This is a well-researched and rigorously build "french dialect" of ML which has been matured into an industry-strength toolchain. Native code compiler is what distinguish Ocaml from Erlang or Scala.
Think of it as less polished, strict Haskell (Applicative Order, Lexical Scoping, like Scala)
Unlike Scala the Java ecosystem bloatware is not required.
See also Declarative, Haskell, Kundalini