Using Elixir and Elm at my day job.

Coming from a more Python/Java/PHP/JS background, Elixir was a lot easier to pick up and doesn't frustrate me as much. Most of the remaining scary bits involve concurrency and process supervision trees.

Macros are powerful, but also easy to use in a way that makes everything hard to debug. For those unfamiliar with them, it's a bit like a function except any expressions you call it with are not evaluated first, but arrive as metadata that can be used to assemble and run new code.