module main

fn f_a() int {
    println('a')
    return 1
}

fn test_closure_with_fn_ref_var() {
    f := f_a
    ref := &f
    println('ref=0x${ptr_str(ref)}')

    handler := fn [ref] () int { // ref_fn is captured as a direct function pointer (*fn) instead of a pointer to a function (**fn)
        println('in closure: ref=0x${ptr_str(ref)}')
        deref_fn := *ref
        println('in closure: deref=0x${ptr_str(deref_fn)}')
        return deref_fn()
    }

    f()
    deref := *ref
    println('deref=0x${ptr_str(deref)}')
    assert deref() == 1
    assert handler() == 1
}

type Fun = fn () int

fn test_closure_with_fn_ref_var_option() {
    opt := ?Fun(f_a)

    handler := fn [opt] () int {
        if g := opt {
            return g()
        }
        return 0
    }

    assert handler() == 1
}