Not for me. I've gone back and forth between projects that required functional languages, and projects that didn't across different companies. Bad code is bad code no matter what language it's written in. What makes me love my day job is whether I have the ability to make it better, and if those that work with me are aligned in wanting to do so.

I think practitioners of functional languages get a little preachy when really, exposure to functional languages should just be assumed to be part of the basic training of any engineer. It's a tool and as good as it is for some things, it's absolutely awful for others.

What are functional languages, as a group, "absolutely awful" at?

Low level code. Drivers, interfacing on COM/serial/USB ports, graphics programming or anything that requires more finely tuned data structures you have to manage yourself, low latency work where you can't afford to have a random GC happen at a bad point in the run loop...

Lots of things.

But then you'd be ready to start on a new day job with tools and concepts you really enjoy using ;-)

It's not just a matter of syntax and such but a whole new way of thinking - specifically immutability, functional aspect, using lightweight processes, hot code loading, sane handling of crashes and restart, easy tracing, etc. allow approaching and solving problem in whole new ways that is often a lot more efficient (both performance wise but also operations-wise).

Even if you switch to using other language you'd find yourself trying to apply some of these techniques so it is a useful set of things to learn about.

I was never able to find work with Clojure. Always had endless jobs available for JS though.

But agreed, it's still worth the effort to learn as many new languages as possible. It will make you a better programmer.

Haskell and Erlang were particularly eye-opening for me, but Scheme/Clojure was a great entry point into FP.

I got lucky and found an Erlang one. In general there are a lot less of those than other jobs. It's kind of a double-edged sword, there are lot of Java / JS / Python / C++ jobs but there are also a lot of programmers who apply for those.

If I had found an Elixir job I would have taken that as well, most of the harder to grok concepts are pretty much the same between the languages. And I do prefer Erlang I find it simpler so far.

Not necessary. Boring CRUD apps are similarly boring in Elixir/Erlang/Haskell/Ocaml as well...