Just pick which parts of your data structures you want indexed using an
easy to use template-haskell function.  Spare yourself the need to
write, run, and maintain code that marshalls your data to/from an
external relational database just for efficient queries.  The
happstack-ixset relies on generics and TH to spare you the boilerplate
normally required for such tasks.

WWW:	http://happstack.com/