import "math.h"

struct Vec {
    float x
    float y
}

fn length(Vec v) -> float {
    return sqrt(v.x * v.x + v.y * v.y)
}

fn add(Vec a, Vec b) -> Vec {
    return Vec(a.x + b.x, a.y + b.y)
}

fn describe(Vec v) -> str {
    return "(" + str(v.x) + ", " + str(v.y) + ") of length " + str(length(v))
}

// a method in a module: callable as v.scaled(2) wherever Vec is used
fn Vec.scaled(float k) -> Vec {
    return Vec(self.x * k, self.y * k)
}