Groundhog is pretty awesome[1]. Persistent also works, but it does some wonky stuff on SQL databases. Acid-state is really neat! Of course, there's stuff like postgresql-simple, but that's not very type safe.
Did not know about Groundhog, thanks. Looking into the docs Groundhog does not support joins (same deal with Persistent), which I'd say is a deal breaker for most (non-trivial) applications.
Acid-state is a different beast entirely, seems to be similar to Clojure's Datomic.
That leaves us with Esqueleto for real world type safe database access (with no SQL Server or Oracle support).
I want to jump ship from Scala to Haskell but there are some gaps to be filled yet before leaving the batteries included Java ecosystem.
Do you have any experience with Database Supported Haskell (DSH) [1]? I've just recently found it and it seems very nice. I didn't have the time to test it though.
[1]https://www.fpcomplete.com/school/to-infinity-and-beyond/pic...
Edit: Also, esqueleto has a pretty okay looking hackage page[2], but I've never used esqueleto, so I don't really know.
[2]http://hackage.haskell.org/package/esqueleto