As Haskell shows, typeclasses are not ruled out by type inference. There is a reason they can't be added to OCaml, though, and it is functors. OCaml's functor

As Haskell shows, typeclasses are not ruled out by type inference. There is a reason they can't be added to OCaml, though, and it is functors. OCaml's functors are fundamentally incompatible with typeclasses. I think one of the problems with getting new people into OCaml is that you feel the pain of not having typeclasses long before you understand the power of functors.