> Go – very little hidden, everything in text on the page, LLMs are great. Java, similar. But writing Haskell, it's pretty bad, Erlang, not wonderful. You need much more of a mental model for those languages.

I don't think that follows. It could just be that there is way more Go and Java code to train on than Haskell and Erlang. Haskell's terseness and symbol-named operators probably don't help either.