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For me, Erlang was the ladder to functional programming. Once I’ve mastered Erlang to be able to write gossiperl (http://gossiperl.com, not maintained in a long time), all immutable programming became easy. Maps, flat maps, recursion, no side effects, all became clear.

After Erlang, I’ve enjoyed Scala a lot. Especially Akka.

I do tons of go now and when I need actors in go (not very often because channels are rather straightforward), I use proto.actor: https://github.com/AsynkronIT/protoactor-go.

Erlang is awesome. I can definitely recommend the “Designing for scalability with Erlang/OTP”: https://www.oreilly.com/library/view/designing-for-scalabili.... This is the book which finally made me “get it”.