> ghci
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 6.5, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package base-1.0 ... linking ... done.
Prelude> :m Control.Monad.Instances Control.Monad.Reader
Prelude Control.Monad.Reader Control.Monad.Instances> :i Monad
class Monad m where
  (>>=) :: m a -> (a -> m b) -> m b
  (>>) :: m a -> m b -> m b
  return :: a -> m a
  fail :: String -> m a
        -- Imported from GHC.Base
instance Monad Maybe -- Imported from Data.Maybe
instance Monad ((->) r) -- Imported from Control.Monad.Instances
instance (Monad m) => Monad (ReaderT r m)
  -- Imported from Control.Monad.Reader
instance Monad (Reader r) -- Imported from Control.Monad.Reader
instance Monad IO -- Imported from GHC.IOBase
instance Monad [] -- Imported from GHC.Base
Prelude Control.Monad.Reader Control.Monad.Instances>