type Range_int(start: int, end: int, current: int);

func range(start: int, end: int) -> Range_int {
    Range_int(start: start, end: end, current: start)
}

func advance(r: Range_int) -> Range_int {
    // FIXME: Inline this in the line after once parsing is fixed
    old_current = r.current;
    new_current = old_current + 1;
    new_start = r.start;
    new_end = r.end;
    Range_int(start: new_start, end: new_end, current: new_current)
}

func current(r: Range_int) -> Maybe_int {
    old_current = r.current;
    mut old_end = r.end;
    old_end = old_end - 1;
    gone_past = old_current > old_end;

    // FIXME: Once #320 is fixed, replace
    // if r.current > r.end - 1 {
    if gone_past {
        nothing()
    } else {
        some(r.current)
    }
}