On Sat, May 1, 2010 at 3:33 PM, Ivan Lazar Miljenovic <ivan.miljenovic at gmail.com> wrote: > You need to know which library they're in. You can use the ghc-pkg tool to do this: $ ghc-pkg find-module Control.Monad.State /usr/lib/ghc-6.12.1/package.conf.d monads-fd-0.0.0.1 mtl-1.1.0.2