> I personally am not really interested in rewriting AQL at all, but rewriting AQL in Haskell would be a fun project for someone.

I came here to learn category theory. In particular, how to leverage it better in Haskell.

If you want to help me learn, I am happy to explore AQL in Haskell. But I'll need your help, since I'm not clever enough to understand translate Java code.

I can try to fix your broken Haskell code. What's next after that? Try to do a Grothendieck construction?