Quickly going through https://learnyousomeerlang.com/ to discover OTP, processes and supervisor and you're ready to code.
After learning Erlang, and writing some basic stuff with it, I discovered Elixir and had nothing to learn except:
- "defmodule" instead of "package"
- "@callback" / "@behaviour" instead of "callback" / "behaviour"
- ":an_atom" instead of "an_atom"