Merlin [1] can provide type information for OCaml and integrates with emacs, vim and sublime (at least). One can easily select any expression and get its type.

Merlin [1] can provide type information for OCaml and integrates with emacs, vim and sublime (at least). One can easily select any expression and get its type. From experience, it's very convenient to spot mistakes leading to properly typed code, but not with the expected type(s). [1] https://opam.ocaml.org/blog/merlin-2-0-0-released/ https://opam.ocaml.org/blog/merlin-2-0-0-released/