[nickbauman]

Last I checked OCaml is single-threaded concurrency. My testing comparing Java with Clojure is they clock in about the same but Clojure pushes you away from locking where Java pushes you toward it but hard. Clojure isn't pure functional but it's enough that it makes a huge difference to achieving correctness without the performance compromise.

[pjmlp]

The multi-core runtime for OCaml already exists, just isn't fully feature complete to be integrated into the stable version.

https://github.com/ocamllabs/ocaml-multicore