This is just like training your dog to walk on its hind legs balancing a ball on its nose; it is an achievement, of sorts, but tells you nothing about dogkeeping. Nobody actually coding C++ does this, and a working programmer has no reason to pay it any attention beyond its novelty value. Anyway, Clang 8 and up do not allow it.

You can do overwhelmingly harder-to-understand-or-justify things in Haskell, and most are about as important. But some of those are essential.