Since F# was derived from OCaml, I think readers may also be interested in taking a look at the OCaml-Java project:
http://ocamljava.x9c.fr/
(It's essentially what it says in the tin...)
(It's essentially what it says in the tin...)
By stagnation I mostly meant the comparatively tiny ecosystem of libraries vis-a-vis, e.g. JVM-based languages. In particular, with Akka, Scala has much nicer support for concurrency. The ability to call, and be called by, Java code in the smoothes possible way is also beneficial for my use cases.
I'm surprised that GADTs were added, because a few years ago I visited the Gallium team at INRIA who develop Ocaml, and asked about GADTs. I was told by one of the senior Ocaml developers that there were no plans for the inclusion on this feature.