I personally found Ocaml to be perfect for learning typed (Hindly Milner) functional programming. Haskell with its strong syntactic support was good to learn a

I personally found Ocaml to be perfect for learning typed (Hindly Milner) functional programming. Haskell with its strong syntactic support was good to learn about Monads and how to work with enforced purity. From there, I went back to Ocaml, using both Monadic IO and Ocaml's better module/functor system.