// 실행 의미를 한 파일에 모은 것: ?, mut, struct, match, scope.
//
// 기대 출력:
//   7
//   6
//   err
//   in scope

import "cool.dev/std/int" as Int

pub capability Console {
    fn print(s: String) effects {Console.print}
}

pub enum E {
    Bad,
}

pub copyable struct P {
    x: Int,
    y: Int,
}

pub fn half(n: Int) -> Result[Int, E] {
    if n % 2 == 0 {
        Ok(n / 2)
    } else {
        Err(Bad)
    }
}

pub fn twice(n: Int) -> Result[Int, E] {
    let a = half(n)?
    let b = half(a)?
    Ok(a + b)
}

pub fn show_res(r: Result[Int, E]) -> String {
    match r {
        Ok(v) => Int.show(v),
        Err(_) => "err",
    }
}

pub fn main(c: Console, root: TaskScope) effects {Console.print} {
    let mut total = 0
    let p = P { x: 3, y: 4 }
    total = total + p.x + p.y
    c.print(Int.show(total))
    c.print(show_res(twice(8)))
    c.print(show_res(twice(7)))
    scope sc = root {
        sc.spawn(fn() {
            c.print("in scope")
        })
    }
}