To have the equivalent outside the .net world, there could be a Ocaml for JVM, that would allow to fall back to a ecosystem of libraries and toolchains. I think there have been some experiments to do that, but not a finished one to my knowledge.
I think Scala is the main functional offering for JVM, no?
Although with C#'s the direction of travel (bringing in pattern matching, record types, etc.) I reckon C# and F# will end up more like Scala and OCaml, rather than Java and OCaml.
