[tathougies]

Interestingly enough, Haskell has an inefficient version of the relational algebra builtin. The default monad instance for list provides all the semantics you need. Beam steels from this intuition. Most Haskell developers are familiar with using the list monad, so things come somewhat naturally.

The types go a bit crazier than lists internally, but the aim is minimize the times manual intervention is required