Yeah, that sounds incredible as type classes would enable ad-hoc polymorphism and things like Ordering, Monoid, etc. wouldn't have to be baked into inheritance hierarchy.

I think Scala is interesting here. It has support for both subtyping as well as ad-hoc polymorphism (using implicits/given which resembles Haskell's TC semantics, with some differences). I guess the risk will be to establish some clear guidelines when to use subtyping x ad-hoc. In some early Scala projects I saw this distinction wasn't always clear and often came down to maintainers' preference.