Amazing for:

- Web -> Phoenix ( https://www.phoenixframework.org/ )

- Parallel data processing (like scrapers, ETLs, etc...) -> GenStage / Flow / Broadway ( https://hexdocs.pm/gen_stage/GenStage.html )

- IOT -> Nerves ( https://www.nerves-project.org/ )

Soon:

Mobile Apps -> Elixir Desktop ( https://github.com/elixir-desktop/desktop )

ML -> NX ( https://github.com/elixir-nx )

Presumably, concurrency and fault-tolerance?

concurrency, general purpose computing, excellent developer ergonomics and tooling. Great community.

> general purpose computing

As a huge Erlang fan, I’m not certain I’d say “general purpose computing” is a strength of it though.

Python and Ruby are general purpose computer programing languages. Is there anything they do extremely well that erlang/elixir, can't?

From the following:

https://www.erlang.org/faq/introduction.html

    1 What is Erlang
    1.1  In a nutshell, what is Erlang?
    Erlang is a general-purpose programming language and runtime environment. 
    Erlang has built-in support for concurrency, distribution and fault tolerance.

server side computing is probably my take - it does handle more than that, eg. nerves but server side computing is the big win.

another example of Erlang for concurrency -> MQTT server (i.e., https://github.com/emqx/emqtt)