The advantage of Haskell is higher quality code with fewer bugs even when you write fewer unit tests. The advantage is the same whether humans write the code or AI writes it.

This might not be noticeable if you only write short programs: if the human can put the entire program in the head or if the AI can keep the whole thing in the context window. It matters much more when the program gets bigger.

Fewer bugs is such a wild claim. Especially since study after study has shown that to be wishful thinking. Haskell apps have just as many bugs in general as anything else.