[jfaucett]

"It's entirely possible to understand that the programming languages you know aren't as important as what you've built along with your knowledge of software engineering and computer science fundamentals, and yet still want input on the next PL you'll learn in your free time."

I get what you mean, but it still makes very little sense to me. If he had said I want to make a client/server chat system, then we could make a real suggestions between elixir and scala. He also wants to be able to write concurrent systems, the best way to do this is of course write concurrent systems, not learning concurrent lang structs in scala or elixir. Only when you write a distributed system are you going to encounter all the networking and data integrity problems that arise at those lower levels and these are the things that are important to know and will give him reasons to choose elixir or scala or erlang or golang or whatever works best for him while building that.