I am curious about people's experiences who are really good and use the following languages regularly: C, OCaml / Haskell (although Haskell feels way different to me), Common Lisp (or any Lisp), Erlang / Elixir, and Forth / Factor. To me, these languages seem to be significantly different. Edit (before I will not be able to do so): thank you for everyone's replies (in advance, too)!
For what it's worth, I actually really enjoyed using Haskell. It did force me to think differently about problems and I feel that this has carried over to writing cleaner code in non-functional languages like Go/Java. I liked it so much so that I wrote a book about writing functional code in Go along with a supporting OSS library.
Would I recommend it for really large-scale applications? Maybe not, because you'd want a mature ecosystem with a lot of support, and the secondary issue is that you want to have a large candidate pool when hiring people.
Small disclaimer though, the last time I used Haskell professionally was in 2018-2019, so it's not 'recent' experience.