Sure, there's one, 'loop2(_, 101).'.

If it wasn't a toy problem but rather a larger set of rules describing a more salient algorithm it would matter more whether you could pour in more facts as data enters the system.

I get your point, I personally do a lot of crude concurrency with POSIX fork() and shell spawns from within suitable programming languages, e.g. Picolisp, Elixir.