I can't speak for Erlang, but I use Elixir and not primarily for the concurrency model. I just really like the language (and it's functional-but-accessible approach), relative speed (compared to Ruby), fault-tolerance, community.

In particular the fault tolerance and process-based approach is just awesome. I regularly find myself writing code with just the 'happy path' (and only the obvious error handling), which just feels a ton nicer than the more defensive approach I generally take in other languages.

The tooling around the language is also really nice.

I can’t speak for Elixir, but I love Erlang for exactly those reasons.

Ha, I do suppose all those count for Erlang too. I get the impression that syntax-wise it's very much a matter of taste, although for some Elixir's macros might make it preferable.

You’re gonna lose some of those features also on Lambda. The speed is gonna be subject to the time to cold start the VM, the times for this are not great for the JVM or .net runtimes.

Erlang has way more advantages than its concurrency model but none of these can be used in a lambda I guess. It is just good to have diversity, many will disagree but you get used to love the Erlang syntax and being able to run it in AWS lambda is kind of nice to not change the stack.

I wrote a Lambda function that does lots of concurrent checks and then reports back the results at the end of its execution. Concurrency works fine for my usecase.

Great to hear, did you use gen_server and supervisors or just spawn/3?