If you spend your life talking about bool having two values, and then need to act as if it has three or 256 values or whatever, that's where the weirdness lives.

In C, true doesn't necessarily equal true.

In Java (myBool != TRUE) does not imply that (myBool == FALSE).

Maybe you could do with some weirdness!

In Haskell: Bool has two members: True & False. (If it's True, it's True. If it's not True, it's False). Unit has one members: () Void has zero members.

To be fair I'm not sure why Void was raised as an example in the article, and I've never used it. I didn't turn up any useful-looking implementations on hoogle[1] either.

[1] https://hoogle.haskell.org/?hoogle=a+-%3E+Void&scope=set%3As...