Whoa... how on earth does this work? How does it interpret the sections as Reader monads? > That's a job for the reader monad. > > > Lambda Fu, form 53 - silent reader of truth > > import Control.Monad > import Control.Monad.Reader > > filter (liftM2 (&&) (< 0.5) (> -0.5)) xs > > > > Regards, > apfelmus