I spent around 15 years building web backends in PHP (from your grandma’s herbal cosmetics to a 50 million exit)
All my backends are currently written in haskell, usually with elm on the frontend.
This is largely due to my subjective but, negative experience with dynamic and/or object-oriented languages, and the discovery of abstract data types and their direct connections to logic (i.e. a product type is a logical AND, a sum type is logical OR and a function type is just a logical implication etc.)
I’m still keeping rust in my back-pocket though, for those times when I exhaust the latency guarantees of haskell; but compared to php/python/ruby, haskell is a walkover win.
This does require you to have a decent onboarding plan, but with Elm as the first step it’s trivial to get people hooked on haskell, since its type classes provide an extreme improvement over what Elm provides. And you essentially get the motivation for the fundamental type classes (functor, applicative, monad) for free, since people have been using all the abstractions discretely in Elm, and suddenly get them all connected in a neat package in haskell.