I've wondered this exact same thing myself for other languages. I doubt its a lack of familiarity since I would bet most compiler/language authors are aware of

I've wondered this exact same thing myself for other languages. I doubt its a lack of familiarity since I would bet most compiler/language authors are aware of most Haskell concepts/idioms. I think it probably has more to do with function definition semantics in non-functional languages but it seems that could be easily worked around... Anyway the haskell way, especially with Typeclasses, has to be clearest way to express type constraints for functions I've encountered at least from a code readability standpoint.