mod extern "./foo"

fn extern "c" hello() unit
let extern answer: int

fn extern "c" printf(fmt: ptr[u8], ..) i32

fn main() unit = {
    println("Hello, World!")
    unsafe hello()
    run(print-answer)
    do-add(add, 1, 2)
    unsafe printf("num = %d\n".ptr, map(1, id))
}

fn print-answer() unit = {
    unsafe printf("The answer is %d\n".ptr, answer)
}

fn add(a: int, b: int) int = {
    a + b
}

fn do-add(f: fn(int, int) int, a: int, b: int) unit = {
    unsafe printf("a + b = %d\n".ptr, f(a, b))
}

fn run(f: fn() unit) unit = f()

fn id[T](x: T) T = x

fn map[A, B](val: A, f: fn(A) B) B =
    f(val)