Checkers [1] is a library for reusable QuickCheck properties, particularly for standard type classes (class laws and class morphisms [2]). Most of Reactive [3] can be specified and tested using just these properties. Also lots of support for randomly generating data values (thanks to Thomas Davie). Please share any comments & suggestions on the discussion (talk) page at [1]. You can configure, build, and install all in the usual way with Cabal commands. runhaskell Setup.lhs configure runhaskell Setup.lhs build runhaskell Setup.lhs install References: [1] http://haskell.org/haskellwiki/checkers [2] http://conal.net/papers/simply-reactive [3] http://haskell.org/haskellwiki/reactive