Haskell checks all those boxes, plus it’s been around for 28 years. Yes, I am a fanboy. That said, it’s a hard language to learn.

Seems like there’s a mass migration away from Ruby for performance reasons, with people flocking to languages with familiar syntax, e.g., Elixir, Crystal, even though there are very different language semantics.

I never realized Haskell was compiled. Checking it out!!

The post is good enough to get me interested in the language, but it seriously lacks a "current limitations / issues" section to be really great.

Yes, lack of true parallelism is my one gripe, though they are planning on adding that post 1.0 from what I understand. I think I'll add a limitations section like you suggested.

All of that said, guys, there are plenty of popular languages right now that don't have true parallelism. Also if you really need parallelism you could do threading in C and link against it, so I don't know if lack of out-of-the-box parallelism really qualifies as a severe limitation per say. I will definitely add a section about this however.

Crystal is good, but still has serious limitations. When I look at the feature list I would rather recommend Pony which does have multi-core support, and is safe to do so. It's also a tad faster than Crystal.

Do does the green thread model support multiple cores?

If not, then that’s a major thing that should be declared upfront.