I don't think a single relevant implementation is a problem, especially when therer are not a lot of people working on these languages. I'm also surprised that

I don't think a single relevant implementation is a problem, especially when therer are not a lot of people working on these languages. I'm also surprised that you think OCaml is moving too fast. The multicore took a lot of time to have a proper design and backwards compatibiltiy, and old code compiles really well.