iterator: @value <T> type = {
    public x: T = 0;
    operator++: (inout this) -> forward iterator<T> requires true = { x++; return this; }
}

iterator2: @value <T> type = {
    public x: T = 0;
}
operator++: <T> (inout it: iterator2<T>) -> forward iterator2<T> requires true = { it.x++; return it; }

int main() {
    {
    iterator<int> i;
    std::cout << (++i).x;
    std::cout << (++i).x;
    std::cout << i++.x;
    std::cout << i++.x;
    std::cout << i.x << "\n";
    }

    {
    iterator2<int> i;
    std::cout << (++i).x;
    std::cout << (++i).x;
    std::cout << i++.x;
    std::cout << i++.x;
    std::cout << i.x << "\n";
    }
}



number: @struct type = {
  operator<=>: (this, that) -> _;
  operator-: (this, _) -> int = 0;
}

number_line: @struct <Op: i8, Id: i32> type = {
  this: number;
}

number_line_pre_increment: <Id: i32> type  == number_line<0b1110, Id>;
number_line_pre_decrement: <Id: i32> type  == number_line<0b1101, Id>;
number_line_post_increment: <Id: i32> type == number_line<0b1011, Id>;
number_line_post_decrement: <Id: i32> type == number_line<0b0111, Id>;

operator++: <Op: i8, Id: i32> (inout x: number_line<Op, Id>) -> forward number_line<Op, Id> requires bool(Op & 1) = x;
operator--: <Op: i8, Id: i32> (inout x: number_line<Op, Id>) -> forward number_line<Op, Id> requires bool(Op & 2) = x;

operator++: (inout x: number_line_pre_increment<0>) -> forward number_line_pre_increment<0> = x;
operator--: (inout x: number_line_pre_decrement<0>) -> forward number_line_pre_decrement<0> = x;

operator++: (inout x: number_line_pre_increment<1>) -> forward const number_line_pre_increment<1> = x;
operator--: (inout x: number_line_pre_decrement<1>) -> forward const number_line_pre_decrement<1> = x;