To be fair, F# is, instead of a new language, mostly a re-implementation of OCaml for .Net platform, in the same camp as IronRuby and IronPython. They even refer it as Caml.net sometimes:

http://research.microsoft.com/en-us/um/cambridge/projects/fs...

F# has been around for well over 5 years, although the last 5 years have seen many new features to it.

It's 9 years old, which is more than 5 years.

Is F# in the past 5 years? I remembered it as being a bit older.