What are people's thoughts about using constraint kinds in the prelude, so you can make things with class constraints monads? Like making a Set monad. This sta

What are people's thoughts about using constraint kinds in the prelude, so you can make things with class constraints monads? Like making a Set monad. This stack overflow answer shows what I'm talking about http://stackoverflow.com/a/22314189/1080531 http://stackoverflow.com/a/22314189/1080531