diff --git a/Control/Monad/Trans/Accum.hs b/Control/Monad/Trans/Accum.hs
index cb06eba..9ae05f2 100644
--- a/Control/Monad/Trans/Accum.hs
+++ b/Control/Monad/Trans/Accum.hs
@@ -115,7 +115,7 @@ execAccum m w = snd (runAccum m w)
 -- and return the final value, discarding the final output.
 --
 -- * @'evalAccum' m w = 'fst' ('runAccum' m w)@
-evalAccum :: (Monoid w) => Accum w a -> w -> a
+evalAccum :: Accum w a -> w -> a
 evalAccum m w = fst (runAccum m w)
 {-# INLINE evalAccum #-}
 
@@ -173,7 +173,7 @@ execAccumT m w = do
 -- history and return the final value, discarding the final output.
 --
 -- * @'evalAccumT' m w = 'liftM' 'fst' ('runAccumT' m w)@
-evalAccumT :: (Monad m, Monoid w) => AccumT w m a -> w -> m a
+evalAccumT :: (Monad m) => AccumT w m a -> w -> m a
 evalAccumT m w = do
     ~(a, _) <- runAccumT m w
     return a
@@ -191,7 +191,7 @@ instance (Functor m) => Functor (AccumT w m) where
     fmap f = mapAccumT $ fmap $ \ ~(a, w) -> (f a, w)
     {-# INLINE fmap #-}
 
-instance (Monoid w, Functor m, Monad m) => Applicative (AccumT w m) where
+instance (Monoid w, Monad m) => Applicative (AccumT w m) where
     pure a  = AccumT $ const $ return (a, mempty)
     {-# INLINE pure #-}
     mf <*> mv = AccumT $ \ w -> do
@@ -200,13 +200,13 @@ instance (Monoid w, Functor m, Monad m) => Applicative (AccumT w m) where
       return (f v, w' `mappend` w'')
     {-# INLINE (<*>) #-}
 
-instance (Monoid w, Functor m, MonadPlus m) => Alternative (AccumT w m) where
+instance (Monoid w, MonadPlus m) => Alternative (AccumT w m) where
     empty   = AccumT $ const mzero
     {-# INLINE empty #-}
     m <|> n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w
     {-# INLINE (<|>) #-}
 
-instance (Monoid w, Functor m, Monad m) => Monad (AccumT w m) where
+instance (Monoid w, Monad m) => Monad (AccumT w m) where
 #if !(MIN_VERSION_base(4,8,0))
     return a  = AccumT $ const $ return (a, mempty)
     {-# INLINE return #-}
@@ -227,13 +227,13 @@ instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (AccumT w m) where
     {-# INLINE fail #-}
 #endif
 
-instance (Monoid w, Functor m, MonadPlus m) => MonadPlus (AccumT w m) where
+instance (Monoid w, MonadPlus m) => MonadPlus (AccumT w m) where
     mzero       = AccumT $ const mzero
     {-# INLINE mzero #-}
     m `mplus` n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w
     {-# INLINE mplus #-}
 
-instance (Monoid w, Functor m, MonadFix m) => MonadFix (AccumT w m) where
+instance (Monoid w, MonadFix m) => MonadFix (AccumT w m) where
     mfix m = AccumT $ \ w -> mfix $ \ ~(a, _) -> runAccumT (m a) w
     {-# INLINE mfix #-}
 
@@ -243,7 +243,7 @@ instance (Monoid w) => MonadTrans (AccumT w) where
         return (a, mempty)
     {-# INLINE lift #-}
 
-instance (Monoid w, Functor m, MonadIO m) => MonadIO (AccumT w m) where
+instance (Monoid w, MonadIO m) => MonadIO (AccumT w m) where
     liftIO = lift . liftIO
     {-# INLINE liftIO #-}
 
diff --git a/Control/Monad/Trans/Except.hs b/Control/Monad/Trans/Except.hs
index 049a0f3..51d5ca0 100644
--- a/Control/Monad/Trans/Except.hs
+++ b/Control/Monad/Trans/Except.hs
@@ -198,7 +198,7 @@ instance (Traversable f) => Traversable (ExceptT e f) where
         ExceptT <$> traverse (either (pure . Left) (fmap Right . f)) a
     {-# INLINE traverse #-}
 
-instance (Functor m, Monad m) => Applicative (ExceptT e m) where
+instance (Monad m) => Applicative (ExceptT e m) where
     pure a = ExceptT $ return (Right a)
     {-# INLINE pure #-}
     ExceptT f <*> ExceptT v = ExceptT $ do
@@ -214,7 +214,7 @@ instance (Functor m, Monad m) => Applicative (ExceptT e m) where
     m *> k = m >>= \_ -> k
     {-# INLINE (*>) #-}
 
-instance (Functor m, Monad m, Monoid e) => Alternative (ExceptT e m) where
+instance (Monad m, Monoid e) => Alternative (ExceptT e m) where
     empty = ExceptT $ return (Left mempty)
     {-# INLINE empty #-}
     ExceptT mx <|> ExceptT my = ExceptT $ do
diff --git a/Control/Monad/Trans/Maybe.hs b/Control/Monad/Trans/Maybe.hs
index cab161d..52ee337 100644
--- a/Control/Monad/Trans/Maybe.hs
+++ b/Control/Monad/Trans/Maybe.hs
@@ -146,7 +146,7 @@ instance (Traversable f) => Traversable (MaybeT f) where
     traverse f (MaybeT a) = MaybeT <$> traverse (traverse f) a
     {-# INLINE traverse #-}
 
-instance (Functor m, Monad m) => Applicative (MaybeT m) where
+instance (Monad m) => Applicative (MaybeT m) where
     pure = MaybeT . return . Just
     {-# INLINE pure #-}
     mf <*> mx = MaybeT $ do
@@ -162,7 +162,7 @@ instance (Functor m, Monad m) => Applicative (MaybeT m) where
     m *> k = m >>= \_ -> k
     {-# INLINE (*>) #-}
 
-instance (Functor m, Monad m) => Alternative (MaybeT m) where
+instance (Monad m) => Alternative (MaybeT m) where
     empty = MaybeT (return Nothing)
     {-# INLINE empty #-}
     x <|> y = MaybeT $ do
diff --git a/Control/Monad/Trans/RWS/CPS.hs b/Control/Monad/Trans/RWS/CPS.hs
index f089db6..4a26425 100644
--- a/Control/Monad/Trans/RWS/CPS.hs
+++ b/Control/Monad/Trans/RWS/CPS.hs
@@ -214,7 +214,7 @@ instance (Functor m) => Functor (RWST r w s m) where
     fmap f m = RWST $ \ r s w -> (\ (a, s', w') -> (f a, s', w')) <$> unRWST m r s w
     {-# INLINE fmap #-}
 
-instance (Functor m, Monad m) => Applicative (RWST r w s m) where
+instance (Monad m) => Applicative (RWST r w s m) where
     pure a = RWST $ \ _ s w -> return (a, s, w)
     {-# INLINE pure #-}
 
@@ -224,7 +224,7 @@ instance (Functor m, Monad m) => Applicative (RWST r w s m) where
         return (f x, s'', w'')
     {-# INLINE (<*>) #-}
 
-instance (Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+instance (MonadPlus m) => Alternative (RWST r w s m) where
     empty = RWST $ \ _ _ _ -> mzero
     {-# INLINE empty #-}
 
@@ -253,7 +253,7 @@ instance (Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where
     {-# INLINE fail #-}
 #endif
 
-instance (Functor m, MonadPlus m) => MonadPlus (RWST r w s m) where
+instance (MonadPlus m) => MonadPlus (RWST r w s m) where
     mzero = empty
     {-# INLINE mzero #-}
     mplus = (<|>)
diff --git a/Control/Monad/Trans/RWS/Lazy.hs b/Control/Monad/Trans/RWS/Lazy.hs
index 5fd8f2d..0f1c750 100644
--- a/Control/Monad/Trans/RWS/Lazy.hs
+++ b/Control/Monad/Trans/RWS/Lazy.hs
@@ -190,7 +190,7 @@ instance (Functor m) => Functor (RWST r w s m) where
         fmap (\ ~(a, s', w) -> (f a, s', w)) $ runRWST m r s
     {-# INLINE fmap #-}
 
-instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
+instance (Monoid w, Monad m) => Applicative (RWST r w s m) where
     pure a = RWST $ \ _ s -> return (a, s, mempty)
     {-# INLINE pure #-}
     RWST mf <*> RWST mx  = RWST $ \ r s -> do
@@ -199,7 +199,7 @@ instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
         return (f x, s'', w `mappend` w')
     {-# INLINE (<*>) #-}
 
-instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+instance (Monoid w, MonadPlus m) => Alternative (RWST r w s m) where
     empty = RWST $ \ _ _ -> mzero
     {-# INLINE empty #-}
     RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s
diff --git a/Control/Monad/Trans/RWS/Strict.hs b/Control/Monad/Trans/RWS/Strict.hs
index a7f66db..e43fad8 100644
--- a/Control/Monad/Trans/RWS/Strict.hs
+++ b/Control/Monad/Trans/RWS/Strict.hs
@@ -194,7 +194,7 @@ instance (Functor m) => Functor (RWST r w s m) where
         fmap (\ (a, s', w) -> (f a, s', w)) $ runRWST m r s
     {-# INLINE fmap #-}
 
-instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
+instance (Monoid w, Monad m) => Applicative (RWST r w s m) where
     pure a = RWST $ \ _ s -> return (a, s, mempty)
     {-# INLINE pure #-}
     RWST mf <*> RWST mx = RWST $ \ r s -> do
@@ -203,7 +203,7 @@ instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
         return (f x, s'', w `mappend` w')
     {-# INLINE (<*>) #-}
 
-instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+instance (Monoid w, MonadPlus m) => Alternative (RWST r w s m) where
     empty = RWST $ \ _ _ -> mzero
     {-# INLINE empty #-}
     RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s
diff --git a/Control/Monad/Trans/Select.hs b/Control/Monad/Trans/Select.hs
index 29eb6c4..8feff89 100644
--- a/Control/Monad/Trans/Select.hs
+++ b/Control/Monad/Trans/Select.hs
@@ -106,7 +106,7 @@ instance (Functor m) => Functor (SelectT r m) where
     fmap f (SelectT g) = SelectT (fmap f . g . (. f))
     {-# INLINE fmap #-}
 
-instance (Functor m, Monad m) => Applicative (SelectT r m) where
+instance (Monad m) => Applicative (SelectT r m) where
     pure = lift . return
     {-# INLINE pure #-}
     SelectT gf <*> SelectT gx = SelectT $ \ k -> do
@@ -117,7 +117,7 @@ instance (Functor m, Monad m) => Applicative (SelectT r m) where
     m *> k = m >>= \_ -> k
     {-# INLINE (*>) #-}
 
-instance (Functor m, MonadPlus m) => Alternative (SelectT r m) where
+instance (MonadPlus m) => Alternative (SelectT r m) where
     empty = mzero
     {-# INLINE empty #-}
     (<|>) = mplus
diff --git a/Control/Monad/Trans/State/Lazy.hs b/Control/Monad/Trans/State/Lazy.hs
index 67fd597..e8f7e55 100644
--- a/Control/Monad/Trans/State/Lazy.hs
+++ b/Control/Monad/Trans/State/Lazy.hs
@@ -213,7 +213,7 @@ instance (Functor m) => Functor (StateT s m) where
         fmap (\ ~(a, s') -> (f a, s')) $ runStateT m s
     {-# INLINE fmap #-}
 
-instance (Functor m, Monad m) => Applicative (StateT s m) where
+instance (Monad m) => Applicative (StateT s m) where
     pure a = StateT $ \ s -> return (a, s)
     {-# INLINE pure #-}
     StateT mf <*> StateT mx = StateT $ \ s -> do
@@ -224,7 +224,7 @@ instance (Functor m, Monad m) => Applicative (StateT s m) where
     m *> k = m >>= \_ -> k
     {-# INLINE (*>) #-}
 
-instance (Functor m, MonadPlus m) => Alternative (StateT s m) where
+instance (MonadPlus m) => Alternative (StateT s m) where
     empty = StateT $ \ _ -> mzero
     {-# INLINE empty #-}
     StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s
diff --git a/Control/Monad/Trans/State/Strict.hs b/Control/Monad/Trans/State/Strict.hs
index 040c871..64016da 100644
--- a/Control/Monad/Trans/State/Strict.hs
+++ b/Control/Monad/Trans/State/Strict.hs
@@ -206,7 +206,7 @@ instance (Functor m) => Functor (StateT s m) where
         fmap (\ (a, s') -> (f a, s')) $ runStateT m s
     {-# INLINE fmap #-}
 
-instance (Functor m, Monad m) => Applicative (StateT s m) where
+instance (Monad m) => Applicative (StateT s m) where
     pure a = StateT $ \ s -> return (a, s)
     {-# INLINE pure #-}
     StateT mf <*> StateT mx = StateT $ \ s -> do
@@ -217,7 +217,7 @@ instance (Functor m, Monad m) => Applicative (StateT s m) where
     m *> k = m >>= \_ -> k
     {-# INLINE (*>) #-}
 
-instance (Functor m, MonadPlus m) => Alternative (StateT s m) where
+instance (MonadPlus m) => Alternative (StateT s m) where
     empty = StateT $ \ _ -> mzero
     {-# INLINE empty #-}
     StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s
diff --git a/Control/Monad/Trans/Writer/CPS.hs b/Control/Monad/Trans/Writer/CPS.hs
index 3b63c49..d04d246 100644
--- a/Control/Monad/Trans/Writer/CPS.hs
+++ b/Control/Monad/Trans/Writer/CPS.hs
@@ -169,7 +169,7 @@ instance (Functor m) => Functor (WriterT w m) where
     fmap f m = WriterT $ \ w -> (\ (a, w') -> (f a, w')) <$> unWriterT m w
     {-# INLINE fmap #-}
 
-instance (Functor m, Monad m) => Applicative (WriterT w m) where
+instance (Monad m) => Applicative (WriterT w m) where
     pure a = WriterT $ \ w -> return (a, w)
     {-# INLINE pure #-}
 
@@ -179,7 +179,7 @@ instance (Functor m, Monad m) => Applicative (WriterT w m) where
         return (f x, w'')
     {-# INLINE (<*>) #-}
 
-instance (Functor m, MonadPlus m) => Alternative (WriterT w m) where
+instance (MonadPlus m) => Alternative (WriterT w m) where
     empty = WriterT $ const mzero
     {-# INLINE empty #-}
 
@@ -208,7 +208,7 @@ instance (Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where
     {-# INLINE fail #-}
 #endif
 
-instance (Functor m, MonadPlus m) => MonadPlus (WriterT w m) where
+instance (MonadPlus m) => MonadPlus (WriterT w m) where
     mzero = empty
     {-# INLINE mzero #-}
     mplus = (<|>)
diff --git a/cabal.project b/cabal.project
new file mode 100644
index 0000000..0111f91
--- /dev/null
+++ b/cabal.project
@@ -0,0 +1,6 @@
+
+packages: .
+
+program-options
+  ghc-options:
+    -Wall -Wredundant-constraints -Werror