Having learnt Ruby and a bit of Erlang, I'm interested in Elixir so I fire this tangential question:
How would you recommend to learn Elixir? And a follow-up: some ideas for personal Elixir-based projects?
The official Elixir guide runs you through the basics all the way to the more complicated concepts: https://elixir-lang.org/getting-started/introduction.html
For a fun and complicated Elixir project, you could try building a process pipeline that uses all your CPU cores to crunch some data. Look into Elixir Flow [0], for example, which has a fun guide on counting words in a file.
Elixir & Phoenix work well for web projects. The Phoenix framework is very well built on a solid core; it differs from other frameworks in that it feels more like a library, rather than a monstrosity that forces you to bend your application to its requirements. There's a lot of nice utilities that are easily pluggable and writing "plugs" yourself is rather simple as well. Phoenix has served me well when building microservices, too.
Elixir's biggest deficiency is that it does not have a proper type system. There is a very basic one, but it doesn't really help a whole lot. When working with Elixir, a type system is something that I miss the most. The way that Erlang & Beam VM are built makes it slightly easier to deal with errors at run-time, but catching stupidities at compile-time would still be immensely valuable.