I've tried using Erlang once or twice. I inherited an open source project written in it, wanted to maintain it a bit but I couldn't make head nor tail of it, and I'm a good programmer (but very busy with other things). There were too many things to learn to get started working with the Erlang ecosystem and I didn't really have the time.

I didn't find any good tools.

The error messages were obtuse.

I didn't understand how simple shit like configuration files worked. I couldn't find any place where the file was 'opened' from code. I chalked it up to the magic of the underlying framework or whatever.