X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FTypeable.hs;h=7a8b7332267b549bd191f96a8725dacce5ea7671;hb=6b1a36a595eddf1e124529646afdb75c76a9966d;hp=6c0d3e658b1e25fae38ec30d7fadf734924f547a;hpb=cd4a447f92e0186b6fc20f911f489ff61af933e4;p=haskell-directory.git

diff --git a/Data/Typeable.hs b/Data/Typeable.hs
index 6c0d3e6..7a8b733 100644
--- a/Data/Typeable.hs
+++ b/Data/Typeable.hs
@@ -1,4 +1,11 @@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude -fallow-overlapping-instances #-}
+
+-- The -fallow-overlapping-instances flag allows the user to over-ride
+-- the instances for Typeable given here.  In particular, we provide an instance
+--	instance ... => Typeable (s a) 
+-- But a user might want to say
+--	instance ... => Typeable (MyType a b)
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Typeable
@@ -9,12 +16,12 @@
 -- Stability   :  experimental
 -- Portability :  portable
 --
--- The Typeable class reifies types to some extent by associating type
+-- The 'Typeable' class reifies types to some extent by associating type
 -- representations to types. These type representations can be compared,
 -- and one can in turn define a type-safe cast operation. To this end,
 -- an unsafe cast is guarded by a test for type (representation)
--- equivalence. The module Data.Dynamic uses Typeable for an
--- implementation of dynamics. The module Data.Generics uses Typeable
+-- equivalence. The module "Data.Dynamic" uses Typeable for an
+-- implementation of dynamics. The module "Data.Generics" uses Typeable
 -- and type-safe cast (but not dynamics) to support the \"Scrap your
 -- boilerplate\" style of generic programming.
 --
@@ -28,32 +35,52 @@ module Data.Typeable
 
 	-- * Type-safe cast
 	cast,			-- :: (Typeable a, Typeable b) => a -> Maybe b
-	cast0,			-- a flexible variation on cast
+	gcast,			-- a generalisation of cast
 
 	-- * Type representations
 	TypeRep,	-- abstract, instance of: Eq, Show, Typeable
 	TyCon,		-- abstract, instance of: Eq, Show, Typeable
+	showsTypeRep,
 
 	-- * Construction of type representations
 	mkTyCon,	-- :: String  -> TyCon
-	mkAppTy,	-- :: TyCon   -> [TypeRep] -> TypeRep
+	mkTyConApp,	-- :: TyCon   -> [TypeRep] -> TypeRep
+	mkAppTy,	-- :: TypeRep -> TypeRep   -> TypeRep
 	mkFunTy,	-- :: TypeRep -> TypeRep   -> TypeRep
-	applyTy,	-- :: TypeRep -> TypeRep   -> Maybe TypeRep
 
 	-- * Observation of type representations
-	typerepTyCon,	-- :: TypeRep -> TyCon
-	typerepArgs,	-- :: TypeRep -> [TypeRep]
-	tyconString,	-- :: TyCon   -> String
-
-	-- * The Typeable1 class
-	Typeable1( typeOf1 ),	-- :: t a -> TyCon
-	Typeable2( typeOf2 ),	-- :: t a b -> TyCon
-	cast1,			-- :: ... => c (t a) -> Maybe (c (t' a))
-	cast2			-- :: ... => c (t a b) -> Maybe (c (t' a b))
+	splitTyConApp,	-- :: TypeRep -> (TyCon, [TypeRep])
+	funResultTy,	-- :: TypeRep -> TypeRep   -> Maybe TypeRep
+	typeRepTyCon,	-- :: TypeRep -> TyCon
+	typeRepArgs,	-- :: TypeRep -> [TypeRep]
+	tyConString,	-- :: TyCon   -> String
+	typeRepKey,	-- :: TypeRep -> IO Int
+
+	-- * The other Typeable classes
+	-- | /Note:/ The general instances are provided for GHC only.
+	Typeable1( typeOf1 ),	-- :: t a -> TypeRep
+	Typeable2( typeOf2 ),	-- :: t a b -> TypeRep
+	Typeable3( typeOf3 ),	-- :: t a b c -> TypeRep
+	Typeable4( typeOf4 ),	-- :: t a b c d -> TypeRep
+	Typeable5( typeOf5 ),	-- :: t a b c d e -> TypeRep
+	Typeable6( typeOf6 ),	-- :: t a b c d e f -> TypeRep
+	Typeable7( typeOf7 ),	-- :: t a b c d e f g -> TypeRep
+	gcast1,			-- :: ... => c (t a) -> Maybe (c (t' a))
+	gcast2,			-- :: ... => c (t a b) -> Maybe (c (t' a b))
+
+	-- * Default instances
+	-- | /Note:/ These are not needed by GHC, for which these instances
+	-- are generated by general instance declarations.
+	typeOfDefault,	-- :: (Typeable1 t, Typeable a) => t a -> TypeRep
+	typeOf1Default,	-- :: (Typeable2 t, Typeable a) => t a b -> TypeRep
+	typeOf2Default,	-- :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
+	typeOf3Default,	-- :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
+	typeOf4Default,	-- :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
+	typeOf5Default,	-- :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
+	typeOf6Default	-- :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
 
   ) where
 
-
 import qualified Data.HashTable as HT
 import Data.Maybe
 import Data.Either
@@ -67,17 +94,36 @@ import GHC.Show
 import GHC.Err
 import GHC.Num
 import GHC.Float
-import GHC.Real( rem, Ratio )
-import GHC.IOBase
-import GHC.Ptr		-- So we can give Typeable instance for Ptr
-import GHC.Stable	-- So we can give Typeable instance for StablePtr
+import GHC.Real		( rem, Ratio )
+import GHC.IOBase	(IORef,newIORef,unsafePerformIO)
+
+-- These imports are so we can define Typeable instances
+-- It'd be better to give Typeable instances in the modules themselves
+-- but they all have to be compiled before Typeable
+import GHC.IOBase	( IO, MVar, Exception, ArithException, IOException, 
+			  ArrayException, AsyncException, Handle )
+import GHC.ST		( ST )
+import GHC.STRef	( STRef )
+import GHC.Ptr          ( Ptr, FunPtr )
+import GHC.ForeignPtr   ( ForeignPtr )
+import GHC.Stable	( StablePtr, newStablePtr, freeStablePtr,
+			  deRefStablePtr, castStablePtrToPtr,
+			  castPtrToStablePtr )
+import GHC.Exception	( block )
+import GHC.Arr		( Array, STArray )
+
 #endif
 
 #ifdef __HUGS__
-import Hugs.Prelude
-import Hugs.IO
-import Hugs.IORef
-import Hugs.IOExts
+import Hugs.Prelude	( Key(..), TypeRep(..), TyCon(..), Ratio,
+			  Exception, ArithException, IOException,
+			  ArrayException, AsyncException, Handle,
+			  Ptr, FunPtr, ForeignPtr, StablePtr )
+import Hugs.IORef	( IORef, newIORef, readIORef, writeIORef )
+import Hugs.IOExts	( unsafePerformIO, unsafeCoerce )
+	-- For the Typeable instance
+import Hugs.Array	( Array )
+import Hugs.ConcBase	( MVar )
 #endif
 
 #ifdef __GLASGOW_HASKELL__
@@ -88,19 +134,23 @@ unsafeCoerce = unsafeCoerce#
 #ifdef __NHC__
 import NonStdUnsafeCoerce (unsafeCoerce)
 import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
-#else
-#include "Typeable.h"
+import IO (Handle)
+import Ratio (Ratio)
+	-- For the Typeable instance
+import NHC.FFI	( Ptr,FunPtr,StablePtr,ForeignPtr )
+import Array	( Array )
 #endif
 
+#include "Typeable.h"
 
 #ifndef __HUGS__
+
 -------------------------------------------------------------
 --
 --		Type representations
 --
 -------------------------------------------------------------
 
-
 -- | A concrete representation of a (monomorphic) type.  'TypeRep'
 -- supports reasonably efficient equality.
 data TypeRep = TypeRep !Key TyCon [TypeRep] 
@@ -115,11 +165,23 @@ data TyCon = TyCon !Key String
 
 instance Eq TyCon where
   (TyCon t1 _) == (TyCon t2 _) = t1 == t2
-
 #endif
 
+-- | Returns a unique integer associated with a 'TypeRep'.  This can
+-- be used for making a mapping ('Data.IntMap.IntMap') with TypeReps
+-- as the keys, for example.  It is guaranteed that @t1 == t2@ if and only if
+-- @typeRepKey t1 == typeRepKey t2@.
+--
+-- It is in the 'IO' monad because the actual value of the key may
+-- vary from run to run of the program.  You should only rely on
+-- the equality property, not any actual key value.  The relative ordering
+-- of keys has no meaning either.
+--
+typeRepKey :: TypeRep -> IO Int
+typeRepKey (TypeRep (Key i) _ _) = return i
+
 	-- 
-	-- let fTy = mkTyCon "Foo" in show (mkAppTy (mkTyCon ",,")
+	-- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
 	--                                 [fTy,fTy,fTy])
 	-- 
 	-- returns "(Foo,Foo,Foo)"
@@ -132,28 +194,36 @@ instance Eq TyCon where
 ----------------- Construction --------------------
 
 -- | Applies a type constructor to a sequence of types
-mkAppTy  :: TyCon -> [TypeRep] -> TypeRep
-mkAppTy tc@(TyCon tc_k _) args 
+mkTyConApp  :: TyCon -> [TypeRep] -> TypeRep
+mkTyConApp tc@(TyCon tc_k _) args 
   = TypeRep (appKeys tc_k arg_ks) tc args
   where
     arg_ks = [k | TypeRep k _ _ <- args]
 
-funTc :: TyCon
-funTc = mkTyCon "->"
-
--- | A special case of 'mkAppTy', which applies the function 
+-- | A special case of 'mkTyConApp', which applies the function 
 -- type constructor to a pair of types.
 mkFunTy  :: TypeRep -> TypeRep -> TypeRep
-mkFunTy f a = mkAppTy funTc [f,a]
+mkFunTy f a = mkTyConApp funTc [f,a]
+
+-- | Splits a type constructor application
+splitTyConApp :: TypeRep -> (TyCon,[TypeRep])
+splitTyConApp (TypeRep _ tc trs) = (tc,trs)
 
 -- | Applies a type to a function type.  Returns: @'Just' u@ if the
 -- first argument represents a function of type @t -> u@ and the
 -- second argument represents a function of type @t@.  Otherwise,
 -- returns 'Nothing'.
-applyTy :: TypeRep -> TypeRep -> Maybe TypeRep
-applyTy (TypeRep _ tc [t1,t2]) t3
-  | tc == funTc && t1 == t3	= Just t2
-applyTy _ _     		= Nothing
+funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep
+funResultTy trFun trArg
+  = case splitTyConApp trFun of
+      (tc, [t1,t2]) | tc == funTc && t1 == trArg -> Just t2
+      _ -> Nothing
+
+-- | Adds a TypeRep argument to a TypeRep.
+mkAppTy :: TypeRep -> TypeRep -> TypeRep
+mkAppTy (TypeRep tr_k tc trs) arg_tr
+  = let (TypeRep arg_k _ _) = arg_tr
+     in  TypeRep (appKey tr_k arg_k) tc (trs++[arg_tr])
 
 -- If we enforce the restriction that there is only one
 -- @TyCon@ for a type & it is shared among all its uses,
@@ -179,25 +249,19 @@ mkTyCon :: String	-- ^ the name of the type constructor (should be unique
 	-> TyCon	-- ^ A unique 'TyCon' object
 mkTyCon str = TyCon (mkTyConKey str) str
 
-
-
 ----------------- Observation ---------------------
 
-
 -- | Observe the type constructor of a type representation
-typerepTyCon :: TypeRep -> TyCon
-typerepTyCon (TypeRep _ tc _) = tc
-
+typeRepTyCon :: TypeRep -> TyCon
+typeRepTyCon (TypeRep _ tc _) = tc
 
 -- | Observe the argument types of a type representation
-typerepArgs :: TypeRep -> [TypeRep]
-typerepArgs (TypeRep _ _ args) = args
-
+typeRepArgs :: TypeRep -> [TypeRep]
+typeRepArgs (TypeRep _ _ args) = args
 
 -- | Observe string encoding of a type representation
-tyconString :: TyCon   -> String
-tyconString  (TyCon _ str) = str
-
+tyConString :: TyCon   -> String
+tyConString  (TyCon _ str) = str
 
 ----------------- Showing TypeReps --------------------
 
@@ -207,7 +271,9 @@ instance Show TypeRep where
       [] -> showsPrec p tycon
       [x]   | tycon == listTc -> showChar '[' . shows x . showChar ']'
       [a,r] | tycon == funTc  -> showParen (p > 8) $
-			         showsPrec 9 a . showString " -> " . showsPrec 8 r
+			         showsPrec 9 a .
+                                 showString " -> " .
+                                 showsPrec 8 r
       xs | isTupleTyCon tycon -> showTuple tycon xs
 	 | otherwise	     ->
 	    showParen (p > 9) $
@@ -215,6 +281,9 @@ instance Show TypeRep where
 	    showChar ' '      . 
 	    showArgs tys
 
+showsTypeRep :: TypeRep -> ShowS
+showsTypeRep = shows
+
 instance Show TyCon where
   showsPrec _ (TyCon _ s) = showString s
 
@@ -237,10 +306,9 @@ showTuple (TyCon _ str) args = showChar '(' . go str args
   go (',':xs) (a:as) = showsPrec 10 a . showChar ',' . go xs as
   go _ _   = showChar ')'
 
-
 -------------------------------------------------------------
 --
---	The Typeable class
+--	The Typeable class and friends
 --
 -------------------------------------------------------------
 
@@ -253,6 +321,126 @@ class Typeable a where
   -- any instance of 'Typeable', so that it is safe to pass 'undefined' as
   -- the argument.
 
+-- | Variant for unary type constructors
+class Typeable1 t where
+  typeOf1 :: t a -> TypeRep
+
+-- | For defining a 'Typeable' instance from any 'Typeable1' instance.
+typeOfDefault :: (Typeable1 t, Typeable a) => t a -> TypeRep
+typeOfDefault x = typeOf1 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a -> a
+   argType =  undefined
+
+-- | Variant for binary type constructors
+class Typeable2 t where
+  typeOf2 :: t a b -> TypeRep
+
+-- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
+typeOf1Default :: (Typeable2 t, Typeable a) => t a b -> TypeRep
+typeOf1Default x = typeOf2 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b -> a
+   argType =  undefined
+
+-- | Variant for 3-ary type constructors
+class Typeable3 t where
+  typeOf3 :: t a b c -> TypeRep
+
+-- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
+typeOf2Default :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
+typeOf2Default x = typeOf3 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b c -> a
+   argType =  undefined
+
+-- | Variant for 4-ary type constructors
+class Typeable4 t where
+  typeOf4 :: t a b c d -> TypeRep
+
+-- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
+typeOf3Default :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
+typeOf3Default x = typeOf4 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b c d -> a
+   argType =  undefined
+
+-- | Variant for 5-ary type constructors
+class Typeable5 t where
+  typeOf5 :: t a b c d e -> TypeRep
+
+-- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
+typeOf4Default :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
+typeOf4Default x = typeOf5 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b c d e -> a
+   argType =  undefined
+
+-- | Variant for 6-ary type constructors
+class Typeable6 t where
+  typeOf6 :: t a b c d e f -> TypeRep
+
+-- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
+typeOf5Default :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
+typeOf5Default x = typeOf6 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b c d e f -> a
+   argType =  undefined
+
+-- | Variant for 7-ary type constructors
+class Typeable7 t where
+  typeOf7 :: t a b c d e f g -> TypeRep
+
+-- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
+typeOf6Default :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
+typeOf6Default x = typeOf7 x `mkAppTy` typeOf (argType x)
+ where
+   argType :: t a b c d e f g -> a
+   argType =  undefined
+
+#ifdef __GLASGOW_HASKELL__
+-- Given a @Typeable@/n/ instance for an /n/-ary type constructor,
+-- define the instances for partial applications.
+-- Programmers using non-GHC implementations must do this manually
+-- for each type constructor.
+-- (The INSTANCE_TYPEABLE/n/ macros in Typeable.h include this.)
+
+-- | One Typeable instance for all Typeable1 instances
+instance (Typeable1 s, Typeable a)
+       => Typeable (s a) where
+  typeOf = typeOfDefault
+
+-- | One Typeable1 instance for all Typeable2 instances
+instance (Typeable2 s, Typeable a)
+       => Typeable1 (s a) where
+  typeOf1 = typeOf1Default
+
+-- | One Typeable2 instance for all Typeable3 instances
+instance (Typeable3 s, Typeable a)
+       => Typeable2 (s a) where
+  typeOf2 = typeOf2Default
+
+-- | One Typeable3 instance for all Typeable4 instances
+instance (Typeable4 s, Typeable a)
+       => Typeable3 (s a) where
+  typeOf3 = typeOf3Default
+
+-- | One Typeable4 instance for all Typeable5 instances
+instance (Typeable5 s, Typeable a)
+       => Typeable4 (s a) where
+  typeOf4 = typeOf4Default
+
+-- | One Typeable5 instance for all Typeable6 instances
+instance (Typeable6 s, Typeable a)
+       => Typeable5 (s a) where
+  typeOf5 = typeOf5Default
+
+-- | One Typeable6 instance for all Typeable7 instances
+instance (Typeable7 s, Typeable a)
+       => Typeable6 (s a) where
+  typeOf6 = typeOf6Default
+
+#endif /* __GLASGOW_HASKELL__ */
 
 -------------------------------------------------------------
 --
@@ -268,10 +456,9 @@ cast x = r
                then Just $ unsafeCoerce x
 	       else Nothing
 
-
 -- | A flexible variation parameterised in a type constructor
-cast0 :: (Typeable a, Typeable b) => c a -> Maybe (c b)
-cast0 x = r
+gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
+gcast x = r
  where
   r = if typeOf (getArg x) == typeOf (getArg (fromJust r))
         then Just $ unsafeCoerce x
@@ -279,111 +466,97 @@ cast0 x = r
   getArg :: c x -> x 
   getArg = undefined
 
+-- | Cast for * -> *
+gcast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a)) 
+gcast1 x = r
+ where
+  r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
+       then Just $ unsafeCoerce x
+       else Nothing
+  getArg :: c x -> x 
+  getArg = undefined
 
+-- | Cast for * -> * -> *
+gcast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b)) 
+gcast2 x = r
+ where
+  r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
+       then Just $ unsafeCoerce x
+       else Nothing
+  getArg :: c x -> x 
+  getArg = undefined
 
 -------------------------------------------------------------
 --
---	Instances of the Typeable class for Prelude types
+--	Instances of the Typeable classes for Prelude types
 --
 -------------------------------------------------------------
 
-listTc :: TyCon
-listTc = mkTyCon "[]"
-
-instance Typeable a => Typeable [a] where
-  typeOf ls = mkAppTy listTc [typeOf ((undefined :: [a] -> a) ls)]
-	-- In GHC we can say
-	--	typeOf (undefined :: a)
-	-- using scoped type variables, but we use the 
-	-- more verbose form here, for compatibility with Hugs
-
-unitTc :: TyCon
-unitTc = mkTyCon "()"
-
-instance Typeable () where
-  typeOf _ = mkAppTy unitTc []
+INSTANCE_TYPEABLE0((),unitTc,"()")
+INSTANCE_TYPEABLE1([],listTc,"[]")
+INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
+INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
+INSTANCE_TYPEABLE2(Either,eitherTc,"Either")
+INSTANCE_TYPEABLE2((->),funTc,"->")
+INSTANCE_TYPEABLE1(IO,ioTc,"IO")
 
-tup2Tc :: TyCon
-tup2Tc = mkTyCon ","
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+-- Types defined in GHC.IOBase
+INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
+INSTANCE_TYPEABLE0(Exception,exceptionTc,"Exception")
+INSTANCE_TYPEABLE0(IOException,ioExceptionTc,"IOException")
+INSTANCE_TYPEABLE0(ArithException,arithExceptionTc,"ArithException")
+INSTANCE_TYPEABLE0(ArrayException,arrayExceptionTc,"ArrayException")
+INSTANCE_TYPEABLE0(AsyncException,asyncExceptionTc,"AsyncException")
+#endif
 
-instance (Typeable a, Typeable b) => Typeable (a,b) where
-  typeOf tu = mkAppTy tup2Tc [typeOf ((undefined :: (a,b) -> a) tu),
-			      typeOf ((undefined :: (a,b) -> b) tu)]
+-- Types defined in GHC.Arr
+INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
 
-tup3Tc :: TyCon
-tup3Tc = mkTyCon ",,"
+#ifdef __GLASGOW_HASKELL__
+-- Hugs has these too, but their Typeable<n> instances are defined
+-- elsewhere to keep this module within Haskell 98.
+-- This is important because every invocation of runhugs or ffihugs
+-- uses this module via Data.Dynamic.
+INSTANCE_TYPEABLE2(ST,stTc,"ST")
+INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
+INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
+#endif
 
-instance ( Typeable a , Typeable b , Typeable c) => Typeable (a,b,c) where
-  typeOf tu = mkAppTy tup3Tc [typeOf ((undefined :: (a,b,c) -> a) tu),
-			      typeOf ((undefined :: (a,b,c) -> b) tu),
-			      typeOf ((undefined :: (a,b,c) -> c) tu)]
+#ifndef __NHC__
+INSTANCE_TYPEABLE2((,),pairTc,",")
+INSTANCE_TYPEABLE3((,,),tup3Tc,",,")
 
 tup4Tc :: TyCon
 tup4Tc = mkTyCon ",,,"
 
-instance ( Typeable a
-	 , Typeable b
-	 , Typeable c
-	 , Typeable d) => Typeable (a,b,c,d) where
-  typeOf tu = mkAppTy tup4Tc [typeOf ((undefined :: (a,b,c,d) -> a) tu),
-			      typeOf ((undefined :: (a,b,c,d) -> b) tu),
-			      typeOf ((undefined :: (a,b,c,d) -> c) tu),
-			      typeOf ((undefined :: (a,b,c,d) -> d) tu)]
+instance Typeable4 (,,,) where
+  typeOf4 tu = mkTyConApp tup4Tc []
+
 tup5Tc :: TyCon
 tup5Tc = mkTyCon ",,,,"
 
-instance ( Typeable a
-	 , Typeable b
-	 , Typeable c
-	 , Typeable d
-	 , Typeable e) => Typeable (a,b,c,d,e) where
-  typeOf tu = mkAppTy tup5Tc [typeOf ((undefined :: (a,b,c,d,e) -> a) tu),
-			      typeOf ((undefined :: (a,b,c,d,e) -> b) tu),
-			      typeOf ((undefined :: (a,b,c,d,e) -> c) tu),
-			      typeOf ((undefined :: (a,b,c,d,e) -> d) tu),
-			      typeOf ((undefined :: (a,b,c,d,e) -> e) tu)]
+instance Typeable5 (,,,,) where
+  typeOf5 tu = mkTyConApp tup5Tc []
 
 tup6Tc :: TyCon
-tup6Tc = mkTyCon ",,,,"
-
-instance ( Typeable a
-	 , Typeable b
-	 , Typeable c
-	 , Typeable d
-	 , Typeable e
-         , Typeable f) => Typeable (a,b,c,d,e,f) where
-  typeOf tu = mkAppTy tup6Tc 
-      [typeOf (         (undefined :: (a,b,c,d,e,f) -> a) tu),
-	        typeOf ((undefined :: (a,b,c,d,e,f) -> b) tu),
-		typeOf ((undefined :: (a,b,c,d,e,f) -> c) tu),
-		typeOf ((undefined :: (a,b,c,d,e,f) -> d) tu),
-		typeOf ((undefined :: (a,b,c,d,e,f) -> e) tu),
-		typeOf ((undefined :: (a,b,c,d,e,f) -> f) tu)]
+tup6Tc = mkTyCon ",,,,,"
+
+instance Typeable6 (,,,,,) where
+  typeOf6 tu = mkTyConApp tup6Tc []
 
 tup7Tc :: TyCon
-tup7Tc = mkTyCon ",,,,"
-
-instance ( Typeable a
-	 , Typeable b
-	 , Typeable c
-	 , Typeable d
-	 , Typeable e
-         , Typeable f
-         , Typeable g) => Typeable (a,b,c,d,e,f,g) where
-  typeOf tu = mkAppTy tup7Tc
-      [typeOf (               (undefined :: (a,b,c,d,e,f,g) -> a) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> b) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> c) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> d) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> e) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> f) tu),
-		      typeOf ((undefined :: (a,b,c,d,e,f,g) -> g) tu)]
-
-instance (Typeable a, Typeable b) => Typeable (a -> b) where
-  typeOf f = mkFunTy (typeOf ((undefined :: (a -> b) -> a) f))
-		     (typeOf ((undefined :: (a -> b) -> b) f))
+tup7Tc = mkTyCon ",,,,,,"
 
+instance Typeable7 (,,,,,,) where
+  typeOf7 tu = mkTyConApp tup7Tc []
+#endif /* __NHC__ */
 
+INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
+INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
+INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
+INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
+INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
 
 -------------------------------------------------------
 --
@@ -391,21 +564,17 @@ instance (Typeable a, Typeable b) => Typeable (a -> b) where
 --
 -------------------------------------------------------
 
-#ifndef __NHC__
 INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
 INSTANCE_TYPEABLE0(Char,charTc,"Char")
 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
 INSTANCE_TYPEABLE0(Int,intTc,"Int")
+#ifndef __NHC__
+INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
+#endif
 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
-INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
-INSTANCE_TYPEABLE2(Either,eitherTc,"Either")
-INSTANCE_TYPEABLE1(IO,ioTc,"IO")
-INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
-INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
-INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
 
 INSTANCE_TYPEABLE0(Int8,int8Tc,"Int8")
 INSTANCE_TYPEABLE0(Int16,int16Tc,"Int16")
@@ -420,15 +589,10 @@ INSTANCE_TYPEABLE0(Word64,word64Tc,"Word64")
 INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
 INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
 
-INSTANCE_TYPEABLE1(IORef,ioRefTc,"IORef")
-#endif
-
 #ifdef __GLASGOW_HASKELL__
-INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
+INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
 #endif
 
-
-
 ---------------------------------------------
 --
 --		Internals 
@@ -444,19 +608,38 @@ data KeyPr = KeyPr !Key !Key deriving( Eq )
 hashKP :: KeyPr -> Int32
 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
 
-data Cache = Cache { next_key :: !(IORef Key),
+data Cache = Cache { next_key :: !(IORef Key),	-- Not used by GHC (calls genSym instead)
 		     tc_tbl   :: !(HT.HashTable String Key),
 		     ap_tbl   :: !(HT.HashTable KeyPr Key) }
 
 {-# NOINLINE cache #-}
+#ifdef __GLASGOW_HASKELL__
+foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
+    getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
+#endif
+
 cache :: Cache
 cache = unsafePerformIO $ do
 		empty_tc_tbl <- HT.new (==) HT.hashString
 		empty_ap_tbl <- HT.new (==) hashKP
 		key_loc      <- newIORef (Key 1) 
-		return (Cache { next_key = key_loc,
-				tc_tbl = empty_tc_tbl, 
-				ap_tbl = empty_ap_tbl })
+		let ret = Cache {	next_key = key_loc,
+					tc_tbl = empty_tc_tbl, 
+					ap_tbl = empty_ap_tbl }
+#ifdef __GLASGOW_HASKELL__
+		block $ do
+			stable_ref <- newStablePtr ret
+			let ref = castStablePtrToPtr stable_ref
+			ref2 <- getOrSetTypeableStore ref
+			if ref==ref2
+				then deRefStablePtr stable_ref
+				else do
+					freeStablePtr stable_ref
+					deRefStablePtr
+						(castPtrToStablePtr ref2)
+#else
+		return ret
+#endif
 
 newKey :: IORef Key -> IO Key
 #ifdef __GLASGOW_HASKELL__
@@ -468,16 +651,6 @@ newKey kloc = do { k@(Key i) <- readIORef kloc ;
 #endif
 
 #ifdef __GLASGOW_HASKELL__
--- In GHC we use the RTS's genSym function to get a new unique,
--- because in GHCi we might have two copies of the Data.Typeable
--- library running (one in the compiler and one in the running
--- program), and we need to make sure they don't share any keys.  
---
--- This is really a hack.  A better solution would be to centralise the
--- whole mutable state used by this module, i.e. both hashtables.  But
--- the current solution solves the immediate problem, which is that
--- dynamics generated in one world with one type were erroneously
--- being recognised by the other world as having a different type.
 foreign import ccall unsafe "genSymZh"
   genSym :: IO Int
 #endif
@@ -508,78 +681,3 @@ appKey k1 k2
 
 appKeys :: Key -> [Key] -> Key
 appKeys k ks = foldl appKey k ks
-
-
-
-------------------------------------------------------------------------------
---
---	Typeable adopted for unary type constructors
---	This adoption is at an experimental stage.
---
-------------------------------------------------------------------------------
-
-
--- | Variant for unary type constructors
-class Typeable1 t where
-  typeOf1 :: t a -> TyCon
-
-
--- | Variant for binary type constructors
-class Typeable2 t where
-  typeOf2 :: t a b -> TyCon
-
-
-#ifndef __NHC__
-
--- | Instance for lists
-instance Typeable1 [] where
-  typeOf1 _ = typerepTyCon (typeOf (undefined::[()]))
-
-
--- | Instance for maybes
-instance Typeable1 Maybe where
-  typeOf1 _ = typerepTyCon (typeOf (undefined::Maybe ()))
-
-
--- | Instance for ratios
-instance Typeable1 Ratio where
-  typeOf1 _ = typerepTyCon (typeOf (undefined::Ratio ()))
-
-
--- | Instance for products
-instance Typeable2 (,) where
-  typeOf2 _ = typerepTyCon (typeOf (undefined::((),())))
-
-
--- | Instance for sums
-instance Typeable2 Either where
-  typeOf2 _ = typerepTyCon (typeOf (undefined::Either () ()))
-
-
--- | Instance for functions
-instance Typeable2 (->) where
-  typeOf2 _ = typerepTyCon (typeOf (undefined::() -> ()))
-
-#endif
-
-
--- | Cast for * -> *
-cast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a)) 
-cast1 x = r
- where
-  r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
-       then Just $ unsafeCoerce x
-       else Nothing
-  getArg :: c x -> x 
-  getArg = undefined
-
-
--- | Cast for * -> * -> *
-cast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b)) 
-cast2 x = r
- where
-  r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
-       then Just $ unsafeCoerce x
-       else Nothing
-  getArg :: c x -> x 
-  getArg = undefined