alt Hacker NewsHaskell would be my vote, and Rust too, actually, both because of their very strong type systems. The type system lets you very quickly figure out what something is before you figure out what something does, and it turns out that separating those two concerns as hard as those two languages do often results in doing the whole one-two punch faster.
Haskell does not qualify for a large training set, though. (Nor for readability in my opinion)
I think I have never seen haskell software made wih LLM's but well, aside from university, I have not seen Haskell code at all. (Also Haskell purists I would associate with people who avoid LLM's)
I would rather go with Rust given these choices.
But I have good results with typescript (or javascript for simpler things). Really large set of examples. Tools optimized for it, agents debugging in the browser works allmost out of the box. And well, a elaborate typesystem.