That's purely a library oversight which has become mired in backwards compatibility (don't track any of that onto my carpet :P). It would be trivial to specify

That's purely a library oversight which has become mired in backwards compatibility (don't track any of that onto my carpet :P). It would be trivial to specify that all Monads are also Functors by changing the definition of the Monad class a little bit: class Functor m => Monad m where