ML's first-class modules let you achieve many of the same things as type classes. In fact, a lot of people in the Haskell community would like something a bit c

ML's first-class modules let you achieve many of the same things as type classes. In fact, a lot of people in the Haskell community would like something a bit closer to ML (in other words, more powerful) in this regard. Monads can be formulated in any language with first-class functions. Monadic I/O is more distinctively Haskellish, and of course Haskell has syntactic sugar to make using them easier, but as a tool and a concept they're far from unique to Haskell.