According to http://www.cs.chalmers.se/~rjmh/QuickCheck/ Quickcheck is distributed with ghc. I seem to recall this came with ghc 6.4. After upgrading to ghc 6.6, however, I don't seem to have it anymore. Do I need to install it from cabal? If so, I assume this would start by wgetting http://hackage.haskell.org/packages/archive/QuickCheck/QuickCheck-1.0.tar.gz and building that. thomas. thartman@linodewhyou:~/learning/haskell/lists$ ghci ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done. Prelude> :m Control.Monad Prelude Control.Monad> :m Test.QuickCheck Could not find module `Test.QuickCheck': Use -v to see a list of the files searched for. Prelude Control.Monad> :m Quickcheck Could not find module `Quickcheck': Use -v to see a list of the files searched for. Prelude Control.Monad>