Closed
Description
This issue was originally filed by @tomyeh
IMO, it is not worth to introduce such kind of complexity to the language. There is nothing hard to implement without them.
It actually reminds me the chaos of undefined and null found in JavaScript. Sure, it helps some very specific cases, but, at the end, it only confuses the developers.
For example, it is too subtle and error-prone, if the following statement behaves different (assume it takes different actions based on ?check)
foo(abc);
foo(abc, null);