Don't use functional programming languages
You aren’t God.
You are a programmer. Use a language that maps to how you think. That’s fast.
Using an unnatural language? That’s slow.
Plus of course python has way more library support, stackoverflow support, reddit support, friend support, better gpt support, and programmer market liquidity.
JaneStreet of Ocaml fame has had to write everything themselves in Ocaml…because nobody else wrote it in Ocaml. That’s slow. Yes they’re good, but not because of Ocaml. At best, you could say a Prop shop needs to write everything anyways for security reasons so its less slow, but I doubt even that’s true.
Now functional programming ideas. Like map, filter, reduce. Those are great, go study them. I highly recommend SICP, posibly the greatest book on programming ever written. It uses LISP, but only as a teaching device to express the books ideas.
And now, in JavaScript (haven’t read it)
Haskell isn't the only functional language... (I agree, Haskell has a limited ecosystem). What about Scala? Runs on the JVM, totally interoperable with any Java library, and a rich ecosystem. I spent about oh... close to a decade loving Scala and pushing back against anything else.
Not that I'd point to Scala as a model citizen of functional programming. Letting programmers freely mix Java and Scala, functional and non-functional... I've seen some really scary messes come of that...! Still it was my favorite for most of a decade.
Or, Elixir. Elegant, powerful, one of the oldest and most robust runtimes out there (built on Erlang, which dates back to the 80's). Rock solid, efficient, and pure... and a very rich ecosystem.
I've been doing functional programming for so long anything else is just painful. I can't think procedurally anymore, at least not without grumbling about it full time. :) But map, filter, reduce... if that's the extent of functional programming you've experienced, I think you're missing the bigger picture. The idea of programming without side effects. Using recursion for everything. True language-level pattern matching... it's elegant. Just like a pure equation.
If you haven't played with Elixir give it a shot. It might change your opinion.