *ET = mapEntryTy(t);
-    Value *keyAddr = tmp(key.v);
-    Value *added = tmpOf(b.getInt32Ty());
-    std::vector<Value *> args = mapArgs(map, keyAddr, t);
-    args.push_back(added);
-    Value *entry = mapEntry(map, t, b.CreateCall(rt("finch_map_slot"), args));
-    BasicBlock *fresh = newBlock("map.new"), *have = newBlock("map.have");
-    b.CreateCondBr(b.CreateICmpNE(b.CreateLoad(b.getInt32Ty(), added), b.getInt32(0)), fresh, have);
-    b.SetInsertPoint(fresh);
-    copyAt(b.CreateStructGEP(ET, entry, 1), keyAddr, *t.key);
-    if (fill) b.CreateStore(own(defaultValue(*t.elem, p)), b.CreateStructGEP(ET, entry, 2));
-    b.CreateBr(have);
-    b.SetInsertPoint(have);
-    return entry;
-}
-
-// Every live entry, in insertion order: body(entry number, entry address).
-void Codegen::forEachEntry(Value *map, const FType &t, const std::function<void(Value *, Value *)> &body) {
-    Value *used = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(ty(t), map, 2));
-    forN(used, [&](Value *i) {
-        Value *entry = mapEntry(map, t, i);
-        Value *hash = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(mapEntryTy(t), entry, 0));
-        BasicBlock *live = newBlock("entry.live"), *next = newBlock("entry.next");
-        b.CreateCondBr(b.CreateICmpNE(hash, b.getInt64(0)), live, next);
-        b.SetInsertPoint(live);
-        body(i, entry);
-        b.CreateBr(next);
-        b.SetInsertPoint(next);
-    });
-}
-
-// A key as text for error messages: "bob" or 42
-Value *Codegen::keyText(const Value_ &key) {
-    Value *out = tmpOf(ty(FType::Str));
-    const FType &t = key.type;
-    if (t.kind == FType::Str) {
-        Value *q = tmp(strConst("\"")), *half = tmpOf(ty(FType::Str));
-        b.CreateCall(rt("finch_str_concat"), {half, q, tmp(key.v)});
-        b.CreateCall(rt("finch_str_concat"), {out, half, q});
-    } else if (t.isSigned()) {
-        b.CreateCall(rt("finch_str_from_int"), {out, b.CreateSExt(key.v, b.getInt64Ty())});
-    } else if (t.isUnsigned()) {
-        b.CreateCall(rt("finch_str_from_uint"), {out, b.CreateZExt(key.v, b.getInt64Ty())});
-    } else if (t.kind == FType::Char) {
-        b.CreateCall(rt("finch_str_from_char"), {out, key.v});
-    } else {
-        b.CreateCall(rt("finch_str_from_bool"), {out, b.CreateZExt(key.v, b.getInt32Ty())});
-    }
-    return out;
-}
-
-// m[key]: reading a missing key stops the program; writing (m[k] = v, m[k] += 1, m[k].push(x)) adds it
-LRef Codegen::mapIndex(const IndexExpr &e, LRef &obj, const FType &t, bool forWrite) {
-    Pos p = e.pos;
-    FType kt = *t.key, vt = *t.elem;
-    Value_ key = coerce(exprWant(*e.index, kt), kt, e.index->pos, "the key");
-    if (forWrite) {
-        if (!obj.isPlace) failAt(p.file, p.line, p.col, "this is a temporary map, it can't be changed");
-        Value *entry = mapSlot(obj.pl.addr, t, key, p, true);
-        release(key);
-        return {true, {b.CreateStructGEP(mapEntryTy(t), entry, 2), vt}, {}};
-    }
-    Value *map = obj.isPlace ? obj.pl.addr : tmp(obj.val.v);
-    Value *i = b.CreateCall(rt("finch_map_find"), mapArgs(map, tmp(key.v), t));
-    BasicBlock *missing = newBlock("map.missing"), *found = newBlock("map.found");
-    b.CreateCondBr(b.CreateICmpSLT(i, b.getInt64(0)), missing, found);
-    b.SetInsertPoint(missing);
-    b.CreateCall(rt("finch_map_missing"), {fileName(p), b.getInt64(p.line), keyText(key)});
-    b.CreateUnreachable();
-    b.SetInsertPoint(found);
-    release(key);
-    Value *valueAddr = b.CreateStructGEP(mapEntryTy(t), mapEntry(map, t, i), 2);
-    if (obj.isPlace) return {true, {valueAddr, vt}, {}};
-    Value *v = b.CreateLoad(ty(vt), valueAddr);  // from a temporary map: take the value, drop the rest
-    Value_ out{v, vt};
-    if (owning(vt) && obj.val.fresh) out = {copyValue(v, vt), vt, false, true};
-    release(obj.val);
-    return {false, {}, out};
-}
-
-// ["a": 1, "b": 2], or [:] where the type is known
-Value_ Codegen::mapLit(const MapLitExpr &e, const FType *want) {
-    Pos p = e.pos;
-    FType t;
-    Value_ k0, v0;  // the first entry, when it decides the types
-    bool first = false;
-    if (want && want->kind == FType::Map) {
-        t = *want;
-    } else if (e.keys.empty()) {
-        failAt(p.file, p.line, p.col, "an empty [:] needs a type, like: map[str]int m = [:]");
-    } else {
-        // number values written in the code are all floats if any of them has a dot
-        bool allNum = true, anyFloat = false;
-        for (auto &x : e.values) {
-            const Expr *y = x.get();
-            if (y->kind == ExprKind::Unary && static_cast<const UnaryExpr *>(y)->op == '-') y = static_cast<const UnaryExpr *>(y)->operand.get();
-            if (y->kind == ExprKind::Float) anyFloat = true;
-            else if (y->kind != ExprKind::Int) allNum = false;
-        }
-        k0 = expr(*e.keys[0]);
-        v0 = expr(*e.values[0]);
-        Pos kp = e.keys[0]->pos, vp = e.values[0]->pos;
-        if (k0.type.kind == FType::Void || k0.type.kind == FType::Null) failAt(kp.file, kp.line, kp.col, "a map key needs a value with a type");
-        if (v0.type.kind == FType::Void || v0.type.kind == FType::Null) failAt(vp.file, vp.line, vp.col, "a map value needs a value with a type");
-        t = resolve(FType::mapOf(k0.type, allNum && anyFloat ? FType(FType::F64) : v0.type), kp);
-        first = true;
-    }
-    Value *map = tmp(zero(t));
-    StructType *ET = mapEntryTy(t);
-    Held held(*this);
-    holdAddr(map, t);  // the entries so far, if a later one leaves early
-    for (size_t i = 0; i < e.keys.size(); i++) {
-        Held entry(*this);
-        Value_ k = i == 0 && first ? k0 : exprWant(*e.keys[i], *t.key);
-        k = coerce(k, *t.key, e.keys[i]->pos, "every key of this map");
-        hold(k);
-        Value_ v = i == 0 && first ? v0 : exprWant(*e.values[i], *t.elem);
-        Value *vv = own(coerce(v, *t.elem, e.values[i]->pos, "every value of this map"));
-        Value *valueAddr = b.CreateStructGEP(ET, mapSlot(map, t, k, p, false), 2);
-        dropAt(valueAddr, *t.elem);  // a key given twice: the last value wins
-        b.CreateStore(vv, valueAddr);
-        release(k);
-    }
-    return {b.CreateLoad(ty(t), map), t, false, true};
-}
-
-Value_ Codegen::mapMethod(const MethodExpr &m, Value_ *recv) {
-    Pos p = m.pos;
-    const std::string &n = m.name;
-    FType t = recv->type, kt = *t.key, vt = *t.elem;
-    StructType *ET = mapEntryTy(t);
-    Value *map = recv->v;
-    auto need = [&](size_t k) { checkArgs(m.args, m.argNames, k, p, n); };
-    auto keyArg = [&]() { return coerce(exprWant(*m.args[0], kt), kt, m.args[0]->pos, "the key"); };
-    if (g_index)
-        for (const BuiltinDoc &d : kMapMethods)
-            if (n == d.name) note(Pos{p.line, p.col + 1, p.file}, n.size(), "```finch\n" + std::string(d.signature) + "\n```\n" + d.doc);
-
-    if (n == "has") {
-        need(1);
-        Value_ k = keyArg();
-        Value *i = b.CreateCall(rt("finch_map_find"), mapArgs(map, tmp(k.v), t));
-        release(k);
-        return {b.CreateICmpSGE(i, b.getInt64(0)), FType::Bool};
-    }
-    if (n == "get") {  // m.get(key, default): the default is only computed when the key is missing
-        need(2);
-        Value_ k = keyArg();
-        Value *i = b.CreateCall(rt("finch_map_find"), mapArgs(map, tmp(k.v), t));
-        release(k);
-        BasicBlock *found = newBlock("get.found"), *missing = newBlock("get.missing"), *end = newBlock("get.end");
-        b.CreateCondBr(b.CreateICmpSGE(i, b.getInt64(0)), found, missing);
-        b.SetInsertPoint(found);
-        Value *v = b.CreateLoad(ty(vt), b.CreateStructGEP(ET, mapEntry(map, t, i), 2));
-        v = copyValue(v, vt);
-        BasicBlock *foundEnd = b.GetInsertBlock();
-        b.CreateBr(end);
-        b.SetInsertPoint(missing);
-        Value *d = own(coerce(exprWant(*m.args[1], vt), vt, m.args[1]->pos, "the default"));
-        BasicBlock *missingEnd = b.GetInsertBlock();
-        b.CreateBr(end);
-        b.SetInsertPoint(end);
-        PHINode *phi = b.CreatePHI(ty(vt), 2);
-        phi->addIncoming(v, foundEnd);
-        phi->addIncoming(d, missingEnd);
-        return {phi, vt, false, owning(vt)};
-    }
-    if (n == "remove") {  // true if the key was there
-        need(1);
-        Value_ k = keyArg();
-        Value *i = b.CreateCall(rt("finch_map_find"), mapArgs(map, tmp(k.v), t));
-        release(k);
-        BasicBlock *hit = newBlock("remove.hit"), *end = newBlock("remove.end");
-        Value *was = b.CreateICmpSGE(i, b.getInt64(0));
-        b.CreateCondBr(was, hit, end);
-        b.SetInsertPoint(hit);
-        Value *entry = mapEntry(map, t, i);
-        dropAt(b.CreateStructGEP(ET, entry, 1), kt);
-        dropAt(b.CreateStructGEP(ET, entry, 2), vt);
-        b.CreateCall(rt("finch_map_remove_at"), {map, i, b.getInt64(dl->getTypeAllocSize(ET))});
-        b.CreateBr(end);
-        b.SetInsertPoint(end);
-        return {was, FType::Bool};
-    }
-    if (n == "clear") {
-        need(0);
-        if (owning(kt) || owning(vt))
-            forEachEntry(map, t, [&](Value *, Value *entry) {
-                dropAt(b.CreateStructGEP(ET, entry, 1), kt);
-                dropAt(b.CreateStructGEP(ET, entry, 2), vt);
-            });
-        b.CreateCall(rt("finch_map_clear"), {map});
-        return {nullptr, FType::Void};
-    }
-    if (n == "keys" || n == "values") {  // a new array, in insertion order
-        need(0);
-        FType et = n == "keys" ? kt : vt;
-        unsigned field = n == "keys" ? 1 : 2;
-        FType at = FType::arrayOf(et);
-        Value *out = tmpOf(ty(at));
-        Value *len = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(ty(t), map, 1));
-        b.CreateCall(rt("finch_arr_make"), {out, len, elemSize(et)});
-        Value *data = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(at), out, 0));
-        Value *j = tmp(b.getInt64(0));
-        forEachEntry(map, t, [&](Value *, Value *entry) {
-            Value *jv = b.CreateLoad(b.getInt64Ty(), j);
-            copyAt(b.CreateInBoundsGEP(ty(et), data, jv), b.CreateStructGEP(ET, entry, field), et);
-            b.CreateStore(b.CreateAdd(jv, b.getInt64(1)), j);
-        });
-        return {b.CreateLoad(ty(at), out), at, false, true};
-    }
-    failAt(p.file, p.line, p.col, "a map has no method '" + n + "' (it has: has, get, remove, clear, keys, values; and m[key], .len)");
-}
-
-}  // namespace finch

src/codegen_types.cpp

@@ -1,580 +0,0 @@
-// Code generation, part 2: types, conversions, ownership (copy/drop) and printing.
-
-#include "codegen_impl.h"
-
-using namespace llvm;
-
-namespace finch {
-
-// ---------- types ----------
-
-llvm::Type *Codegen::ty(const FType &t) {
-    switch (t.kind) {
-    case FType::Void: return b.getVoidTy();
-    case FType::Bool: return b.getInt1Ty();
-    case FType::Char:
-    case FType::I8:
-    case FType::U8: return b.getInt8Ty();
-    case FType::I16:
-    case FType::U16: return b.getInt16Ty();
-    case FType::I32:
-    case FType::U32: return b.getInt32Ty();
-    case FType::I64:
-    case FType::U64: return b.getInt64Ty();
-    case FType::F32: return b.getFloatTy();
-    case FType::F64: return b.getDoubleTy();
-    case FType::Str:
-    case FType::Array: return StructType::get(ctx, {b.getPtrTy(), b.getInt64Ty(), b.getInt64Ty()});
-    case FType::Map: {
-        llvm::Type *P = b.getPtrTy(), *I = b.getInt64Ty();
-        return StructType::get(ctx, {P, I, I, I, P, I, I});  // entries, len, used, cap, index, icap, adds
-    }
-    case FType::Ptr:
-    case FType::Null: return b.getPtrTy();
-    case FType::Fixed: return ArrayType::get(ty(*t.elem), t.count);
-    case FType::Struct: return t.info->llvm;
-    case FType::Named: break;
-    }
-    std::fprintf(stderr, "internal compiler error: unresolved type %s\n", t.show().c_str());
-    std::exit(2);
-}
-
-FType Codegen::resolve(const FType &t, Pos p) { return resolveT(t, p, true); }
-
-StructInfo *Codegen::findStruct(const std::string &module, const std::string &name, bool qualified) {
-    if (qualified) {
-        if (module == "C") {
-            auto it = cStructs.find(name);
-            return it == cStructs.end() ? nullptr : it->second;
-        }
-        auto m = modules.find(module);
-        if (m == modules.end()) return nullptr;
-        auto it = m->second.structs.find(name);
-        return it == m->second.structs.end() ? nullptr : it->second;
-    }
-    auto &here = modules[curModule].structs;
-    if (auto it = here.find(name); it != here.end()) return it->second;
-    if (auto it = cStructs.find(name); it != cStructs.end()) return it->second;
-    return nullptr;
-}
-
-FType Codegen::resolveT(const FType &t, Pos p, bool deep) {
-    switch (t.kind) {
-    case FType::Ptr:
-        if (!t.elem) return t;
-        return FType::ptrTo(resolveT(*t.elem, p, false));
-    case FType::Array: return FType::arrayOf(resolveT(*t.elem, p, false));
-    case FType::Map: {
-        FType k = resolveT(*t.key, p, true);
-        if (!k.isInt() && k.kind != FType::Char && k.kind != FType::Bool && k.kind != FType::Str)
-            failAt(p.file, p.line, p.col, "a map key must be a whole number, a char, a bool or a str, not " + k.show());
-        FType v = resolveT(*t.elem, p, false);
-        if (v.kind == FType::Void) failAt(p.file, p.line, p.col, "a map value can't have the type 'nothing'");
-        return FType::mapOf(k, v);
-    }
-    case FType::Fixed: {
-        FType f = t;
-        f.elem = std::make_shared<FType>(resolveT(*t.elem, p, deep));
-        return f;
-    }
-    case FType::Named: {
-        bool qualified = !t.module.empty();
-        if (qualified && t.module != "C" && !modules[curModule].imports.count(t.module))
-            failAt(p.file, p.line, p.col, "'" + t.module + "' is not imported here (add: import " + t.module + ")");
-        StructInfo *s = findStruct(t.module, t.name, qualified);
-        if (!s) failAt(p.file, p.line, p.col, "there is no type named '" + t.show() + "'");
-        FType r(FType::Struct);
-        r.info = s;
-        r.name = s->name;
-        r.module = s->module == "C" ? "" : s->module;  // shown as math.Vec; C and main-file structs by name
-        if (deep) resolveStruct(s);
-        return r;
-    }
-    default: return t;
-    }
-}
-
-void Codegen::resolveStruct(StructInfo *s) {
-    if (s->state == 2) return;
-    if (s->state == 1)
-        failAt(s->pos.file, s->pos.line, s->pos.col,
-               "the struct " + s->name + " contains itself; use ptr[" + s->name + "] or []" + s->name + " for that field");
-    s->state = 1;
-    std::string savedModule = curModule;
-    curModule = s->isC ? "" : s->module;
-
-    std::vector<llvm::Type *> elems;
-    if (!s->isC) {
-        for (const Field &f : s->decl->fields) {
-            StructInfo::F nf;
-            nf.name = f.name;
-            nf.type = resolveT(f.type, f.pos, true);
-            if (nf.type.kind == FType::Void) failAt(f.pos.file, f.pos.line, f.pos.col, "a field can't have the type 'nothing'");
-            nf.init = f.init.get();
-            nf.pos = f.namePos;
-            nf.llvmIndex = elems.size();
-            elems.push_back(ty(nf.type));
-            s->owning |= owning(nf.type);
-            s->fields.push_back(nf);
-        }
-        s->llvm->setBody(elems);
-    } else {
-        // Lay the C struct out byte for byte: explicit padding, packed, exactly C's offsets.
-        long long off = 0;
-        Pos none;
-        for (const CField &cf : s->cstruct->fields) {
-            if (cf.hidden || cf.offset < off) continue;
-            FType ft = resolveT(cf.type, none, true);
-            llvm::Type *lt = ty(ft);
-            long long size = dl->getTypeAllocSize(lt);
-            if (size != cf.size) continue;  // something Finch can't mirror; the padding covers it
-            if (cf.offset > off) elems.push_back(ArrayType::get(b.getInt8Ty(), cf.offset - off));
-            StructInfo::F nf;
-            nf.name = cf.name;
-            nf.type = ft;
-            nf.llvmIndex = elems.size();
-            elems.push_back(lt);
-            s->fields.push_back(nf);
-            off = cf.offset + size;
-        }
-        if (s->cstruct->size > off) elems.push_back(ArrayType::get(b.getInt8Ty(), s->cstruct->size - off));
-        s->llvm->setBody(elems, true);
-        if (s->cstruct->hasHidden && s->unsupported.empty()) s->unsupported = "has fields Finch can't see (unions or bit fields)";
-    }
-    curModule = savedModule;
-    s->state = 2;
-}
-
-bool Codegen::owning(const FType &t) {
-    switch (t.kind) {
-    case FType::Str:
-    case FType::Array:
-    case FType::Map: return true;
-    case FType::Struct:
-        resolveStruct(t.info);
-        return t.info->owning;
-    default: return false;
-    }
-}
-
-Constant *Codegen::zero(const FType &t) { return Constant::getNullValue(ty(t)); }
-
-Value_ Codegen::defaultValue(const FType &t, Pos p) {
-    if (t.kind == FType::Struct && !t.info->isC) {
-        for (auto &f : t.info->fields)
-            if (f.init) return construct(t.info, {}, {}, p);
-    }
-    return {zero(t), t, false, owning(t)};
-}
-
-// Can every value of `from` be stored in `to`? (i8 -> i32 yes, i32 -> u32 no)
-bool Codegen::widens(const FType &from, const FType &to) {
-    if (!from.isInt() || !to.isInt()) return false;
-    if (from.isSigned() && to.isUnsigned()) return false;
-    return to.bits() > from.bits();
-}
-
-// Does the constant number `c` (of type `from`) fit into `to`?
-bool Codegen::fits(ConstantInt *c, const FType &from, const FType &to) {
-    if (!to.isInt()) return false;
-    bool negative = from.isSigned() && c->isNegative();
-    if (negative && to.isUnsigned()) return false;
-    if (negative) return c->getSExtValue() >= -(1LL << (to.bits() - 1));
-    unsigned long long v = c->getZExtValue();
-    if (to.bits() == 64) return to.isUnsigned() || v <= (unsigned long long)INT64_MAX;
-    unsigned long long max = to.isUnsigned() ? (1ULL << to.bits()) - 1 : (1ULL << (to.bits() - 1)) - 1;
-    return v <= max;
-}
-
-Value *Codegen::intCast(Value *v, const FType &from, const FType &to) { return b.CreateIntCast(v, ty(to), from.isSigned()); }
-
-Value *Codegen::intToFloat(Value *v, const FType &from, const FType &to) {
-    return from.isSigned() ? b.CreateSIToFP(v, ty(to)) : b.CreateUIToFP(v, ty(to));
-}
-
-// Implicit conversions: only the ones that can't surprise you.
-Value_ Codegen::coerce(Value_ v, const FType &want, Pos p, const std::string &what) {
-    const FType &from = v.type;
-    if (from == want) return v;
-    if (from.kind == FType::Null && want.isPtr()) return {ConstantPointerNull::get(b.getPtrTy()), want};
-    // any pointer fits an untyped `ptr`; an untyped ptr fits any pointer
-    if (want.isPtr() && from.isPtr() && (!want.elem || !from.elem)) return {v.v, want};
-
-    if (from.isInt() && want.isInt()) {
-        auto *c = v.literal ? dyn_cast<ConstantInt>(v.v) : nullptr;
-        if ((c && fits(c, from, want)) || widens(from, want)) return {intCast(v.v, from, want), want, (bool)c};
-        if (c)
-            failAt(p.file, p.line, p.col, "the number " + std::to_string(from.isSigned() ? c->getSExtValue() : (long long)c->getZExtValue()) +
-                                              " doesn't fit in " + want.show());
-    }
-    if (from.isInt() && want.isFloat()) return {intToFloat(v.v, from, want), want, v.literal};
-    if (from.kind == FType::F32 && want.kind == FType::F64) return {b.CreateFPExt(v.v, ty(want)), want};
-    if (from.kind == FType::F64 && want.kind == FType::F32 && v.literal) return {b.CreateFPTrunc(v.v, ty(want)), want, true};
-
-    std::string msg = what + " must be " + want.show() + ", but this is " + from.show();
-    if (from.isNumber() && want.isNumber())
-        msg += " (use " + want.show() + "(...) to convert" + (from.isFloat() && want.isInt() ? ", it cuts off the fraction)" : ")");
-    else if (want.kind == FType::Str && (from.isNumber() || from.kind == FType::Bool || from.kind == FType::Char))
-        msg += " (turn it into text with str(...))";
-    else if (want.isPtr() && from.kind == FType::Str)
-        msg += " (use .ptr to get the text's address)";
-    if (from.kind == FType::Null) msg = what + " can't be null (only pointers can)";
-    failAt(p.file, p.line, p.col, msg);
-}
-
-// ---------- ownership ----------
-
-Value *Codegen::tmpOf(llvm::Type *t) {
-    Function *f = b.GetInsertBlock()->getParent();
-    IRBuilder<> entry(&f->getEntryBlock(), f->getEntryBlock().begin());
-    AllocaInst *a = entry.CreateAlloca(t);
-    if (t->isStructTy()) a->setAlignment(Align(16));
-    return a;
-}
-
-Value *Codegen::tmp(Value *v) {
-    Value *a = tmpOf(v->getType());
-    b.CreateStore(v, a);
-    return a;
-}
-
-Value *Codegen::own(const Value_ &v) {
-    if (!owning(v.type) || v.fresh) return v.v;
-    return copyValue(v.v, v.type);
-}
-
-void Codegen::release(const Value_ &v) {
-    // constants (string literals, empty arrays) own no memory: nothing to free
-    if (v.fresh && v.v && !isa<Constant>(v.v) && owning(v.type)) dropValue(v.v, v.type);
-}
-
-Value *Codegen::copyValue(Value *v, const FType &t) {
-    if (!owning(t)) return v;
-    Value *out = tmpOf(ty(t));
-    copyAt(out, tmp(v), t);
-    return b.CreateLoad(ty(t), out);
-}
-
-void Codegen::dropValue(Value *v, const FType &t) {
-    if (owning(t)) dropAt(tmp(v), t);
-}
-
-void Codegen::dropAt(Value *addr, const FType &t) {
-    if (!owning(t)) return;
-    if (t.kind == FType::Str) b.CreateCall(rt("finch_str_drop"), {addr});
-    else b.CreateCall(dropFn(t), {addr});
-}
-
-void Codegen::copyAt(Value *dst, Value *src, const FType &t) {
-    if (!owning(t)) {
-        b.CreateStore(b.CreateLoad(ty(t), src), dst);
-        return;
-    }
-    if (t.kind == FType::Str) b.CreateCall(rt("finch_str_copy"), {dst, src});
-    else b.CreateCall(copyFn(t), {dst, src});
-}
-
-void Codegen::forN(Value *n, const std::function<void(Value *)> &body) {
-    Value *i = tmpOf(b.getInt64Ty());
-    b.CreateStore(b.getInt64(0), i);
-    BasicBlock *cond = newBlock("n.cond"), *loop = newBlock("n.body"), *end = newBlock("n.end");
-    b.CreateBr(cond);
-    b.SetInsertPoint(cond);
-    Value *iv = b.CreateLoad(b.getInt64Ty(), i);
-    b.CreateCondBr(b.CreateICmpSLT(iv, n), loop, end);
-    b.SetInsertPoint(loop);
-    body(iv);
-    b.CreateStore(b.CreateAdd(iv, b.getInt64(1)), i);
-    b.CreateBr(cond);
-    b.SetInsertPoint(end);
-}
-
-std::string Codegen::typeKey(const FType &t) {
-    switch (t.kind) {
-    case FType::Array: return "arr_" + typeKey(*t.elem);
-    case FType::Map: return "map_" + typeKey(*t.key) + "_" + typeKey(*t.elem);
-    case FType::Fixed: return "fix" + std::to_string(t.count) + "_" + typeKey(*t.elem);
-    case FType::Ptr: return "ptr";
-    case FType::Struct: return "S_" + (t.info->module.empty() ? std::string("main") : t.info->module) + "_" + t.info->name;
-    default: return t.show();
-    }
-}
-
-// Helper functions are generated once per type and shared; they have no source position.
-struct HelperScope {
-    Codegen &cg;
-    IRBuilderBase::InsertPointGuard guard;
-    DISubprogram *savedFn;
-    HelperScope(Codegen &c, Function *f) : cg(c), guard(c.b), savedFn(c.diFn) {
-        c.diFn = nullptr;
-        c.b.SetInsertPoint(BasicBlock::Create(c.ctx, "entry", f));
-        c.b.SetCurrentDebugLocation(DebugLoc());
-    }
-    ~HelperScope() { cg.diFn = savedFn; }
-};
-
-Function *Codegen::dropFn(const FType &t) {
-    std::string key = "drop." + typeKey(t);
-    if (auto it = helpers.find(key); it != helpers.end()) return it->second;
-    Function *f = Function::Create(FunctionType::get(b.getVoidTy(), {b.getPtrTy()}, false), Function::InternalLinkage,
-                                   "finch." + key, mod.get());
-    helpers[key] = f;
-    HelperScope hs(*this, f);
-    Value *a = f->getArg(0);
-    if (t.kind == FType::Array) {
-        FType et = *t.elem;
-        if (owning(et)) {
-            Value *data = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(t), a, 0));
-            Value *len = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(ty(t), a, 1));
-            forN(len, [&](Value *i) { dropAt(b.CreateInBoundsGEP(ty(et), data, i), et); });
-        }
-        b.CreateCall(rt("finch_arr_free"), {a});
-    } else if (t.kind == FType::Map) {
-        FType kt = *t.key, vt = *t.elem;
-        if (owning(kt) || owning(vt))
-            forEachEntry(a, t, [&](Value *, Value *entry) {
-                dropAt(b.CreateStructGEP(mapEntryTy(t), entry, 1), kt);
-                dropAt(b.CreateStructGEP(mapEntryTy(t), entry, 2), vt);
-            });
-        b.CreateCall(rt("finch_map_free"), {a});
-    } else if (t.kind == FType::Struct) {
-        for (auto &fl : t.info->fields)
-            if (owning(fl.type)) dropAt(b.CreateStructGEP(t.info->llvm, a, fl.llvmIndex), fl.type);
-    }
-    b.CreateRetVoid();
-    return f;
-}
-
-Function *Codegen::copyFn(const FType &t) {
-    std::string key = "copy." + typeKey(t);
-    if (auto it = helpers.find(key); it != helpers.end()) return it->second;
-    Function *f = Function::Create(FunctionType::get(b.getVoidTy(), {b.getPtrTy(), b.getPtrTy()}, false),
-                                   Function::InternalLinkage, "finch." + key, mod.get());
-    helpers[key] = f;
-    HelperScope hs(*this, f);
-    Value *dst = f->getArg(0), *src = f->getArg(1);
-    if (t.kind == FType::Array) {
-        FType et = *t.elem;
-        b.CreateCall(rt("finch_arr_clone_raw"), {dst, src, elemSize(et)});
-        if (owning(et)) {
-            Value *d = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(t), dst, 0));
-            Value *s = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(t), src, 0));
-            Value *len = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(ty(t), src, 1));
-            forN(len, [&](Value *i) {
-                copyAt(b.CreateInBoundsGEP(ty(et), d, i), b.CreateInBoundsGEP(ty(et), s, i), et);
-            });
-        }
-    } else if (t.kind == FType::Map) {
-        StructType *ET = mapEntryTy(t);
-        FType kt = *t.key, vt = *t.elem;
-        b.CreateCall(rt("finch_map_clone_raw"), {dst, src, b.getInt64(dl->getTypeAllocSize(ET))});
-        if (owning(kt) || owning(vt))  // the slots were copied byte for byte: now give the copy its own keys and values
-            forEachEntry(src, t, [&](Value *i, Value *from) {
-                Value *to = mapEntry(dst, t, i);
-                copyAt(b.CreateStructGEP(ET, to, 1), b.CreateStructGEP(ET, from, 1), kt);
-                copyAt(b.CreateStructGEP(ET, to, 2), b.CreateStructGEP(ET, from, 2), vt);
-            });
-    } else if (t.kind == FType::Struct) {
-        b.CreateStore(b.CreateLoad(ty(t), src), dst);
-        for (auto &fl : t.info->fields)
-            if (owning(fl.type))
-                copyAt(b.CreateStructGEP(t.info->llvm, dst, fl.llvmIndex), b.CreateStructGEP(t.info->llvm, src, fl.llvmIndex), fl.type);
-    }
-    b.CreateRetVoid();
-    return f;
-}
-
-// ---------- strings ----------
-
-Value *Codegen::strConst(const std::string &s) {
-    Constant *g = b.CreateGlobalString(s, "str");
-    return ConstantStruct::get(cast<StructType>(ty(FType::Str)), {g, b.getInt64(s.size()), b.getInt64(0)});
-}
-
-// str -> char* for C (an empty str may have no memory at all; C gets "" then)
-Value *Codegen::cstr(Value *s) {
-    Value *p = b.CreateExtractValue(s, 0);
-    return b.CreateSelect(b.CreateIsNull(p), b.CreateGlobalString("", "empty"), p);
-}
-
-Value_ Codegen::strFromC(Value *p) {
-    Value *out = tmpOf(ty(FType::Str));
-    b.CreateCall(rt("finch_str_from_c"), {out, p});
-    return {b.CreateLoad(ty(FType::Str), out), FType::Str};
-}
-
-Value *Codegen::elemSize(const FType &t) { return b.getInt64(dl->getTypeAllocSize(ty(t))); }
-
-// ---------- printing ----------
-
-void Codegen::printf_(const std::string &fmt, std::vector<Value *> args) {
-    args.insert(args.begin(), b.CreateGlobalString(fmt, "fmt"));
-    b.CreateCall(libc("printf", b.getInt32Ty(), {b.getPtrTy()}, true), args);
-}
-
-void Codegen::emitPrint(Value *v, const FType &t, bool quoted) {
-    if (t.isSigned()) printf_("%lld", {b.CreateSExt(v, b.getInt64Ty())});
-    else if (t.isUnsigned()) printf_("%llu", {b.CreateZExt(v, b.getInt64Ty())});
-    else if (t.isFloat()) printf_("%g", {b.CreateFPExt(v, b.getDoubleTy())});
-    else if (t.kind == FType::Char) printf_(quoted ? "'%c'" : "%c", {b.CreateZExt(v, b.getInt32Ty())});
-    else if (t.kind == FType::Bool) printf_("%s", {b.CreateSelect(v, b.CreateGlobalString("true", "true"), b.CreateGlobalString("false", "false"))});
-    else if (t.kind == FType::Str)
-        printf_(quoted ? "\"%.*s\"" : "%.*s", {b.CreateTrunc(b.CreateExtractValue(v, 1), b.getInt32Ty()), cstr(v)});
-    else {  // pointers, arrays, maps, structs: built as text first (the same text str(x) gives)
-        Value *buf = tmp(zero(FType::Str));
-        emitFormat(buf, v, t, quoted);
-        b.CreateCall(rt("finch_buf_print"), {buf});
-    }
-}
-
-void Codegen::bufText(Value *buf, const std::string &text) {
-    b.CreateCall(rt("finch_buf_add"), {buf, b.CreateGlobalString(text, "txt"), b.getInt64(text.size())});
-}
-
-void Codegen::emitFormat(Value *buf, Value *v, const FType &t, bool quoted) {
-    if (t.isSigned()) b.CreateCall(rt("finch_buf_int"), {buf, b.CreateSExt(v, b.getInt64Ty())});
-    else if (t.isUnsigned()) b.CreateCall(rt("finch_buf_uint"), {buf, b.CreateZExt(v, b.getInt64Ty())});
-    else if (t.isFloat()) b.CreateCall(rt("finch_buf_float"), {buf, b.CreateFPExt(v, b.getDoubleTy())});
-    else if (t.kind == FType::Char) b.CreateCall(rt("finch_buf_char"), {buf, v, b.getInt32(quoted)});
-    else if (t.kind == FType::Bool) b.CreateCall(rt("finch_buf_bool"), {buf, b.CreateZExt(v, b.getInt32Ty())});
-    else if (t.kind == FType::Str) b.CreateCall(rt("finch_buf_str"), {buf, tmp(v), b.getInt32(quoted)});
-    else if (t.isPtr() || t.kind == FType::Null) b.CreateCall(rt("finch_buf_ptr"), {buf, v});  // the same everywhere: null or 0x...
-    else b.CreateCall(formatFn(t), {buf, tmp(v)});
-}
-
-// One function per array / map / struct type: (str *buf, T *value)
-Function *Codegen::formatFn(const FType &t) {
-    std::string key = "format." + typeKey(t);
-    if (auto it = helpers.find(key); it != helpers.end()) return it->second;
-    Function *f = Function::Create(FunctionType::get(b.getVoidTy(), {b.getPtrTy(), b.getPtrTy()}, false),
-                                   Function::InternalLinkage, "finch." + key, mod.get());
-    helpers[key] = f;
-    HelperScope hs(*this, f);
-    Value *buf = f->getArg(0), *a = f->getArg(1);
-    if (t.kind == FType::Array || t.kind == FType::Fixed) {
-        FType et = *t.elem;
-        Value *data, *len;
-        if (t.kind == FType::Fixed) {
-            data = a;
-            len = b.getInt64(t.count);
-        } else {
-            data = b.CreateLoad(b.getPtrTy(), b.CreateStructGEP(ty(t), a, 0));
-            len = b.CreateLoad(b.getInt64Ty(), b.CreateStructGEP(ty(t), a, 1));
-        }
-        bufText(buf, "[");
-        forN(len, [&](Value *i) {
-            BasicBlock *sep = newBlock("sep"), *item = newBlock("item");
-            b.CreateCondBr(b.CreateICmpSGT(i, b.getInt64(0)), sep, item);
-            b.SetInsertPoint(sep);
-            bufText(buf, ", ");
-            b.CreateBr(item);
-            b.SetInsertPoint(item);
-            emitFormat(buf, b.CreateLoad(ty(et), b.CreateInBoundsGEP(ty(et), data, i)), et, true);
-        });
-        bufText(buf, "]");
-    } else if (t.kind == FType::Map) {  // {"a": 1, "b": 2}
-        StructType *ET = mapEntryTy(t);
-        Value *firstItem = tmp(b.getInt1(true));
-        bufText(buf, "{");
-        forEachEntry(a, t, [&](Value *, Value *entry) {
-            BasicBlock *sep = newBlock("sep"), *item = newBlock("item");
-            b.CreateCondBr(b.CreateLoad(b.getInt1Ty(), firstItem), item, sep);
-            b.SetInsertPoint(sep);
-            bufText(buf, ", ");
-            b.CreateBr(item);
-            b.SetInsertPoint(item);
-            b.CreateStore(b.getInt1(false), firstItem);
-            emitFormat(buf, b.CreateLoad(ty(*t.key), b.CreateStructGEP(ET, entry, 1)), *t.key, true);
-            bufText(buf, ": ");
-            emitFormat(buf, b.CreateLoad(ty(*t.elem), b.CreateStructGEP(ET, entry, 2)), *t.elem, true);
-        });
-        bufText(buf, "}");
-    } else if (t.kind == FType::Struct) {
-        bufText(buf, t.info->name + "(");
-        bool first = true;
-        for (auto &fl : t.info->fields) {
-            if (fl.hidden) continue;
-            bufText(buf, (first ? "" : ", ") + fl.name + ": ");
-            first = false;
-            emitFormat(buf, b.CreateLoad(ty(fl.type), b.CreateStructGEP(t.info->llvm, a, fl.llvmIndex)), fl.type, true);
-        }
-        bufText(buf, ")");
-    }
-    b.CreateRetVoid();
-    return f;
-}
-
-// ---------- debug info ----------
-
-DIType *Codegen::diType(const FType &t) {
-    std::string key = typeKey(t);
-    if (auto it = diTypes.find(key); it != diTypes.end()) return it->second;
-    DIType *d = nullptr;
-    auto basic = [&](const char *n, unsigned bits, unsigned enc) { return di->createBasicType(n, bits, enc); };
-    switch (t.kind) {
-    case FType::Void: return nullptr;
-    case FType::Bool: d = basic("bool", 8, dwarf::DW_ATE_boolean); break;
-    case FType::Char: d = basic("char", 8, dwarf::DW_ATE_signed_char); break;
-    case FType::I8: d = basic("i8", 8, dwarf::DW_ATE_signed); break;
-    case FType::I16: d = basic("i16", 16, dwarf::DW_ATE_signed); break;
-    case FType::I32: d = basic("i32", 32, dwarf::DW_ATE_signed); break;
-    case FType::I64: d = basic("int", 64, dwarf::DW_ATE_signed); break;
-    case FType::U8: d = basic("u8", 8, dwarf::DW_ATE_unsigned); break;
-    case FType::U16: d = basic("u16", 16, dwarf::DW_ATE_unsigned); break;
-    case FType::U32: d = basic("u32", 32, dwarf::DW_ATE_unsigned); break;
-    case FType::U64: d = basic("u64", 64, dwarf::DW_ATE_unsigned); break;
-    case FType::F32: d = basic("f32", 32, dwarf::DW_ATE_float); break;
-    case FType::F64: d = basic("float", 64, dwarf::DW_ATE_float); break;
-    case FType::Ptr:
-    case FType::Null: d = di->createPointerType(t.elem ? diType(*t.elem) : nullptr, 64, 0, std::nullopt, t.show()); break;
-    case FType::Fixed:
-        d = di->createArrayType(t.count * (uint64_t)dl->getTypeAllocSizeInBits(ty(*t.elem)), 0, diType(*t.elem),
-                                di->getOrCreateArray({di->getOrCreateSubrange(0, t.count)}));
-        break;
-    case FType::Str:
-    case FType::Array: {
-        DIType *et = t.kind == FType::Str ? diType(FType::Char) : diType(*t.elem);
-        DIType *pt = di->createPointerType(et, 64);
-        DIType *i64 = diType(FType::I64);
-        DIFile *f = diFiles[0];
-        Metadata *els[] = {di->createMemberType(diUnit, "ptr", f, 0, 64, 64, 0, DINode::FlagZero, pt),
-                           di->createMemberType(diUnit, "len", f, 0, 64, 64, 64, DINode::FlagZero, i64),
-                           di->createMemberType(diUnit, "cap", f, 0, 64, 64, 128, DINode::FlagZero, i64)};
-        d = di->createStructType(diUnit, t.show(), f, 0, 192, 64, DINode::FlagZero, nullptr, di->getOrCreateArray(els));
-        break;
-    }
-    case FType::Map: {  // shown by its parts; the entries are behind `entries`
-        DIType *i64 = diType(FType::I64), *pt = di->createPointerType(nullptr, 64);
-        DIFile *f = diFiles[0];
-        const char *names[] = {"entries", "len", "used", "cap", "index", "icap", "adds"};
-        std::vector<Metadata *> els;
-        for (unsigned k = 0; k < 7; k++)
-            els.push_back(di->createMemberType(diUnit, names[k], f, 0, 64, 64, 64 * k, DINode::FlagZero, k == 0 || k == 4 ? pt : i64));
-        d = di->createStructType(diUnit, t.show(), f, 0, 448, 64, DINode::FlagZero, nullptr, di->getOrCreateArray(els));
-        break;
-    }
-    case FType::Struct: {
-        StructInfo *s = t.info;
-        DIFile *f = s->isC ? diFiles[0] : diFiles[s->pos.file];
-        auto *fwd = di->createReplaceableCompositeType(dwarf::DW_TAG_structure_type, s->name, diUnit, f, s->pos.line);
-        diTypes[key] = fwd;
-        const StructLayout *lay = dl->getStructLayout(s->llvm);
-        std::vector<Metadata *> els;
-        for (auto &fl : s->fields) {
-            uint64_t bits = dl->getTypeAllocSizeInBits(ty(fl.type));
-            els.push_back(di->createMemberType(diUnit, fl.name, f, s->pos.line, bits, 8, lay->getElementOffsetInBits(fl.llvmIndex),
-                                               DINode::FlagZero, diType(fl.type)));
-        }
-        DICompositeType *real = di->createStructType(diUnit, s->name, f, s->pos.line, lay->getSizeInBits(), 8,
-                                                     DINode::FlagZero, nullptr, di->getOrCreateArray(els));
-        di->replaceTemporary(TempDIType(fwd), real);
-        d = real;
-        break;
-    }
-    case FType::Named: return nullptr;
-    }
-    diTypes[key] = d;
-    return d;
-}
-
-}  // namespace finch

src/docs.fch

@@ -0,0 +1,109 @@
+// One description of every built-in function and method, shared by the compiler (the index the language
+// server asks for) and the language server (hover, completion, signature help).
+
+struct Doc {
+    str name
+    str signature
+    str text
+}
+
+fn doc(str name, str signature, str text) -> Doc {
+    return Doc(name: name, signature: signature, text: text)
+}
+
+fn builtins() -> []Doc {
+    return [
+        doc("print", "print(a, b, ...)", "Prints the values separated by spaces, then a new line. Works with every type."),
+        doc("input", "input(str question = \"\") -> str", "Shows the question and reads one line typed by the user, without the newline."),
+        doc("read_file", "read_file(str path) -> str", "The whole file as text. Stops the program if it can't be read, unless handled: read_file(p) or { ... }, try read_file(p)."),
+        doc("write_file", "write_file(str path, str text) -> bool", "Writes (replaces) the file. true if it worked; with or / try, the reason it didn't."),
+        doc("file_exists", "file_exists(str path) -> bool", "Is there a file at this path?"),
+        doc("delete_file", "delete_file(str path) -> bool", "Deletes the file. true if it worked; with or / try, the reason it didn't."),
+        doc("error", "error(str message)", "The failure a fallible function returns: return error(\"...\"). The caller handles it with or / try."),
+        doc("shell", "shell(str command) -> int", "Runs a command in the system's shell and gives back its exit code."),
+        doc("exit", "exit(int code)", "Ends the program right away with this exit code."),
+        doc("addr", "addr(x) -> ptr[T]", "A pointer to a variable, field or element. addr(function) gives C a callback."),
+        doc("new", "new(value) -> ptr[T]", "Puts a copy of the value on the heap. Give it back with free(...)."),
+        doc("free", "free(ptr p)", "Gives back memory from new(...) (or from C), freeing what the value owns."),
+        doc("str", "str(x) -> str", "Turns a number, bool, char, []u8 or C char pointer into text."),
+        doc("int", "int(x) -> int", "Converts to a whole number: cuts off fractions, parses text (stops the program if it isn't a number, unless handled: int(s) or 0)."),
+        doc("float", "float(x) -> float", "Converts to a decimal number; parses text (int(s) or 0.0 handles bad text)."),
+        doc("char", "char(int n) -> char", "The character with this code."),
+        doc("bool", "bool(int n) -> bool", "true for any number but 0."),
+        doc("ptr", "ptr(x) -> ptr", "An untyped pointer: from a typed pointer, or from a number (an address or offset for C).")
+    ]
+}
+
+fn arrayMethods() -> []Doc {
+    return [
+        doc("len", ".len -> int", "The number of elements."),
+        doc("ptr", ".ptr -> ptr[T]", "The address of the first element, for C."),
+        doc("push", "push(T x)", "Adds x at the end."),
+        doc("pop", "pop() -> T", "Removes the last element and gives it back."),
+        doc("insert", "insert(int i, T x)", "Puts x at position i, moving the rest."),
+        doc("remove", "remove(int i) -> T", "Removes position i and gives it back."),
+        doc("clear", "clear()", "Removes everything."),
+        doc("resize", "resize(int n)", "Makes the array n long; new elements are zero."),
+        doc("find", "find(T x) -> int", "The index of x, or -1."),
+        doc("contains", "contains(T x) -> bool", "Is x in the array?"),
+        doc("sort", "sort()", "Sorts in place (numbers, chars, str)."),
+        doc("reverse", "reverse()", "Reverses in place."),
+        doc("slice", "slice(int start, int end) -> []T", "A new array with the elements start to end-1."),
+        doc("join", "join(str sep) -> str", "For []str: one text with sep between the parts.")
+    ]
+}
+
+fn strMethods() -> []Doc {
+    return [
+        doc("len", ".len -> int", "The number of bytes."),
+        doc("ptr", ".ptr -> ptr[char]", "The address of the text, for C (valid while the str lives)."),
+        doc("sub", "sub(int start, int end) -> str", "The part from start to end-1."),
+        doc("find", "find(str t) -> int", "Where t starts, or -1."),
+        doc("contains", "contains(str t) -> bool", "Does the text contain t?"),
+        doc("starts_with", "starts_with(str t) -> bool", "Does the text start with t?"),
+        doc("ends_with", "ends_with(str t) -> bool", "Does the text end with t?"),
+        doc("split", "split(str sep) -> []str", "The parts between each sep; split(\"\") gives single characters."),
+        doc("trim", "trim() -> str", "Without spaces and newlines at both ends."),
+        doc("upper", "upper() -> str", "With a-z changed to A-Z."),
+        doc("lower", "lower() -> str", "With A-Z changed to a-z."),
+        doc("replace", "replace(str from, str to) -> str", "Every from replaced by to."),
+        doc("repeat", "repeat(int n) -> str", "The text n times."),
+        doc("bytes", "bytes() -> []u8", "The bytes of the text.")
+    ]
+}
+
+fn mapMethods() -> []Doc {
+    return [
+        doc("len", ".len -> int", "The number of keys."),
+        doc("has", "has(K key) -> bool", "Is the key in the map?"),
+        doc("get", "get(K key, V default) -> V", "The value for key, or default if the key isn't there."),
+        doc("remove", "remove(K key) -> bool", "Removes the key and its value; true if it was there."),
+        doc("clear", "clear()", "Removes everything."),
+        doc("keys", "keys() -> []K", "The keys, in the order they were added."),
+        doc("values", "values() -> []V", "The values, in the order their keys were added.")
+    ]
+}
+
+fn keywords() -> []str {
+    return ["fn", "return", "if", "else", "while", "for", "in", "break", "continue", "true", "false", "null", "import",
+            "link", "struct", "enum", "match", "export", "defer", "or", "try", "self"]
+}
+
+fn typeNames() -> []str {
+    return ["int", "float", "bool", "char", "str", "ptr", "map", "i8", "i16", "i32", "i64", "u8", "u16", "u32", "u64", "f32", "f64"]
+}
+
+// the entry called `name`, or an empty Doc
+fn find([]Doc list, str name) -> Doc {
+    for d in list {
+        if d.name == name {
+            return d
+        }
+    }
+    return Doc()
+}
+
+// the text of a hover for a documented built-in
+fn hover(Doc d) -> str {
+    return "```finch\n" + d.signature + "\n```\n" + d.text
+}

src/error.h

@@ -1,48 +0,0 @@
-#pragma once
-
-#include <cstdio>
-#include <cstdlib>
-#include <string>
-#include <vector>
-
-// Every source file the compiler has read; positions point into this list.
-struct SourceFile {
-    std::string path;
-    std::string text;
-};
-inline std::vector<SourceFile> g_files;
-inline int g_curFile = 0;  // the file the lexer/parser is working on
-
-// The language server needs errors as values: it shows them in the editor and keeps running.
-struct FinchError {
-    int file, line, col;
-    std::string msg;
-};
-inline bool g_throwErrors = false;
-
-// Finch stops at the first error and shows exactly where it is.
-[[noreturn]] inline void failAt(int file, int line, int col, const std::string &msg) {
-    if (g_throwErrors) throw FinchError{file, line, col, msg};
-    const SourceFile &f = g_files.at(file);
-    std::fprintf(stderr, "%s:%d:%d: error: %s\n", f.path.c_str(), line, col, msg.c_str());
-
-    size_t start = 0;
-    for (int l = 1; l < line && start != std::string::npos; l++) {
-        start = f.text.find('\n', start);
-        if (start != std::string::npos) start++;
-    }
-    if (line > 0 && start != std::string::npos && start < f.text.size()) {
-        std::string text = f.text.substr(start, f.text.find('\n', start) - start);
-        std::string pad;
-        int c = 1;  // columns count characters; skip UTF-8 continuation bytes
-        for (size_t k = 0; k < text.size() && c < col; k++) {
-            if (((unsigned char)text[k] & 0xC0) == 0x80) continue;
-            pad += text[k] == '\t' ? '\t' : ' ';
-            c++;
-        }
-        std::fprintf(stderr, "%5d | %s\n      | %s^\n", line, text.c_str(), pad.c_str());
-    }
-    std::exit(1);
-}
-
-[[noreturn]] inline void fail(int line, int col, const std::string &msg) { failAt(g_curFile, line, col, msg); }

src/host.fch

@@ -0,0 +1,83 @@
+// What differs between the systems the compiler itself runs on: how a command line is quoted and run,
+// where temporary files go, making and removing files. This one is for Linux and macOS (name_windows.fch has
+// the Windows one).
+import "stdlib.h"
+import "unistd.h"
+import "clang-c/Index.h"
+
+// libclang's description of a file that isn't on disk: its Length is C's `unsigned long`, which is 64 bits here
+fn unsavedFile(str name, str contents) -> CXUnsavedFile {
+    return CXUnsavedFile(Filename: name.ptr, Contents: contents.ptr, Length: u64(contents.len))
+}
+
+fn quote(str a) -> str {
+    return "'" + a.replace("'", "'\\''") + "'"
+}
+
+// run a command line through the shell; its exit code
+fn run(str cmd) -> int {
+    return shell(cmd)
+}
+
+fn nullDevice() -> str {
+    return "/dev/null"
+}
+
+// the folder for temporary files
+fn tempDir() -> str {
+    t := getenv("TMPDIR")
+    if t.len > 0 {
+        if t.ends_with("/") {
+            return t.sub(0, t.len - 1)
+        }
+        return t
+    }
+    return "/tmp"
+}
+
+fn pathSeparator() -> str {
+    return ":"
+}
+
+fn pid() -> int {
+    return int(getpid())
+}
+
+// the folder the compiler was started in
+fn cwd() -> str {
+    return getenv("PWD")
+}
+
+// where files that are made once and kept go
+fn cacheDir() -> str {
+    x := getenv("XDG_CACHE_HOME")
+    if x.len > 0 {
+        return x + "/finch"
+    }
+    h := getenv("HOME")
+    if h.len > 0 {
+        return h + "/.cache/finch"
+    }
+    return tempDir() + "/finch-cache"
+}
+
+// the editor protocol is bytes, not text lines
+fn binaryStdio() {
+}
+
+fn makeDirs(str path) {
+    shell("mkdir -p " + quote(path))
+}
+
+fn remove(str path) {
+    delete_file(path)
+}
+
+fn removeTree(str path) {
+    shell("rm -rf " + quote(path))
+}
+
+// move a file over another
+fn move(str from, str to) {
+    shell("mv " + quote(from) + " " + quote(to))
+}

src/host_windows.fch

@@ -0,0 +1,104 @@
+// What differs between the systems the compiler itself runs on: how a command line is quoted and run,
+// where temporary files go, making and removing files. This one is for Windows (host.fch is for Linux and macOS).
+import "stdlib.h"
+import "stdio.h"
+import "process.h"
+import "direct.h"
+import "io.h"
+import "clang-c/Index.h"
+
+// a Windows argument: in double quotes, with the quotes inside doubled up the way CreateProcess reads them
+// libclang's description of a file that isn't on disk: its Length is C's `unsigned long`, which is 32 bits on Windows
+fn unsavedFile(str name, str contents) -> CXUnsavedFile {
+    return CXUnsavedFile(Filename: name.ptr, Contents: contents.ptr, Length: u32(contents.len))
+}
+
+fn quote(str a) -> str {
+    return "\"" + a.replace("\"", "\\\"") + "\""
+}
+
+// Paths use / inside the compiler; cmd.exe wants \
+fn native(str path) -> str {
+    return path.replace("/", "\\")
+}
+
+// run a command line through cmd.exe; its exit code.
+// system() runs `cmd /c <line>`, and cmd drops the first and last quote of a line that starts with one: so the line
+// gets one more pair around it.
+fn run(str cmd) -> int {
+    return shell("\"" + cmd + "\"")
+}
+
+fn nullDevice() -> str {
+    return "NUL"
+}
+
+fn tempDir() -> str {
+    for name in ["TEMP", "TMP"] {
+        t := getenv(name)
+        if t.len > 0 {
+            return t.replace("\\", "/")
+        }
+    }
+    return "."
+}
+
+fn pathSeparator() -> str {
+    return ";"
+}
+
+fn pid() -> int {
+    return int(getpid())
+}
+
+fn cwd() -> str {
+    here := _getcwd(null, 0)           // C allocates the buffer
+    if here.len == 0 {
+        return "."
+    }
+    return here.replace("\\", "/")
+}
+
+fn cacheDir() -> str {
+    x := getenv("LOCALAPPDATA")
+    if x.len > 0 {
+        return x.replace("\\", "/") + "/finch"
+    }
+    return tempDir() + "/finch-cache"
+}
+
+// the editor protocol is bytes, not text lines: no \r\n translation on stdin and stdout
+fn binaryStdio() {
+    _setmode(0, 32768)              // _O_BINARY
+    _setmode(1, 32768)
+}
+
+fn makeDirs(str path) {
+    p := path.replace("\\", "/")
+    at := 0
+    for part in p.split("/") {
+        if at > 0 {
+            at += 1
+        }
+        at += part.len
+        if part.len == 0 || part.ends_with(":") {
+            continue                // "" before a leading / and the drive letter
+        }
+        sofar := p.sub(0, at)
+        _mkdir(sofar)               // fails when it is there already, which is fine
+    }
+}
+
+fn remove(str path) {
+    delete_file(path)
+}
+
+fn removeTree(str path) {
+    shell("\"rmdir /s /q " + quote(native(path)) + " 2> NUL\"")
+}
+
+// move a file over another
+fn move(str from, str to) {
+    delete_file(to)
+    rename(from, to)
+}

src/index.h

@@ -1,39 +0,0 @@
-#pragma once
-// What the compiler learns about a program while checking it, for the language server:
-// what each name is, its type, and where it was defined.
-
-#include <string>
-#include <vector>
-
-struct SymRef {  // a name in the source
-    int file, line, col, len;
-    std::string hover;          // markdown shown on mouse-over
-    int defFile = -1, defLine = 0, defCol = 0;
-};
-
-struct VarInfo {  // a variable or parameter, for completion
-    std::string name, type;
-    int file, line, col;
-    int fnFile, fnLine, fnEnd;  // the function it lives in
-};
-
-struct FnInfo {
-    std::string module, name, signature, doc;
-    std::vector<std::string> params;
-    int file, line, col, endLine;
-};
-
-struct StructIndex {
-    std::string module, name;
-    std::vector<std::pair<std::string, std::string>> fields;  // name, type
-    int file, line, col;
-};
-
-struct SemIndex {
-    std::vector<SymRef> refs;
-    std::vector<VarInfo> vars;
-    std::vector<FnInfo> fns;
-    std::vector<StructIndex> structs;
-};
-
-inline SemIndex *g_index = nullptr;  // set by the language server; null when compiling

src/lexer.cpp

@@ -1,214 +0,0 @@
-#include "lexer.h"
-#include "error.h"
-
-#include <cctype>
-#include <unordered_map>
-
-static const std::unordered_map<std::string, Tok> keywords = {
-    {"fn", Tok::Fn},       {"return", Tok::Return}, {"if", Tok::If},
-    {"else", Tok::Else},   {"while", Tok::While},   {"for", Tok::For},
-    {"in", Tok::In},       {"break", Tok::Break},   {"continue", Tok::Continue},
-    {"true", Tok::True},   {"false", Tok::False},   {"null", Tok::Null},
-    {"import", Tok::Import}, {"link", Tok::Link},   {"struct", Tok::Struct},
-    {"defer", Tok::Defer},  {"or", Tok::OrElse},     {"try", Tok::Try},
-};
-
-std::vector<Token> lex(int file) {
-    g_curFile = file;
-    const std::string &src = g_files[file].text;
-    std::vector<Token> out;
-    size_t i = 0;
-    int line = 1, col = 1;
-    bool newline = true;
-
-    auto advance = [&]() {
-        if (src[i] == '\n') { line++; col = 1; newline = true; }
-        else if (((unsigned char)src[i] & 0xC0) != 0x80) col++;  // count characters, not UTF-8 bytes
-        i++;
-    };
-    auto peek = [&](size_t off = 0) -> char {
-        return i + off < src.size() ? src[i + off] : '\0';
-    };
-
-    while (i < src.size()) {
-        char c = src[i];
-
-        if (std::isspace((unsigned char)c)) { advance(); continue; }
-        if (c == '/' && peek(1) == '/') {
-            while (i < src.size() && src[i] != '\n') advance();
-            continue;
-        }
-        if (c == '/' && peek(1) == '*') {
-            int l = line, cl = col;
-            advance(); advance();
-            while (i < src.size() && !(src[i] == '*' && peek(1) == '/')) advance();
-            if (i >= src.size()) fail(l, cl, "comment is never closed (missing */)");
-            advance(); advance();
-            continue;
-        }
-
-        Token t{Tok::End, "", line, col, newline};
-        newline = false;
-
-        if (std::isalpha((unsigned char)c) || c == '_') {
-            size_t start = i;
-            while (std::isalnum((unsigned char)peek()) || peek() == '_') advance();
-            t.text = src.substr(start, i - start);
-            auto kw = keywords.find(t.text);
-            t.kind = kw != keywords.end() ? kw->second : Tok::Ident;
-        } else if (std::isdigit((unsigned char)c)) {
-            size_t start = i;
-            t.kind = Tok::Int;
-            if (c == '0' && (peek(1) == 'x' || peek(1) == 'X')) {  // 0xFF
-                advance(); advance();
-                while (std::isxdigit((unsigned char)peek()) || peek() == '_') advance();
-                if (i - start == 2) fail(t.line, t.col, "'0x' needs hex digits after it, like 0xFF");
-            } else {
-                while (std::isdigit((unsigned char)peek()) || peek() == '_') advance();
-                // "1..5" is a range, not the float "1."
-                if (peek() == '.' && std::isdigit((unsigned char)peek(1))) {
-                    t.kind = Tok::Float;
-                    advance();
-                    while (std::isdigit((unsigned char)peek()) || peek() == '_') advance();
-                }
-            }
-            for (size_t k = start; k < i; k++)
-                if (src[k] != '_') t.text += src[k];
-        } else if (c == '"' || c == '\'') {
-            char quote = c;
-            t.kind = quote == '"' ? Tok::String : Tok::Char;
-            advance();
-            while (peek() != quote) {
-                if (peek() == '\0' || peek() == '\n')
-                    fail(t.line, t.col, quote == '"' ? "string is never closed (missing \")"
-                                                     : "char is never closed (missing ')");
-                char ch = peek();
-                advance();
-                if (ch == '\\') {
-                    char e = peek();
-                    advance();
-                    switch (e) {
-                    case 'n': ch = '\n'; break;
-                    case 't': ch = '\t'; break;
-                    case 'r': ch = '\r'; break;
-                    case '0': ch = '\0'; break;
-                    case '\\': ch = '\\'; break;
-                    case '"': ch = '"'; break;
-                    case '\'': ch = '\''; break;
-                    default: fail(line, col - 1, std::string("unknown escape \\") + e);
-                    }
-                }
-                t.text += ch;
-            }
-            advance();
-            if (t.kind == Tok::Char && t.text.size() != 1)
-                fail(t.line, t.col, "a char holds exactly one character, like 'a'");
-        } else {
-            char n = peek(1);
-            auto two = [&](Tok k) { t.kind = k; advance(); advance(); };
-            auto one = [&](Tok k) { t.kind = k; advance(); };
-            switch (c) {
-            case '(': one(Tok::LParen); break;
-            case ')': one(Tok::RParen); break;
-            case '{': one(Tok::LBrace); break;
-            case '}': one(Tok::RBrace); break;
-            case '[': one(Tok::LBracket); break;
-            case ']': one(Tok::RBracket); break;
-            case ',': one(Tok::Comma); break;
-            case '%': n == '=' ? two(Tok::PercentEq) : one(Tok::Percent); break;
-            case '^': one(Tok::Caret); break;
-            case '~': one(Tok::Tilde); break;
-            case '.': n == '.' ? two(Tok::DotDot) : one(Tok::Dot); break;
-            case '+': n == '=' ? two(Tok::PlusEq) : one(Tok::Plus); break;
-            case '-': n == '=' ? two(Tok::MinusEq) : n == '>' ? two(Tok::Arrow) : one(Tok::Minus); break;
-            case '*': n == '=' ? two(Tok::StarEq) : one(Tok::Star); break;
-            case '/': n == '=' ? two(Tok::SlashEq) : one(Tok::Slash); break;
-            case '=': n == '=' ? two(Tok::Eq) : one(Tok::Assign); break;
-            case '!': n == '=' ? two(Tok::NotEq) : one(Tok::Not); break;
-            case '<': n == '=' ? two(Tok::LessEq) : n == '<' ? two(Tok::Shl) : one(Tok::Less); break;
-            case '>': n == '=' ? two(Tok::GreaterEq) : n == '>' ? two(Tok::Shr) : one(Tok::Greater); break;
-            case ':': n == '=' ? two(Tok::Declare) : one(Tok::Colon); break;
-            case '&': n == '&' ? two(Tok::And) : one(Tok::Amp); break;
-            case '|': n == '|' ? two(Tok::Or) : one(Tok::Pipe); break;
-            default: {
-                // show the whole UTF-8 character, not just its first byte
-                size_t len = (c & 0xE0) == 0xC0 ? 2 : (c & 0xF0) == 0xE0 ? 3 : (c & 0xF8) == 0xF0 ? 4 : 1;
-                std::string ch = src.substr(i, len);
-                std::string hint = (unsigned char)c >= 0x80 ? " (names use only a-z, A-Z, 0-9 and _; other letters only go inside \"text\")" : "";
-                fail(line, col, "unexpected character '" + ch + "'" + hint);
-            }
-            }
-        }
-        out.push_back(t);
-    }
-    out.push_back({Tok::End, "", line, col, true});
-    return out;
-}
-
-const char *tokName(Tok t) {
-    switch (t) {
-    case Tok::End: return "end of file";
-    case Tok::Ident: return "a name";
-    case Tok::Int: return "a number";
-    case Tok::Float: return "a number";
-    case Tok::String: return "a string";
-    case Tok::Char: return "a char";
-    case Tok::Fn: return "'fn'";
-    case Tok::Return: return "'return'";
-    case Tok::If: return "'if'";
-    case Tok::Else: return "'else'";
-    case Tok::While: return "'while'";
-    case Tok::For: return "'for'";
-    case Tok::In: return "'in'";
-    case Tok::Break: return "'break'";
-    case Tok::Continue: return "'continue'";
-    case Tok::True: return "'true'";
-    case Tok::False: return "'false'";
-    case Tok::Null: return "'null'";
-    case Tok::Import: return "'import'";
-    case Tok::Link: return "'link'";
-    case Tok::Struct: return "'struct'";
-    case Tok::Defer: return "'defer'";
-    case Tok::OrElse: return "'or'";
-    case Tok::Try: return "'try'";
-    case Tok::Colon: return "':'";
-    case Tok::LParen: return "'('";
-    case Tok::RParen: return "')'";
-    case Tok::LBrace: return "'{'";
-    case Tok::RBrace: return "'}'";
-    case Tok::LBracket: return "'['";
-    case Tok::RBracket: return "']'";
-    case Tok::Comma: return "','";
-    case Tok::Dot: return "'.'";
-    case Tok::Arrow: return "'->'";
-    case Tok::DotDot: return "'..'";
-    case Tok::Plus: return "'+'";
-    case Tok::Minus: return "'-'";
-    case Tok::Star: return "'*'";
-    case Tok::Slash: return "'/'";
-    case Tok::Percent: return "'%'";
-    case Tok::Amp: return "'&'";
-    case Tok::Pipe: return "'|'";
-    case Tok::Caret: return "'^'";
-    case Tok::Tilde: return "'~'";
-    case Tok::Shl: return "'<<'";
-    case Tok::Shr: return "'>>'";
-    case Tok::PercentEq: return "'%='";
-    case Tok::Assign: return "'='";
-    case Tok::Declare: return "':='";
-    case Tok::PlusEq: return "'+='";
-    case Tok::MinusEq: return "'-='";
-    case Tok::StarEq: return "'*='";
-    case Tok::SlashEq: return "'/='";
-    case Tok::Eq: return "'=='";
-    case Tok::NotEq: return "'!='";
-    case Tok::Less: return "'<'";
-    case Tok::LessEq: return "'<='";
-    case Tok::Greater: return "'>'";
-    case Tok::GreaterEq: return "'>='";
-    case Tok::And: return "'&&'";
-    case Tok::Or: return "'||'";
-    case Tok::Not: return "'!'";
-    }
-    return "?";
-}

src/lexer.fch

@@ -24,7 +24,7 @@ fn isHex(char c) -> bool {
 
 fn isKeyword(str w) -> bool {
     keywords := ["fn", "return", "if", "else", "while", "for", "in", "break", "continue", "true", "false",
-                 "null", "import", "link", "struct", "defer", "or", "try"]
+                 "null", "import", "link", "struct", "defer", "or", "try", "enum", "match", "export"]
     return keywords.contains(w)
 }
 
@@ -195,7 +195,20 @@ fn lex(str src, str path) -> []Token {
         } else {
             op := operator(lx)
             if op.len == 0 {
-                fail(lx, t.line, t.col, "unexpected character '" + str(c) + "'")
+                // show the whole UTF-8 character, not just its first byte
+                n := 1
+                if (int(c) & 0xE0) == 0xC0 {
+                    n = 2
+                } else if (int(c) & 0xF0) == 0xE0 {
+                    n = 3
+                } else if (int(c) & 0xF8) == 0xF0 {
+                    n = 4
+                }
+                hint := ""
+                if int(c) >= 0x80 {
+                    hint = " (names use only a-z, A-Z, 0-9 and _; other letters only go inside \"text\")"
+                }
+                fail(lx, t.line, t.col, "unexpected character '" + lx.src.sub(lx.i, lx.i + n) + "'" + hint)
             }
             for k in 0..op.len {
                 advance(lx)

src/lexer.h

@@ -1,36 +0,0 @@
-#pragma once
-
-#include <string>
-#include <vector>
-
-enum class Tok {
-    End,
-    Ident, Int, Float, String, Char,
-
-    // keywords
-    Fn, Return, If, Else, While, For, In, Break, Continue, True, False, Null, Import, Link, Struct, Defer,
-    OrElse, Try,  // or, try
-
-    // punctuation
-    LParen, RParen, LBrace, RBrace, LBracket, RBracket, Comma, Colon, Dot, DotDot, Arrow,
-
-    // operators
-    Plus, Minus, Star, Slash, Percent,
-    Amp, Pipe, Caret, Tilde, Shl, Shr,             // & | ^ ~ << >>
-    Assign, Declare,                               // =  :=
-    PlusEq, MinusEq, StarEq, SlashEq, PercentEq,   // += -= *= /= %=
-    Eq, NotEq, Less, LessEq, Greater, GreaterEq,
-    And, Or, Not,
-};
-
-struct Token {
-    Tok kind;
-    std::string text;
-    int line;
-    int col;
-    bool newlineBefore;  // token starts a new line: ends the previous statement
-};
-
-// Lexes g_files[file].text.
-std::vector<Token> lex(int file);
-const char *tokName(Tok t);

src/linker.fch

@@ -0,0 +1,299 @@
+// From LLVM IR to a program: compile the IR, add the runtime (compiled once and kept), link the C libraries
+// and C files the program asks for, and turn the linker's complaints into something a person can act on.
+import platform
+import cimport
+import host
+
+// 32-bit FNV-1a, as hex: names the cached runtime object after what it was built from
+fn fingerprint(str text) -> str {
+    u32 h = 2166136261
+    for c in text {
+        h = (h ^ u32(c)) * 16777619
+    }
+    digits := "0123456789abcdef"
+    []str parts
+    for k in 0..8 {
+        parts.push(str(digits[int((h >> u32(28 - 4 * k)) & 15)]))
+    }
+    return parts.join("")
+}
+
+fn quote(str a) -> str {
+    return host.quote(a)
+}
+
+// "-lname", or whatever pkg-config says the library needs
+fn libFlags(str name, platform.Target tg) -> str {
+    if name.ends_with(".framework") {
+        return "-framework " + quote(name.sub(0, name.len - 10))         // macOS: link "Cocoa.framework"
+    }
+    if !tg.cross {
+        tmp := host.tempDir() + "/finch_pkg_flags_" + str(host.pid()) + ".txt"
+        code := host.run("pkg-config --libs " + quote(name) + " > " + quote(tmp) + " 2> " + host.nullDevice())
+        if code == 0 && file_exists(tmp) {
+            flags := (read_file(tmp) or "").trim()
+            host.remove(tmp)
+            if flags.len > 0 {
+                return flags
+            }
+        }
+    }
+    return quote("-l" + name)
+}
+
+// "GLFW/glfw3.h" -> "glfw": a decent first guess for the library's name
+fn guessLib(str header) -> str {
+    name := header
+    slash := name.find("/")
+    while slash >= 0 {
+        name = name.sub(slash + 1, name.len)
+        slash = name.find("/")
+    }
+    dot := name.len
+    for i in 0..name.len {
+        if name[i] == '.' {
+            dot = i
+        }
+    }
+    name = name.sub(0, dot)
+    while name.len > 0 && name[name.len - 1] >= '0' && name[name.len - 1] <= '9' {
+        name = name.sub(0, name.len - 1)
+    }
+    return name.lower()
+}
+
+struct Names {
+    []str items
+}
+
+fn Names.add(str x) {
+    if x.len > 0 && !self.items.contains(x) {
+        self.items.push(x)
+    }
+}
+
+// the text after `marker` up to the next one of `stops`
+fn between(str line, str marker, str stops) -> str {
+    a := line.find(marker)
+    if a < 0 {
+        return ""
+    }
+    rest := line.sub(a + marker.len, line.len)
+    n := 0
+    while n < rest.len && !stops.contains(str(rest[n])) {
+        n += 1
+    }
+    return rest.sub(0, n)
+}
+
+// The linker speaks in riddles; say what is missing and what to write.
+fn linkFailed(str output, cimport.CImports ci, platform.Target tg) -> int {
+    missing := Names()
+    libs := Names()
+    for line in output.split("\n") {
+        l := line.trim()
+        if l.contains("undefined reference to `") {
+            missing.add(between(l, "undefined reference to `", "'"))
+        } else if l.contains("undefined symbol: ") {
+            missing.add(between(l, "undefined symbol: ", " \n"))
+        } else if l.contains("unresolved external symbol ") {
+            missing.add(between(l, "unresolved external symbol ", " \n\r"))
+        } else if l.contains("cannot find -l") {
+            libs.add(between(l, "cannot find -l", ": \n\r"))
+        } else if l.contains("library not found for -l") {
+            libs.add(between(l, "library not found for -l", ": \n\r"))
+        } else if l.contains("ld: library '") {
+            libs.add(between(l, "ld: library '", "'"))
+        } else if l.contains("framework '") && l.contains("not found") {
+            libs.add(between(l, "framework '", "'") + ".framework")
+        } else if l.starts_with("\"") && l.contains("\", referenced from:") {
+            // Apple ld: "_name", referenced from:
+            name := l.sub(1, l.find("\", referenced from:"))
+            if tg.darwin && name.starts_with("_") {
+                name = name.sub(1, name.len)
+            }
+            missing.add(name)
+        }
+    }
+    if missing.items.len == 0 && libs.items.len == 0 {
+        print(output + "error: linking failed")
+        return 1
+    }
+    for lib in libs.items {
+        print("error: the library '" + lib + "' wasn't found. Is it installed? (on Nix: add it to shell.nix)")
+    }
+    // the missing functions, grouped by the header they came from
+    []str headers
+    []Names byHeader
+    for name in missing.items {
+        header := ""
+        if ci.fns.has(name) {
+            header = ci.fns[name].header
+        }
+        k := headers.find(header)
+        if k < 0 {
+            headers.push(header)
+            byHeader.push(Names())
+            k = headers.len - 1
+        }
+        byHeader[k].add(name)
+    }
+    for k in 0..headers.len {
+        names := byHeader[k].items
+        []str shown
+        for i in 0..names.len {
+            if i < 3 {
+                shown.push(names[i])
+            }
+        }
+        list := shown.join(", ")
+        if names.len > 3 {
+            list = list + " and " + str(names.len - 3) + " more"
+        }
+        if headers[k].len == 0 {
+            print("error: no code found for " + list)
+            continue
+        }
+        verb := "come"
+        if names.len == 1 {
+            verb = "comes"
+        }
+        print("error: " + list + " " + verb + " from \"" + headers[k] + "\", but its library isn't linked")
+        print("  the header only says the functions exist; their code lives in a library.")
+        print("  add this at the top of your file (with the library's real name):")
+        print("")
+        print("      link \"" + guessLib(headers[k]) + "\"")
+        print("")
+    }
+    return 1
+}
+
+// The runtime, compiled once per system and compiler and kept in the cache folder.
+fn runtimeObject(str rt, platform.Target tg, str cc) -> str! {
+    source := try read_file(rt)
+    dir := host.cacheDir()
+    obj := dir + "/rt-" + fingerprint(source + cc + tg.triple + "2.5") + ".o"
+    if file_exists(obj) {
+        return obj
+    }
+    host.makeDirs(dir)
+    part := obj + ".part" + str(host.pid())
+    pic := " -fPIC"
+    if tg.windows {
+        pic = ""
+    }
+    log := part + ".log"
+    code := host.run(cc + " -O2" + pic + " -c " + quote(rt) + " -o " + quote(part) + " > " + quote(log) + " 2>&1")
+    if code != 0 {
+        text := read_file(log) or ""
+        host.remove(part)
+        host.remove(log)
+        return error(text + "error: couldn't build the Finch runtime with '" + cc + "' (is a C compiler installed?)")
+    }
+    host.remove(log)
+    host.move(part, obj)
+    return obj
+}
+
+struct Build {
+    str out             // the program
+    str ir              // its LLVM IR, as text
+    str rt              // the runtime's source file
+    str opt             // -O2 or -O0
+    str extra           // -g, -fPIC ...
+    bool shared
+    []str links         // what the program asked to link: a library name, a .c file (with its folder), a .o or .a
+}
+
+// IR -> program. 0 if it worked.
+fn build(Build b, platform.Target tg, cimport.CImports ci) -> int {
+    clang := getenv("FINCH_CLANG")
+    if clang.len == 0 {
+        clang = "clang"
+    }
+    // the C compiler of the runtime and the linker: the target's own when building for another system
+    cc := clang
+    if tg.cross {
+        cc = tg.cc
+    } else if getenv("FINCH_CC").len > 0 {
+        cc = getenv("FINCH_CC")
+    }
+    rtobj := runtimeObject(b.rt, tg, cc) or {
+        print(err)
+        return 1
+    }
+    ll := b.out + ".ll"
+    obj := b.out + ".o"
+    write_file(ll, b.ir)
+    target := ""
+    if tg.cross || tg.windows {
+        target = " --target=" + tg.triple
+    }
+    log := b.out + ".log"
+    code := host.run(clang + target + " " + b.opt + b.extra + " -w -c " + quote(ll) + " -o " + quote(obj) + " > " + quote(log) + " 2>&1")
+    host.remove(ll)
+    if code != 0 {
+        print(read_file(log) or "")
+        print("error: clang couldn't compile the program's IR")
+        host.remove(obj)
+        host.remove(log)
+        return 1
+    }
+    cmd := cc + " " + quote(obj) + " " + quote(rtobj) + " -o " + quote(b.out)
+    if !tg.msvc {
+        cmd = cmd + " -lm"
+    }
+    if getenv("FINCH_LDFLAGS").len > 0 {
+        cmd = cmd + " " + getenv("FINCH_LDFLAGS")          // more flags for the linker, like -L/where/libclang/is
+    }
+    if b.shared {
+        if tg.darwin {
+            cmd = cmd + " -dynamiclib"
+        } else {
+            cmd = cmd + " -shared"
+        }
+    }
+    []str temps
+    for l in b.links {
+        if l.ends_with(".c") {
+            // the program's own C file, built along with it
+            o := b.out + "." + str(temps.len) + ".o"
+            pic := " -fPIC"
+            if tg.windows {
+                pic = ""
+            }
+            c := host.run(cc + " -O2" + pic + " -c " + quote(l) + " -o " + quote(o) + " > " + quote(log) + " 2>&1")
+            if c != 0 {
+                print((read_file(log) or "") + "error: couldn't compile " + l)
+                host.remove(obj)
+                host.remove(log)
+                host.remove(o)
+                return 1
+            }
+            temps.push(o)
+            cmd = cmd + " " + quote(o)
+        } else if l.ends_with(".o") || l.ends_with(".a") {
+            cmd = cmd + " " + quote(l)
+        } else {
+            cmd = cmd + " " + libFlags(l, tg)
+        }
+    }
+    status := host.run(cmd + " > " + quote(log) + " 2>&1")
+    output := read_file(log) or ""
+    host.remove(obj)
+    host.remove(log)
+    for t in temps {
+        host.remove(t)
+    }
+    if status == 127 {
+        print("error: no C compiler found to link with ('" + cc + "'; install one, or set FINCH_CC)")
+        return 1
+    }
+    if status != 0 {
+        return linkFailed(output, ci, tg)
+    }
+    if output.len > 0 {
+        print(output)           // warnings, if any
+    }
+    return 0
+}

src/loader.cpp

@@ -1,74 +0,0 @@
-#include "loader.h"
-#include "error.h"
-#include "lexer.h"
-#include "parser.h"
-#include "target.h"
-
-#include <llvm/ADT/SmallString.h>
-#include <llvm/Support/FileSystem.h>
-#include <llvm/Support/Path.h>
-
-#include <cstdio>
-#include <cstdlib>
-#include <fstream>
-#include <sstream>
-
-using namespace llvm;
-
-static bool readFile(const std::string &path, std::string &out) {
-    std::ifstream in(path, std::ios::binary);
-    if (!in) return false;
-    std::stringstream ss;
-    ss << in.rdbuf();
-    out = ss.str();
-    return true;
-}
-
-std::string normalizePath(const std::string &path) {
-    SmallString<256> p(path);
-    sys::fs::make_absolute(p);
-    sys::path::remove_dots(p, true);
-    sys::path::native(p);
-    return std::string(p.str());
-}
-
-void Loader::load(const std::string &path, const std::string &module, Pos from) {
-    std::string text;
-    bool found = false;
-    if (overrides) {
-        auto it = overrides->find(normalizePath(path));
-        if (it != overrides->end()) text = it->second, found = true;
-    }
-    if (!found && !readFile(path, text)) {
-        if (from.line) failAt(from.file, from.line, from.col, "can't find the module '" + module + "' (looked for " + path + ")");
-        std::fprintf(stderr, "error: can't open '%s'\n", path.c_str());
-        std::exit(1);
-    }
-    int idx = (int)g_files.size();
-    g_files.push_back({path, text});
-    Program p = parse(lex(idx), idx);
-    p.module = module;
-    p.path = path;
-    std::vector<Import> mods;
-    for (const Import &im : p.imports)
-        if (!im.isC) mods.push_back(im);
-    progs.push_back(std::move(p));
-    for (const Import &im : mods) {
-        if (im.path == "main") failAt(im.pos.file, im.pos.line, im.pos.col, "'main' can't be imported");
-        if (loaded[im.path]) continue;
-        loaded[im.path] = true;
-        load(findModule(dirOf(path), im.path), im.path, im.pos);
-    }
-}
-
-// next to the importing file, then in $FINCH_PATH folders
-std::string Loader::findModule(const std::string &dir, const std::string &name) {
-    std::string here = dir + "/" + name + ".fch";
-    if (sys::fs::exists(here)) return here;
-    if (const char *fp = std::getenv("FINCH_PATH")) {
-        std::stringstream ss(fp);
-        for (std::string d; std::getline(ss, d, pathListSeparator());)
-            if (!d.empty() && sys::fs::exists(d + "/" + name + ".fch")) return d + "/" + name + ".fch";
-    }
-    return here;
-}

src/loader.h

@@ -1,20 +0,0 @@
-#pragma once
-// Reads the main file and, recursively, every Finch module it imports.
-
-#include "ast.h"
-
-#include <map>
-#include <string>
-#include <vector>
-
-struct Loader {
-    std::vector<Program> progs;
-    std::map<std::string, bool> loaded;          // module name -> seen
-    const std::map<std::string, std::string> *overrides = nullptr;  // path -> text (files open in an editor)
-
-    void load(const std::string &path, const std::string &module, Pos from);
-    static std::string findModule(const std::string &dir, const std::string &name);
-};
-
-// A path made absolute and tidy, so two spellings of one file compare equal.
-std::string normalizePath(const std::string &path);

src/lsp.cpp

@@ -1,580 +0,0 @@
-// The Finch language server: `finch lsp` speaks the Language Server Protocol on stdin/stdout.
-//
-// Every time a document changes it is checked by the real compiler (lexer, parser, type
-// checker and code generator, without optimizing or writing anything), with errors thrown
-// instead of ending the process and a semantic index (index.h) collecting what each name is.
-// Hover, go-to-definition, completion, signature help and document symbols read that index.
-
-#include "builtins_doc.h"
-#include "cimport.h"
-#include "codegen.h"
-#include "error.h"
-#include "index.h"
-#include "loader.h"
-#include "target.h"
-
-#include <llvm/MC/TargetRegistry.h>
-#include <llvm/Support/FileSystem.h>
-#include <llvm/Support/JSON.h>
-#include <llvm/Support/Path.h>
-#include <llvm/Support/TargetSelect.h>
-#include <llvm/Target/TargetMachine.h>
-
-#include <algorithm>
-#include <cstdio>
-#include <iostream>
-#include <map>
-#include <memory>
-#include <set>
-#include <string>
-#include <vector>
-
-#ifdef _WIN32
-#include <fcntl.h>
-#include <io.h>
-#endif
-
-using namespace llvm;
-
-namespace {
-
-// ---------- URIs ----------
-
-std::string uriToPath(const std::string &uri) {
-    std::string s = uri.rfind("file://", 0) == 0 ? uri.substr(7) : uri;
-    std::string out;
-    for (size_t i = 0; i < s.size(); i++) {
-        if (s[i] == '%' && i + 2 < s.size()) {
-            out += (char)std::stoi(s.substr(i + 1, 2), nullptr, 16);
-            i += 2;
-        } else {
-            out += s[i];
-        }
-    }
-#ifdef _WIN32
-    if (out.size() > 2 && out[0] == '/' && out[2] == ':') out = out.substr(1);  // /c:/x -> c:/x
-#endif
-    return normalizePath(out);
-}
-
-std::string pathToUri(const std::string &path) {
-    std::string p = normalizePath(path), out = "file://";
-#ifdef _WIN32
-    for (char &c : p)
-        if (c == '\\') c = '/';
-    out += "/";
-#endif
-    for (unsigned char c : p) {
-        if (isalnum(c) || c == '/' || c == '-' || c == '_' || c == '.' || c == '~' || c == ':') out += (char)c;
-        else {
-            char buf[4];
-            std::snprintf(buf, sizeof buf, "%%%02X", c);
-            out += buf;
-        }
-    }
-    return out;
-}
-
-// ---------- one check of a document ----------
-
-struct Diagnostic {
-    std::string path;
-    int line, col;
-    std::string msg;
-};
-
-struct Analysis {
-    std::vector<SourceFile> files;
-    SemIndex index;
-    std::vector<Diagnostic> diags;
-    std::set<std::string> modules;  // modules the document imports
-    const CImports *c = nullptr;
-};
-
-class Server {
-public:
-    int run();
-
-private:
-    std::map<std::string, std::string> docs;  // normalized path -> text
-    std::map<std::string, std::shared_ptr<Analysis>> results;  // last check of each open document
-    std::map<std::string, std::shared_ptr<Analysis>> lastGood; // last check without errors
-    std::map<std::string, std::unique_ptr<CImports>> headerCache;
-    std::set<std::string> diagnosed;  // paths we published errors for
-    TargetMachine *tm = nullptr;
-    bool shutdown = false;
-
-    // protocol
-    bool readMessage(json::Value &out);
-    void send(const json::Value &v);
-    void reply(const json::Value &id, json::Value result);
-    void notify(const std::string &method, json::Value params);
-    void handle(const json::Object &msg);
-
-    // features
-    void check(const std::string &path);
-    json::Value hover(const std::string &path, int line, int col);
-    json::Value definition(const std::string &path, int line, int col);
-    json::Value completion(const std::string &path, int line, int col);
-    json::Value symbols(const std::string &path);
-    json::Value signatureHelp(const std::string &path, int line, int col);
-
-    const SymRef *refAt(const Analysis &a, const std::string &path, int line, int col);
-    std::string lineText(const std::string &path, int line);
-};
-
-bool Server::readMessage(json::Value &out) {
-    size_t length = 0;
-    std::string header;
-    while (std::getline(std::cin, header)) {
-        if (!header.empty() && header.back() == '\r') header.pop_back();
-        if (header.empty()) break;
-        if (header.rfind("Content-Length:", 0) == 0) length = std::stoul(header.substr(15));
-    }
-    if (!std::cin || length == 0) return false;
-    std::string body(length, '\0');
-    std::cin.read(&body[0], length);
-    Expected<json::Value> v = json::parse(body);
-    if (!v) {
-        consumeError(v.takeError());
-        return true;  // skip a broken message
-    }
-    out = std::move(*v);
-    return true;
-}
-
-void Server::send(const json::Value &v) {
-    std::string body;
-    raw_string_ostream os(body);
-    os << v;
-    os.flush();
-    std::cout << "Content-Length: " << body.size() << "\r\n\r\n" << body;
-    std::cout.flush();
-}
-
-void Server::reply(const json::Value &id, json::Value result) {
-    send(json::Object{{"jsonrpc", "2.0"}, {"id", id}, {"result", std::move(result)}});
-}
-
-void Server::notify(const std::string &method, json::Value params) {
-    send(json::Object{{"jsonrpc", "2.0"}, {"method", method}, {"params", std::move(params)}});
-}
-
-int Server::run() {
-#ifdef _WIN32
-    _setmode(_fileno(stdin), _O_BINARY);
-    _setmode(_fileno(stdout), _O_BINARY);
-#endif
-    initTargets();
-    setTarget("");
-    std::string err;
-    const Target *target = TargetRegistry::lookupTarget(g_target.triple, err);
-    if (!target) return 1;
-    tm = target->createTargetMachine(g_target.triple, "generic", "", TargetOptions(), Reloc::PIC_);
-
-    json::Value msg(nullptr);
-    while (readMessage(msg)) {
-        if (const json::Object *o = msg.getAsObject()) handle(*o);
-        if (shutdown && !std::cin) break;
-    }
-    return 0;
-}
-
-static int intAt(const json::Object *o, const char *key) {
-    if (!o) return 0;
-    if (auto v = o->getInteger(key)) return (int)*v;
-    return 0;
-}
-
-void Server::handle(const json::Object &msg) {
-    std::string method = msg.getString("method").value_or("").str();
-    const json::Value *id = msg.get("id");
-    const json::Object *params = msg.getObject("params");
-    auto docPath = [&]() -> std::string {
-        if (!params) return "";
-        const json::Object *td = params->getObject("textDocument");
-        return td ? uriToPath(td->getString("uri").value_or("").str()) : "";
-    };
-    // positions: LSP is 0-based (line, UTF-16 column); Finch is 1-based (line, character)
-    auto position = [&](int &line, int &col) {
-        const json::Object *pos = params ? params->getObject("position") : nullptr;
-        line = intAt(pos, "line") + 1;
-        col = intAt(pos, "character") + 1;
-    };
-
-    if (method == "initialize") {
-        json::Object caps{
-            {"textDocumentSync", json::Object{{"openClose", true}, {"change", 1}, {"save", true}}},
-            {"hoverProvider", true},
-            {"definitionProvider", true},
-            {"documentSymbolProvider", true},
-            {"completionProvider", json::Object{{"triggerCharacters", json::Array{"."}}}},
-            {"signatureHelpProvider", json::Object{{"triggerCharacters", json::Array{"(", ","}}}},
-        };
-        reply(*id, json::Object{{"capabilities", std::move(caps)},
-                                {"serverInfo", json::Object{{"name", "finch"}, {"version", FINCH_VERSION}}}});
-    } else if (method == "shutdown") {
-        shutdown = true;
-        reply(*id, nullptr);
-    } else if (method == "exit") {
-        std::exit(shutdown ? 0 : 1);
-    } else if (method == "textDocument/didOpen" || method == "textDocument/didChange") {
-        std::string path = docPath();
-        if (method == "textDocument/didOpen") {
-            docs[path] = params->getObject("textDocument")->getString("text").value_or("").str();
-        } else if (const json::Array *changes = params->getArray("contentChanges")) {
-            if (!changes->empty())
-                if (const json::Object *ch = changes->back().getAsObject()) docs[path] = ch->getString("text").value_or("").str();
-        }
-        check(path);
-    } else if (method == "textDocument/didSave") {
-        check(docPath());
-    } else if (method == "textDocument/didClose") {
-        std::string path = docPath();
-        docs.erase(path);
-        results.erase(path);
-        lastGood.erase(path);
-        notify("textDocument/publishDiagnostics", json::Object{{"uri", pathToUri(path)}, {"diagnostics", json::Array{}}});
-    } else if (id) {
-        int line = 0, col = 0;
-        position(line, col);
-        std::string path = docPath();
-        if (method == "textDocument/hover") reply(*id, hover(path, line, col));
-        else if (method == "textDocument/definition") reply(*id, definition(path, line, col));
-        else if (method == "textDocument/completion") reply(*id, completion(path, line, col));
-        else if (method == "textDocument/documentSymbol") reply(*id, symbols(path));
-        else if (method == "textDocument/signatureHelp") reply(*id, signatureHelp(path, line, col));
-        else send(json::Object{{"jsonrpc", "2.0"}, {"id", *id},
-                               {"error", json::Object{{"code", -32601}, {"message", "not supported: " + method}}}});
-    }
-}
-
-// Check `path` with the real compiler, keep the index, publish errors.
-void Server::check(const std::string &path) {
-    auto a = std::make_shared<Analysis>();
-    g_files.clear();
-    g_throwErrors = true;
-    g_index = &a->index;
-    try {
-        Loader loader;
-        loader.overrides = &docs;
-        loader.load(path, "", Pos{});
-        std::vector<Import> imports;
-        std::vector<std::string> dirs;
-        std::string key;
-        for (const Program &p : loader.progs) {
-            for (const Import &im : p.imports) {
-                imports.push_back(im);
-                if (im.isC) key += im.path + "\n";
-                else if (p.module.empty()) a->modules.insert(im.path);
-            }
-            std::string d = dirOf(p.path);
-            if (std::find(dirs.begin(), dirs.end(), d) == dirs.end()) dirs.push_back(d), key += "@" + d + "\n";
-        }
-        auto &cached = headerCache[key];  // headers are slow to read: once per set of imports
-        if (!cached) cached = std::make_unique<CImports>(importHeaders(imports, dirs));
-        a->c = cached.get();
-        LLVMContext ctx;
-        generate(loader.progs, *cached, ctx, *tm, false);
-    } catch (const FinchError &e) {
-        std::string file = e.file >= 0 && e.file < (int)g_files.size() ? normalizePath(g_files[e.file].path) : path;
-        a->diags.push_back({file, e.line, e.col, e.msg});
-    }
-    g_index = nullptr;
-    g_throwErrors = false;
-    a->files = g_files;
-
-    // While the code is half-typed (`p.`, `add(1, `) it doesn't compile; completion and signature
-    // help keep using what the last good version knew. Hover and definition use the newest refs.
-    if (a->diags.empty()) {
-        lastGood[path] = a;
-    } else if (auto good = lastGood.find(path); good != lastGood.end()) {
-        const Analysis &g = *good->second;
-        for (const FnInfo &f : g.index.fns) a->index.fns.push_back(f);
-        for (const StructIndex &st : g.index.structs) a->index.structs.push_back(st);
-        for (const VarInfo &v : g.index.vars) a->index.vars.push_back(v);
-        if (a->modules.empty()) a->modules = g.modules;
-        if (!a->c) a->c = g.c;
-    }
-    results[path] = a;
-
-    std::map<std::string, json::Array> byFile;
-    byFile[path];
-    for (const std::string &p : diagnosed) byFile[p];  // clear errors that went away
-    diagnosed.clear();
-    for (const Diagnostic &d : a->diags) {
-        int line = std::max(0, d.line - 1), col = std::max(0, d.col - 1);
-        byFile[d.path].push_back(json::Object{
-            {"range", json::Object{{"start", json::Object{{"line", line}, {"character", col}}},
-                                   {"end", json::Object{{"line", line}, {"character", col + 1}}}}},
-            {"severity", 1},
-            {"source", "finch"},
-            {"message", d.msg}});
-        diagnosed.insert(d.path);
-    }
-    for (auto &[p, list] : byFile)
-        notify("textDocument/publishDiagnostics", json::Object{{"uri", pathToUri(p)}, {"diagnostics", std::move(list)}});
-}
-
-const SymRef *Server::refAt(const Analysis &a, const std::string &path, int line, int col) {
-    for (const SymRef &r : a.index.refs) {
-        if (r.line != line || col < r.col || col > r.col + r.len) continue;
-        if (r.file < 0 || r.file >= (int)a.files.size() || normalizePath(a.files[r.file].path) != path) continue;
-        return &r;
-    }
-    return nullptr;
-}
-
-json::Value Server::hover(const std::string &path, int line, int col) {
-    auto it = results.find(path);
-    if (it == results.end()) return nullptr;
-    const SymRef *r = refAt(*it->second, path, line, col);
-    if (!r) return nullptr;
-    return json::Object{{"contents", json::Object{{"kind", "markdown"}, {"value", r->hover}}}};
-}
-
-json::Value Server::definition(const std::string &path, int line, int col) {
-    auto it = results.find(path);
-    if (it == results.end()) return nullptr;
-    const Analysis &a = *it->second;
-    const SymRef *r = refAt(a, path, line, col);
-    if (!r || r->defFile < 0 || r->defFile >= (int)a.files.size()) return nullptr;
-    int l = r->defLine - 1, c = r->defCol - 1;
-    return json::Object{{"uri", pathToUri(a.files[r->defFile].path)},
-                        {"range", json::Object{{"start", json::Object{{"line", l}, {"character", c}}},
-                                               {"end", json::Object{{"line", l}, {"character", c}}}}}};
-}
-
-std::string Server::lineText(const std::string &path, int line) {
-    auto it = docs.find(path);
-    if (it == docs.end()) return "";
-    size_t start = 0;
-    for (int l = 1; l < line && start != std::string::npos; l++) {
-        start = it->second.find('\n', start);
-        if (start != std::string::npos) start++;
-    }
-    if (start == std::string::npos) return "";
-    return it->second.substr(start, it->second.find('\n', start) - start);
-}
-
-// LSP CompletionItemKind
-enum { KMethod = 2, KFunction = 3, KField = 5, KVariable = 6, KModule = 9, KKeyword = 14, KSnippet = 15,
-       KConstant = 21, KStruct = 22, KTypeParam = 25 };
-
-static json::Value item(const std::string &label, int kind, const std::string &detail = "", const std::string &doc = "") {
-    json::Object o{{"label", label}, {"kind", kind}};
-    if (!detail.empty()) o["detail"] = detail;
-    if (!doc.empty()) o["documentation"] = json::Object{{"kind", "markdown"}, {"value", doc}};
-    return o;
-}
-
-json::Value Server::completion(const std::string &path, int line, int col) {
-    json::Array items;
-    auto it = results.find(path);
-    std::shared_ptr<Analysis> a = it == results.end() ? nullptr : it->second;
-
-    // what's before the cursor: "name." or "name.partial"?
-    std::string text = lineText(path, line);
-    // columns count characters, but we only need the ASCII part right before the cursor
-    std::string before;
-    {
-        int c = 1;
-        size_t k = 0;
-        for (; k < text.size() && c < col; k++)
-            if (((unsigned char)text[k] & 0xC0) != 0x80) c++;
-        before = text.substr(0, k);
-    }
-    size_t end = before.size();
-    while (end > 0 && (isalnum((unsigned char)before[end - 1]) || before[end - 1] == '_')) end--;
-    bool afterDot = end > 0 && before[end - 1] == '.';
-
-    if (afterDot) {
-        size_t s = end - 1;
-        while (s > 0 && (isalnum((unsigned char)before[s - 1]) || before[s - 1] == '_' || before[s - 1] == ']' || before[s - 1] == '[')) s--;
-        std::string owner = before.substr(s, end - 1 - s);
-        if (size_t br = owner.find('['); br != std::string::npos) owner = owner.substr(0, br) + "[]";
-        if (!a) return json::Object{{"isIncomplete", false}, {"items", std::move(items)}};
-
-        // a module?
-        if (a->modules.count(owner)) {
-            std::set<std::string> seen;
-            for (const FnInfo &f : a->index.fns)
-                if (f.module == owner && seen.insert(f.name).second) items.push_back(item(f.name, KFunction, f.signature));
-            for (const StructIndex &s2 : a->index.structs)
-                if (s2.module == owner && seen.insert(s2.name).second) items.push_back(item(s2.name, KStruct, "struct " + s2.name));
-            return json::Object{{"isIncomplete", false}, {"items", std::move(items)}};
-        }
-        // a variable: find its type (the innermost one declared before the cursor)
-        bool element = owner.size() > 2 && owner.compare(owner.size() - 2, 2, "[]") == 0;
-        std::string name = element ? owner.substr(0, owner.size() - 2) : owner;
-        std::string type;
-        for (const VarInfo &v : a->index.vars)
-            if (v.name == name && v.line <= line && line <= v.fnEnd + 1) type = v.type;
-        if (element && type.rfind("[]", 0) == 0) type = type.substr(2);
-        if (element && type == "str") type = "char";
-        if (element && type.rfind("map[", 0) == 0) {  // m[key].  -> the value type
-            int depth = 0;
-            for (size_t k = 3; k < type.size(); k++) {
-                if (type[k] == '[') depth++;
-                else if (type[k] == ']' && --depth == 0) {
-                    type = type.substr(k + 1);
-                    break;
-                }
-            }
-        }
-        if (type.rfind("ptr[", 0) == 0) type = type.substr(4, type.size() - 5);  // fields through a pointer
-        if (type == "str") {
-            for (const BuiltinDoc &d : kStrMethods) items.push_back(item(d.name, d.name[0] == 'l' || d.name[0] == 'p' ? KField : KMethod, d.signature, d.doc));
-        } else if (type.rfind("[]", 0) == 0) {
-            for (const BuiltinDoc &d : kArrayMethods) items.push_back(item(d.name, std::string(d.name) == "len" || std::string(d.name) == "ptr" ? KField : KMethod, d.signature, d.doc));
-        } else if (type.rfind("map[", 0) == 0) {
-            for (const BuiltinDoc &d : kMapMethods) items.push_back(item(d.name, std::string(d.name) == "len" ? KField : KMethod, d.signature, d.doc));
-        } else if (!type.empty()) {
-            std::string mod, sname = type;
-            if (size_t dot = type.find('.'); dot != std::string::npos) mod = type.substr(0, dot), sname = type.substr(dot + 1);
-            for (const StructIndex &s2 : a->index.structs)
-                if (s2.name == sname && (mod.empty() || s2.module == mod))
-                    for (auto &[fname, ftype] : s2.fields) items.push_back(item(fname, KField, ftype + " " + fname));
-            std::set<std::string> seen;
-            for (const FnInfo &f : a->index.fns)  // methods: indexed as Struct.name
-                if (f.name.size() > sname.size() + 1 && f.name.compare(0, sname.size() + 1, sname + ".") == 0 &&
-                    seen.insert(f.name).second)
-                    items.push_back(item(f.name.substr(sname.size() + 1), KMethod, f.signature));
-            if (type.rfind("ptr", 0) == 0 || items.empty()) items.push_back(item("value", KField, "the value the pointer points to"));
-        }
-        return json::Object{{"isIncomplete", false}, {"items", std::move(items)}};
-    }
-
-    std::string prefix = before.substr(end);
-    for (const char *k : kKeywords) items.push_back(item(k, KKeyword));
-    for (const char *t : kTypeNames) items.push_back(item(t, KTypeParam, "type"));
-    for (const BuiltinDoc &d : kBuiltins) items.push_back(item(d.name, KFunction, d.signature, d.doc));
-    if (a) {
-        std::set<std::string> seen;
-        for (const VarInfo &v : a->index.vars)  // variables of the function around the cursor
-            if (v.fnLine <= line && line <= v.fnEnd && v.line <= line && seen.insert(v.name).second)
-                items.push_back(item(v.name, KVariable, v.type + " " + v.name));
-        for (const FnInfo &f : a->index.fns)
-            if (f.module.empty() && seen.insert(f.name).second) items.push_back(item(f.name, KFunction, f.signature));
-        for (const StructIndex &s : a->index.structs)
-            if (s.module.empty() && seen.insert(s.name).second) items.push_back(item(s.name, KStruct, "struct " + s.name));
-        for (const std::string &m : a->modules) items.push_back(item(m, KModule, "module " + m));
-        // C names only once something is typed: headers declare thousands
-        if (a->c && !prefix.empty()) {
-            for (auto &[name, f] : a->c->fns)
-                if (name.rfind(prefix, 0) == 0 && f.unsupported.empty()) items.push_back(item(name, KFunction, "C: " + f.header));
-            for (auto &[name, k] : a->c->consts)
-                if (name.rfind(prefix, 0) == 0) items.push_back(item(name, KConstant, "C constant"));
-            for (auto &[name, s] : a->c->structs)
-                if (name.rfind(prefix, 0) == 0) items.push_back(item(name, KStruct, "C struct"));
-        }
-    }
-    return json::Object{{"isIncomplete", !prefix.empty()}, {"items", std::move(items)}};
-}
-
-json::Value Server::symbols(const std::string &path) {
-    json::Array out;
-    auto it = results.find(path);
-    if (it == results.end()) return out;
-    const Analysis &a = *it->second;
-    auto inDoc = [&](int file) { return file >= 0 && file < (int)a.files.size() && normalizePath(a.files[file].path) == path; };
-    auto range = [](int l1, int c1, int l2) {
-        return json::Object{{"start", json::Object{{"line", l1 - 1}, {"character", c1 - 1}}},
-                            {"end", json::Object{{"line", std::max(l1, l2) - 1}, {"character", 0}}}};
-    };
-    for (const FnInfo &f : a.index.fns)
-        if (inDoc(f.file))
-            out.push_back(json::Object{{"name", f.name}, {"detail", f.signature}, {"kind", 12},
-                                       {"range", range(f.line, f.col, f.endLine + 1)}, {"selectionRange", range(f.line, f.col, f.line)}});
-    for (const StructIndex &s : a.index.structs)
-        if (inDoc(s.file)) {
-            json::Array kids;
-            for (auto &[n, t] : s.fields) kids.push_back(json::Object{{"name", n}, {"detail", t}, {"kind", 8},
-                                                                      {"range", range(s.line, s.col, s.line)}, {"selectionRange", range(s.line, s.col, s.line)}});
-            out.push_back(json::Object{{"name", s.name}, {"kind", 23}, {"range", range(s.line, s.col, s.line)},
-                                       {"selectionRange", range(s.line, s.col, s.line)}, {"children", std::move(kids)}});
-        }
-    return out;
-}
-
-// Inside `name(a, b|`: which function, and which argument.
-json::Value Server::signatureHelp(const std::string &path, int line, int col) {
-    auto it = results.find(path);
-    std::shared_ptr<Analysis> a = it == results.end() ? nullptr : it->second;
-    std::string text;
-    for (int l = std::max(1, line - 5); l < line; l++) text += lineText(path, l) + "\n";
-    std::string cur = lineText(path, line);
-    text += cur.substr(0, std::min<size_t>(cur.size(), col - 1));
-
-    int depth = 0, commas = 0;
-    size_t k = text.size();
-    while (k > 0) {
-        char ch = text[--k];
-        if (ch == ')' || ch == ']') depth++;
-        else if (ch == '[') depth--;
-        else if (ch == '(') {
-            if (depth == 0) break;
-            depth--;
-        } else if (ch == ',' && depth == 0) commas++;
-        if (k == 0) return nullptr;
-    }
-    size_t e = k;
-    while (k > 0 && (isalnum((unsigned char)text[k - 1]) || text[k - 1] == '_' || text[k - 1] == '.')) k--;
-    std::string callee = text.substr(k, e - k);
-    if (callee.empty()) return nullptr;
-    std::string name = callee.substr(callee.rfind('.') == std::string::npos ? 0 : callee.rfind('.') + 1);
-    std::string mod = callee.find('.') == std::string::npos ? "" : callee.substr(0, callee.find('.'));
-
-    std::string label, doc;
-    std::vector<std::string> params;
-    if (a) {
-        for (const FnInfo &f : a->index.fns) {
-            bool method = f.name.size() > name.size() && f.name.compare(f.name.size() - name.size() - 1, name.size() + 1, "." + name) == 0;
-            if ((f.name == name && (f.module == mod || (mod.empty() && f.module.empty()) || !a->modules.count(mod))) ||
-                (method && !mod.empty() && !a->modules.count(mod)))  // p.move(  -> Point.move
-                label = f.signature, params = f.params;
-        }
-        if (label.empty())
-            for (const StructIndex &s : a->index.structs)
-                if (s.name == name) {
-                    label = name + "(";
-                    for (size_t i = 0; i < s.fields.size(); i++) {
-                        params.push_back(s.fields[i].second + " " + s.fields[i].first);
-                        label += (i ? ", " : "") + params.back();
-                    }
-                    label += ")";
-                }
-        if (label.empty() && a->c)
-            if (auto f = a->c->fns.find(name); f != a->c->fns.end()) {
-                label = name + "(";
-                for (size_t i = 0; i < f->second.params.size(); i++) {
-                    params.push_back(f->second.params[i].show());
-                    label += (i ? ", " : "") + params.back();
-                }
-                label += f->second.variadic ? ", ...)" : ")";
-                doc = "C function from " + f->second.header;
-            }
-    }
-    if (label.empty()) {
-        auto look = [&](const BuiltinDoc *f, const BuiltinDoc *l) {
-            for (; f != l && label.empty(); ++f)
-                if (name == f->name) label = f->signature, doc = f->doc;
-        };
-        look(std::begin(kBuiltins), std::end(kBuiltins));
-        if (!mod.empty()) {
-            look(std::begin(kArrayMethods), std::end(kArrayMethods));
-            look(std::begin(kStrMethods), std::end(kStrMethods));
-            look(std::begin(kMapMethods), std::end(kMapMethods));
-        }
-    }
-    if (label.empty()) return nullptr;
-    json::Array ps;
-    for (const std::string &p : params) ps.push_back(json::Object{{"label", p}});
-    json::Object sig{{"label", label}, {"parameters", std::move(ps)}};
-    if (!doc.empty()) sig["documentation"] = doc;
-    return json::Object{{"signatures", json::Array{std::move(sig)}}, {"activeSignature", 0}, {"activeParameter", commas}};
-}
-
-}  // namespace
-
-int runLanguageServer() { return Server().run(); }

src/lsp.fch

@@ -0,0 +1,876 @@
+// The language server: `finch lsp`. An editor talks to it over stdin and stdout (JSON-RPC, as the Language Server
+// Protocol says) and gets errors while it types, hover, go to definition, completion, an outline and signature
+// help.
+//
+// It asks the compiler instead of being one: for every change it runs `finch index` on the text the editor has
+// (see the index records in gen.fch), and answers from what comes back.
+import json
+import host
+import docs
+import "stdio.h"
+import "stdlib.h"
+
+// ---------- what one run of the compiler told ----------
+
+struct Ref {
+    str file
+    int line
+    int col
+    int len
+    str defFile
+    int defLine
+    int defCol
+    str hover
+}
+
+struct VarRec {
+    str name
+    str type
+    str file
+    int line
+    int col
+    str fnFile
+    int fnLine
+    int fnEnd
+}
+
+struct FnRec {
+    str module
+    str name
+    str recv
+    str file
+    int line
+    int col
+    int endLine
+    str signature
+    []str params
+}
+
+struct StructRec {
+    str module
+    str name
+    str file
+    int line
+    int col
+    []str fields
+    []str types
+}
+
+struct EnumRec {
+    str module
+    str name
+    str file
+    int line
+    int col
+    []str variants
+}
+
+struct Diag {
+    bool has
+    str file
+    int line
+    int col
+    str message
+}
+
+struct Analysis {
+    []Ref refs
+    []VarRec vars
+    []FnRec fns
+    []StructRec structs
+    []EnumRec enums
+    []str imports
+    Diag diag
+}
+
+struct Server {
+    str self                        // the compiler's file: what to run for each check
+    str tmp                         // a folder for the copies of the editor's text
+    map[str]str docs                // path -> the text the editor has
+    map[str]Analysis results        // path -> the last check
+    map[str]Analysis good           // path -> the last check that found no error
+    []str diagnosed                 // the files an error was shown for
+    bool stopping
+}
+
+// ---------- paths and text ----------
+
+fn hexval(char c) -> int {
+    if c >= '0' && c <= '9' {
+        return int(c) - int('0')
+    }
+    if c >= 'a' && c <= 'f' {
+        return int(c) - int('a') + 10
+    }
+    if c >= 'A' && c <= 'F' {
+        return int(c) - int('A') + 10
+    }
+    return -1
+}
+
+fn uriToPath(str uri) -> str {
+    s := uri
+    if s.starts_with("file://") {
+        s = s.sub(7, s.len)
+    }
+    []u8 out
+    i := 0
+    while i < s.len {
+        if s[i] == '%' && i + 2 < s.len + 0 && hexval(s[i + 1]) >= 0 && hexval(s[i + 2]) >= 0 {
+            out.push(u8(hexval(s[i + 1]) * 16 + hexval(s[i + 2])))
+            i += 3
+        } else {
+            out.push(u8(s[i]))
+            i += 1
+        }
+    }
+    return str(out)
+}
+
+fn pathToUri(str path) -> str {
+    digits := "0123456789ABCDEF"
+    []str parts = ["file://"]
+    for c in path {
+        n := int(c)
+        if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || "/-_.~".contains(str(c)) {
+            parts.push(str(c))
+        } else {
+            parts.push("%" + str(digits[(n / 16) % 16]) + str(digits[n % 16]))
+        }
+    }
+    return parts.join("")
+}
+
+// "\n" written as two characters, back to a line break
+fn unesc(str s) -> str {
+    []str parts
+    i := 0
+    while i < s.len {
+        if s[i] == '\\' && i + 1 < s.len {
+            if s[i + 1] == 'n' {
+                parts.push("\n")
+            } else {
+                parts.push(str(s[i + 1]))
+            }
+            i += 2
+        } else {
+            parts.push(str(s[i]))
+            i += 1
+        }
+    }
+    return parts.join("")
+}
+
+fn lineOf(str text, int line) -> str {
+    lines := text.split("\n")
+    if line >= 1 && line <= lines.len {
+        return lines[line - 1]
+    }
+    return ""
+}
+
+// ---------- the protocol ----------
+
+fn readLine() -> str {
+    []u8 bytes
+    while true {
+        c := getchar()
+        if c < 0 {
+            return ""
+        }
+        if c == 10 {
+            break
+        }
+        bytes.push(u8(c))
+    }
+    line := str(bytes)
+    if line.ends_with("\r") {
+        line = line.sub(0, line.len - 1)
+    }
+    return line
+}
+
+// the next message; an error at the end of the input
+fn readMessage() -> json.Json! {
+    length := 0
+    while true {
+        header := readLine()
+        if header.len == 0 {
+            if length > 0 {
+                break
+            }
+            if feof(stdin) != 0 {
+                return error("the editor closed the connection")
+            }
+            continue
+        }
+        if header.starts_with("Content-Length:") {
+            length = int(header.sub(15, header.len).trim()) or 0
+        }
+    }
+    []u8 body
+    for i in 0..length {
+        c := getchar()
+        if c < 0 {
+            return error("the message was cut short")
+        }
+        body.push(u8(c))
+    }
+    return try json.parse(str(body))
+}
+
+fn send(json.Json v) {
+    body := json.stringify(v)
+    head := "Content-Length: " + str(body.len) + "\r\n\r\n"
+    text := head + body
+    fwrite(text.ptr, 1, u64(text.len), stdout)
+    fflush(stdout)
+}
+
+fn reply(json.Json id, json.Json result) {
+    m := json.new_object()
+    m.set("jsonrpc", json.new_text("2.0"))
+    m.set("id", id)
+    m.set("result", result)
+    send(m)
+}
+
+fn notify(str method, json.Json params) {
+    m := json.new_object()
+    m.set("jsonrpc", json.new_text("2.0"))
+    m.set("method", json.new_text(method))
+    m.set("params", params)
+    send(m)
+}
+
+fn num(int n) -> json.Json {
+    return json.new_number(float(n))
+}
+
+fn position(int line, int col) -> json.Json {
+    p := json.new_object()
+    p.set("line", num(line))
+    p.set("character", num(col))
+    return p
+}
+
+fn range(int line, int col, int endCol) -> json.Json {
+    r := json.new_object()
+    r.set("start", position(line, col))
+    r.set("end", position(line, endCol))
+    return r
+}
+
+// ---------- asking the compiler ----------
+
+fn splitTabs(str line) -> []str {
+    return line.split("\t")
+}
+
+fn intOf(str s) -> int {
+    return int(s) or 0
+}
+
+// "path:line:col: error: message" -> a diagnostic
+fn parseDiag(str line) -> Diag {
+    at := line.find(": error: ")
+    if at < 0 {
+        return Diag()
+    }
+    where := line.sub(0, at)
+    message := line.sub(at + 9, line.len)
+    // the last two colon-separated numbers are the line and column
+    parts := where.split(":")
+    if parts.len < 3 {
+        return Diag()
+    }
+    col := intOf(parts[parts.len - 1])
+    ln := intOf(parts[parts.len - 2])
+    []str pathParts
+    for i in 0..parts.len - 2 {
+        pathParts.push(parts[i])
+    }
+    return Diag(has: true, file: pathParts.join(":"), line: ln, col: col, message: message)
+}
+
+fn parseOutput(str output) -> Analysis {
+    a := Analysis()
+    for line in output.split("\n") {
+        if line.starts_with("@") {
+            f := splitTabs(line)
+            tag := f[0]
+            if tag == "@R" && f.len >= 9 {
+                a.refs.push(Ref(file: f[1], line: intOf(f[2]), col: intOf(f[3]), len: intOf(f[4]), defFile: f[5], defLine: intOf(f[6]), defCol: intOf(f[7]), hover: unesc(f[8])))
+            } else if tag == "@V" && f.len >= 9 {
+                a.vars.push(VarRec(name: f[1], type: f[2], file: f[3], line: intOf(f[4]), col: intOf(f[5]), fnFile: f[6], fnLine: intOf(f[7]), fnEnd: intOf(f[8])))
+            } else if tag == "@F" && f.len >= 10 {
+                a.fns.push(FnRec(module: f[1], name: f[2], recv: f[3], file: f[4], line: intOf(f[5]), col: intOf(f[6]), endLine: intOf(f[7]), signature: unesc(f[8]), params: f[9].split("|")))
+            } else if tag == "@S" && f.len >= 6 {
+                a.structs.push(StructRec(module: f[1], name: f[2], file: f[3], line: intOf(f[4]), col: intOf(f[5])))
+            } else if tag == "@SF" && f.len >= 5 && a.structs.len > 0 {
+                k := a.structs.len - 1
+                a.structs[k].fields.push(f[3])
+                a.structs[k].types.push(f[4])
+            } else if tag == "@E" && f.len >= 7 {
+                a.enums.push(EnumRec(module: f[1], name: f[2], file: f[3], line: intOf(f[4]), col: intOf(f[5]), variants: f[6].split(",")))
+            } else if tag == "@I" && f.len >= 2 {
+                a.imports.push(f[1])
+            }
+        } else if !a.diag.has {
+            a.diag = parseDiag(line)
+        }
+    }
+    return a
+}
+
+fn Server.analyse(str path) {
+    // the editor's text, as files the compiler can read: it asks for the file by its real name
+    host.makeDirs(self.tmp)
+    overlays := ""
+    n := 0
+    for p in self.docs.keys() {
+        copy := self.tmp + "/doc" + str(n) + ".fch"
+        write_file(copy, self.docs[p])
+        overlays = overlays + " --overlay " + host.quote(p + "=" + copy)
+        n += 1
+    }
+    out := self.tmp + "/out.txt"
+    host.run(host.quote(self.self) + " index " + host.quote(path) + overlays + " > " + host.quote(out) + " 2>&1")
+    a := parseOutput(read_file(out) or "")
+    if !a.diag.has {
+        self.good[path] = a
+    } else if self.good.has(path) {
+        // half-typed code doesn't compile: completion and signatures keep using what the last good version knew
+        g := self.good[path]
+        a.fns = g.fns
+        a.structs = g.structs
+        a.enums = g.enums
+        a.vars = g.vars
+        if a.imports.len == 0 {
+            a.imports = g.imports
+        }
+    }
+    self.results[path] = a
+    self.publish(path, a)
+}
+
+fn Server.publish(str path, Analysis a) {
+    // the files to say something about: the one checked, and any that had an error that is gone
+    []str files = [path]
+    for d in self.diagnosed {
+        if !files.contains(d) {
+            files.push(d)
+        }
+    }
+    []str now
+    for f in files {
+        list := json.new_list()
+        if a.diag.has && a.diag.file == f {
+            line := a.diag.line - 1
+            if line < 0 {
+                line = 0
+            }
+            col := a.diag.col - 1
+            if col < 0 {
+                col = 0
+            }
+            d := json.new_object()
+            d.set("range", range(line, col, col + 1))
+            d.set("severity", num(1))
+            d.set("source", json.new_text("finch"))
+            d.set("message", json.new_text(a.diag.message))
+            list.push(d)
+            now.push(f)
+        }
+        p := json.new_object()
+        p.set("uri", json.new_text(pathToUri(f)))
+        p.set("diagnostics", list)
+        notify("textDocument/publishDiagnostics", p)
+    }
+    self.diagnosed = now
+}
+
+// ---------- the questions ----------
+
+fn refAt(Analysis a, str path, int line, int col) -> int {
+    for i in 0..a.refs.len {
+        r := a.refs[i]
+        if r.line == line && col >= r.col && col <= r.col + r.len && r.file == path {
+            return i
+        }
+    }
+    return -1
+}
+
+fn hoverAt(Analysis a, str path, int line, int col) -> json.Json {
+    i := refAt(a, path, line, col)
+    if i < 0 {
+        return json.new_null()
+    }
+    contents := json.new_object()
+    contents.set("kind", json.new_text("markdown"))
+    contents.set("value", json.new_text(a.refs[i].hover))
+    out := json.new_object()
+    out.set("contents", contents)
+    return out
+}
+
+fn definitionAt(Analysis a, str path, int line, int col) -> json.Json {
+    i := refAt(a, path, line, col)
+    if i < 0 || a.refs[i].defFile.len == 0 {
+        return json.new_null()
+    }
+    r := a.refs[i]
+    out := json.new_object()
+    out.set("uri", json.new_text(pathToUri(r.defFile)))
+    out.set("range", range(r.defLine - 1, r.defCol - 1, r.defCol - 1))
+    return out
+}
+
+fn symbolsOf(Analysis a, str path) -> json.Json {
+    list := json.new_list()
+    for f in a.fns {
+        if f.file != path {
+            continue
+        }
+        kind := 12                      // Function
+        name := f.name
+        if f.recv.len > 0 {
+            kind = 6                    // Method
+            name = f.recv + "." + f.name
+        }
+        list.push(symbol(name, kind, f.line, f.col, f.endLine))
+    }
+    for s in a.structs {
+        if s.file == path {
+            list.push(symbol(s.name, 23, s.line, s.col, s.line + s.fields.len + 1))
+        }
+    }
+    for e in a.enums {
+        if e.file == path {
+            list.push(symbol(e.name, 10, e.line, e.col, e.line + e.variants.len + 1))
+        }
+    }
+    return list
+}
+
+fn symbol(str name, int kind, int line, int col, int endLine) -> json.Json {
+    s := json.new_object()
+    s.set("name", json.new_text(name))
+    s.set("kind", num(kind))
+    full := json.new_object()
+    full.set("start", position(line - 1, 0))
+    full.set("end", position(endLine, 0))
+    s.set("range", full)
+    s.set("selectionRange", range(line - 1, col - 1, col - 1))
+    return s
+}
+
+// ---------- completion ----------
+
+fn item(str label, int kind, str detail, str text) -> json.Json {
+    o := json.new_object()
+    o.set("label", json.new_text(label))
+    o.set("kind", num(kind))
+    if detail.len > 0 {
+        o.set("detail", json.new_text(detail))
+    }
+    if text.len > 0 {
+        d := json.new_object()
+        d.set("kind", json.new_text("markdown"))
+        d.set("value", json.new_text(text))
+        o.set("documentation", d)
+    }
+    return o
+}
+
+fn isWordChar(char c) -> bool {
+    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_'
+}
+
+fn methodItems(ptr[json.Json] items, []docs.Doc list) {
+    for d in list {
+        kind := 2                       // Method
+        if d.signature.starts_with(".") {
+            kind = 5                    // Field
+        }
+        items.push(item(d.name, kind, d.signature, d.text))
+    }
+}
+
+// the variable called `name` that is in scope at `line` (the innermost one declared before it)
+fn varNamed(Analysis a, str path, str name, int line) -> VarRec {
+    found := VarRec()
+    for v in a.vars {
+        if v.name == name && v.line <= line && line <= v.fnEnd + 1 && v.fnFile == path {
+            found = v
+        }
+    }
+    return found
+}
+
+fn completionAt(Analysis a, str text, str path, int line, int col) -> json.Json {
+    items := json.new_list()
+    lineText := lineOf(text, line)
+    end := col - 1
+    if end > lineText.len {
+        end = lineText.len
+    }
+    before := lineText.sub(0, end)
+    // the word being typed, and whether a dot comes right before it
+    wordStart := before.len
+    while wordStart > 0 && isWordChar(before[wordStart - 1]) {
+        wordStart -= 1
+    }
+    afterDot := wordStart > 0 && before[wordStart - 1] == '.'
+    if afterDot {
+        s := wordStart - 1
+        while s > 0 && (isWordChar(before[s - 1]) || before[s - 1] == '[' || before[s - 1] == ']') {
+            s -= 1
+        }
+        owner := before.sub(s, wordStart - 1)
+        element := false
+        br := owner.find("[")
+        if br >= 0 {
+            owner = owner.sub(0, br)
+            element = true
+        }
+        // a module: its functions, structs and enums
+        if a.imports.contains(owner) {
+            for f in a.fns {
+                if f.module == owner && f.recv.len == 0 {
+                    items.push(item(f.name, 3, f.signature, ""))
+                }
+            }
+            for st in a.structs {
+                if st.module == owner {
+                    items.push(item(st.name, 22, "struct " + st.name, ""))
+                }
+            }
+            for en in a.enums {
+                if en.module == owner {
+                    items.push(item(en.name, 13, "enum " + en.name, ""))
+                }
+            }
+            return completionList(items)
+        }
+        // an enum: its variants
+        for en in a.enums {
+            if en.name == owner && varNamed(a, path, owner, line).name.len == 0 {
+                for v in en.variants {
+                    items.push(item(v, 20, en.name + "." + v, ""))
+                }
+                return completionList(items)
+            }
+        }
+        // a variable: by its type
+        type := varNamed(a, path, owner, line).type
+        if element && type.starts_with("[]") {
+            type = type.sub(2, type.len)
+        } else if element && type == "str" {
+            type = "char"
+        }
+        if type.starts_with("ptr[") && type.ends_with("]") {
+            type = type.sub(4, type.len - 1)
+        }
+        if type.starts_with("[]") {
+            methodItems(addr(items), docs.arrayMethods())
+        } else if type == "str" {
+            methodItems(addr(items), docs.strMethods())
+        } else if type.starts_with("map[") {
+            methodItems(addr(items), docs.mapMethods())
+        } else {
+            base := type
+            for st in a.structs {
+                if st.name == base {
+                    for k in 0..st.fields.len {
+                        items.push(item(st.fields[k], 5, st.types[k], ""))
+                    }
+                }
+            }
+            for f in a.fns {
+                if f.recv == base {
+                    items.push(item(f.name, 2, f.signature, ""))
+                }
+            }
+        }
+        return completionList(items)
+    }
+    // not after a dot: what is in scope
+    seen := Names()
+    for v in a.vars {
+        if v.line <= line && line <= v.fnEnd + 1 && v.fnFile == path && seen.add(v.name) {
+            items.push(item(v.name, 6, v.type, ""))
+        }
+    }
+    for f in a.fns {
+        if f.recv.len == 0 && f.module == "" && seen.add(f.name) {
+            items.push(item(f.name, 3, f.signature, ""))
+        }
+    }
+    for st in a.structs {
+        if st.module == "" && seen.add(st.name) {
+            items.push(item(st.name, 22, "struct " + st.name, ""))
+        }
+    }
+    for en in a.enums {
+        if en.module == "" && seen.add(en.name) {
+            items.push(item(en.name, 13, "enum " + en.name, ""))
+        }
+    }
+    for m in a.imports {
+        if seen.add(m) {
+            items.push(item(m, 9, "module", ""))
+        }
+    }
+    for d in docs.builtins() {
+        if seen.add(d.name) {
+            items.push(item(d.name, 3, d.signature, d.text))
+        }
+    }
+    for k in docs.keywords() {
+        if seen.add(k) {
+            items.push(item(k, 14, "", ""))
+        }
+    }
+    for t in docs.typeNames() {
+        if seen.add(t) {
+            items.push(item(t, 25, "", ""))
+        }
+    }
+    return completionList(items)
+}
+
+struct Names {
+    []str items
+}
+
+fn Names.add(str x) -> bool {
+    if self.items.contains(x) {
+        return false
+    }
+    self.items.push(x)
+    return true
+}
+
+fn completionList(json.Json items) -> json.Json {
+    o := json.new_object()
+    o.set("isIncomplete", json.new_bool(false))
+    o.set("items", items)
+    return o
+}
+
+// ---------- signature help ----------
+
+fn signatureAt(Analysis a, str text, str path, int line, int col) -> json.Json {
+    lineText := lineOf(text, line)
+    end := col - 1
+    if end > lineText.len {
+        end = lineText.len
+    }
+    before := lineText.sub(0, end)
+    // back to the `(` that is still open, counting the commas at its own level
+    depth := 0
+    commas := 0
+    open := -1
+    i := before.len - 1
+    while i >= 0 {
+        c := before[i]
+        if c == ')' || c == ']' {
+            depth += 1
+        } else if c == '(' || c == '[' {
+            if depth == 0 {
+                if c == '(' {
+                    open = i
+                    break
+                }
+            } else {
+                depth -= 1
+            }
+        } else if c == ',' && depth == 0 {
+            commas += 1
+        }
+        i -= 1
+    }
+    if open < 0 {
+        return json.new_null()
+    }
+    nameEnd := open
+    nameStart := nameEnd
+    while nameStart > 0 && isWordChar(before[nameStart - 1]) {
+        nameStart -= 1
+    }
+    name := before.sub(nameStart, nameEnd)
+    if name.len == 0 {
+        return json.new_null()
+    }
+    recv := ""
+    if nameStart > 0 && before[nameStart - 1] == '.' {
+        // a method: its struct from the type of what comes before the dot
+        s := nameStart - 1
+        while s > 0 && isWordChar(before[s - 1]) {
+            s -= 1
+        }
+        owner := before.sub(s, nameStart - 1)
+        type := varNamed(a, path, owner, line).type
+        if type.starts_with("ptr[") && type.ends_with("]") {
+            type = type.sub(4, type.len - 1)
+        }
+        recv = type
+    }
+    for f in a.fns {
+        if f.name == name && f.recv == recv {
+            sig := json.new_object()
+            sig.set("label", json.new_text(f.signature))
+            params := json.new_list()
+            for p in f.params {
+                if p.len > 0 {
+                    one := json.new_object()
+                    one.set("label", json.new_text(p))
+                    params.push(one)
+                }
+            }
+            sig.set("parameters", params)
+            sigs := json.new_list()
+            sigs.push(sig)
+            out := json.new_object()
+            out.set("signatures", sigs)
+            out.set("activeSignature", num(0))
+            out.set("activeParameter", num(commas))
+            return out
+        }
+    }
+    d := docs.find(docs.builtins(), name)
+    if d.name.len > 0 {
+        sig := json.new_object()
+        sig.set("label", json.new_text(d.signature))
+        sig.set("documentation", json.new_text(d.text))
+        sigs := json.new_list()
+        sigs.push(sig)
+        out := json.new_object()
+        out.set("signatures", sigs)
+        out.set("activeSignature", num(0))
+        out.set("activeParameter", num(commas))
+        return out
+    }
+    return json.new_null()
+}
+
+// ---------- the messages ----------
+
+fn textOf(json.Json params) -> str {
+    return params.get("textDocument").get("text").str_or("")
+}
+
+fn pathOf(json.Json params) -> str {
+    return uriToPath(params.get("textDocument").get("uri").str_or(""))
+}
+
+fn Server.answer(json.Json msg) {
+    method := msg.get("method").str_or("")
+    params := msg.get("params")
+    id := msg.get("id")
+    match method {
+        "initialize" -> {
+            caps := json.new_object()
+            caps.set("textDocumentSync", num(1))
+            caps.set("hoverProvider", json.new_bool(true))
+            caps.set("definitionProvider", json.new_bool(true))
+            caps.set("documentSymbolProvider", json.new_bool(true))
+            comp := json.new_object()
+            dot := json.new_list()
+            dot.push(json.new_text("."))
+            comp.set("triggerCharacters", dot)
+            caps.set("completionProvider", comp)
+            sigp := json.new_object()
+            trig := json.new_list()
+            trig.push(json.new_text("("))
+            trig.push(json.new_text(","))
+            sigp.set("triggerCharacters", trig)
+            caps.set("signatureHelpProvider", sigp)
+            result := json.new_object()
+            result.set("capabilities", caps)
+            info := json.new_object()
+            info.set("name", json.new_text("finch"))
+            result.set("serverInfo", info)
+            reply(id, result)
+        }
+        "shutdown" -> {
+            self.stopping = true
+            reply(id, json.new_null())
+        }
+        "exit" -> {
+            exit(0)
+        }
+        "textDocument/didOpen" -> {
+            path := pathOf(params)
+            self.docs[path] = textOf(params)
+            self.analyse(path)
+        }
+        "textDocument/didChange" -> {
+            path := pathOf(params)
+            changes := params.get("contentChanges")
+            if changes.len() > 0 {
+                self.docs[path] = changes.at(changes.len() - 1).get("text").str_or("")
+                self.analyse(path)
+            }
+        }
+        "textDocument/didSave" -> {
+            path := pathOf(params)
+            if self.docs.has(path) {
+                self.analyse(path)
+            }
+        }
+        "textDocument/didClose" -> {
+            path := pathOf(params)
+            self.docs.remove(path)
+            self.results.remove(path)
+            self.good.remove(path)
+            empty := json.new_object()
+            empty.set("uri", json.new_text(pathToUri(path)))
+            empty.set("diagnostics", json.new_list())
+            notify("textDocument/publishDiagnostics", empty)
+        }
+        "textDocument/hover", "textDocument/definition", "textDocument/completion", "textDocument/documentSymbol", "textDocument/signatureHelp" -> {
+            path := pathOf(params)
+            line := params.get("position").get("line").int_or(0) + 1
+            col := params.get("position").get("character").int_or(0) + 1
+            if !self.results.has(path) {
+                reply(id, json.new_null())
+                return
+            }
+            a := self.results[path]
+            text := ""
+            if self.docs.has(path) {
+                text = self.docs[path]
+            }
+            match method {
+                "textDocument/hover" -> reply(id, hoverAt(a, path, line, col))
+                "textDocument/definition" -> reply(id, definitionAt(a, path, line, col))
+                "textDocument/completion" -> reply(id, completionAt(a, text, path, line, col))
+                "textDocument/documentSymbol" -> reply(id, symbolsOf(a, path))
+                else -> reply(id, signatureAt(a, text, path, line, col))
+            }
+        }
+        else -> {
+            // a request we don't know gets an answer so the editor does not wait; notifications get none
+            if id.kind != json.Kind.Null {
+                reply(id, json.new_null())
+            }
+        }
+    }
+}
+
+// finch lsp
+fn run(str self) -> int {
+    host.binaryStdio()
+    s := Server(self: self, tmp: host.tempDir() + "/finch_lsp_" + str(host.pid()))
+    while true {
+        msg := readMessage() or {
+            break
+        }
+        s.answer(msg)
+    }
+    host.removeTree(s.tmp)
+    return 0
+}

src/main.cpp

@@ -1,350 +0,0 @@
-#include "cimport.h"
-#include "codegen.h"
-#include "error.h"
-#include "lexer.h"
-#include "loader.h"
-#include "parser.h"
-#include "target.h"
-
-#include <llvm/Config/llvm-config.h>
-#include <llvm/IR/LegacyPassManager.h>
-#include <llvm/MC/TargetRegistry.h>
-#include <llvm/Passes/PassBuilder.h>
-#include <llvm/Support/FileSystem.h>
-#include <llvm/Support/Path.h>
-#include <llvm/Support/TargetSelect.h>
-#include <llvm/Target/TargetMachine.h>
-#include <llvm/TargetParser/Host.h>
-
-#include <algorithm>
-#include <cctype>
-#include <cstdio>
-#include <cstdlib>
-#include <cstring>
-#include <fstream>
-#include <map>
-#include <sstream>
-#include <string>
-#include <vector>
-
-#include "rt_source.inc"  // kRuntimeSource: runtime/finch_rt.c, embedded at build time
-
-using namespace llvm;
-
-static void usage() {
-    std::fprintf(stderr,
-                 "Finch " FINCH_VERSION " - small, quick, sharp.\n\n"
-                 "usage:\n"
-                 "  finch run   <file.fch> [args...]    compile and run\n"
-                 "  finch build <file.fch> [-o name]    compile to a program\n"
-                 "  finch ir    <file.fch>              show the generated LLVM IR\n"
-                 "  finch version                      show the version\n"
-                 "  finch lsp                          the language server, for editors (VS Code, Kate, ...)\n"
-                 "\n"
-                 "  -l <lib>          link a C library, same as  link \"lib\"  in the file\n"
-                 "  --target <name>   build for another system: windows, linux, arm64 (Linux), macos,\n"
-                 "                    or an LLVM triple\n"
-                 "  -g                add debug info (gdb / lldb / Visual Studio)\n"
-                 "  -O0               skip optimizations (to read the raw IR)\n");
-    std::exit(1);
-}
-
-// ---------- LLVM ----------
-
-static void optimize(Module &mod, TargetMachine *tm) {
-    LoopAnalysisManager lam;
-    FunctionAnalysisManager fam;
-    CGSCCAnalysisManager cgam;
-    ModuleAnalysisManager mam;
-    PassBuilder pb(tm);
-    pb.registerModuleAnalyses(mam);
-    pb.registerCGSCCAnalyses(cgam);
-    pb.registerFunctionAnalyses(fam);
-    pb.registerLoopAnalyses(lam);
-    pb.crossRegisterProxies(lam, fam, cgam, mam);
-    pb.buildPerModuleDefaultPipeline(OptimizationLevel::O2).run(mod, mam);
-}
-
-static TargetMachine *targetMachine() {
-    initTargets();
-    const Triple &triple = g_target.triple;
-    if (!triple.isX86() && !triple.isAArch64()) {
-        std::fprintf(stderr, "error: Finch generates code for x86-64 and ARM64, not for %s\n", triple.getArchName().str().c_str());
-        std::exit(1);
-    }
-    std::string err;
-    const Target *target = TargetRegistry::lookupTarget(triple, err);
-    if (!target) {
-        std::fprintf(stderr, "error: %s\n", err.c_str());
-        std::exit(1);
-    }
-    return target->createTargetMachine(triple, "generic", "", TargetOptions(), Reloc::PIC_);
-}
-
-static void emitObject(Module &mod, TargetMachine *tm, const std::string &path) {
-    std::error_code ec;
-    raw_fd_ostream out(path, ec, sys::fs::OF_None);
-    if (ec) {
-        std::fprintf(stderr, "error: can't write '%s': %s\n", path.c_str(), ec.message().c_str());
-        std::exit(1);
-    }
-    legacy::PassManager pm;
-    if (tm->addPassesToEmitFile(pm, out, nullptr, CodeGenFileType::ObjectFile)) {
-        std::fprintf(stderr, "error: this machine can't produce object files\n");
-        std::exit(1);
-    }
-    pm.run(mod);
-}
-
-// ---------- linking ----------
-
-// The runtime is compiled once per version and kept in ~/.cache/finch.
-static std::string runtimeObject() {
-    std::string dir = cacheDir();
-    size_t hash = std::hash<std::string>()(std::string(kRuntimeSource) + FINCH_VERSION + g_target.cc + g_target.triple.str());
-    std::string obj = dir + (g_target.windows && !g_target.cross ? "\\" : "/") + "rt-" + std::to_string(hash) + ".o";
-    if (sys::fs::exists(obj)) return obj;
-
-    sys::fs::create_directories(dir);
-    std::string src = obj + ".c", part = obj + ".part";
-    {
-        std::ofstream out(src);
-        out << kRuntimeSource;
-    }
-    std::string output;
-    std::string pic = g_target.windows ? "" : " -fPIC";
-    int status = capture(g_target.cc + " -O2" + pic + " -c " + shellQuote(src) + " -o " + shellQuote(part), output);
-    std::remove(src.c_str());
-    if (status != 0) {
-        std::fprintf(stderr, "%serror: couldn't build the Finch runtime with '%s' (is a C compiler installed?)\n", output.c_str(),
-                     g_target.cc.c_str());
-        std::exit(1);
-    }
-    sys::fs::rename(part, obj);
-    return obj;
-}
-
-// pkg-config knows the right paths for a library if it has one; otherwise plain -l<name>.
-static std::string libFlags(const std::string &lib) {
-    std::string out;
-    // macOS: link "Cocoa.framework" -> -framework Cocoa
-    if (lib.size() > 10 && lib.compare(lib.size() - 10, 10, ".framework") == 0)
-        return " -framework " + shellQuote(lib.substr(0, lib.size() - 10));
-    if (!g_target.cross && capture("pkg-config --libs " + shellQuote(lib), out) == 0) {
-        while (!out.empty() && std::isspace((unsigned char)out.back())) out.pop_back();
-        return " " + out;
-    }
-    return " " + shellQuote("-l" + lib);
-}
-
-// "GLFW/glfw3.h" -> "glfw": a decent first guess for the library's name.
-static std::string guessLib(const std::string &header) {
-    std::string name = header.substr(header.find_last_of('/') + 1);
-    name = name.substr(0, name.rfind('.'));
-    while (!name.empty() && std::isdigit((unsigned char)name.back())) name.pop_back();
-    for (char &ch : name) ch = std::tolower((unsigned char)ch);
-    return name;
-}
-
-// The linker speaks in riddles; turn its complaints into something you can act on.
-[[noreturn]] static void linkFailed(const std::string &output, const CImports &c) {
-    std::vector<std::string> missing, missingLibs;
-    auto addOnce = [](std::vector<std::string> &v, const std::string &x) {
-        if (std::find(v.begin(), v.end(), x) == v.end()) v.push_back(x);
-    };
-    std::istringstream lines(output);
-    for (std::string l; std::getline(lines, l);) {
-        size_t a;
-        if ((a = l.find("undefined reference to `")) != std::string::npos) {
-            a += 24;
-            addOnce(missing, l.substr(a, l.find('\'', a) - a));
-        } else if ((a = l.find("undefined symbol: ")) != std::string::npos) {
-            a += 18;
-            addOnce(missing, l.substr(a, l.find_first_of(" \n", a) - a));
-        } else if ((a = l.find("unresolved external symbol ")) != std::string::npos) {  // MSVC link.exe
-            a += 27;
-            addOnce(missing, l.substr(a, l.find_first_of(" \n\r", a) - a));
-        } else if ((a = l.find("cannot open file '")) != std::string::npos ||        // MSVC: LNK1104
-                   (a = l.find("cannot open input file '")) != std::string::npos ||  // MSVC: LNK1181
-                   (a = l.find("could not open '")) != std::string::npos) {       // lld-link
-            a = l.find('\'', a) + 1;
-            std::string lib = l.substr(a, l.find('\'', a) - a);
-            if (lib.size() > 4 && lib.compare(lib.size() - 4, 4, ".lib") == 0) lib = lib.substr(0, lib.size() - 4);
-            addOnce(missingLibs, lib);
-        } else if ((a = l.find("cannot find -l")) != std::string::npos ||
-                   (a = l.find("library not found for -l")) != std::string::npos) {  // older Apple ld
-            a = l.find("-l", a) + 2;
-            addOnce(missingLibs, l.substr(a, l.find_first_of(": \n\r", a) - a));
-        } else if ((a = l.find("ld: library '")) != std::string::npos) {  // Apple ld: library 'x' not found
-            a += 13;
-            addOnce(missingLibs, l.substr(a, l.find('\'', a) - a));
-        } else if ((a = l.find("framework '")) != std::string::npos && l.find("not found") != std::string::npos) {
-            a += 11;
-            addOnce(missingLibs, l.substr(a, l.find('\'', a) - a) + ".framework");
-        } else if (l.rfind("  \"", 0) == 0 && (a = l.find("\", referenced from:")) != std::string::npos) {
-            // Apple ld: Undefined symbols for architecture arm64:\n  "_name", referenced from:
-            std::string name = l.substr(3, a - 3);
-            if (g_target.darwin && !name.empty() && name[0] == '_') name.erase(0, 1);
-            addOnce(missing, name);
-        }
-    }
-    if (missing.empty() && missingLibs.empty()) {
-        std::fprintf(stderr, "%serror: linking failed\n", output.c_str());
-        std::exit(1);
-    }
-
-    for (const std::string &lib : missingLibs)
-        std::fprintf(stderr, "error: the library '%s' wasn't found. Is it installed? (on Nix: add it to shell.nix)\n", lib.c_str());
-
-    std::vector<std::pair<std::string, std::vector<std::string>>> byHeader;
-    for (const std::string &name : missing) {
-        auto f = c.fns.find(name);
-        std::string header = f == c.fns.end() ? "" : f->second.header;
-        auto it = std::find_if(byHeader.begin(), byHeader.end(), [&](auto &g) { return g.first == header; });
-        if (it == byHeader.end()) byHeader.push_back({header, {name}});
-        else it->second.push_back(name);
-    }
-    for (auto &[header, names] : byHeader) {
-        std::string list;
-        for (size_t k = 0; k < names.size() && k < 3; k++) list += (k ? ", " : "") + names[k];
-        if (names.size() > 3) list += " and " + std::to_string(names.size() - 3) + " more";
-        if (header.empty()) {
-            std::fprintf(stderr, "error: no code found for %s\n", list.c_str());
-            continue;
-        }
-        std::fprintf(stderr,
-                     "error: %s come%s from \"%s\", but its library isn't linked\n"
-                     "  the header only says the functions exist; their code lives in a library.\n"
-                     "  add this at the top of your file (with the library's real name):\n\n"
-                     "      link \"%s\"\n\n",
-                     list.c_str(), names.size() == 1 ? "s" : "", header.c_str(), guessLib(header).c_str());
-    }
-    std::exit(1);
-}
-
-static bool endsWith(const std::string &s, const char *x) {
-    size_t n = std::strlen(x);
-    return s.size() > n && s.compare(s.size() - n, n, x) == 0;
-}
-
-static void link(const std::string &obj, const std::string &exe, const std::vector<std::string> &libs,
-                 const CImports &c) {
-    std::string cmd = g_target.cc + " " + shellQuote(obj) + " " + shellQuote(runtimeObject()) + " -o " + shellQuote(exe);
-    if (!g_target.msvc) cmd += " -lm";
-    std::vector<std::string> temps;
-    for (const std::string &l : libs) {
-        if (endsWith(l, ".c")) {  // compile the user's C file
-            std::string o = obj + "." + std::to_string(temps.size()) + ".o", output;
-            std::string pic = g_target.windows ? "" : " -fPIC";
-            if (capture(g_target.cc + " -O2" + pic + " -c " + shellQuote(l) + " -o " + shellQuote(o), output) != 0) {
-                std::fprintf(stderr, "%serror: couldn't compile %s\n", output.c_str(), l.c_str());
-                std::exit(1);
-            }
-            temps.push_back(o);
-            cmd += " " + shellQuote(o);
-        } else if (endsWith(l, ".o") || endsWith(l, ".a")) {
-            cmd += " " + shellQuote(l);
-        } else {
-            cmd += libFlags(l);
-        }
-    }
-    std::string output;
-    int status = capture(cmd, output);
-    std::remove(obj.c_str());
-    for (const std::string &t : temps) std::remove(t.c_str());
-    if (status == 127) {
-        std::fprintf(stderr, "error: no C compiler found to link with ('%s'; install one, or set FINCH_CC)\n", g_target.cc.c_str());
-        std::exit(1);
-    }
-    if (status != 0) linkFailed(output, c);
-    std::fputs(output.c_str(), stderr);  // warnings, if any
-}
-
-static std::string stem(const std::string &path) {
-    size_t slash = path.find_last_of("/\\");
-    std::string name = slash == std::string::npos ? path : path.substr(slash + 1);
-    size_t dot = name.rfind('.');
-    return dot == std::string::npos ? name : name.substr(0, dot);
-}
-
-int runLanguageServer();  // lsp.cpp
-
-int main(int argc, char **argv) {
-    if (argc == 2 && std::string(argv[1]) == "lsp") return runLanguageServer();
-    if (argc == 2 && (std::string(argv[1]) == "version" || std::string(argv[1]) == "--version")) {
-        std::printf("finch %s (LLVM %s)\n", FINCH_VERSION, LLVM_VERSION_STRING);
-        return 0;
-    }
-    if (argc < 3) usage();
-    std::string cmd = argv[1], file = argv[2];
-    if (cmd != "run" && cmd != "build" && cmd != "ir") usage();
-    std::string out = stem(file);
-    std::vector<std::string> libs, programArgs;
-    std::string targetName;
-    bool optimizeCode = true, debug = false, outGiven = false;
-    for (int i = 3; i < argc; i++) {
-        std::string a = argv[i];
-        if (cmd == "run" && !programArgs.empty()) programArgs.push_back(a);
-        else if (a == "-o" && i + 1 < argc && cmd == "build") out = argv[++i], outGiven = true;
-        else if (a == "--target" && i + 1 < argc) targetName = argv[++i];
-        else if (a == "-O0") optimizeCode = false;
-        else if (a == "-g") debug = true;
-        else if (a == "-l" && i + 1 < argc) libs.push_back(argv[++i]);
-        else if (a.rfind("-l", 0) == 0 && a.size() > 2) libs.push_back(a.substr(2));
-        else if (cmd == "run") programArgs.push_back(a);
-        else usage();
-    }
-
-    setTarget(targetName);
-    if (!outGiven) out += g_target.exe;
-
-    Loader loader;
-    loader.load(file, "", Pos{});
-    std::vector<Import> allImports;
-    std::vector<std::string> dirs;
-    for (const Program &p : loader.progs) {
-        allImports.insert(allImports.end(), p.imports.begin(), p.imports.end());
-        for (const Link &l : p.links) {
-            bool file = endsWith(l.lib, ".c") || endsWith(l.lib, ".o") || endsWith(l.lib, ".a");
-            std::string path = file && !sys::path::is_absolute(l.lib) ? dirOf(p.path) + "/" + l.lib : l.lib;
-            if (file && !sys::fs::exists(path)) failAt(l.pos.file, l.pos.line, l.pos.col, "can't find the file '" + path + "'");
-            libs.push_back(path);
-        }
-        if (std::find(dirs.begin(), dirs.end(), dirOf(p.path)) == dirs.end()) dirs.push_back(dirOf(p.path));
-    }
-    CImports c = importHeaders(allImports, dirs);
-    LLVMContext ctx;
-    TargetMachine *tm = targetMachine();
-    std::unique_ptr<Module> mod = generate(loader.progs, c, ctx, *tm, debug);
-    if (optimizeCode) optimize(*mod, tm);
-
-    if (cmd == "ir") {
-        mod->print(outs(), nullptr);
-        return 0;
-    }
-
-    std::string obj = out + ".o";
-    if (cmd == "run") {
-        SmallString<128> tmp;
-        sys::fs::createTemporaryFile("finch", g_target.windows ? "exe" : "", tmp);
-        out = tmp.str().str();
-        obj = out + ".o";
-    }
-    emitObject(*mod, tm, obj);
-    link(obj, out, libs, c);
-
-    if (cmd == "run") {
-        std::string line = shellQuote(out);
-        for (const std::string &a : programArgs) line += " " + shellQuote(a);
-        line = runPrefix() + line;  // wine / qemu for programs built for another system
-#ifdef _WIN32
-        line = "\"" + line + "\"";  // cmd /c strips one pair of outer quotes
-#endif
-        std::string crash;
-        int status = runCommand(line, &crash);
-        std::remove(out.c_str());
-        if (!crash.empty()) std::fprintf(stderr, "\nthe program crashed: %s\n", crash.c_str());
-        return status;
-    }
-    return 0;
-}

src/main.fch

@@ -0,0 +1,330 @@
+// finch-boot: the Finch compiler written in Finch.
+//
+//   finch-boot build <file.fch> [-o name]    compile a program
+//   finch-boot ir    <file.fch>              print the LLVM IR
+//
+// It reads the program and the modules it imports, checks it, writes LLVM IR as text
+// and lets clang turn that into a program, linked with Finch's C runtime.
+import lexer
+import ast
+import parser
+import gen
+import cimport
+import platform
+import linker
+import lsp
+import host
+import embedded
+import "stdlib.h"
+
+fn dirOf(str path) -> str {
+    i := path.len - 1
+    while i >= 0 && path[i] != '/' {
+        i -= 1
+    }
+    if i < 0 {
+        return "."
+    }
+    return path.sub(0, i)
+}
+
+fn stem(str path) -> str {
+    name := path.sub(dirOf(path).len + 1, path.len)
+    if dirOf(path) == "." && !path.starts_with("./") {
+        name = path
+    }
+    dot := name.find(".")
+    if dot > 0 {
+        return name.sub(0, dot)
+    }
+    return name
+}
+
+struct Loader {
+    []ast.Program progs
+    []str files
+    []str loaded
+    str os              // "windows", "macos" or "linux": a module may have a version for each (time_windows.fch)
+    str std             // the standard library's folder, or ""
+    []str paths         // FINCH_PATH: more folders to look for modules in
+    []str overlayPaths  // --overlay path=file: read `path` from `file` (the text an editor has, not saved yet)
+    []str overlayFiles
+}
+
+fn textOfFile(ptr[Loader] l, str path) -> str {
+    k := l.overlayPaths.find(path)
+    if k >= 0 {
+        return read_file(l.overlayFiles[k])
+    }
+    return read_file(path)
+}
+
+// import json: the file next to the one that imports it, else the standard library's.
+// A program's own json.fch wins over the library's.
+fn findModule(ptr[Loader] l, str from, str name) -> str {
+    // in each folder, the version for this system first: time_windows.fch, then time.fch
+    local := dirOf(from) + "/" + name + ".fch"
+    if file_exists(dirOf(from) + "/" + name + "_" + l.os + ".fch") {
+        return dirOf(from) + "/" + name + "_" + l.os + ".fch"
+    }
+    if file_exists(local) {
+        return local
+    }
+    for d in l.paths {
+        if file_exists(d + "/" + name + "_" + l.os + ".fch") {
+            return d + "/" + name + "_" + l.os + ".fch"
+        }
+        if file_exists(d + "/" + name + ".fch") {
+            return d + "/" + name + ".fch"
+        }
+    }
+    if l.std.len > 0 {
+        if file_exists(l.std + "/" + name + "_" + l.os + ".fch") {
+            return l.std + "/" + name + "_" + l.os + ".fch"
+        }
+        if file_exists(l.std + "/" + name + ".fch") {
+            return l.std + "/" + name + ".fch"
+        }
+    }
+    return local
+}
+
+fn load(ptr[Loader] l, str path, str module) {
+    if !file_exists(path) && !l.overlayPaths.contains(path) {
+        if module.len > 0 {
+            print("error: can't find the module '" + module + "' (looked for " + path + ")")
+        } else {
+            print("error: can't open '" + path + "'")
+        }
+        exit(1)
+    }
+    src := textOfFile(l, path)
+    file := l.files.len
+    l.files.push(path)
+    prog := parser.parse(lexer.lex(src, path), file, path)
+    prog.module = module
+    prog.path = path
+    imports := prog.imports
+    l.progs.push(prog)
+    for name in imports {
+        if !l.loaded.contains(name) {
+            l.loaded.push(name)
+            load(l, findModule(l, path, name), name)
+        }
+    }
+}
+
+fn usage() {
+    print("Finch -- the compiler is written in Finch")
+    print("usage:")
+    print("  finch run <file.fch> [args...]     build and run a program")
+    print("  finch build <file.fch> [-o name]   build a program")
+    print("  finch ir <file.fch>                print the LLVM IR")
+    print("  finch version                      show the version")
+    print("  finch lsp                          the language server, for editors (VS Code, Kate, ...)")
+    print("options:")
+    print("  -O0               no optimization (faster to build)")
+    print("  -l <lib>          link a library (the same as  link \"lib\"  in the program)")
+    print("  -I <dir>          look for imported C headers there too")
+    print("  -g                debug info (for gdb and lldb; use -O0 with it)")
+    print("  --target <name>   build for another system: windows, linux, arm64 (Linux), macos, or an LLVM triple")
+    exit(1)
+}
+
+// The runtime and the standard library are carried inside the compiler (embedded.fch). When they aren't found as
+// files next to it, they are written to the cache folder, once, and used from there.
+fn unpack() -> str {
+    names := embedded.names()
+    dir := host.cacheDir() + "/files-" + linker.fingerprint(embedded.texts().join("\n"))
+    if file_exists(dir + "/done") {
+        return dir
+    }
+    texts := embedded.texts()
+    for i in 0..names.len {
+        host.makeDirs(dirOf(dir + "/" + names[i]))
+        write_file(dir + "/" + names[i], texts[i])
+    }
+    write_file(dir + "/done", "")
+    return dir
+}
+
+fn main([]str args) -> int {
+    if args.len == 2 && (args[1] == "version" || args[1] == "--version") {
+        print("Finch 2.4.0 (the compiler is written in Finch)")
+        return 0
+    }
+    if args.len == 2 && args[1] == "lsp" {
+        return lsp.run(args[0])             // the language server, for editors
+    }
+    if args.len < 3 {
+        usage()
+    }
+    cmd := args[1]
+    file := args[2]
+    if cmd != "build" && cmd != "run" && cmd != "ir" && cmd != "index" {
+        usage()
+    }
+    out := stem(file)
+    outGiven := false
+    shared := false
+    debug := false
+    targetName := ""
+    opt := "-O2"
+    []str extraLibs
+    []str extraDirs
+    []str overlayPaths
+    []str overlayFiles
+    []str progArgs
+    ai := 3
+    while ai < args.len {
+        a := args[ai]
+        if cmd == "run" && progArgs.len > 0 {          // after the first argument of the program, all of them are its
+            progArgs.push(a)
+        } else if a == "-o" && ai + 1 < args.len && cmd == "build" {
+            out = args[ai + 1]
+            outGiven = true
+            ai += 1
+        } else if a == "--shared" && cmd == "build" {
+            shared = true
+        } else if a == "-O0" {
+            opt = "-O0"
+        } else if a == "-l" && ai + 1 < args.len {
+            extraLibs.push(args[ai + 1])
+            ai += 1
+        } else if a.starts_with("-l") && a.len > 2 {
+            extraLibs.push(a.sub(2, a.len))
+        } else if a == "-I" && ai + 1 < args.len {
+            extraDirs.push(args[ai + 1])
+            ai += 1
+        } else if a == "--overlay" && ai + 1 < args.len {
+            both := args[ai + 1].split("=")
+            overlayPaths.push(both[0])
+            overlayFiles.push(both[1])
+            ai += 1
+        } else if a == "-g" {
+            debug = true
+        } else if a == "--target" && ai + 1 < args.len {
+            targetName = args[ai + 1]
+            ai += 1
+        } else if cmd == "run" {
+            progArgs.push(a)
+        } else {
+            usage()
+        }
+        ai += 1
+    }
+    tg := platform.select(targetName)
+    if cmd == "run" {
+        out = host.tempDir() + "/finch_run_" + str(host.pid()) + "_" + stem(file) + tg.exe
+    } else if shared && !outGiven {
+        if tg.windows {
+            out = out + ".dll"
+        } else if tg.darwin {
+            out = "lib" + out + ".dylib"
+        } else {
+            out = "lib" + out + ".so"
+        }
+    } else if !outGiven {
+        out = out + tg.exe
+    }
+
+    loader := Loader()
+    loader.os = "linux"
+    if tg.windows {
+        loader.os = "windows"
+    } else if tg.darwin {
+        loader.os = "macos"
+    }
+    for cand in [dirOf(args[0]) + "/../std", dirOf(args[0]) + "/std", dirOf(args[0]) + "/../share/finch/std", "std"] {
+        if loader.std.len == 0 && file_exists(cand + "/path.fch") {
+            loader.std = cand
+        }
+    }
+    if loader.std.len == 0 {
+        loader.std = unpack() + "/std"
+    }
+    loader.overlayPaths = overlayPaths
+    loader.overlayFiles = overlayFiles
+    for d in getenv("FINCH_PATH").split(host.pathSeparator()) {
+        if d.len > 0 {
+            loader.paths.push(d)
+        }
+    }
+    load(addr(loader), file, "")
+
+    // C headers, from every file; their folders are searched first for "local.h"
+    []cimport.Header headers
+    []str seen
+    []str dirs = extraDirs
+    []str links = extraLibs
+    for prog in loader.progs {
+        d := dirOf(prog.path)
+        if !dirs.contains(d) {
+            dirs.push(d)
+        }
+        for i in 0..prog.cimports.len {
+            if !seen.contains(prog.cimports[i]) {
+                seen.push(prog.cimports[i])
+                headers.push(cimport.Header(path: prog.cimports[i], where: prog.cwhere[i]))
+            }
+        }
+        for l in prog.links {
+            if l.ends_with(".c") || l.ends_with(".o") || l.ends_with(".a") {
+                links.push(d + "/" + l)             // the program's own C code, next to the .fch file
+            } else {
+                links.push(l)
+            }
+        }
+    }
+    triple := ""
+    if tg.cross || tg.windows {
+        triple = tg.triple          // on Windows libclang.dll would otherwise assume MSVC, while clang may be MinGW
+    }
+    ci := cimport.importHeaders(headers, dirs, triple, tg.windows, tg.cc) or {
+        print(err)
+        return 1
+    }
+    ir := gen.generate(loader.progs, loader.files, ci, gen.Options(shared: shared, debug: debug, index: cmd == "index", cwd: host.cwd(), target: tg))
+    if cmd == "ir" || cmd == "index" {
+        print(ir)
+        return 0
+    }
+
+    // the runtime is Finch's C file; FINCH_RT can point somewhere else
+    rt := getenv("FINCH_RT")
+    if rt.len == 0 {
+        rt = dirOf(args[0]) + "/../runtime/finch_rt.c"
+    }
+    if !file_exists(rt) {
+        rt = dirOf(args[0]) + "/runtime/finch_rt.c"
+    }
+    if !file_exists(rt) {
+        rt = dirOf(args[0]) + "/../share/finch/runtime/finch_rt.c"
+    }
+    if !file_exists(rt) && file_exists("runtime/finch_rt.c") {
+        rt = "runtime/finch_rt.c"
+    }
+    if !file_exists(rt) {
+        rt = unpack() + "/runtime/finch_rt.c"
+    }
+    extra := ""
+    if shared {
+        extra = " -fPIC"
+    }
+    if debug {
+        extra = extra + " -g"      // or clang drops the debug info that is in the IR
+    }
+    if linker.build(linker.Build(out: out, ir: ir, rt: rt, opt: opt, extra: extra, shared: shared, links: links), tg, ci) != 0 {
+        return 1
+    }
+    if cmd == "run" {
+        []str quoted
+        for a in progArgs {
+            quoted.push(linker.quote(a))
+        }
+        status := host.run(tg.runner + linker.quote(out) + " " + quoted.join(" "))
+        host.remove(out)
+        return status
+    }
+    return 0
+}

src/parser.cpp

@@ -1,602 +0,0 @@
-#include "parser.h"
-#include "error.h"
-
-#include <algorithm>
-#include <cerrno>
-#include <climits>
-#include <cstdlib>
-#include <cstring>
-#include <unordered_map>
-
-bool typeFromName(const std::string &name, Type &out) {
-    static const std::unordered_map<std::string, Type::Kind> names = {
-        {"int", Type::I64},  {"float", Type::F64}, {"bool", Type::Bool}, {"char", Type::Char},
-        {"str", Type::Str},  {"ptr", Type::Ptr},   {"i8", Type::I8},     {"i16", Type::I16},
-        {"i32", Type::I32},  {"i64", Type::I64},   {"u8", Type::U8},     {"u16", Type::U16},
-        {"u32", Type::U32},  {"u64", Type::U64},   {"f32", Type::F32},   {"f64", Type::F64},
-    };
-    auto it = names.find(name);
-    if (it == names.end()) return false;
-    out = Type(it->second);
-    return true;
-}
-
-namespace {
-
-bool isTypeName(const std::string &name) {
-    Type t;
-    return typeFromName(name, t);
-}
-
-class Parser {
-public:
-    Parser(const std::vector<Token> &t, int f) : toks(t), file(f) {}
-
-    Program program() {
-        Program p;
-        while (!at(Tok::End)) {
-            switch (cur().kind) {
-            case Tok::Import: p.imports.push_back(import()); break;
-            case Tok::Link: p.links.push_back(link()); break;
-            case Tok::Struct: p.structs.push_back(structDecl()); break;
-            default: p.fns.push_back(function()); break;
-            }
-        }
-        return p;
-    }
-
-private:
-    const std::vector<Token> &toks;
-    int file;
-    size_t i = 0;
-    int parenDepth = 0;  // inside ( ) and [ ] newlines don't end anything
-
-    const Token &cur() const { return toks[i]; }
-    const Token &peekTok(size_t off = 1) const { return toks[std::min(i + off, toks.size() - 1)]; }
-    const Token &next() { return toks[i++]; }
-    bool at(Tok k) const { return cur().kind == k; }
-    Pos pos() const { return {cur().line, cur().col, file}; }
-
-    std::string describe(const Token &t) const {
-        return t.kind == Tok::Ident ? "'" + t.text + "'" : tokName(t.kind);
-    }
-
-    bool accept(Tok k) {
-        if (!at(k)) return false;
-        i++;
-        return true;
-    }
-    const Token &expect(Tok k, const char *what = nullptr) {
-        if (!at(k))
-            fail(cur().line, cur().col,
-                 std::string("expected ") + (what ? what : tokName(k)) + ", found " + describe(cur()));
-        return next();
-    }
-    [[noreturn]] void unexpected(const char *ctx) {
-        fail(cur().line, cur().col, "unexpected " + describe(cur()) + " " + ctx);
-    }
-
-    // A token can continue an expression only if it is on the same line (or we're inside brackets).
-    bool sameLine() const { return parenDepth > 0 || !cur().newlineBefore; }
-
-    // int, u8, ptr, ptr[int], []str, map[str]int, Point, math.Vec ...
-    Type type() {
-        if (accept(Tok::LBracket)) {
-            expect(Tok::RBracket, "']' (an array type looks like []int)");
-            return Type::arrayOf(type());
-        }
-        if (!at(Tok::Ident)) unexpected("(expected a type like int, str, []int, ptr[int] or a struct name)");
-        if (cur().text == "map" && peekTok().kind == Tok::LBracket) {
-            next();
-            next();
-            Type k = type();
-            expect(Tok::RBracket, "']' (a map type looks like map[str]int)");
-            return Type::mapOf(k, type());
-        }
-        std::string name = next().text;
-        Type t;
-        if (typeFromName(name, t)) {
-            if (t.kind == Type::Ptr && accept(Tok::LBracket)) {
-                t = Type::ptrTo(type());
-                expect(Tok::RBracket);
-            }
-            return t;
-        }
-        t = Type(Type::Named);
-        t.name = name;
-        if (at(Tok::Dot) && peekTok().kind == Tok::Ident) {  // module.Struct
-            next();
-            t.module = name;
-            t.name = next().text;
-        }
-        return t;
-    }
-
-    // Does a declaration like `int x`, `ptr[int] p`, `[]int a`, `Point p` or `math.Vec v` start here?
-    bool atDeclaration() const {
-        if (at(Tok::LBracket)) return peekTok().kind == Tok::RBracket;
-        if (!at(Tok::Ident)) return false;
-        Tok n = peekTok().kind;
-        if (n == Tok::Ident) return !peekTok().newlineBefore;
-        if ((cur().text == "ptr" || cur().text == "map") && n == Tok::LBracket) return true;
-        return n == Tok::Dot && peekTok(2).kind == Tok::Ident && peekTok(3).kind == Tok::Ident &&
-               !peekTok(3).newlineBefore;
-    }
-
-    // ---------- top level ----------
-
-    Import import() {
-        Import im;
-        im.pos = pos();
-        expect(Tok::Import);
-        if (at(Tok::Ident)) {
-            im.isC = false;
-            im.path = next().text;
-        } else {
-            im.path = expect(Tok::String, "a module name (import math) or a C header in quotes (import \"stdio.h\")").text;
-        }
-        return im;
-    }
-
-    Link link() {
-        Link l;
-        l.pos = pos();
-        expect(Tok::Link);
-        l.lib = expect(Tok::String, "a library name in quotes, like link \"glfw\"").text;
-        auto ends = [&](const char *x) { size_t n = std::strlen(x); return l.lib.size() > n && l.lib.compare(l.lib.size() - n, n, x) == 0; };
-        if (ends(".c") || ends(".o") || ends(".a")) return l;  // your own C code, next to the .fch file
-        if (l.lib.rfind("lib", 0) == 0 || l.lib.find(".so") != std::string::npos || l.lib.find('/') != std::string::npos)
-            fail(l.pos.line, l.pos.col, "write just the library's name: for libglfw.so that's  link \"glfw\"");
-        return l;
-    }
-
-    StructDecl structDecl() {
-        StructDecl s;
-        s.pos = pos();
-        expect(Tok::Struct);
-        s.namePos = pos();
-        s.name = expect(Tok::Ident, "a struct name").text;
-        if (isTypeName(s.name)) fail(s.pos.line, s.pos.col, "'" + s.name + "' is a built-in type name, pick another");
-        Pos open = pos();
-        expect(Tok::LBrace);
-        while (!at(Tok::RBrace)) {
-            if (at(Tok::End)) fail(open.line, open.col, "this '{' is never closed (missing '}')");
-            Field f;
-            f.pos = pos();
-            if (!atDeclaration()) unexpected("(a field looks like: int x  or  str name = \"default\")");
-            f.type = type();
-            f.namePos = pos();
-            f.name = expect(Tok::Ident, "a field name").text;
-            for (const Field &other : s.fields)
-                if (other.name == f.name) fail(f.pos.line, f.pos.col, "the field '" + f.name + "' is listed twice");
-            if (accept(Tok::Assign)) f.init = expr();
-            s.fields.push_back(std::move(f));
-            endOfStatement();
-        }
-        next();
-        return s;
-    }
-
-    FnDecl function() {
-        FnDecl fn;
-        fn.pos = pos();
-        if (at(Tok::Ident) && isTypeName(cur().text))
-            fail(fn.pos.line, fn.pos.col, "functions start with 'fn', like: fn add(int a, int b) -> int { ... }");
-        expect(Tok::Fn, "'fn', 'struct', 'import' or 'link' (every function starts with fn)");
-
-        fn.namePos = pos();
-        fn.name = expect(Tok::Ident, "a function name").text;
-        if (accept(Tok::Dot)) {  // fn Point.move(...): a method
-            fn.recv = fn.name;
-            fn.recvPos = fn.namePos;
-            fn.namePos = pos();
-            fn.name = expect(Tok::Ident, "a method name (fn Point.name(...))").text;
-        }
-        expect(Tok::LParen);
-        parenDepth++;
-        if (!at(Tok::RParen)) {
-            do {
-                Param p;
-                p.pos = pos();
-                p.type = type();
-                p.namePos = pos();
-                p.name = expect(Tok::Ident, "a parameter name").text;
-                fn.params.push_back(p);
-            } while (accept(Tok::Comma));
-        }
-        parenDepth--;
-        expect(Tok::RParen);
-        fn.ret = Type(Type::Void);
-        if (accept(Tok::Arrow)) {
-            if (!at(Tok::Not)) fn.ret = type();
-            fn.fallible = accept(Tok::Not);  // -> int!  or  -> !
-            if (!fn.fallible && fn.ret.kind == Type::Void) unexpected("(after '->' comes a type, or ! for a function that can fail)");
-        }
-        fn.body = block();
-        return fn;
-    }
-
-    // ---------- statements ----------
-
-    BlockPtr block() {
-        auto b = std::make_unique<BlockStmt>(pos());
-        expect(Tok::LBrace);
-        int saved = parenDepth;
-        parenDepth = 0;
-        while (!at(Tok::RBrace)) {
-            if (at(Tok::End)) fail(b->pos.line, b->pos.col, "this '{' is never closed (missing '}')");
-            b->body.push_back(statement());
-            endOfStatement();
-        }
-        parenDepth = saved;
-        b->end = pos();
-        next();
-        return b;
-    }
-
-    void endOfStatement() {
-        if (at(Tok::RBrace) || at(Tok::End) || cur().newlineBefore) return;
-        unexpected("(put each statement on its own line)");
-    }
-
-    StmtPtr statement() {
-        Pos p = pos();
-        switch (cur().kind) {
-        case Tok::If: return ifStmt();
-        case Tok::While: {
-            next();
-            auto s = std::make_unique<WhileStmt>(p);
-            s->cond = expr();
-            s->body = block();
-            return s;
-        }
-        case Tok::For: {
-            next();
-            Pos varPos = pos();
-            std::string var = expect(Tok::Ident, "a loop variable name").text;
-            std::string var2;
-            Pos var2Pos;
-            if (accept(Tok::Comma)) {  // for i, x in list  /  for key, value in map
-                var2Pos = pos();
-                var2 = expect(Tok::Ident, "a second loop variable name").text;
-            }
-            expect(Tok::In);
-            ExprPtr first = expr();
-            if (!var2.empty() && at(Tok::DotDot)) fail(var2Pos.line, var2Pos.col, "a range (for i in 0..n) has one loop variable");
-            if (accept(Tok::DotDot)) {  // for i in 0..10
-                auto s = std::make_unique<ForStmt>(p);
-                s->var = var;
-                s->varPos = varPos;
-                s->from = std::move(first);
-                s->to = expr();
-                s->body = block();
-                return s;
-            }
-            auto s = std::make_unique<ForEachStmt>(p);  // for x in list
-            s->var = var;
-            s->varPos = varPos;
-            s->var2 = var2;
-            s->var2Pos = var2Pos;
-            s->list = std::move(first);
-            s->body = block();
-            return s;
-        }
-        case Tok::Return: {
-            next();
-            auto s = std::make_unique<ReturnStmt>(p);
-            if (!at(Tok::RBrace) && !cur().newlineBefore) s->value = expr();
-            return s;
-        }
-        case Tok::Break: next(); return std::make_unique<BreakStmt>(p);
-        case Tok::Continue: next(); return std::make_unique<ContinueStmt>(p);
-        case Tok::Defer: {
-            next();
-            if (at(Tok::Defer)) fail(p.line, p.col, "defer inside defer is not allowed");
-            return std::make_unique<DeferStmt>(p, statement());
-        }
-        case Tok::LBrace: return block();
-        case Tok::Fn: fail(p.line, p.col, "functions can't be inside other functions (move it out)");
-        case Tok::Struct: fail(p.line, p.col, "structs go outside functions, at the top level of the file");
-        case Tok::Import:
-        case Tok::Link: fail(p.line, p.col, "import and link go at the top of the file, outside functions");
-        default: break;
-        }
-
-        // int x = 5, Point p, []int a
-        if (atDeclaration()) {
-            auto s = std::make_unique<VarDeclStmt>(p);
-            s->hasType = true;
-            s->type = type();
-            s->namePos = pos();
-            s->name = expect(Tok::Ident, "a variable name").text;
-            if (accept(Tok::Assign)) s->init = expr();
-            return s;
-        }
-
-        // x := 5
-        if (at(Tok::Ident) && peekTok().kind == Tok::Declare) {
-            auto s = std::make_unique<VarDeclStmt>(p);
-            s->hasType = false;
-            s->namePos = pos();
-            s->name = next().text;
-            next();
-            s->init = expr();
-            return s;
-        }
-
-        ExprPtr e = expr();
-
-        // x = 5, p.value += 1, a[i] = 2, ...
-        char op = 0;
-        switch (cur().kind) {
-        case Tok::Assign: op = '='; break;
-        case Tok::PlusEq: op = '+'; break;
-        case Tok::MinusEq: op = '-'; break;
-        case Tok::StarEq: op = '*'; break;
-        case Tok::SlashEq: op = '/'; break;
-        case Tok::PercentEq: op = '%'; break;
-        case Tok::Declare:
-            fail(cur().line, cur().col, "':=' creates a new variable, so the left side must be a plain name");
-        default: break;
-        }
-        if (op && sameLine()) {
-            if (e->kind != ExprKind::Var && e->kind != ExprKind::Member && e->kind != ExprKind::Index)
-                fail(p.line, p.col, "only a variable, a field, an element or p.value can be assigned to");
-            auto s = std::make_unique<AssignStmt>(p);
-            s->target = std::move(e);
-            s->op = op;
-            next();
-            s->value = expr();
-            return s;
-        }
-
-        if (e->kind != ExprKind::Call && e->kind != ExprKind::Method && e->kind != ExprKind::Try && e->kind != ExprKind::OrElse)
-            fail(p.line, p.col, "this value is computed but never used");
-        return std::make_unique<ExprStmt>(p, std::move(e));
-    }
-
-    StmtPtr ifStmt() {
-        auto s = std::make_unique<IfStmt>(pos());
-        expect(Tok::If);
-        s->cond = expr();
-        s->then = block();
-        if (accept(Tok::Else)) {
-            if (at(Tok::If)) s->otherwise = ifStmt();
-            else s->otherwise = block();
-        }
-        return s;
-    }
-
-    // ---------- expressions (lowest to highest precedence) ----------
-
-    // f(x) or fallback  /  f(x) or { ... }: the lowest precedence, right to left
-    ExprPtr expr() {
-        ExprPtr l = orExpr();
-        if (!sameLine() || !at(Tok::OrElse)) return l;
-        Pos p = pos();
-        next();
-        auto e = std::make_unique<OrElseExpr>(p, std::move(l));
-        if (at(Tok::LBrace)) e->block = block();
-        else e->fallback = expr();
-        return e;
-    }
-
-    ExprPtr orExpr() {
-        ExprPtr l = andExpr();
-        while (sameLine() && at(Tok::Or)) {
-            Pos p = pos();
-            next();
-            l = std::make_unique<BinaryExpr>(p, BinOp::Or, std::move(l), andExpr());
-        }
-        return l;
-    }
-
-    ExprPtr andExpr() {
-        ExprPtr l = compare();
-        while (sameLine() && at(Tok::And)) {
-            Pos p = pos();
-            next();
-            l = std::make_unique<BinaryExpr>(p, BinOp::And, std::move(l), compare());
-        }
-        return l;
-    }
-
-    ExprPtr compare() {
-        ExprPtr l = additive();
-        while (sameLine()) {
-            BinOp op;
-            switch (cur().kind) {
-            case Tok::Eq: op = BinOp::Eq; break;
-            case Tok::NotEq: op = BinOp::NotEq; break;
-            case Tok::Less: op = BinOp::Less; break;
-            case Tok::LessEq: op = BinOp::LessEq; break;
-            case Tok::Greater: op = BinOp::Greater; break;
-            case Tok::GreaterEq: op = BinOp::GreaterEq; break;
-            default: return l;
-            }
-            Pos p = pos();
-            next();
-            l = std::make_unique<BinaryExpr>(p, op, std::move(l), additive());
-        }
-        return l;
-    }
-
-    // Precedence is Go's, not C's: bit operators bind tighter than comparisons,
-    // so `x & 1 == 0` means `(x & 1) == 0`.
-    ExprPtr additive() {  // + - | ^
-        ExprPtr l = multiplicative();
-        while (sameLine()) {
-            BinOp op;
-            switch (cur().kind) {
-            case Tok::Plus: op = BinOp::Add; break;
-            case Tok::Minus: op = BinOp::Sub; break;
-            case Tok::Pipe: op = BinOp::BitOr; break;
-            case Tok::Caret: op = BinOp::BitXor; break;
-            default: return l;
-            }
-            Pos p = pos();
-            next();
-            l = std::make_unique<BinaryExpr>(p, op, std::move(l), multiplicative());
-        }
-        return l;
-    }
-
-    ExprPtr multiplicative() {  // * / % << >> &
-        ExprPtr l = unary();
-        while (sameLine()) {
-            BinOp op;
-            switch (cur().kind) {
-            case Tok::Star: op = BinOp::Mul; break;
-            case Tok::Slash: op = BinOp::Div; break;
-            case Tok::Percent: op = BinOp::Mod; break;
-            case Tok::Shl: op = BinOp::Shl; break;
-            case Tok::Shr: op = BinOp::Shr; break;
-            case Tok::Amp: op = BinOp::BitAnd; break;
-            default: return l;
-            }
-            Pos p = pos();
-            next();
-            l = std::make_unique<BinaryExpr>(p, op, std::move(l), unary());
-        }
-        return l;
-    }
-
-    ExprPtr unary() {
-        Pos p = pos();
-        if (accept(Tok::Minus)) return std::make_unique<UnaryExpr>(p, '-', unary());
-        if (accept(Tok::Not)) return std::make_unique<UnaryExpr>(p, '!', unary());
-        if (accept(Tok::Tilde)) return std::make_unique<UnaryExpr>(p, '~', unary());
-        if (accept(Tok::Try)) return std::make_unique<TryExpr>(p, postfix());
-        return postfix();
-    }
-
-    // p.value, a.len, a[i], a.push(x), math.sqrt(2)
-    ExprPtr postfix() {
-        ExprPtr e = primary();
-        while (sameLine()) {
-            Pos p = pos();
-            if (accept(Tok::Dot)) {
-                std::string name = expect(Tok::Ident, "a name after '.'").text;
-                if (at(Tok::LParen) && !cur().newlineBefore) {
-                    auto m = std::make_unique<MethodExpr>(p, std::move(e), name);
-                    args(m->args, m->argNames);
-                    e = std::move(m);
-                } else {
-                    e = std::make_unique<MemberExpr>(p, std::move(e), name);
-                }
-            } else if (at(Tok::LBracket)) {
-                next();
-                parenDepth++;
-                ExprPtr index = expr();
-                parenDepth--;
-                expect(Tok::RBracket);
-                e = std::make_unique<IndexExpr>(p, std::move(e), std::move(index));
-            } else {
-                return e;
-            }
-        }
-        return e;
-    }
-
-    // ( arg, name: arg, ... ) -- we are at the '('
-    void args(std::vector<ExprPtr> &out, std::vector<std::string> &names) {
-        expect(Tok::LParen);
-        parenDepth++;
-        if (!at(Tok::RParen)) {
-            do {
-                if (at(Tok::RParen)) break;  // a trailing comma is fine
-                std::string name;
-                if (at(Tok::Ident) && peekTok().kind == Tok::Colon) {
-                    name = next().text;
-                    next();
-                }
-                names.push_back(name);
-                out.push_back(expr());
-            } while (accept(Tok::Comma));
-        }
-        parenDepth--;
-        expect(Tok::RParen);
-    }
-
-    ExprPtr primary() {
-        Pos p = pos();
-        const Token &t = cur();
-        switch (t.kind) {
-        case Tok::Int: {
-            next();
-            errno = 0;
-            unsigned long long v = std::strtoull(t.text.c_str(), nullptr, t.text.size() > 1 && (t.text[1] == 'x' || t.text[1] == 'X') ? 16 : 10);
-            if (errno == ERANGE || v > (unsigned long long)LLONG_MAX)
-                fail(p.line, p.col, "number is too big for int");
-            return std::make_unique<IntExpr>(p, (long long)v);
-        }
-        case Tok::Float: next(); return std::make_unique<FloatExpr>(p, std::strtod(t.text.c_str(), nullptr));
-        case Tok::True: next(); return std::make_unique<BoolExpr>(p, true);
-        case Tok::False: next(); return std::make_unique<BoolExpr>(p, false);
-        case Tok::Null: next(); return std::make_unique<NullExpr>(p);
-        case Tok::Char: next(); return std::make_unique<CharExpr>(p, t.text[0]);
-        case Tok::String: next(); return std::make_unique<StrExpr>(p, t.text);
-        case Tok::LParen: {
-            next();
-            parenDepth++;
-            ExprPtr e = expr();
-            parenDepth--;
-            expect(Tok::RParen);
-            return e;
-        }
-        case Tok::LBracket: {  // [1, 2, 3]  or a map: ["a": 1, "b": 2], [:]
-            next();
-            parenDepth++;
-            if (accept(Tok::Colon)) {
-                parenDepth--;
-                expect(Tok::RBracket, "']' (an empty map is [:])");
-                return std::make_unique<MapLitExpr>(p);
-            }
-            if (!at(Tok::RBracket)) {
-                ExprPtr first = expr();
-                if (accept(Tok::Colon)) {
-                    auto m = std::make_unique<MapLitExpr>(p);
-                    m->keys.push_back(std::move(first));
-                    m->values.push_back(expr());
-                    while (accept(Tok::Comma) && !at(Tok::RBracket)) {  // a trailing comma is fine
-                        m->keys.push_back(expr());
-                        expect(Tok::Colon, "':' (every map entry is key: value)");
-                        m->values.push_back(expr());
-                    }
-                    parenDepth--;
-                    expect(Tok::RBracket);
-                    return m;
-                }
-                auto a = std::make_unique<ArrayLitExpr>(p);
-                a->elems.push_back(std::move(first));
-                while (accept(Tok::Comma) && !at(Tok::RBracket)) a->elems.push_back(expr());
-                parenDepth--;
-                expect(Tok::RBracket);
-                return a;
-            }
-            auto a = std::make_unique<ArrayLitExpr>(p);
-            parenDepth--;
-            expect(Tok::RBracket);
-            return a;
-        }
-        case Tok::Ident: {
-            next();
-            if (at(Tok::LParen) && !cur().newlineBefore) {
-                auto call = std::make_unique<CallExpr>(p, t.text);
-                args(call->args, call->argNames);
-                return call;
-            }
-            if (isTypeName(t.text))
-                fail(p.line, p.col, "a type name alone is not a value (did you mean " + t.text + "(...)?)");
-            return std::make_unique<VarExpr>(p, t.text);
-        }
-        default: unexpected("(expected a value)");
-        }
-    }
-};
-
-}  // namespace
-
-Program parse(const std::vector<Token> &tokens, int file) {
-    return Parser(tokens, file).program();
-}

src/parser.fch

@@ -125,10 +125,80 @@ fn parseType(ptr[Parser] p) -> ast.Type {
         t.module = name
         t.name = next(p).text
     }
+    // Stack[int], Pair[str, int]: the type arguments of a generic struct
+    if at(p, "[") && !cur(p).nl && peekKind(p, 1) != "]" {
+        next(p)
+        while true {
+            t.elem.push(parseType(p))
+            if !accept(p, ",") {
+                break
+            }
+        }
+        expect(p, "]", "']' after the type arguments")
+    }
     return t
 }
 
+// Stack[int] name: a generic type, then a name on the same line. (a[i] by itself is an index.)
+fn genericDeclAhead(ptr[Parser] p) -> bool {
+    if !at(p, "ident") || peekKind(p, 1) != "[" || peekKind(p, 2) == "]" {
+        return false
+    }
+    depth := 0
+    i := p.i + 1
+    while i < p.toks.len {
+        k := p.toks[i].kind
+        if k == "[" {
+            depth += 1
+        } else if k == "]" {
+            depth -= 1
+            if depth == 0 {
+                return i + 1 < p.toks.len && p.toks[i + 1].kind == "ident" && !p.toks[i + 1].nl
+            }
+        } else if k == "eof" || p.toks[i].nl && depth == 0 {
+            return false
+        }
+        i += 1
+    }
+    return false
+}
+
+// The same, when the name was just taken and the parser stands on the `[`.
+fn genericCallAheadFrom(ptr[Parser] p) -> bool {
+    p.i -= 1
+    r := genericCallAhead(p)
+    p.i += 1
+    return r
+}
+
+// Is the `[` after this name followed, once it closes, by `(`? Then it is  max[int](...)  and not an index.
+fn genericCallAhead(ptr[Parser] p) -> bool {
+    if peekKind(p, 1) != "[" || p.toks[p.i + 1].nl || peekKind(p, 2) == "]" {
+        return false
+    }
+    depth := 0
+    i := p.i + 1
+    while i < p.toks.len {
+        k := p.toks[i].kind
+        if k == "[" {
+            depth += 1
+        } else if k == "]" {
+            depth -= 1
+            if depth == 0 {
+                return i + 1 < p.toks.len && p.toks[i + 1].kind == "(" && !p.toks[i + 1].nl
+            }
+        } else if k == "eof" || p.toks[i].nl {
+            return false
+        }
+        i += 1
+    }
+    return false
+}
+
 fn atDeclaration(ptr[Parser] p) -> bool {
+    if genericDeclAhead(p) {
+        return true
+    }
     if at(p, "[") {
         return peekKind(p, 1) == "]"
     }
@@ -159,12 +229,31 @@ fn parseProgram(ptr[Parser] p) -> ast.Program {
     while !at(p, "eof") {
         if at(p, "import") {
             t := next(p)
-            if !at(p, "ident") {
-                fail(p, t, "the self-hosted compiler only imports Finch modules (import name)")
+            if at(p, "string") {
+                prog.cwhere.push(p.path + ":" + str(t.line) + ":" + str(t.col))
+                prog.cimports.push(next(p).text)
+            } else {
+                if !at(p, "ident") {
+                    fail(p, t, "expected a module name or a C header after 'import'")
+                }
+                prog.imports.push(next(p).text)
             }
-            prog.imports.push(next(p).text)
+        } else if at(p, "link") {
+            lt := next(p)
+            lib := expect(p, "string", "a library name in quotes, like link \"glfw\"").text
+            ownCode := lib.ends_with(".c") || lib.ends_with(".o") || lib.ends_with(".a")      // your own C code, next to the .fch file
+            if !ownCode && (lib.starts_with("lib") || lib.contains(".so") || lib.contains("/")) {
+                fail(p, lt, "write just the library's name: for libglfw.so that's  link \"glfw\"")
+            }
+            prog.links.push(lib)
         } else if at(p, "struct") {
             prog.structs.push(parseStruct(p))
+        } else if at(p, "enum") {
+            e := parseEnum(p)
+            prog.enums.push(e)
+            if e.flag {
+                prog.structs.push(sumStruct(e))       // an enum with values inside is stored as a struct (see sumStruct)
+            }
         } else {
             prog.fns.push(parseFn(p))
         }
@@ -172,10 +261,151 @@ fn parseProgram(ptr[Parser] p) -> ast.Program {
     return prog
 }
 
+// enum Color { Red, Green, Blue }      enum Status { Ok = 200, NotFound = 404 }
+// The variants are numbered from 0 (or from the last number given) and are written Color.Red.
+// A variant can hold values:  enum Shape { Circle(float), Rect(float, float), Point }  (e.flag is then true).
+fn parseEnum(ptr[Parser] p) -> ast.Node {
+    e := node(p, "enum")
+    expect(p, "enum", "'enum'")
+    e.name = expect(p, "ident", "an enum name").text
+    expect(p, "{", "'{'")
+    while !at(p, "}") {
+        if at(p, "eof") {
+            fail(p, cur(p), "an enum is never closed (missing '}')")
+        }
+        v := node(p, "variant")
+        v.name = expect(p, "ident", "a variant name, like Red").text
+        if accept(p, "(") {
+            e.flag = true
+            while !at(p, ")") {
+                f := node(p, "field")
+                f.ty = parseType(p)
+                v.kids.push(f)
+                if !accept(p, ",") {
+                    break
+                }
+            }
+            expect(p, ")", "')' after the values of the variant")
+            if v.kids.len == 0 {
+                fail(p, cur(p), "the variant " + v.name + " has empty () : write just " + v.name + " if it holds nothing")
+            }
+        }
+        if accept(p, "=") {
+            if e.flag {
+                fail(p, cur(p), "a variant can't have both values inside and a number")
+            }
+            sign := ""
+            if accept(p, "-") {
+                sign = "-"
+            }
+            v.text = sign + expect(p, "int", "a whole number, like  Ok = 200").text
+        }
+        e.kids.push(v)
+        if !accept(p, ",") {
+            endOfStatement(p)
+        }
+    }
+    next(p)
+    if e.kids.len == 0 {
+        fail(p, cur(p), "the enum " + e.name + " has no variants")
+    }
+    if e.flag {
+        for v in e.kids {
+            if v.text.len > 0 {
+                fail(p, cur(p), "an enum whose variants hold values can't number them (" + v.name + " = " + v.text + ")")
+            }
+        }
+    }
+    return e
+}
+
+// An enum whose variants hold values is a struct underneath: a `tag` (which variant it is) and, one after the other,
+// the values of every variant (Rect's are Rect_0, Rect_1). Only the tag's variant has values; the rest stay
+// empty. It's simple and it makes copying, dropping and methods the struct's own.
+fn sumStruct(ast.Node e) -> ast.Node {
+    s := ast.Node(kind: "struct", name: e.name, line: e.line, col: e.col, file: e.file)
+    tag := ast.Node(kind: "field", name: "tag", line: e.line, col: e.col, file: e.file)
+    tag.ty = ast.simple("int")
+    s.kids.push(tag)
+    for v in e.kids {
+        for j in 0..v.kids.len {
+            f := ast.Node(kind: "field", name: v.name + "_" + str(j), line: v.line, col: v.col, file: v.file)
+            f.ty = v.kids[j].ty
+            s.kids.push(f)
+        }
+    }
+    return s
+}
+
+// match value {  A, B -> ...   C -> ...   else -> ... }
+// As a statement the arms are statements or { blocks }; as an expression they are expressions.
+fn parseMatch(ptr[Parser] p, bool asExpr) -> ast.Node {
+    m := node(p, "match")
+    m.flag = asExpr
+    expect(p, "match", "'match'")
+    m.kids.push(parseExpr(p))
+    expect(p, "{", "'{'")
+    saved := p.depth
+    p.depth = 0
+    while !at(p, "}") {
+        if at(p, "eof") {
+            fail(p, cur(p), "a match is never closed (missing '}')")
+        }
+        arm := node(p, "arm")
+        pats := node(p, "patterns")
+        if accept(p, "else") {
+            arm.flag = true
+        } else {
+            while true {
+                pats.kids.push(parseExpr(p))
+                if !accept(p, ",") {
+                    break
+                }
+            }
+        }
+        arm.kids.push(pats)
+        expect(p, "->", "'->' after the value to match, like   Red -> print(\"red\")")
+        if at(p, "{") && !asExpr {
+            arm.kids.push(parseBlock(p))
+        } else if asExpr {
+            arm.kids.push(parseExpr(p))
+        } else {
+            arm.kids.push(parseStatement(p))
+        }
+        m.kids.push(arm)
+        if !accept(p, ",") {
+            endOfStatement(p)
+        }
+    }
+    p.depth = saved
+    next(p)
+    if m.kids.len == 1 {
+        fail(p, cur(p), "a match needs at least one arm")
+    }
+    return m
+}
+
+// [T, U]
+fn parseTParams(ptr[Parser] p) -> []str {
+    []str names
+    expect(p, "[", "'['")
+    while true {
+        names.push(expect(p, "ident", "a type parameter name, like T").text)
+        if !accept(p, ",") {
+            break
+        }
+    }
+    expect(p, "]", "']' after the type parameters")
+    return names
+}
+
 fn parseStruct(ptr[Parser] p) -> ast.Node {
     s := node(p, "struct")
     expect(p, "struct", "'struct'")
     s.name = expect(p, "ident", "a struct name").text
+    if at(p, "[") {
+        s.tparams = parseTParams(p)
+    }
     expect(p, "{", "'{'")
     while !at(p, "}") {
         if at(p, "eof") {
@@ -199,8 +429,15 @@ fn parseStruct(ptr[Parser] p) -> ast.Node {
 
 fn parseFn(ptr[Parser] p) -> ast.Node {
     f := node(p, "fn")
+    f.exported = accept(p, "export")
+    if at(p, "ident") && isTypeName(cur(p).text) {
+        fail(p, cur(p), "functions start with 'fn', like: fn add(int a, int b) -> int { ... }")
+    }
     expect(p, "fn", "'fn', 'struct' or 'import'")
     f.name = expect(p, "ident", "a function name").text
+    if at(p, "[") {
+        f.tparams = parseTParams(p)         // fn max[T](...)   or the struct's, in  fn Stack[T].push(...)
+    }
     if accept(p, ".") {
         f.recv = f.name
         f.name = expect(p, "ident", "a method name").text
@@ -231,6 +468,7 @@ fn parseFn(ptr[Parser] p) -> ast.Node {
         }
     }
     f.kids.push(parseBlock(p))
+    f.endLine = f.kids[f.kids.len - 1].endLine
     return f
 }
 
@@ -249,6 +487,7 @@ fn parseBlock(ptr[Parser] p) -> ast.Node {
         endOfStatement(p)
     }
     p.depth = saved
+    blk.endLine = cur(p).line
     next(p)
     return blk
 }
@@ -285,6 +524,9 @@ fn parseStatement(ptr[Parser] p) -> ast.Node {
         s.kids.push(parseBlock(p))
         return s
     }
+    if k == "match" {
+        return parseMatch(p, false)
+    }
     if k == "return" {
         s := node(p, "return")
         next(p)
@@ -524,6 +766,9 @@ fn parsePrimary(ptr[Parser] p) -> ast.Node {
         expect(p, ")", "')'")
         return inner
     }
+    if k == "match" {
+        return parseMatch(p, true)
+    }
     if k == "[" {
         next(p)
         e.kind = "array"
@@ -552,6 +797,21 @@ fn parsePrimary(ptr[Parser] p) -> ast.Node {
     if k == "ident" {
         next(p)
         e.name = t.text
+        if at(p, "[") && p.toks[p.i - 1].kind == "ident" && genericCallAheadFrom(p) {
+            // max[int](3, 4), Stack[int]()
+            next(p)
+            e.ty = ast.Type(kind: "targs")
+            while true {
+                e.ty.elem.push(parseType(p))
+                if !accept(p, ",") {
+                    break
+                }
+            }
+            expect(p, "]", "']' after the type arguments")
+            e.kind = "call"
+            parseArgs(p, addr(e))
+            return e
+        }
         if at(p, "(") && !cur(p).nl {
             e.kind = "call"
             parseArgs(p, addr(e))

src/parser.h

@@ -1,7 +0,0 @@
-#pragma once
-
-#include "ast.h"
-#include "lexer.h"
-
-// Parses one file's tokens; `file` is its index in g_files.
-Program parse(const std::vector<Token> &tokens, int file);

src/platform.fch

@@ -0,0 +1,97 @@
+// The system a program is built for, and what depends on it: the C compiler that links, the file
+// name of the program, how it is run here, and (through the flags) the C calling convention.
+// The same as src/target.cpp.
+import host
+import "stdlib.h"
+
+struct Target {
+    str triple          // "" = the system the compiler runs on
+    bool windows        // Microsoft x64 calling convention, .exe
+    bool msvc
+    bool darwin         // macOS
+    bool arm64          // AAPCS64
+    bool cross          // another system than the one the compiler runs on
+    str exe             // ".exe" or ""
+    str cc              // the C compiler that links (the IR is always compiled by clang)
+    str runner          // how to run a program for it here: "", "wine ", "qemu-aarch64 "
+}
+
+fn firstLine(str text) -> str {
+    parts := text.trim().split("\n")
+    return parts[0].trim()
+}
+
+// what clang calls the system it runs on, like x86_64-pc-linux-gnu
+fn hostTriple() -> str {
+    tmp := host.tempDir() + "/finch_triple_" + str(host.pid()) + ".txt"
+    host.run("clang -dumpmachine > " + host.quote(tmp) + " 2> " + host.nullDevice())
+    out := read_file(tmp) or ""
+    host.remove(tmp)
+    if out.trim().len == 0 {
+        return "x86_64-unknown-linux-gnu"
+    }
+    return firstLine(out)
+}
+
+// "windows", "linux", "macos", "arm64" (ARM64 Linux), or a full LLVM triple; "" = this system
+fn select(str name) -> Target {
+    hostName := hostTriple()
+    t := name
+    if name.len == 0 {
+        t = hostName
+    } else if name == "windows" {
+        t = "x86_64-w64-mingw32"
+    } else if name == "linux" {
+        t = "x86_64-unknown-linux-gnu"
+    } else if name == "arm64" || name == "aarch64" || name == "linux-arm64" {
+        t = "aarch64-unknown-linux-gnu"
+    } else if name == "macos" {
+        if hostName.starts_with("aarch64") || hostName.starts_with("arm64") {
+            t = "arm64-apple-macosx14.0.0"
+        } else {
+            t = "x86_64-apple-macosx14.0.0"
+        }
+    }
+    if t == "x86_64-w64-windows-gnu" {
+        t = "x86_64-w64-mingw32"        // what clang calls the same system when it runs on Windows
+    }
+    tg := Target(triple: t)
+    tg.windows = t.contains("windows") || t.contains("mingw") || t.contains("msvc") || t.contains("win32")
+    tg.msvc = t.contains("msvc")
+    tg.darwin = t.contains("apple") || t.contains("darwin") || t.contains("macos")
+    tg.arm64 = t.starts_with("aarch64") || t.starts_with("arm64")
+    hostArm := hostName.starts_with("aarch64") || hostName.starts_with("arm64")
+    hostDarwin := hostName.contains("apple") || hostName.contains("darwin")
+    hostWin := hostName.contains("windows") || hostName.contains("mingw") || hostName.contains("msvc")
+    tg.cross = tg.windows != hostWin || tg.darwin != hostDarwin || tg.arm64 != hostArm
+    tg.exe = ""
+    if tg.windows {
+        tg.exe = ".exe"
+    }
+    // FINCH_CC chooses the C compiler for any target
+    fc := getenv("FINCH_CC")
+    if fc.len > 0 {
+        tg.cc = fc
+    } else if tg.cross && tg.windows {
+        tg.cc = "x86_64-w64-mingw32-gcc"
+    } else if tg.cross && tg.arm64 && !tg.darwin {
+        tg.cc = "aarch64-linux-gnu-gcc"
+    } else if tg.cross {
+        tg.cc = "clang --target=" + t
+    } else if host.pathSeparator() == ";" {
+        tg.cc = "clang"             // Windows has no cc
+    } else {
+        tg.cc = "cc"
+    }
+    if tg.cross && tg.windows {
+        tg.runner = "wine "
+    } else if tg.cross && tg.arm64 && !tg.darwin {
+        tg.runner = "qemu-aarch64 "
+    }
+    return tg
+}
+
+// C's plain `char`: signed on x86 and Apple, not on ARM64 Linux
+fn charIsSigned(Target t) -> bool {
+    return !t.arm64 || t.darwin || t.windows
+}

src/target.cpp

@@ -1,158 +0,0 @@
-#include "target.h"
-
-#include <llvm/Support/TargetSelect.h>
-#include <llvm/TargetParser/Host.h>
-
-#include <cstdio>
-#include <cstdlib>
-#include <cstring>
-
-#ifdef _WIN32
-#define popen _popen
-#define pclose _pclose
-#else
-#include <sys/wait.h>
-#endif
-
-static bool hostIsWindows() {
-#ifdef _WIN32
-    return true;
-#else
-    return false;
-#endif
-}
-
-// The Finch-generated code needs these LLVM backends (the same C functions LLVM's own tools call).
-extern "C" {
-#ifdef FINCH_TARGET_X86
-void LLVMInitializeX86TargetInfo();
-void LLVMInitializeX86Target();
-void LLVMInitializeX86TargetMC();
-void LLVMInitializeX86AsmPrinter();
-#endif
-#ifdef FINCH_TARGET_AARCH64
-void LLVMInitializeAArch64TargetInfo();
-void LLVMInitializeAArch64Target();
-void LLVMInitializeAArch64TargetMC();
-void LLVMInitializeAArch64AsmPrinter();
-#endif
-}
-
-void initTargets() {
-#ifdef FINCH_TARGET_X86
-    LLVMInitializeX86TargetInfo();
-    LLVMInitializeX86Target();
-    LLVMInitializeX86TargetMC();
-    LLVMInitializeX86AsmPrinter();
-#endif
-#ifdef FINCH_TARGET_AARCH64
-    LLVMInitializeAArch64TargetInfo();
-    LLVMInitializeAArch64Target();
-    LLVMInitializeAArch64TargetMC();
-    LLVMInitializeAArch64AsmPrinter();
-#endif
-    llvm::InitializeNativeTarget();
-    llvm::InitializeNativeTargetAsmPrinter();
-}
-
-void setTarget(const std::string &name) {
-    std::string host = llvm::sys::getDefaultTargetTriple();
-    llvm::Triple hostTriple(llvm::Triple::normalize(host));
-    std::string t = name;
-    if (name.empty()) t = host;
-    else if (name == "windows") t = hostIsWindows() ? host : "x86_64-w64-mingw32";
-    else if (name == "linux") t = "x86_64-unknown-linux-gnu";
-    else if (name == "arm64" || name == "aarch64" || name == "linux-arm64") t = "aarch64-unknown-linux-gnu";
-    else if (name == "macos") t = hostTriple.isAArch64() ? "arm64-apple-macosx14.0.0" : "x86_64-apple-macosx14.0.0";
-    g_target.triple = llvm::Triple(llvm::Triple::normalize(t));
-    g_target.windows = g_target.triple.isOSWindows();
-    g_target.msvc = g_target.triple.isWindowsMSVCEnvironment();
-    g_target.darwin = g_target.triple.isOSDarwin();
-    g_target.cross = hostTriple.getOS() != g_target.triple.getOS() || hostTriple.getArch() != g_target.triple.getArch();
-    g_target.exe = g_target.windows ? ".exe" : "";
-
-    // FINCH_CC chooses the C compiler for any target; CC only when not cross-compiling.
-    if (const char *fc = std::getenv("FINCH_CC")) g_target.cc = fc;
-    else if (!g_target.cross && std::getenv("CC")) g_target.cc = std::getenv("CC");
-    else if (g_target.cross && g_target.windows) g_target.cc = "x86_64-w64-mingw32-gcc";
-    else if (g_target.cross && g_target.triple.isAArch64() && g_target.triple.isOSLinux()) g_target.cc = "aarch64-linux-gnu-gcc";
-    else if (g_target.cross) g_target.cc = "clang --target=" + g_target.triple.str();
-    else if (hostIsWindows()) g_target.cc = "clang";
-    else g_target.cc = "cc";
-}
-
-std::string runPrefix() {
-    if (!g_target.cross) return "";
-    if (g_target.windows && !hostIsWindows()) return "wine ";
-    if (g_target.triple.isAArch64() && g_target.triple.isOSLinux()) return "qemu-aarch64 ";
-    return "";
-}
-
-std::string shellQuote(const std::string &s) {
-#ifdef _WIN32
-    // cmd.exe: double quotes; a " inside a file name is impossible on Windows
-    return "\"" + s + "\"";
-#else
-    std::string out = "'";
-    for (char ch : s) out += ch == '\'' ? std::string("'\\''") : std::string(1, ch);
-    return out + "'";
-#endif
-}
-
-static int exitStatus(int status) {
-#ifdef _WIN32
-    return status;
-#else
-    if (status == -1) return -1;
-    if (WIFEXITED(status)) return WEXITSTATUS(status);
-    if (WIFSIGNALED(status)) return 128 + WTERMSIG(status);
-    return -1;
-#endif
-}
-
-int capture(const std::string &cmd, std::string &output) {
-    FILE *p = popen((cmd + " 2>&1").c_str(), "r");
-    if (!p) return -1;
-    char buf[4096];
-    size_t n;
-    while ((n = std::fread(buf, 1, sizeof buf, p)) > 0) output.append(buf, n);
-    return exitStatus(pclose(p));
-}
-
-int runCommand(const std::string &cmd, std::string *crash) {
-    std::fflush(stdout);
-    int status = std::system(cmd.c_str());
-#ifndef _WIN32
-    if (crash && status != -1 && WIFSIGNALED(status)) *crash = strsignal(WTERMSIG(status));
-#else
-    // a crashed Windows program exits with an NTSTATUS code like 0xC0000005
-    if (crash && (unsigned)status >= 0xC0000000u) {
-        char buf[64];
-        std::snprintf(buf, sizeof buf, "exception 0x%08X%s", (unsigned)status,
-                      (unsigned)status == 0xC0000005u ? " (access violation)" : (unsigned)status == 0xC00000FDu ? " (stack overflow)" : "");
-        *crash = buf;
-    }
-#endif
-    return exitStatus(status);
-}
-
-const char *nullDevice() { return hostIsWindows() ? "NUL" : "/dev/null"; }
-
-std::string cacheDir() {
-#ifdef _WIN32
-    if (const char *l = std::getenv("LOCALAPPDATA")) return std::string(l) + "\\finch";
-    if (const char *t = std::getenv("TEMP")) return std::string(t) + "\\finch";
-    return "finch-cache";
-#else
-    if (const char *x = std::getenv("XDG_CACHE_HOME")) return std::string(x) + "/finch";
-    if (const char *h = std::getenv("HOME")) return std::string(h) + "/.cache/finch";
-    return "/tmp/finch-cache";
-#endif
-}
-
-char pathListSeparator() { return hostIsWindows() ? ';' : ':'; }
-
-std::string dirOf(const std::string &path) {
-    size_t slash = hostIsWindows() ? path.find_last_of("/\\") : path.find_last_of('/');
-    return slash == std::string::npos ? "." : path.substr(0, slash);
-}

src/target.h

@@ -1,49 +0,0 @@
-#pragma once
-// The system Finch compiles for, and everything that depends on it:
-// the C compiler used to link, how the shell quotes, file names, the C ABI.
-
-#include <llvm/TargetParser/Triple.h>
-
-#include <string>
-
-struct TargetInfo {
-    llvm::Triple triple;
-    bool darwin = false;    // macOS
-    bool windows = false;   // Windows (MSVC or MinGW): Microsoft x64 calling convention, .exe
-    bool msvc = false;      // the MSVC environment (link with clang + the Windows SDK)
-    bool cross = false;     // compiling for another system than the one we run on
-    std::string cc;         // the C compiler that links programs and builds the runtime
-    std::string exe;        // ".exe" or ""
-};
-
-inline TargetInfo g_target;
-
-// "windows", "linux", "macos", "arm64" (ARM64 Linux), or a full LLVM triple; "" = the system finch runs on
-void setTarget(const std::string &name);
-
-// Register the LLVM backends Finch can generate code for (x86-64, ARM64).
-void initTargets();
-
-// How to run a program built for g_target on this machine ("" = directly, "wine", "qemu-aarch64").
-std::string runPrefix();
-
-// Quote one argument for the shell that runs our commands (sh on Unix, cmd.exe on Windows).
-std::string shellQuote(const std::string &s);
-
-// Run a command; its exit status, and everything it printed in `output`.
-int capture(const std::string &cmd, std::string &output);
-
-// Run a command with its output going to the terminal; its exit status (128+n for a signal).
-int runCommand(const std::string &cmd, std::string *crash = nullptr);
-
-// The null device: /dev/null or NUL.
-const char *nullDevice();
-
-// The folder for cached files (~/.cache/finch, %LOCALAPPDATA%\finch).
-std::string cacheDir();
-
-// Separator of FINCH_PATH entries (':' or ';').
-char pathListSeparator();
-
-// The folder part of a path (both / and \ on Windows).
-std::string dirOf(const std::string &path);

std/finch_win.h

@@ -0,0 +1,6 @@
+/* The Windows functions std/time_windows.fch needs. Declared here, not by including <windows.h>:
+   libclang can't parse that header with MinGW's intrinsics. Both are in kernel32. */
+unsigned long long GetTickCount64(void);
+void Sleep(unsigned long milliseconds);
+int QueryPerformanceCounter(long long *count);
+int QueryPerformanceFrequency(long long *frequency);

std/json.fch

@@ -0,0 +1,518 @@
+// JSON: read it, build it, write it.
+//
+//   import json
+//
+//   doc := try json.parse("{\"name\": \"Finch\", \"tags\": [\"fast\", \"small\"], \"stars\": 5}")
+//   print(doc.get("name").str_or(""))             Finch
+//   print(doc.get("tags").at(1).str_or(""))       small
+//   print(doc.get("stars").int_or(0))             5
+//   print(doc.get("missing").is_null())           true       (a missing key is null, so chains never fail)
+//
+//   out := json.new_object()
+//   out.set("ok", json.new_bool(true))
+//   list := json.new_list()
+//   list.push(json.new_number(1.5))
+//   out.set("values", list)
+//   print(json.stringify(out))                    {"ok":true,"values":[1.5]}
+//   print(json.pretty(out))                       the same, over several lines
+
+enum Kind { Null, Bool, Number, Text, List, Object }
+
+// One JSON value. `kind` says which of the other fields it uses: flag for Bool, num for Number,
+// text for Text, items for List, and items with keys (the same length, in the same order) for Object.
+struct Json {
+    Kind kind
+    bool flag
+    float num
+    str text
+    []Json items
+    []str keys
+}
+
+fn new_null() -> Json {
+    return Json(kind: Kind.Null)
+}
+
+fn new_bool(bool b) -> Json {
+    return Json(kind: Kind.Bool, flag: b)
+}
+
+fn new_number(float n) -> Json {
+    return Json(kind: Kind.Number, num: n)
+}
+
+fn new_text(str s) -> Json {
+    return Json(kind: Kind.Text, text: s)
+}
+
+fn new_list() -> Json {
+    return Json(kind: Kind.List)
+}
+
+fn new_object() -> Json {
+    return Json(kind: Kind.Object)
+}
+
+// ---------- looking inside ----------
+
+fn Json.is_null() -> bool {
+    return self.kind == Kind.Null
+}
+
+// the number of elements of a list, of keys of an object, of bytes of a text; 0 for the rest
+fn Json.len() -> int {
+    return match self.kind {
+        List, Object -> self.items.len
+        Text -> self.text.len
+        else -> 0
+    }
+}
+
+fn Json.has(str key) -> bool {
+    return self.kind == Kind.Object && self.keys.contains(key)
+}
+
+// the value of a key of an object; null if there is none (or this is not an object)
+fn Json.get(str key) -> Json {
+    if self.kind != Kind.Object {
+        return new_null()
+    }
+    i := self.keys.find(key)
+    if i < 0 {
+        return new_null()
+    }
+    return self.items[i]
+}
+
+// the element of a list; null if there is none
+fn Json.at(int i) -> Json {
+    if self.kind != Kind.List || i < 0 || i >= self.items.len {
+        return new_null()
+    }
+    return self.items[i]
+}
+
+// the value if it is of that kind, else what was given
+fn Json.str_or(str fallback) -> str {
+    if self.kind == Kind.Text {
+        return self.text
+    }
+    return fallback
+}
+
+fn Json.float_or(float fallback) -> float {
+    if self.kind == Kind.Number {
+        return self.num
+    }
+    return fallback
+}
+
+fn Json.int_or(int fallback) -> int {
+    if self.kind == Kind.Number {
+        return int(self.num)
+    }
+    return fallback
+}
+
+fn Json.bool_or(bool fallback) -> bool {
+    if self.kind == Kind.Bool {
+        return self.flag
+    }
+    return fallback
+}
+
+// the keys of an object, in the order they were written
+fn Json.names() -> []str {
+    return self.keys
+}
+
+// ---------- building ----------
+
+// add to the end of a list
+fn Json.push(Json v) {
+    self.items.push(v)
+}
+
+// give a key a value in an object; a key that is already there is replaced
+fn Json.set(str key, Json v) {
+    i := self.keys.find(key)
+    if i >= 0 {
+        self.items[i] = v
+        return
+    }
+    self.keys.push(key)
+    self.items.push(v)
+}
+
+// ---------- writing ----------
+
+fn quote(str s) -> str {
+    []str parts = ["\""]
+    for c in s {
+        n := int(c)
+        if c == '"' {
+            parts.push("\\\"")
+        } else if c == '\\' {
+            parts.push("\\\\")
+        } else if c == '\n' {
+            parts.push("\\n")
+        } else if c == '\r' {
+            parts.push("\\r")
+        } else if c == '\t' {
+            parts.push("\\t")
+        } else if n < 32 {
+            parts.push("\\u00" + hexdigit(n / 16) + hexdigit(n % 16))
+        } else {
+            parts.push(str(c))
+        }
+    }
+    parts.push("\"")
+    return parts.join("")
+}
+
+fn hexdigit(int n) -> str {
+    digits := "0123456789abcdef"
+    return str(digits[n])
+}
+
+fn number_text(float n) -> str {
+    if n == float(int(n)) && n > -1000000000000000.0 && n < 1000000000000000.0 {
+        return str(int(n))
+    }
+    return str(n)
+}
+
+struct Writer {
+    []str out
+}
+
+fn write(Json j, str indent, str pad, ptr[Writer] w) {
+    nl := ""
+    inner := ""
+    sep := ","
+    colon := ":"
+    if indent.len > 0 {
+        nl = "\n"
+        inner = pad + indent
+        colon = ": "
+    }
+    match j.kind {
+        Null -> w.out.push("null")
+        Bool -> {
+            if j.flag {
+                w.out.push("true")
+            } else {
+                w.out.push("false")
+            }
+        }
+        Number -> w.out.push(number_text(j.num))
+        Text -> w.out.push(quote(j.text))
+        List -> {
+            if j.items.len == 0 {
+                w.out.push("[]")
+                return
+            }
+            w.out.push("[" + nl)
+            for i, item in j.items {
+                if i > 0 {
+                    w.out.push(sep + nl)
+                }
+                w.out.push(inner)
+                write(item, indent, inner, w)
+            }
+            w.out.push(nl + pad + "]")
+        }
+        Object -> {
+            if j.items.len == 0 {
+                w.out.push("{}")
+                return
+            }
+            w.out.push("{" + nl)
+            for i, item in j.items {
+                if i > 0 {
+                    w.out.push(sep + nl)
+                }
+                w.out.push(inner + quote(j.keys[i]) + colon)
+                write(item, indent, inner, w)
+            }
+            w.out.push(nl + pad + "}")
+        }
+    }
+}
+
+// the value as text on one line
+fn stringify(Json j) -> str {
+    w := Writer()
+    write(j, "", "", addr(w))
+    return w.out.join("")
+}
+
+// the value as text over several lines, indented by two spaces
+fn pretty(Json j) -> str {
+    w := Writer()
+    write(j, "  ", "", addr(w))
+    return w.out.join("")
+}
+
+// ---------- reading ----------
+
+struct Reader {
+    str src
+    int i
+}
+
+// the line and column of a position, for a message
+fn where(ptr[Reader] r) -> str {
+    line := 1
+    col := 1
+    for k in 0..r.i {
+        if k < r.src.len && r.src[k] == '\n' {
+            line += 1
+            col = 1
+        } else {
+            col += 1
+        }
+    }
+    return "line " + str(line) + ", column " + str(col)
+}
+
+fn peek(ptr[Reader] r) -> char {
+    if r.i < r.src.len {
+        return r.src[r.i]
+    }
+    return char(0)
+}
+
+fn skip_space(ptr[Reader] r) {
+    while r.i < r.src.len && (r.src[r.i] == ' ' || r.src[r.i] == '\n' || r.src[r.i] == '\t' || r.src[r.i] == '\r') {
+        r.i += 1
+    }
+}
+
+fn unexpected(ptr[Reader] r, str wanted) -> str {
+    if r.i >= r.src.len {
+        return "json: the text ends where " + wanted + " should be (" + where(r) + ")"
+    }
+    return "json: found '" + str(r.src[r.i]) + "' where " + wanted + " should be (" + where(r) + ")"
+}
+
+// does `word` come next?
+fn comes(ptr[Reader] r, str word) -> bool {
+    return r.src.len - r.i >= word.len && r.src.sub(r.i, r.i + word.len) == word
+}
+
+fn expect_word(ptr[Reader] r, str word) -> ! {
+    if !comes(r, word) {
+        return error(unexpected(r, "'" + word + "'"))
+    }
+    r.i += word.len
+}
+
+fn hex_value(char c) -> int {
+    if c >= '0' && c <= '9' {
+        return int(c) - int('0')
+    }
+    if c >= 'a' && c <= 'f' {
+        return int(c) - int('a') + 10
+    }
+    if c >= 'A' && c <= 'F' {
+        return int(c) - int('A') + 10
+    }
+    return -1
+}
+
+// a code point as UTF-8
+fn utf8(int cp) -> str {
+    []u8 b
+    if cp < 128 {
+        b.push(u8(cp))
+    } else if cp < 2048 {
+        b.push(u8(192 + cp / 64))
+        b.push(u8(128 + cp % 64))
+    } else if cp < 65536 {
+        b.push(u8(224 + cp / 4096))
+        b.push(u8(128 + (cp / 64) % 64))
+        b.push(u8(128 + cp % 64))
+    } else {
+        b.push(u8(240 + cp / 262144))
+        b.push(u8(128 + (cp / 4096) % 64))
+        b.push(u8(128 + (cp / 64) % 64))
+        b.push(u8(128 + cp % 64))
+    }
+    return str(b)
+}
+
+fn read_hex4(ptr[Reader] r) -> int! {
+    n := 0
+    for k in 0..4 {
+        if r.i >= r.src.len || hex_value(r.src[r.i]) < 0 {
+            return error(unexpected(r, "a hexadecimal digit"))
+        }
+        n = n * 16 + hex_value(r.src[r.i])
+        r.i += 1
+    }
+    return n
+}
+
+fn read_string(ptr[Reader] r) -> str! {
+    r.i += 1                    // the opening quote
+    []str parts
+    start := r.i
+    while true {
+        if r.i >= r.src.len {
+            return error("json: a text is never closed (" + where(r) + ")")
+        }
+        c := r.src[r.i]
+        if c == '"' {
+            parts.push(r.src.sub(start, r.i))
+            r.i += 1
+            return parts.join("")
+        }
+        if int(c) < 32 {
+            return error("json: a line break or control character inside a text (" + where(r) + ")")
+        }
+        if c != '\\' {
+            r.i += 1
+            continue
+        }
+        parts.push(r.src.sub(start, r.i))
+        r.i += 1
+        e := peek(r)
+        r.i += 1
+        if e == 'n' {
+            parts.push("\n")
+        } else if e == 't' {
+            parts.push("\t")
+        } else if e == 'r' {
+            parts.push("\r")
+        } else if e == 'b' {
+            parts.push(utf8(8))
+        } else if e == 'f' {
+            parts.push(utf8(12))
+        } else if e == '"' || e == '\\' || e == '/' {
+            parts.push(str(e))
+        } else if e == 'u' {
+            cp := try read_hex4(r)
+            // a pair of 😀 stands for one character above U+FFFF
+            if cp >= 55296 && cp < 56320 && comes(r, "\\u") {
+                r.i += 2
+                low := try read_hex4(r)
+                cp = 65536 + (cp - 55296) * 1024 + (low - 56320)
+            }
+            parts.push(utf8(cp))
+        } else {
+            return error("json: unknown escape \\" + str(e) + " in a text (" + where(r) + ")")
+        }
+        start = r.i
+    }
+}
+
+fn read_number(ptr[Reader] r) -> Json! {
+    start := r.i
+    if peek(r) == '-' {
+        r.i += 1
+    }
+    while r.i < r.src.len && ((r.src[r.i] >= '0' && r.src[r.i] <= '9') || r.src[r.i] == '.' || r.src[r.i] == 'e' || r.src[r.i] == 'E' || r.src[r.i] == '+' || r.src[r.i] == '-') {
+        r.i += 1
+    }
+    n := float(r.src.sub(start, r.i)) or {
+        r.i = start
+        return error(unexpected(r, "a number"))
+    }
+    return new_number(n)
+}
+
+fn read_value(ptr[Reader] r) -> Json! {
+    skip_space(r)
+    c := peek(r)
+    if r.i >= r.src.len {
+        return error(unexpected(r, "a value"))
+    }
+    if c == '{' {
+        obj := new_object()
+        r.i += 1
+        skip_space(r)
+        if peek(r) == '}' {
+            r.i += 1
+            return obj
+        }
+        while true {
+            skip_space(r)
+            if peek(r) != '"' {
+                return error(unexpected(r, "a key in quotes"))
+            }
+            key := try read_string(r)
+            skip_space(r)
+            if peek(r) != ':' {
+                return error(unexpected(r, "':'"))
+            }
+            r.i += 1
+            v := try read_value(r)
+            obj.set(key, v)
+            skip_space(r)
+            if peek(r) == ',' {
+                r.i += 1
+                continue
+            }
+            if peek(r) == '}' {
+                r.i += 1
+                return obj
+            }
+            return error(unexpected(r, "',' or '}'"))
+        }
+    }
+    if c == '[' {
+        list := new_list()
+        r.i += 1
+        skip_space(r)
+        if peek(r) == ']' {
+            r.i += 1
+            return list
+        }
+        while true {
+            v := try read_value(r)
+            list.push(v)
+            skip_space(r)
+            if peek(r) == ',' {
+                r.i += 1
+                continue
+            }
+            if peek(r) == ']' {
+                r.i += 1
+                return list
+            }
+            return error(unexpected(r, "',' or ']'"))
+        }
+    }
+    if c == '"' {
+        s := try read_string(r)
+        return new_text(s)
+    }
+    if c == 't' {
+        try expect_word(r, "true")
+        return new_bool(true)
+    }
+    if c == 'f' {
+        try expect_word(r, "false")
+        return new_bool(false)
+    }
+    if c == 'n' {
+        try expect_word(r, "null")
+        return new_null()
+    }
+    if c == '-' || (c >= '0' && c <= '9') {
+        return try read_number(r)
+    }
+    return error(unexpected(r, "a value"))
+}
+
+// the JSON in `text`; an error with the line and column where it went wrong
+fn parse(str text) -> Json! {
+    r := Reader(src: text)
+    v := try read_value(addr(r))
+    skip_space(addr(r))
+    if r.i < r.src.len {
+        return error(unexpected(addr(r), "the end of the text"))
+    }
+    return v
+}

std/path.fch

@@ -0,0 +1,128 @@
+// Paths, as text. Elements are separated by "/".
+//
+//   import path
+//   path.join("a", "b.txt")        a/b.txt
+//   path.base("/tmp/x/a.tar.gz")   a.tar.gz       path.stem(...)  a.tar       path.ext(...)  .gz
+//   path.dir("/tmp/x/a.txt")       /tmp/x
+//   path.clean("a//b/../c/./d")    a/c/d
+
+// a and b with one separator between; an absolute b replaces a
+fn join(str a, str b) -> str {
+    if a.len == 0 {
+        return b
+    }
+    if b.len == 0 {
+        return a
+    }
+    if b[0] == '/' {
+        return b
+    }
+    if a[a.len - 1] == '/' {
+        return a + b
+    }
+    return a + "/" + b
+}
+
+fn is_abs(str p) -> bool {
+    return p.len > 0 && p[0] == '/'
+}
+
+// the last element: "a/b.txt" -> "b.txt", "a/b/" -> "b", "" -> ".", "/" -> "/"
+fn base(str p) -> str {
+    if p.len == 0 {
+        return "."
+    }
+    end := p.len
+    while end > 1 && p[end - 1] == '/' {
+        end -= 1
+    }
+    if end == 1 && p[0] == '/' {
+        return "/"
+    }
+    start := end
+    while start > 0 && p[start - 1] != '/' {
+        start -= 1
+    }
+    return p.sub(start, end)
+}
+
+// everything before the last element: "a/b.txt" -> "a", "b.txt" -> ".", "/b" -> "/"
+fn dir(str p) -> str {
+    end := p.len
+    while end > 1 && p[end - 1] == '/' {
+        end -= 1
+    }
+    i := end
+    while i > 0 && p[i - 1] != '/' {
+        i -= 1
+    }
+    if i == 0 {
+        return "."
+    }
+    while i > 1 && p[i - 1] == '/' {
+        i -= 1
+    }
+    return p.sub(0, i)
+}
+
+// the part of the last element from its last dot: "a.tar.gz" -> ".gz"; "" when there is none
+fn ext(str p) -> str {
+    b := base(p)
+    i := b.len
+    while i > 0 && b[i - 1] != '.' {
+        i -= 1
+    }
+    if i <= 1 {                 // no dot, or a name that only starts with one (.bashrc)
+        return ""
+    }
+    return b.sub(i - 1, b.len)
+}
+
+// the last element without its extension
+fn stem(str p) -> str {
+    b := base(p)
+    e := ext(p)
+    return b.sub(0, b.len - e.len)
+}
+
+// the elements of a path: "/a/b/c" -> ["a", "b", "c"]
+fn parts(str p) -> []str {
+    []str out
+    for piece in p.split("/") {
+        if piece.len > 0 {
+            out.push(piece)
+        }
+    }
+    return out
+}
+
+// the shortest path with the same meaning: no "//", no ".", and ".." resolved where it can be
+fn clean(str p) -> str {
+    if p.len == 0 {
+        return "."
+    }
+    abs := is_abs(p)
+    []str out
+    for piece in parts(p) {
+        if piece == "." {
+            continue
+        }
+        if piece == ".." {
+            if out.len > 0 && out[out.len - 1] != ".." {
+                out.pop()
+            } else if !abs {
+                out.push("..")
+            }
+            continue
+        }
+        out.push(piece)
+    }
+    joined := out.join("/")
+    if abs {
+        return "/" + joined
+    }
+    if joined.len == 0 {
+        return "."
+    }
+    return joined
+}

std/proc.fch

@@ -0,0 +1,48 @@
+// Programs: run a command, read what it printed, look at the environment.
+//
+//   import proc
+//   code := proc.run("make")                  the exit code; what the command prints goes to the screen
+//   text := try proc.output("git describe")   what the command printed; an error if it failed
+//   proc.env("HOME", "/")                     an environment variable, or the second value if it is not set
+import "stdlib.h"
+import "unistd.h"
+import "time.h"
+
+// run a command; its output goes to the screen. Gives its exit code.
+fn run(str command) -> int {
+    return shell(command)
+}
+
+// run a command and give what it printed. Fails, with its output as the message, if it exits with an error.
+fn output(str command) -> str! {
+    tmp := "/tmp/finch_out_" + str(getpid()) + "_" + str(int(time(null)))
+    code := shell("(" + command + ") > '" + tmp + "' 2>&1")
+    text := read_file(tmp) or ""
+    delete_file(tmp)
+    if code != 0 {
+        return error("'" + command + "' exited with code " + str(code) + ": " + text.trim())
+    }
+    return text
+}
+
+fn env(str name, str fallback) -> str {
+    v := getenv(name)
+    if v.len == 0 {
+        return fallback
+    }
+    return v
+}
+
+fn pid() -> int {
+    return int(getpid())
+}
+
+// the folder the program is running in
+fn cwd() -> str {
+    []char buf
+    for i in 0..4096 {
+        buf.push(char(0))
+    }
+    getcwd(buf.ptr, 4096)
+    return str(buf.ptr)
+}

std/proc_windows.fch

@@ -0,0 +1,45 @@
+// Programs, for Windows. The same functions as proc.fch (that file is for Linux and macOS).
+import "stdlib.h"
+import "process.h"
+import "direct.h"
+import "time.h"
+
+fn run(str command) -> int {
+    return shell(command)
+}
+
+fn output(str command) -> str! {
+    tmp := proc_env("TEMP", ".") + "\\finch_out_" + str(getpid()) + "_" + str(int(time(null)))
+    code := shell(command + " > \"" + tmp + "\" 2>&1")
+    text := read_file(tmp) or ""
+    delete_file(tmp)
+    if code != 0 {
+        return error("'" + command + "' exited with code " + str(code) + ": " + text.trim())
+    }
+    return text
+}
+
+fn proc_env(str name, str fallback) -> str {
+    v := getenv(name)
+    if v.len == 0 {
+        return fallback
+    }
+    return v
+}
+
+fn env(str name, str fallback) -> str {
+    return proc_env(name, fallback)
+}
+
+fn pid() -> int {
+    return int(getpid())
+}
+
+fn cwd() -> str {
+    []char buf
+    for i in 0..4096 {
+        buf.push(char(0))
+    }
+    getcwd(buf.ptr, 4096)
+    return str(buf.ptr)
+}

std/time.fch

@@ -0,0 +1,88 @@
+// Time: the clock, sleeping, and dates.
+//
+//   import time
+//   start := time.millis()          milliseconds from a clock that only goes forward (to measure with)
+//   time.sleep(250)                 wait a quarter of a second
+//   time.now()                      seconds since 1970-01-01 00:00 UTC
+//   d := time.date(time.now())      the parts: d.year, d.month, d.day, d.hour, d.minute, d.second
+//   time.format(time.now(), "%Y-%m-%d %H:%M")      as text, in the computer's time zone
+import "time.h"
+
+struct Date {
+    int year
+    int month       // 1 to 12
+    int day         // 1 to 31
+    int hour
+    int minute
+    int second
+    int weekday     // 0 is Sunday
+    int yearday     // 1 to 366
+}
+
+// seconds since 1970-01-01 00:00 UTC
+fn now() -> int {
+    return int(time(null))
+}
+
+// milliseconds on a clock that only goes forward: for measuring how long something took
+fn millis() -> int {
+    timespec ts
+    clock_gettime(CLOCK_MONOTONIC, addr(ts))
+    return int(ts.tv_sec) * 1000 + int(ts.tv_nsec) / 1000000
+}
+
+fn sleep(int ms) {
+    timespec ts
+    ts.tv_sec = ms / 1000
+    ts.tv_nsec = (ms % 1000) * 1000000
+    nanosleep(addr(ts), null)
+}
+
+fn parts(tm t) -> Date {
+    return Date(year: int(t.tm_year) + 1900, month: int(t.tm_mon) + 1, day: int(t.tm_mday), hour: int(t.tm_hour),
+                minute: int(t.tm_min), second: int(t.tm_sec), weekday: int(t.tm_wday), yearday: int(t.tm_yday) + 1)
+}
+
+// the date and time of a moment, in UTC
+fn date(int unix) -> Date {
+    tm t
+    i64 stamp = unix
+    gmtime_r(addr(stamp), addr(t))
+    return parts(t)
+}
+
+// the date and time of a moment, in the computer's time zone
+fn local(int unix) -> Date {
+    tm t
+    i64 stamp = unix
+    localtime_r(addr(stamp), addr(t))
+    return parts(t)
+}
+
+// a moment as text, in the computer's time zone: %Y year, %m month, %d day, %H hour, %M minute, %S second
+// (the rest of C's strftime works too: %A weekday name, %B month name, ...)
+fn format(int unix, str pattern) -> str {
+    tm t
+    i64 stamp = unix
+    localtime_r(addr(stamp), addr(t))
+    []char buf
+    for i in 0..256 {
+        buf.push(char(0))
+    }
+    strftime(buf.ptr, 256, pattern, addr(t))
+    return str(buf.ptr)
+}
+
+// the number of days in a month (month is 1 to 12)
+fn days_in_month(int year, int month) -> int {
+    if month == 2 {
+        if year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) {
+            return 29
+        }
+        return 28
+    }
+    if month == 4 || month == 6 || month == 9 || month == 11 {
+        return 30
+    }
+    return 31
+}

std/time_windows.fch

@@ -0,0 +1,75 @@
+// Time, for Windows. The same functions as time.fch (that file is for Linux and macOS).
+import "time.h"
+import "finch_win.h"
+
+struct Date {
+    int year
+    int month       // 1 to 12
+    int day         // 1 to 31
+    int hour
+    int minute
+    int second
+    int weekday     // 0 is Sunday
+    int yearday     // 1 to 366
+}
+
+fn now() -> int {
+    return int(time(null))
+}
+
+// milliseconds on a clock that only goes forward (the performance counter: GetTickCount64 ticks every 15 ms)
+fn millis() -> int {
+    i64 count = 0
+    i64 freq = 1
+    QueryPerformanceFrequency(addr(freq))
+    QueryPerformanceCounter(addr(count))
+    return int(count / freq) * 1000 + int(count % freq) * 1000 / int(freq)
+}
+
+fn sleep(int ms) {
+    Sleep(u32(ms))
+}
+
+fn parts(tm t) -> Date {
+    return Date(year: int(t.tm_year) + 1900, month: int(t.tm_mon) + 1, day: int(t.tm_mday), hour: int(t.tm_hour),
+                minute: int(t.tm_min), second: int(t.tm_sec), weekday: int(t.tm_wday), yearday: int(t.tm_yday) + 1)
+}
+
+fn date(int unix) -> Date {
+    tm t
+    i64 stamp = unix
+    _gmtime64_s(addr(t), addr(stamp))
+    return parts(t)
+}
+
+fn local(int unix) -> Date {
+    tm t
+    i64 stamp = unix
+    _localtime64_s(addr(t), addr(stamp))
+    return parts(t)
+}
+
+fn format(int unix, str pattern) -> str {
+    tm t
+    i64 stamp = unix
+    _localtime64_s(addr(t), addr(stamp))
+    []char buf
+    for i in 0..256 {
+        buf.push(char(0))
+    }
+    strftime(buf.ptr, 256, pattern, addr(t))
+    return str(buf.ptr)
+}
+
+fn days_in_month(int year, int month) -> int {
+    if month == 2 {
+        if year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) {
+            return 29
+        }
+        return 28
+    }
+    if month == 4 || month == 6 || month == 9 || month == 11 {
+        return 30
+    }
+    return 31
+}

tests/boot.sh

@@ -1,50 +0,0 @@
-#!/usr/bin/env bash
-# The self-hosted compiler (boot/) must
-#   1. build itself: stage1 (built by build/finch) -> stage2 -> stage3, with identical IR
-#   2. give the same output as build/finch on every test in tests/run it supports
-set -u
-cd "$(dirname "$0")/.."
-tmp=$(mktemp -d)
-trap 'rm -rf "$tmp"' EXIT
-
-build/finch build boot/main.fch -o "$tmp/boot1" || exit 1
-"$tmp/boot1" build boot/main.fch -o "$tmp/boot2" || exit 1
-"$tmp/boot1" ir boot/main.fch > "$tmp/stage2.ll"
-"$tmp/boot2" ir boot/main.fch > "$tmp/stage3.ll"
-if cmp -s "$tmp/stage2.ll" "$tmp/stage3.ll"; then
-    echo "bootstrap: stage 2 and stage 3 are identical ($(wc -l < "$tmp/stage3.ll") lines of IR)"
-else
-    echo "bootstrap: FAILED, stage 2 and stage 3 differ"
-    exit 1
-fi
-
-pass=0; failed=0; skipped=0
-for f in tests/run/*.fch; do
-    grep -q "^fn main" "$f" || continue
-    # the bootstrap compiler doesn't do C imports
-    # (checked in the test and in the modules it imports)
-    files="$f"
-    for m in $(sed -n 's/^import \([a-z_]*\)$/\1/p' "$f"); do files="$files tests/run/$m.fch"; done
-    if grep -qE '^import "|^link ' $files; then
-        skipped=$((skipped + 1))
-        continue
-    fi
-    input="${f%.fch}.in"
-    [ -f "$input" ] || input=/dev/null
-    if ! "$tmp/boot2" build "$f" -o "$tmp/prog" > "$tmp/err" 2>&1; then
-        failed=$((failed + 1))
-        echo "FAIL (compile) $f"
-        head -3 "$tmp/err"
-        continue
-    fi
-    got=$("$tmp/prog" < "$input" 2>&1)
-    if [ "$got" == "$(cat "${f%.fch}.out")" ]; then
-        pass=$((pass + 1))
-    else
-        failed=$((failed + 1))
-        echo "FAIL (output) $f"
-        diff <(echo "$got") "${f%.fch}.out" | head -10
-    fi
-done
-echo "self-hosted compiler: $pass passed, $failed failed, $skipped skipped (features it doesn't have)"
-[ $failed -eq 0 ]

tests/cross.sh

@@ -4,7 +4,7 @@
 #   tests/cross.sh arm64     aarch64 Linux, run with qemu-aarch64
 # e.g. nix-shell -p pkgsCross.mingwW64.buildPackages.gcc wine64 --run 'tests/cross.sh windows'
 #      nix-shell -p pkgsCross.aarch64-multiplatform.buildPackages.gcc qemu \
-#                --run 'FINCH_CC=aarch64-unknown-linux-gnu-gcc tests/cross.sh arm64'
+#                --run 'FINCH_CC=aarch64-unknown-linux-gnu-gcc QEMU_LD_PREFIX=<the aarch64 glibc> tests/cross.sh arm64'
 # (On a real Windows/ARM64/macOS machine, use tests/run.sh with that system's finch.)
 set -u
 cd "$(dirname "$0")"
@@ -24,7 +24,7 @@ run_exe() {  # program, stdin -> output without Windows' \r
     $runner "$1" < "$2" 2>&1 | tr -d '\r'
 }
 
-for f in run/*.fch; do
+for f in run/*.fch new/*.fch; do
     grep -q "^fn main" "$f" || continue
     input="${f%.fch}.in"
     [ -f "$input" ] || input=/dev/null
@@ -40,7 +40,7 @@ for f in run/*.fch; do
     fi
 done
 
-for f in fail/*.fch; do
+for f in fail/*.fch new/fail/*.fch; do
     expect=$(head -1 "$f" | sed -n 's|^// expect: ||p')
     exe="$tmp/$(basename "${f%.fch}")$ext"
     if "$FINCH" build "$f" --target "$target" -o "$exe" > "$tmp/out" 2>&1; then

tests/new/enums.fch

@@ -0,0 +1,75 @@
+enum Color { Red, Green, Blue }
+enum Status { Ok = 200, NotFound = 404, Teapot = 418 }
+
+struct Pixel {
+    Color color
+    int x
+}
+
+fn Color.warm() -> bool {
+    return self == Color.Red
+}
+
+fn Color.next() -> Color {
+    if self == Color.Red {
+        return Color.Green
+    }
+    if self == Color.Green {
+        return Color.Blue
+    }
+    return Color.Red
+}
+
+fn describe(Color c) -> str {
+    return match c {
+        Red -> "red"
+        Green -> "green"
+        Blue -> "blue"
+    }
+}
+
+fn code(Status s) -> str {
+    match s {
+        Status.Ok -> return "fine"
+        Status.NotFound, Status.Teapot -> return "odd"
+    }
+}
+
+fn main() {
+    c := Color.Green
+    print(c, Color.Blue, int(Color.Blue), int(Status.Teapot))
+    print(c == Color.Green, c != Color.Green)
+    print(describe(Color.Red), describe(c.next()), c.warm(), Color.Red.warm())
+    print(code(Status.Ok), code(Status.NotFound))
+    p := Pixel(color: Color.Blue, x: 3)
+    print(p)
+    []Color all = [Color.Red, Color.Blue]
+    print(all, all.len)
+    for col in all {
+        match col {
+            Color.Red -> print("a red one")
+            else -> print("something else")
+        }
+    }
+    s := Status(404)
+    print(s, Status(200))
+    n := 5
+    kind := match n {
+        1, 2, 3 -> "small"
+        4, 5 -> "medium"
+        else -> "large"
+    }
+    print(kind)
+    word := "two"
+    match word {
+        "one" -> print(1)
+        "two" -> {
+            print(2)
+            print("two!")
+        }
+        else -> print("many")
+    }
+    counts := [Color.Red: 2, Color.Blue: 5]
+    print(counts[Color.Blue], counts)
+    print(str(Color.Green) + "!")
+}

tests/new/enums.out

@@ -0,0 +1,14 @@
+Green Blue 2 418
+true false
+red blue false true
+fine odd
+Pixel(color: Blue, x: 3)
+[Red, Blue] 2
+a red one
+something else
+NotFound Ok
+medium
+2
+two!
+5 {Red: 2, Blue: 5}
+Green!

tests/new/fail/enum_bad_number.fch

@@ -0,0 +1,6 @@
+// expect: 7 is not the number of any variant of Color
+enum Color { Red, Green }
+
+fn main() {
+    print(Color(7))
+}

tests/new/fail/enum_compare_order.fch

@@ -0,0 +1,6 @@
+// expect: enums can only be compared with == and !=
+enum Color { Red, Green }
+
+fn main() {
+    print(Color.Red < Color.Green)
+}

tests/new/fail/enum_no_variant.fch

@@ -0,0 +1,6 @@
+// expect: the enum Color has no variant 'Blue'
+enum Color { Red, Green }
+
+fn main() {
+    print(Color.Blue)
+}

tests/new/fail/generic_body_error.fch

@@ -0,0 +1,15 @@
+// expect: (while building bigger[Point])
+struct Point {
+    int x
+}
+
+fn bigger[T](T a, T b) -> T {
+    if a > b {
+        return a
+    }
+    return b
+}
+
+fn main() {
+    print(bigger(Point(1), Point(2)))
+}

tests/new/fail/generic_cant_infer.fch

@@ -0,0 +1,10 @@
+// expect: can't tell what T is here
+fn make[T]() -> []T {
+    []T out
+    return out
+}
+
+fn main() {
+    x := make()
+    print(x)
+}

tests/new/fail/generic_needs_type.fch

@@ -0,0 +1,9 @@
+// expect: 'Stack' is generic, so say which type it holds
+struct Stack[T] {
+    []T items
+}
+
+fn main() {
+    s := Stack()
+    print(s)
+}

tests/new/fail/generic_not_generic.fch

@@ -0,0 +1,8 @@
+// expect: 'add' is not generic, so it takes no type arguments
+fn add(int a, int b) -> int {
+    return a + b
+}
+
+fn main() {
+    print(add[int](1, 2))
+}

tests/new/fail/generic_wrong_count.fch

@@ -0,0 +1,9 @@
+// expect: Stack takes 1 type argument(s)
+struct Stack[T] {
+    []T items
+}
+
+fn main() {
+    Stack[int, str] s
+    print(s)
+}

tests/new/fail/match_arm_after_else.fch

@@ -0,0 +1,8 @@
+// expect: this arm can never be used
+fn main() {
+    n := 3
+    match n {
+        else -> print("any")
+        1 -> print("one")
+    }
+}

tests/new/fail/match_arms_differ.fch

@@ -0,0 +1,9 @@
+// expect: the arms of a match have to give the same type
+fn main() {
+    n := 3
+    x := match n {
+        1 -> "one"
+        else -> 2
+    }
+    print(x)
+}

tests/new/fail/match_missing_variant.fch

@@ -0,0 +1,10 @@
+// expect: doesn't handle Blue
+enum Color { Red, Green, Blue }
+
+fn main() {
+    c := Color.Red
+    match c {
+        Red -> print(1)
+        Green -> print(2)
+    }
+}

tests/new/fail/match_needs_else.fch

@@ -0,0 +1,8 @@
+// expect: needs an 'else' arm
+fn main() {
+    n := 3
+    match n {
+        1 -> print("one")
+        2 -> print("two")
+    }
+}

tests/new/fail/match_not_a_variant.fch

@@ -0,0 +1,11 @@
+// expect: 'Purple' is not a variant of Color
+enum Color { Red, Green }
+
+fn main() {
+    c := Color.Red
+    match c {
+        Red -> print(1)
+        Purple -> print(2)
+        else -> print(3)
+    }
+}

tests/new/fail/payload_missing.fch

@@ -0,0 +1,12 @@
+// expect: this match doesn't handle Point
+enum Shape {
+    Circle(float)
+    Point
+}
+
+fn main() {
+    s := Shape.Circle(1.0)
+    match s {
+        Circle(r) -> print(r)
+    }
+}

tests/new/generics.fch

@@ -0,0 +1,95 @@
+struct Stack[T] {
+    []T items
+}
+
+fn Stack[T].push(T x) {
+    self.items.push(x)
+}
+
+fn Stack[T].pop() -> T {
+    return self.items.pop()
+}
+
+fn Stack[T].size() -> int {
+    return self.items.len
+}
+
+struct Pair[A, B] {
+    A first
+    B second
+}
+
+fn Pair[A, B].swapped() -> Pair[B, A] {
+    return Pair[B, A](self.second, self.first)
+}
+
+struct Point {
+    int x
+    int y
+}
+
+fn max[T](T a, T b) -> T {
+    if a > b {
+        return a
+    }
+    return b
+}
+
+fn first[T]([]T items) -> T {
+    return items[0]
+}
+
+fn count[T]([]T items, T wanted) -> int {
+    n := 0
+    for x in items {
+        if x == wanted {
+            n += 1
+        }
+    }
+    return n
+}
+
+fn show[T](T x) -> str {
+    return "<" + str(x) + ">"
+}
+
+fn convert[T](str s) -> T {
+    return T(s)
+}
+
+fn fill[T](int n, T value) -> []T {
+    []T out
+    for i in 0..n {
+        out.push(value)
+    }
+    return out
+}
+
+fn main() {
+    print(max(3, 9), max(2.5, 1.5), max("apple", "pear"), max('a', 'b'))
+    print(max[float](1, 2.5))
+    print(first(["x", "y"]), first([7, 8]), count([1, 2, 1, 3, 1], 1), count(["a", "b"], "b"))
+    print(show(5), show("hi"), show(Point(1, 2)), show([1, 2]))
+    print(fill(3, "ab"), fill(2, 1.5), fill[int](2, 7))
+
+    Stack[int] s
+    s.push(10)
+    s.push(20)
+    print(s.pop(), s.size(), s)
+
+    names := Stack[str]()
+    names.push("ann")
+    names.push("bob")
+    print(names, names.size())
+
+    pts := Stack[Point]()
+    pts.push(Point(1, 2))
+    print(pts.pop().x)
+
+    p := Pair[str, int]("age", 31)
+    q := p.swapped()
+    print(p, q, q.first + 1)
+    nested := Stack[Pair[int, str]]()
+    nested.push(Pair[int, str](1, "one"))
+    print(nested)
+}

tests/new/generics.out

@@ -0,0 +1,10 @@
+9 2.5 pear b
+2.5
+x 7 3 1
+<5> <hi> <Point(x: 1, y: 2)> <[1, 2]>
+["ab", "ab", "ab"] [1.5, 1.5] [7, 7]
+20 1 Stack[int](items: [10])
+Stack[str](items: ["ann", "bob"]) 2
+1
+Pair[str, int](first: "age", second: 31) Pair[int, str](first: 31, second: "age") 32
+Stack[Pair[int, str]](items: [Pair[int, str](first: 1, second: "one")])

tests/new/payload_enums.fch

@@ -0,0 +1,38 @@
+enum Shape {
+    Circle(float)
+    Rect(float, float)
+    Named(str, []int)
+    Point
+}
+
+fn Shape.area() -> float {
+    return match self {
+        Circle(r) -> 3.0 * r * r
+        Rect(w, h) -> w * h
+        Named(_, sizes) -> float(sizes.len)
+        Point -> 0.0
+    }
+}
+
+fn describe(Shape s) -> str {
+    match s {
+        Shape.Circle(r) -> return "circle " + str(r)
+        Shape.Named(name, _) -> return "named " + name
+        else -> return "other"
+    }
+}
+
+fn main() {
+    shapes := [Shape.Circle(2.0), Shape.Rect(2.0, 3.5), Shape.Named("tri", [1, 2, 3]), Shape.Point]
+    for s in shapes {
+        print(s, s.area(), describe(s))
+    }
+    copy := shapes[2]
+    shapes.clear()
+    print(copy)
+    p := Shape.Point
+    match p {
+        Point -> print("a point")
+        else -> print("no")
+    }
+}

tests/new/payload_enums.out

@@ -0,0 +1,6 @@
+Circle(2) 12 circle 2
+Rect(2, 3.5) 7 other
+Named("tri", [1, 2, 3]) 3 named tri
+Point 0 other
+Named("tri", [1, 2, 3])
+a point

tests/new/std_json.fch

@@ -0,0 +1,35 @@
+import json
+
+fn main() -> ! {
+    doc := try json.parse("{\"name\": \"Finch\", \"tags\": [\"fast\", \"small\"], \"stars\": 5, \"pi\": 3.25, \"ok\": true, \"none\": null, \"nested\": {\"deep\": [1, [2, 3]]}}")
+    print(doc.get("name").str_or(""), doc.get("tags").at(1).str_or(""), doc.get("stars").int_or(0), doc.get("pi").float_or(0.0))
+    print(doc.get("ok").bool_or(false), doc.get("none").is_null(), doc.get("missing").is_null(), doc.has("name"), doc.has("nope"))
+    print(doc.get("nested").get("deep").at(1).at(0).int_or(-1), doc.get("tags").len(), doc.names())
+    print(json.stringify(doc))
+
+    out := json.new_object()
+    out.set("greeting", json.new_text("hi \"there\"\n"))
+    list := json.new_list()
+    list.push(json.new_number(1))
+    list.push(json.new_number(2.5))
+    list.push(json.new_bool(false))
+    list.push(json.new_null())
+    out.set("values", list)
+    out.set("greeting", json.new_text("replaced"))
+    out.set("empty", json.new_object())
+    print(json.stringify(out))
+    print(json.pretty(out))
+
+    again := try json.parse(json.pretty(out))
+    print(json.stringify(again) == json.stringify(out))
+    print((try json.parse("\"caf\\u00e9 \\ud83d\\ude00 \\/\"")).str_or(""))
+    print((try json.parse("  [ ]  ")).len(), (try json.parse("-12.5e1")).float_or(0.0))
+
+    for bad in ["{\"a\": }", "[1, 2", "{\"a\" 1}", "tru", "[1] x", "\"open", "", "[1,\n  oops]"] {
+        json.parse(bad) or {
+            print(err)
+            continue
+        }
+        print("parsed?!", bad)
+    }
+}

tests/new/std_json.out

@@ -0,0 +1,26 @@
+Finch small 5 3.25
+true true true true false
+2 2 ["name", "tags", "stars", "pi", "ok", "none", "nested"]
+{"name":"Finch","tags":["fast","small"],"stars":5,"pi":3.25,"ok":true,"none":null,"nested":{"deep":[1,[2,3]]}}
+{"greeting":"replaced","values":[1,2.5,false,null],"empty":{}}
+{
+  "greeting": "replaced",
+  "values": [
+    1,
+    2.5,
+    false,
+    null
+  ],
+  "empty": {}
+}
+true
+café 😀 /
+0 -125
+json: found '}' where a value should be (line 1, column 7)
+json: the text ends where ',' or ']' should be (line 1, column 6)
+json: found '1' where ':' should be (line 1, column 6)
+json: found 't' where 'true' should be (line 1, column 1)
+json: found 'x' where the end of the text should be (line 1, column 5)
+json: a text is never closed (line 1, column 6)
+json: the text ends where a value should be (line 1, column 1)
+json: found 'o' where a value should be (line 2, column 3)

tests/new/std_path.fch

@@ -0,0 +1,10 @@
+import path
+
+fn main() {
+    print(path.join("a", "b.txt"), path.join("a/", "b"), path.join("", "x"), path.join("a", "/abs"))
+    print(path.base("/tmp/x/a.tar.gz"), path.base("a/b/"), path.base(""), path.base("/"))
+    print(path.dir("/tmp/x/a.txt"), path.dir("b.txt"), path.dir("/b"), path.dir("a/b/"))
+    print(path.ext("a.tar.gz"), path.ext("noext"), path.ext(".bashrc"), path.stem("/x/a.tar.gz"))
+    print(path.clean("a//b/../c/./d"), path.clean("/../a"), path.clean("../../a"), path.clean(""), path.clean("a/.."))
+    print(path.parts("/a//b/c/"), path.is_abs("/a"), path.is_abs("a"))
+}