[elehack]

Go does have a much better concurrency story, OCaml's is rather weak (as others have observed).

For the work I do (data analysis and scientific research, particularly on recommender systems, with system-building to support that), if I need concurrency, it's suitable to run the program on the JVM. So I would use Scala in that case, and OCaml would be fine for the other systems-y stuff.

I personally have taken to writing such code in Haskell these days, but that's largely to practice my FP skills in a manner that's easier to transfer back to Scala.