Thank you very much. The first reason is that I program exclusively using functional programming. That said, the choice is somehow limited. I have very good experiences with Elixir. Statelessly streaming uncritical data to a client is a perfect fit for Erlang's/Elixir's "let-it-fail"-paradigm. If the web-socket crashes server-side just let the supervisor respawn it one-for-one, there is no permanent state. I hope that makes sense.