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