diff --git a/Control/Applicative/Backwards.hs b/Control/Applicative/Backwards.hs
--- a/Control/Applicative/Backwards.hs
+++ b/Control/Applicative/Backwards.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Russell O'Connor 2009
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  libraries@haskell.org
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Applicative/Lift.hs b/Control/Applicative/Lift.hs
--- a/Control/Applicative/Lift.hs
+++ b/Control/Applicative/Lift.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Ross Paterson 2010
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -96,7 +96,7 @@
 
 -- | Apply a transformation to the other computation.
 mapLift :: (f a -> g a) -> Lift f a -> Lift g a
-mapLift f (Pure x) = Pure x
+mapLift _ (Pure x) = Pure x
 mapLift f (Other e) = Other (f e)
 
 -- | An applicative functor that collects a monoid (e.g. lists) of errors.
@@ -125,5 +125,5 @@
 runErrors (Pure x) = Right x
 
 -- | Report an error.
-failure :: (Monoid e) => e -> Errors e a
+failure :: e -> Errors e a
 failure e = Other (Constant e)
diff --git a/Control/Monad/IO/Class.hs b/Control/Monad/IO/Class.hs
--- a/Control/Monad/IO/Class.hs
+++ b/Control/Monad/IO/Class.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Signatures.hs b/Control/Monad/Signatures.hs
--- a/Control/Monad/Signatures.hs
+++ b/Control/Monad/Signatures.hs
@@ -4,11 +4,12 @@
 -- Copyright   :  (c) Ross Paterson 2012
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
 -- Signatures for monad operations that require specialized lifting.
+-- Each signature has a uniformity property that the lifting should satisfy.
 -----------------------------------------------------------------------------
 
 module Control.Monad.Signatures (
@@ -17,16 +18,32 @@
 
 -- | Signature of the @callCC@ operation,
 -- introduced in "Control.Monad.Trans.Cont".
+-- Any lifting function @liftCallCC@ should satisfy
+--
+-- * @'lift' (f k) = f' ('lift' . k) => 'lift' (cf f) = liftCallCC cf f'@
+--
 type CallCC m a b = ((a -> m b) -> m a) -> m a
 
 -- | Signature of the @catchE@ operation,
 -- introduced in "Control.Monad.Trans.Except".
+-- Any lifting function @liftCatch@ should satisfy
+--
+-- * @'lift' (cf m f) = liftCatch ('lift' . cf) ('lift' f)@
+--
 type Catch e m a = m a -> (e -> m a) -> m a
 
 -- | Signature of the @listen@ operation,
 -- introduced in "Control.Monad.Trans.Writer".
+-- Any lifting function @liftListen@ should satisfy
+--
+-- * @'lift' . liftListen = liftListen . 'lift'@
+--
 type Listen w m a = m a -> m (a, w)
 
 -- | Signature of the @pass@ operation,
 -- introduced in "Control.Monad.Trans.Writer".
+-- Any lifting function @liftPass@ should satisfy
+--
+-- * @'lift' . liftPass = liftPass . 'lift'@
+--
 type Pass w m a =  m (a, w -> w) -> m a
diff --git a/Control/Monad/Trans/Class.hs b/Control/Monad/Trans/Class.hs
--- a/Control/Monad/Trans/Class.hs
+++ b/Control/Monad/Trans/Class.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -79,7 +79,8 @@
 In a sequence of monad transformers, most of these operations.can be
 lifted through other transformers using 'lift' or the @map@/XXX/@T@
 combinator, but a few with more complex type signatures require
-specialized lifting combinators, called @lift@/Op/.
+specialized lifting combinators, called @lift@/Op/
+(see "Control.Monad.Signatures").
 -}
 
 {- $strict
diff --git a/Control/Monad/Trans/Cont.hs b/Control/Monad/Trans/Cont.hs
--- a/Control/Monad/Trans/Cont.hs
+++ b/Control/Monad/Trans/Cont.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) The University of Glasgow 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -66,9 +66,10 @@
 
 -- | The result of running a CPS computation with a given final continuation.
 -- (The inverse of 'cont')
-runCont :: Cont r a	-- ^ continuation computation (@Cont@).
-    -> (a -> r)		-- ^ the final continuation, which produces
-			-- the final result (often 'id').
+runCont
+    :: Cont r a         -- ^ continuation computation (@Cont@).
+    -> (a -> r)         -- ^ the final continuation, which produces
+                        -- the final result (often 'id').
     -> r
 runCont m k = runIdentity (runContT m (Identity . k))
 
diff --git a/Control/Monad/Trans/Error.hs b/Control/Monad/Trans/Error.hs
--- a/Control/Monad/Trans/Error.hs
+++ b/Control/Monad/Trans/Error.hs
@@ -11,7 +11,7 @@
 --                (c) Andriy Palamarchuk 2006
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -230,7 +230,7 @@
         Right r -> r
         _       -> error "empty mfix argument"
 
-instance (Error e) => MonadTrans (ErrorT e) where
+instance MonadTrans (ErrorT e) where
     lift m = ErrorT $ do
         a <- m
         return (Right a)
@@ -243,7 +243,7 @@
 -- * @'runErrorT' ('throwError' e) = 'return' ('Left' e)@
 --
 -- * @'throwError' e >>= m = 'throwError' e@
-throwError :: (Monad m, Error e) => e -> ErrorT e m a
+throwError :: (Monad m) => e -> ErrorT e m a
 throwError l = ErrorT $ return (Left l)
 
 -- | Handle an error.
@@ -251,7 +251,7 @@
 -- * @'catchError' h ('lift' m) = 'lift' m@
 --
 -- * @'catchError' h ('throwError' e) = h e@
-catchError :: (Monad m, Error e) =>
+catchError :: (Monad m) =>
     ErrorT e m a                -- ^ the inner computation
     -> (e -> ErrorT e m a)      -- ^ a handler for errors in the inner
                                 -- computation
diff --git a/Control/Monad/Trans/Except.hs b/Control/Monad/Trans/Except.hs
--- a/Control/Monad/Trans/Except.hs
+++ b/Control/Monad/Trans/Except.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (C) 2013 Ross Paterson
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -62,7 +62,7 @@
 -- Computations are either exceptions or normal values.
 --
 -- The 'return' function returns a normal value, while @>>=@ exits on
--- the first exception.  For a variant that continies after an error
+-- the first exception.  For a variant that continues after an error
 -- and collects all the errors, see 'Control.Applicative.Lift.Errors'.
 type Except e = ExceptT e Identity
 
diff --git a/Control/Monad/Trans/Identity.hs b/Control/Monad/Trans/Identity.hs
--- a/Control/Monad/Trans/Identity.hs
+++ b/Control/Monad/Trans/Identity.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) 2007 Magnus Therning
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/List.hs b/Control/Monad/Trans/List.hs
--- a/Control/Monad/Trans/List.hs
+++ b/Control/Monad/Trans/List.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/Maybe.hs b/Control/Monad/Trans/Maybe.hs
--- a/Control/Monad/Trans/Maybe.hs
+++ b/Control/Monad/Trans/Maybe.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) 2007 Yitzak Gale, Eric Kidd
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/RWS.hs b/Control/Monad/Trans/RWS.hs
--- a/Control/Monad/Trans/RWS.hs
+++ b/Control/Monad/Trans/RWS.hs
@@ -5,7 +5,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/RWS/Lazy.hs b/Control/Monad/Trans/RWS/Lazy.hs
--- a/Control/Monad/Trans/RWS/Lazy.hs
+++ b/Control/Monad/Trans/RWS/Lazy.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -205,7 +205,7 @@
 -- | Execute a computation in a modified environment
 --
 -- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@
-local :: (Monoid w, Monad m) => (r -> r) -> RWST r w s m a -> RWST r w s m a
+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a
 local f m = RWST $ \ r s -> runRWST m (f r) s
 
 -- | Retrieve a function of the current environment.
@@ -222,14 +222,14 @@
 writer (a, w) = RWST $ \ _ s -> return (a, s, w)
 
 -- | @'tell' w@ is an action that produces the output @w@.
-tell :: (Monoid w, Monad m) => w -> RWST r w s m ()
+tell :: (Monad m) => w -> RWST r w s m ()
 tell w = RWST $ \ _ s -> return ((),s,w)
 
 -- | @'listen' m@ is an action that executes the action @m@ and adds its
 -- output to the value of the computation.
 --
 -- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@
-listen :: (Monoid w, Monad m) => RWST r w s m a -> RWST r w s m (a, w)
+listen :: (Monad m) => RWST r w s m a -> RWST r w s m (a, w)
 listen m = RWST $ \ r s -> do
     ~(a, s', w) <- runRWST m r s
     return ((a, w), s', w)
@@ -240,7 +240,7 @@
 -- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
 --
 -- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@
-listens :: (Monoid w, Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
+listens :: (Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
 listens f m = RWST $ \ r s -> do
     ~(a, s', w) <- runRWST m r s
     return ((a, f w), s', w)
@@ -250,7 +250,7 @@
 -- to the output.
 --
 -- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@
-pass :: (Monoid w, Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
+pass :: (Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
 pass m = RWST $ \ r s -> do
     ~((a, f), s', w) <- runRWST m r s
     return (a, s', f w)
@@ -262,7 +262,7 @@
 -- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
 --
 -- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@
-censor :: (Monoid w, Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
+censor :: (Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
 censor f m = RWST $ \ r s -> do
     ~(a, s', w) <- runRWST m r s
     return (a, s', f w)
diff --git a/Control/Monad/Trans/RWS/Strict.hs b/Control/Monad/Trans/RWS/Strict.hs
--- a/Control/Monad/Trans/RWS/Strict.hs
+++ b/Control/Monad/Trans/RWS/Strict.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -205,7 +205,7 @@
 -- | Execute a computation in a modified environment
 --
 -- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@
-local :: (Monoid w, Monad m) => (r -> r) -> RWST r w s m a -> RWST r w s m a
+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a
 local f m = RWST $ \ r s -> runRWST m (f r) s
 
 -- | Retrieve a function of the current environment.
@@ -222,14 +222,14 @@
 writer (a, w) = RWST $ \ _ s -> return (a, s, w)
 
 -- | @'tell' w@ is an action that produces the output @w@.
-tell :: (Monoid w, Monad m) => w -> RWST r w s m ()
+tell :: (Monad m) => w -> RWST r w s m ()
 tell w = RWST $ \ _ s -> return ((),s,w)
 
 -- | @'listen' m@ is an action that executes the action @m@ and adds its
 -- output to the value of the computation.
 --
 -- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@
-listen :: (Monoid w, Monad m) => RWST r w s m a -> RWST r w s m (a, w)
+listen :: (Monad m) => RWST r w s m a -> RWST r w s m (a, w)
 listen m = RWST $ \ r s -> do
     (a, s', w) <- runRWST m r s
     return ((a, w), s', w)
@@ -240,7 +240,7 @@
 -- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
 --
 -- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@
-listens :: (Monoid w, Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
+listens :: (Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
 listens f m = RWST $ \ r s -> do
     (a, s', w) <- runRWST m r s
     return ((a, f w), s', w)
@@ -250,7 +250,7 @@
 -- to the output.
 --
 -- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@
-pass :: (Monoid w, Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
+pass :: (Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
 pass m = RWST $ \ r s -> do
     ((a, f), s', w) <- runRWST m r s
     return (a, s', f w)
@@ -262,7 +262,7 @@
 -- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
 --
 -- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@
-censor :: (Monoid w, Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
+censor :: (Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
 censor f m = RWST $ \ r s -> do
     (a, s', w) <- runRWST m r s
     return (a, s', f w)
diff --git a/Control/Monad/Trans/Reader.hs b/Control/Monad/Trans/Reader.hs
--- a/Control/Monad/Trans/Reader.hs
+++ b/Control/Monad/Trans/Reader.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -66,8 +66,9 @@
 
 -- | Runs a @Reader@ and extracts the final value from it.
 -- (The inverse of 'reader'.)
-runReader :: Reader r a		-- ^ A @Reader@ to run.
-    -> r			-- ^ An initial environment.
+runReader
+     :: Reader r a      -- ^ A @Reader@ to run.
+    -> r                -- ^ An initial environment.
     -> a
 runReader m = runIdentity . runReaderT m
 
@@ -152,8 +153,8 @@
 -- (a specialization of 'withReaderT').
 --
 -- * @'runReaderT' ('local' f m) = 'runReaderT' m . f@
-local :: (Monad m)
-    => (r -> r)         -- ^ The function to modify the environment.
+local
+    :: (r -> r)         -- ^ The function to modify the environment.
     -> ReaderT r m a    -- ^ Computation to run in the modified environment.
     -> ReaderT r m a
 local = withReaderT
diff --git a/Control/Monad/Trans/State.hs b/Control/Monad/Trans/State.hs
--- a/Control/Monad/Trans/State.hs
+++ b/Control/Monad/Trans/State.hs
@@ -5,7 +5,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/State/Lazy.hs b/Control/Monad/Trans/State/Lazy.hs
--- a/Control/Monad/Trans/State/Lazy.hs
+++ b/Control/Monad/Trans/State/Lazy.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -252,7 +252,7 @@
 
 -- | In-situ lifting of a @callCC@ operation to the new monad.
 -- This version uses the current state on entering the continuation.
--- It does not satisfy the laws of a monad transformer.
+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").
 liftCallCC' :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
 liftCallCC' callCC f = StateT $ \ s ->
     callCC $ \ c ->
diff --git a/Control/Monad/Trans/State/Strict.hs b/Control/Monad/Trans/State/Strict.hs
--- a/Control/Monad/Trans/State/Strict.hs
+++ b/Control/Monad/Trans/State/Strict.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -249,7 +249,7 @@
 
 -- | In-situ lifting of a @callCC@ operation to the new monad.
 -- This version uses the current state on entering the continuation.
--- It does not satisfy the laws of a monad transformer.
+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").
 liftCallCC' :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
 liftCallCC' callCC f = StateT $ \ s ->
     callCC $ \ c ->
diff --git a/Control/Monad/Trans/Writer.hs b/Control/Monad/Trans/Writer.hs
--- a/Control/Monad/Trans/Writer.hs
+++ b/Control/Monad/Trans/Writer.hs
@@ -5,7 +5,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Control/Monad/Trans/Writer/Lazy.hs b/Control/Monad/Trans/Writer/Lazy.hs
--- a/Control/Monad/Trans/Writer/Lazy.hs
+++ b/Control/Monad/Trans/Writer/Lazy.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -175,14 +175,14 @@
     liftIO = lift . liftIO
 
 -- | @'tell' w@ is an action that produces the output @w@.
-tell :: (Monoid w, Monad m) => w -> WriterT w m ()
+tell :: (Monad m) => w -> WriterT w m ()
 tell w = writer ((), w)
 
 -- | @'listen' m@ is an action that executes the action @m@ and adds its
 -- output to the value of the computation.
 --
 -- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@
-listen :: (Monoid w, Monad m) => WriterT w m a -> WriterT w m (a, w)
+listen :: (Monad m) => WriterT w m a -> WriterT w m (a, w)
 listen m = WriterT $ do
     ~(a, w) <- runWriterT m
     return ((a, w), w)
@@ -193,7 +193,7 @@
 -- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
 --
 -- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@
-listens :: (Monoid w, Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
+listens :: (Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
 listens f m = WriterT $ do
     ~(a, w) <- runWriterT m
     return ((a, f w), w)
@@ -203,7 +203,7 @@
 -- to the output.
 --
 -- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@
-pass :: (Monoid w, Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
+pass :: (Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
 pass m = WriterT $ do
     ~((a, f), w) <- runWriterT m
     return (a, f w)
@@ -215,7 +215,7 @@
 -- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
 --
 -- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@
-censor :: (Monoid w, Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
+censor :: (Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
 censor f m = WriterT $ do
     ~(a, w) <- runWriterT m
     return (a, f w)
diff --git a/Control/Monad/Trans/Writer/Strict.hs b/Control/Monad/Trans/Writer/Strict.hs
--- a/Control/Monad/Trans/Writer/Strict.hs
+++ b/Control/Monad/Trans/Writer/Strict.hs
@@ -9,7 +9,7 @@
 --                (c) Oregon Graduate Institute of Science and Technology, 2001
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
@@ -178,14 +178,14 @@
     liftIO = lift . liftIO
 
 -- | @'tell' w@ is an action that produces the output @w@.
-tell :: (Monoid w, Monad m) => w -> WriterT w m ()
+tell :: (Monad m) => w -> WriterT w m ()
 tell w = writer ((), w)
 
 -- | @'listen' m@ is an action that executes the action @m@ and adds its
 -- output to the value of the computation.
 --
 -- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@
-listen :: (Monoid w, Monad m) => WriterT w m a -> WriterT w m (a, w)
+listen :: (Monad m) => WriterT w m a -> WriterT w m (a, w)
 listen m = WriterT $ do
     (a, w) <- runWriterT m
     return ((a, w), w)
@@ -196,7 +196,7 @@
 -- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
 --
 -- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@
-listens :: (Monoid w, Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
+listens :: (Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
 listens f m = WriterT $ do
     (a, w) <- runWriterT m
     return ((a, f w), w)
@@ -206,7 +206,7 @@
 -- to the output.
 --
 -- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@
-pass :: (Monoid w, Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
+pass :: (Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
 pass m = WriterT $ do
     ((a, f), w) <- runWriterT m
     return (a, f w)
@@ -218,7 +218,7 @@
 -- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
 --
 -- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@
-censor :: (Monoid w, Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
+censor :: (Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
 censor f m = WriterT $ do
     (a, w) <- runWriterT m
     return (a, f w)
diff --git a/Data/Functor/Classes.hs b/Data/Functor/Classes.hs
--- a/Data/Functor/Classes.hs
+++ b/Data/Functor/Classes.hs
@@ -8,11 +8,30 @@
 -- Copyright   :  (c) Ross Paterson 2013
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
--- Prelude classes, lifted to unary type constructors.
+-- Liftings of the Prelude classes 'Eq', 'Ord', 'Read' and 'Show' to
+-- unary type constructors.
+--
+-- These classes are needed to express the constraints on arguments of
+-- transformers in portable Haskell.  Thus for a new transformer @T@,
+-- one might write instances like
+--
+-- > instance (Eq1 f) => Eq (T f a) where ...
+-- > instance (Ord1 f) => Ord (T f a) where ...
+-- > instance (Read1 f) => Read (T f a) where ...
+-- > instance (Show1 f) => Show (T f a) where ...
+--
+-- If these instances can be defined, defining instances of the lifted
+-- classes is mechanical:
+--
+-- > instance (Eq1 f) => Eq1 (T f) where eq1 = (==)
+-- > instance (Ord1 f) => Ord1 (T f) where compare1 = compare
+-- > instance (Read1 f) => Read1 (T f) where readsPrec1 = readsPrec
+-- > instance (Show1 f) => Show1 (T f) where showsPrec1 = showsPrec
+--
 -----------------------------------------------------------------------------
 
 module Data.Functor.Classes (
@@ -22,6 +41,7 @@
     Read1(..),
     Show1(..),
     -- * Helper functions
+    -- $example
     readsData,
     readsUnary,
     readsUnary1,
@@ -31,7 +51,12 @@
     showsBinary1,
   ) where
 
-import Data.Functor.Identity
+#if MIN_VERSION_base(4,8,0)
+import Control.Applicative (Const)
+#else
+import Control.Applicative (Const(Const))
+#endif
+import Data.Functor.Identity (Identity)
 
 -- | Lifting of the 'Eq' class to unary type constructors.
 class Eq1 f where
@@ -71,13 +96,30 @@
 instance (Read a) => Read1 (Either a) where readsPrec1 = readsPrec
 instance (Show a) => Show1 (Either a) where showsPrec1 = showsPrec
 
--- Instances for other functors
+-- Instances for other functors defined in the base package
 
 instance Eq1 Identity where eq1 = (==)
 instance Ord1 Identity where compare1 = compare
 instance Read1 Identity where readsPrec1 = readsPrec
 instance Show1 Identity where showsPrec1 = showsPrec
 
+#if MIN_VERSION_base(4,8,0)
+-- Eq, etc instances for Const were introduced in base-4.8
+instance (Eq a) => Eq1 (Const a) where eq1 = (==)
+instance (Ord a) => Ord1 (Const a) where compare1 = compare
+instance (Read a) => Read1 (Const a) where readsPrec1 = readsPrec
+instance (Show a) => Show1 (Const a) where showsPrec1 = showsPrec
+#else
+instance (Eq a) => Eq1 (Const a) where
+    eq1 (Const x) (Const y) = x == y
+instance (Ord a) => Ord1 (Const a) where
+    compare1 (Const x) (Const y) = compare x y
+instance (Read a) => Read1 (Const a) where
+    readsPrec1 = readsData $ readsUnary "Const" Const
+instance (Show a) => Show1 (Const a) where
+    showsPrec1 d (Const x) = showsUnary "Const" d x
+#endif
+
 -- Building blocks
 
 -- | @'readsData' p d@ is a parser for datatypes where each alternative
@@ -129,3 +171,26 @@
 showsBinary1 name d x y = showParen (d > 10) $
     showString name . showChar ' ' . showsPrec1 11 x .
         showChar ' ' . showsPrec1 11 y
+
+{- $example
+These functions can be used to assemble 'Read' and 'Show' instances for
+new algebraic types.  For example, given the definition
+
+> data T f a = Zero a | One (f a) | Two (f a) (f a)
+
+a standard 'Read' instance may be defined as
+
+> instance (Read1 f, Read a) => Read (T f a) where
+>     readsPrec = readsData $
+>         readsUnary "Zero" Zero `mappend`
+>         readsUnary1 "One" One `mappend`
+>         readsBinary1 "Two" Two
+
+and the corresponding 'Show' instance as
+
+> instance (Show1 f, Show a) => Show (T f a) where
+>     showsPrec d (Zero x) = showsUnary "Zero" d x
+>     showsPrec d (One x) = showsUnary1 "One" d x
+>     showsPrec d (Two x y) = showsBinary1 "Two" d x y
+
+-}
diff --git a/Data/Functor/Compose.hs b/Data/Functor/Compose.hs
--- a/Data/Functor/Compose.hs
+++ b/Data/Functor/Compose.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Ross Paterson 2010
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Data/Functor/Constant.hs b/Data/Functor/Constant.hs
--- a/Data/Functor/Constant.hs
+++ b/Data/Functor/Constant.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Ross Paterson 2010
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Data/Functor/Product.hs b/Data/Functor/Product.hs
--- a/Data/Functor/Product.hs
+++ b/Data/Functor/Product.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Ross Paterson 2010
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Data/Functor/Reverse.hs b/Data/Functor/Reverse.hs
--- a/Data/Functor/Reverse.hs
+++ b/Data/Functor/Reverse.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Russell O'Connor 2009
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  libraries@haskell.org
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/Data/Functor/Sum.hs b/Data/Functor/Sum.hs
--- a/Data/Functor/Sum.hs
+++ b/Data/Functor/Sum.hs
@@ -8,7 +8,7 @@
 -- Copyright   :  (c) Ross Paterson 2014
 -- License     :  BSD-style (see the file LICENSE)
 --
--- Maintainer  :  ross@soi.city.ac.uk
+-- Maintainer  :  R.Paterson@city.ac.uk
 -- Stability   :  experimental
 -- Portability :  portable
 --
diff --git a/changelog b/changelog
--- a/changelog
+++ b/changelog
@@ -1,5 +1,8 @@
 -*-change-log-*-
 
+0.4.3.0 Ross Paterson <R.Paterson@city.ac.uk> Mar 2015
+	* Added Eq1, Ord1, Show1 and Read1 instances for Const
+
 0.4.2.0 Ross Paterson <ross@soi.city.ac.uk> Nov 2014
 	* Dropped compatibility with base-1.x
 	* Data.Functor.Identity in base for GHC >= 7.10
diff --git a/transformers.cabal b/transformers.cabal
--- a/transformers.cabal
+++ b/transformers.cabal
@@ -1,9 +1,9 @@
 name:         transformers
-version:      0.4.2.0
+version:      0.4.3.0
 license:      BSD3
 license-file: LICENSE
 author:       Andy Gill, Ross Paterson
-maintainer:   Ross Paterson <ross@soi.city.ac.uk>
+maintainer:   Ross Paterson <R.Paterson@city.ac.uk>
 category:     Control
 synopsis:     Concrete functor and monad transformers
 description:
@@ -35,7 +35,7 @@
 
 source-repository head
   type: darcs
-  location: http://code.haskell.org/~ross/transformers
+  location: http://hub.darcs.net/ross/transformers
 
 library
   build-depends: base >= 2 && < 6