Do you agree there's a spectrum here (with stuff like Brainfuck being on one end)? If so, I think it's a valid question to ask about a language.
Maybe Haskell is just as easy as Java, maybe it is slightly more difficult, maybe it is slightly easier.
For example, you can't really do embedded DSL's in Java, but you can in Haskell. If my coworker had used that and I had not yet had time to study it, could it be I would struggle a bit more with grokking his code? I dunno, at least to me it seems possible, but since I've not really used Haskell it might be entirely different.