Hi,

I am now releasing Data.Proposition. This library handles
propositions, logical formulae consisting of literals without
quantification. It automatically simplifies a proposition as it is
constructed using simple rules provided by the programmer.
Implementations of propositions in terms of an abstract syntax tree
and as a Binary Decision Diagram (BDD) are provided. A standard
interface is provided for all propositions.

Website: http://www-users.cs.york.ac.uk/~ndm/proposition/
Darcs: darcs get --partial http://www.cs.york.ac.uk/fp/darcs/proposition/
Haddock: http://www.cs.york.ac.uk/fp/haddock/proposition/Data-Proposition.html

The Haddock documentation also has a short example in it.

This library is used substantially in the tool I have developed for my
PhD, and has been extensively tested.

Thanks

Neil