use std.panicking.panic

type Option*[T] {
    Some(value: T)
    None
}

fn or-panic*[T](opt: Option[T]) T =
    match opt {
        Option.Some(v) -> v
        Option.None -> panic("called `or-panic` on a `None` value")
    }

fn is-some*[T](opt: &Option[T]) bool =
    match opt {
        Option.Some(_) -> true
        Option.None -> false
    }

fn is-none*[T](opt: &Option[T]) bool =
    !opt.is-some()

fn map*[A, B](opt: Option[A], f: fn(A) B) Option[B] =
    match opt {
        Option.Some(v) -> Option.Some(f(v))
        Option.None -> Option.None
    }

fn map-or*[A, B](opt: Option[A], default: B, f: fn(A) B) B =
    match opt {
        Option.Some(v) -> f(v)
        Option.None -> default
    }