I wonder what you would get if you crossbred Postgres and Haskell, for example.

Basically adding indexed tables to the Haskell data model, maybe? Some hybrid of relational tables and algebraic data types?

Sometimes even when writing compilers I’ve had a feeling that relational queries and update would be really nice.

There seem to be four main data paradigms: (1) objects with pointers, (2) algebraic data types, (3) relational tables, and (4) Prolog-style clauses.

Some Haskell programs seem to partially reimplement 1, 3, or 4 using 2...