fn get_int() int {
    return 42
}

fn dub_int(i int) int {
    return i * 2
}

struct Fun[F] {
mut:
    call F
}

type FunZero = fn () int

fn main() {
    fun0 := Fun[FunZero]{
        call: get_int
    }
    println(fun0.call())
    println(fun0.call(1234))
    println(fun0.call(1234, 5678))

    fun1 := Fun[fn (int) int]{
        call: dub_int
    }

    println(fun1.call(42))
    println(fun1.call())
    println(fun1.call(42, 43))

    println(fun1.call(true))
    println(fun1.call('text'))
    println(fun1.call(22.2))
}