Without being an expert, I'm pretty sure that OCaml is more strictly functional than Erlang and Javascript, though they all support functional programming to on

Without being an expert, I'm pretty sure that OCaml is more strictly functional than Erlang and Javascript, though they all support functional programming to one extent or another. With languages like Javascript and Ruby, you can program for years without really learning functional concepts. I think OCaml is the opposite; the paradigm of least resistance is functional, even though you can program in other styles (OO, imperative). In terms of functional purity, Haskell > Lisp/Scheme/OCaml/ML > Erlang > Ruby/Javascript > Python > Java > etc.