Can anyone suggest a good constraint library for Haskell?

I've started learning about开发者_运维问答 Constraint programming and I feel it is something that would work well with Haskell (also I enjoy using Haskell).

Are there any mature constraint frameworks for Haskell?

You can do pure logic programing with LogicT.

There's also plenty of interfaces to SAT/SMT solvers. I wrote yices-easy in order to learn more about SMT-based constraint programming.