diff --git a/Control/Categorical/Functor.hs b/Control/Categorical/Functor.hs
--- a/Control/Categorical/Functor.hs
+++ b/Control/Categorical/Functor.hs
@@ -1,13 +1,13 @@
-{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, DeriveDataTypeable, FlexibleContexts, UndecidableInstances, FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleContexts, UndecidableInstances, FlexibleInstances #-}
 -------------------------------------------------------------------------------------------
 -- |
--- Module     : Control.Categorical.Functor
--- Copyright : 2008-2010 Edward Kmett
+-- Module      : Control.Categorical.Functor
+-- Copyright   : 2008-2010 Edward Kmett
 -- License     : BSD3
 --
--- Maintainer   : Edward Kmett <ekmett@gmail.com>
--- Stability    : experimental
--- Portability    : non-portable (functional-dependencies)
+-- Maintainer  : Edward Kmett <ekmett@gmail.com>
+-- Stability   : experimental
+-- Portability : non-portable (functional-dependencies)
 --
 -- A more categorical definition of 'Functor'
 -------------------------------------------------------------------------------------------
@@ -21,13 +21,17 @@
 import Control.Category
 import Prelude hiding (id, (.), Functor(..))
 import qualified Prelude
+#ifdef GLASGOW_HASKELL
 import Data.Data (Data(..), mkDataType, DataType, mkConstr, Constr, constrIndex, Fixity(..))
 import Data.Typeable (Typeable1(..), TyCon, mkTyCon, mkTyConApp, gcast1)
+#endif
 
 -- TODO Data, Typeable
 newtype LiftedFunctor f a = LiftedFunctor (f a)
     deriving (Show, Read)
 
+#ifdef GLASGOW_HASKELL
+
 liftedTyCon :: TyCon
 liftedTyCon = mkTyCon "Control.Categorical.Functor.LiftedFunctor"
 {-# NOINLINE liftedTyCon #-}
@@ -53,10 +57,13 @@
         _ -> error "gunfold"
     dataTypeOf _ = liftedDataType
     dataCast1 f = gcast1 f
+#endif
 
 newtype LoweredFunctor f a = LoweredFunctor (f a)
     deriving (Show, Read)
 
+#ifdef GLASGOW_HASKELL
+
 loweredTyCon :: TyCon
 loweredTyCon = mkTyCon "Control.Categorical.Functor.LoweredFunctor"
 {-# NOINLINE loweredTyCon #-}
@@ -83,6 +90,8 @@
     dataTypeOf _ = loweredDataType
     dataCast1 f = gcast1 f
 
+#endif
+
 class (Category r, Category t) => Functor f r t | f r -> t, f t -> r where
     fmap :: r a b -> t (f a) (f b)
 
@@ -110,4 +119,3 @@
 
 class (Functor f (~>) (~>)) => EndoFunctor f (~>)
 instance (Functor f (~>) (~>)) => EndoFunctor f (~>)
-    
diff --git a/Control/Category/Discrete.hs b/Control/Category/Discrete.hs
--- a/Control/Category/Discrete.hs
+++ b/Control/Category/Discrete.hs
@@ -29,6 +29,9 @@
     id = Refl
     Refl . Refl = Refl
 
+-- instance Groupoid Discrete where
+--  inv Refl = Refl
+
 -- | Discrete a b acts as a proof that a = b, lift that proof into something of kind * -> *
 liftDiscrete :: Discrete a b -> Discrete (f a) (f b)
 liftDiscrete Refl = Refl
diff --git a/Control/Category/Dual.hs b/Control/Category/Dual.hs
--- a/Control/Category/Dual.hs
+++ b/Control/Category/Dual.hs
@@ -1,9 +1,9 @@
-{-# LANGUAGE DeriveDataTypeable, TypeOperators, FlexibleContexts #-}
+{-# LANGUAGE TypeOperators, FlexibleContexts #-}
 -------------------------------------------------------------------------------------------
 -- |
--- Module	 : Control.Category.Dual
--- Copyright : 2008-2010 Edward Kmett
--- License	 : BSD
+-- Module	: Control.Category.Dual
+-- Copyright    : 2008-2010 Edward Kmett
+-- License      : BSD
 --
 -- Maintainer	: Edward Kmett <ekmett@gmail.com>
 -- Stability	: experimental
@@ -14,10 +14,13 @@
 	( Dual(..)
 	) where
 
-import Prelude hiding ((.), id)
+import Prelude ()
 import Control.Category
+
+#ifdef GLASGOW_HASKELL
 import Data.Data (Data(..), mkDataType, DataType, mkConstr, Constr, constrIndex, Fixity(..))
 import Data.Typeable (Typeable2(..), TyCon, mkTyCon, mkTyConApp, gcast1)
+#endif
 
 data Dual k a b = Dual { runDual :: k b a } 
 
@@ -25,6 +28,7 @@
 	id = Dual id
 	Dual f . Dual g = Dual (g . f)
 
+#ifdef GLASGOW_HASKELL
 instance Typeable2 (~>) => Typeable2 (Dual (~>)) where
     typeOf2 tfab = mkTyConApp dataTyCon [typeOf2 (undefined `asDualArgsType` tfab)]
         where asDualArgsType :: f b a -> t f a b -> f b a
@@ -50,3 +54,4 @@
         _ -> error "gunfold"
     dataTypeOf _ = dataDataType
     dataCast1 f = gcast1 f
+#endif
diff --git a/categories.cabal b/categories.cabal
--- a/categories.cabal
+++ b/categories.cabal
@@ -1,8 +1,8 @@
 name:          categories
 category:      Control
-version:       0.58.0.1
+version:       0.58.0.3
 license:       BSD3
-cabal-version: >= 1.2
+cabal-version: >= 1.2.3
 license-file:  LICENSE
 author:        Edward A. Kmett
 maintainer:    Edward A. Kmett <ekmett@gmail.com>
@@ -18,6 +18,17 @@
   default:     False
 
 library
+  extensions: CPP 
+  other-extensions:
+    MultiParamTypeClasses
+    FunctionalDependencies
+    FlexibleContexts
+    FlexibleInstances
+    UndecidableInstances
+    TypeOperators
+    TypeFamilies
+    GADTs
+
   exposed-modules:
     Control.Categorical.Functor,
     Control.Categorical.Bifunctor,
@@ -34,7 +45,8 @@
   build-depends: 
     base >= 4 && < 5,
     void >= 0.5.1 && < 0.6
-    
+
   ghc-options: -Wall 
+
   if flag(Optimize)
     ghc-options: -funbox-strict-fields -O2