[Insanity]

I'm not sure if I would consider myself 'really good', but in a previous life I have used Haskell professionally, albeit only for small-scale applications (alongside a Scala codebase).

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.