This is QuickCheck 2, a library for random testing of program properties. Install it in the usual way: $ cabal install The quickcheck-instances [1] companion package provides instances for types in Haskell Platform packages at the cost of additional dependencies. The make-hugs script makes a Hugs-compatible version of QuickCheck. It may also be useful for other non-GHC implementations. [1]: http://hackage.haskell.org/package/quickcheck-instances