Crystal is more comparable to Go or Swift. I've been working with Crystal a lot the last few months and I'm really enjoying the emphasis on speed. The ecosystem is understandably still immature, but its going to hit 1.0 this year, so I wouldn't build anything big quite yet.

Swift would be a better comparison - both Crystal and Swift are general purpose languages that compile via LLVM. Neither has any special story for concurrency (yet). Go and Elixir/Erlang on the other hand, change your approach to programming.

My understanding of Crystal is limited, but I think of the two, Go is the only one you would probably consider comparing it to, because of its native compilation. I don't think it has a very strong emphasis on concurrency, so comparing it to Elixir likely doesn't make much sense. Take that with a grain of salt though, as I'm not super familiar with the language.

This article has some performance comparisons between Crystal and Elixir in the comments: https://blog.codeship.com/an-introduction-to-crystal-fast-as...