Ah, working in the 80s with Lisp and AI, that's pretty awesome! Thank you for sharing this, but my functional mind would just ask...how have you liked Haskell compared to any of the Lisp(s)?
To answer your question directly, Haskell is too hard for me :-( I'm a pretty crap programmer - I was a professional back when you didn't have to be GOOD at it, you just had to be able to do it!
More interestingly, I wonder whether Haskell has, or lacks, the careful choice of orthogonal features that I love in a language.
You might try OCaml. Haskell (like Common Lisp) is more a big soup of features than a carefully chosen orthogonal set. Standard ML (SML) is maybe more orthogonal than OCaml, but less used in practice.
More interestingly, I wonder whether Haskell has, or lacks, the careful choice of orthogonal features that I love in a language.