-{-# OPTIONS_GHC -fno-implicit-prelude -fallow-overlapping-instances #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude -XOverlappingInstances -funbox-strict-fields #-}
--- The -fallow-overlapping-instances flag allows the user to over-ride
+-- The -XOverlappingInstances flag allows the user to over-ride
-- the instances for Typeable given here. In particular, we provide an instance
--- instance ... => Typeable (s a)
+-- instance ... => Typeable (s a)
-- But a user might want to say
--- instance ... => Typeable (MyType a b)
+-- instance ... => Typeable (MyType a b)
-----------------------------------------------------------------------------
-- |
-- and type-safe cast (but not dynamics) to support the \"Scrap your
-- boilerplate\" style of generic programming.
--
--- Note, only relevant if you use dynamic linking. If you have a program
--- that is statically linked with Data.Typeable, and then dynamically link
--- a program that also uses Data.Typeable, you'll get two copies of the module.
--- That's fine, but behind the scenes, the module uses a mutable variable to
--- allocate unique Ids to type constructors. So in the situation described,
--- there'll be two separate Id allocators, which aren't comparable to each other.
--- This can lead to chaos. (It's a bug that we will fix.) None of
--- this matters if you aren't using dynamic linking.
---
-----------------------------------------------------------------------------
module Data.Typeable
(
- -- * The Typeable class
- Typeable( typeOf ), -- :: a -> TypeRep
-
- -- * Type-safe cast
- cast, -- :: (Typeable a, Typeable b) => a -> Maybe b
- gcast, -- a generalisation of cast
-
- -- * Type representations
- TypeRep, -- abstract, instance of: Eq, Show, Typeable
- TyCon, -- abstract, instance of: Eq, Show, Typeable
-
- -- * Construction of type representations
- mkTyCon, -- :: String -> TyCon
- mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
- mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
- mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
-
- -- * Observation of type representations
- splitTyConApp, -- :: TypeRep -> (TyCon, [TypeRep])
- funResultTy, -- :: TypeRep -> TypeRep -> Maybe TypeRep
- typeRepTyCon, -- :: TypeRep -> TyCon
- typeRepArgs, -- :: TypeRep -> [TypeRep]
- tyConString, -- :: TyCon -> String
-
- -- * 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
+ -- * The Typeable class
+ Typeable( typeOf ), -- :: a -> TypeRep
+
+ -- * Type-safe cast
+ cast, -- :: (Typeable a, Typeable b) => a -> Maybe b
+ 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
+ mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
+ mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
+ mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
+
+ -- * Observation of type representations
+ 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
import Data.Int
import Data.Word
-import Data.List( foldl )
+import Data.List( foldl, intersperse )
+import Unsafe.Coerce
#ifdef __GLASGOW_HASKELL__
import GHC.Base
-import GHC.Show
-import GHC.Err
-import GHC.Num
-import GHC.Float
-import GHC.Real ( rem, Ratio )
-import GHC.IOBase (IORef,newIORef,unsafePerformIO)
+import GHC.Show (Show(..), ShowS,
+ shows, showString, showChar, showParen)
+import GHC.Err (undefined)
+import GHC.Num (Integer, fromInteger, (+))
+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.IOBase ( IO, MVar, Handle, block )
+import GHC.ST ( ST )
+import GHC.STRef ( STRef )
import GHC.Ptr ( Ptr, FunPtr )
-import GHC.ForeignPtr ( ForeignPtr )
-import GHC.Stable ( StablePtr )
-import GHC.Arr ( Array, STArray )
+import GHC.Stable ( StablePtr, newStablePtr, freeStablePtr,
+ deRefStablePtr, castStablePtrToPtr,
+ castPtrToStablePtr )
+import GHC.Arr ( Array, STArray )
#endif
#ifdef __HUGS__
-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__
-unsafeCoerce :: a -> b
-unsafeCoerce = unsafeCoerce#
+import Hugs.Prelude ( Key(..), TypeRep(..), TyCon(..), Ratio,
+ Handle, Ptr, FunPtr, ForeignPtr, StablePtr )
+import Hugs.IORef ( IORef, newIORef, readIORef, writeIORef )
+import Hugs.IOExts ( unsafePerformIO )
+ -- For the Typeable instance
+import Hugs.Array ( Array )
+import Hugs.ConcBase ( MVar )
#endif
#ifdef __NHC__
-import NonStdUnsafeCoerce (unsafeCoerce)
import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
import IO (Handle)
import Ratio (Ratio)
- -- For the Typeable instance
-import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
-import Array ( Array )
+ -- For the Typeable instance
+import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
+import Array ( Array )
#endif
#include "Typeable.h"
-------------------------------------------------------------
--
--- Type representations
+-- Type representations
--
-------------------------------------------------------------
instance Eq TyCon where
(TyCon t1 _) == (TyCon t2 _) = t1 == t2
-
#endif
- --
- -- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
- -- [fTy,fTy,fTy])
- --
- -- returns "(Foo,Foo,Foo)"
- --
- -- The TypeRep Show instance promises to print tuple types
- -- correctly. Tuple type constructors are specified by a
- -- sequence of commas, e.g., (mkTyCon ",,,,") returns
- -- the 5-tuple tycon.
+-- | Returns a unique integer associated with a 'TypeRep'. This can
+-- be used for making a mapping 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 (mkTyConApp (mkTyCon ",,")
+ -- [fTy,fTy,fTy])
+ --
+ -- returns "(Foo,Foo,Foo)"
+ --
+ -- The TypeRep Show instance promises to print tuple types
+ -- correctly. Tuple type constructors are specified by a
+ -- sequence of commas, e.g., (mkTyCon ",,,,") returns
+ -- the 5-tuple tycon.
----------------- Construction --------------------
-- > mkTyCon "a" == mkTyCon "a"
--
-mkTyCon :: String -- ^ the name of the type constructor (should be unique
- -- in the program, so it might be wise to use the
- -- fully qualified name).
- -> TyCon -- ^ A unique 'TyCon' object
+mkTyCon :: String -- ^ the name of the type constructor (should be unique
+ -- in the program, so it might be wise to use the
+ -- fully qualified name).
+ -> TyCon -- ^ A unique 'TyCon' object
mkTyCon str = TyCon (mkTyConKey str) str
----------------- Observation ---------------------
[] -> showsPrec p tycon
[x] | tycon == listTc -> showChar '[' . shows x . showChar ']'
[a,r] | tycon == funTc -> showParen (p > 8) $
- showsPrec 9 a .
+ showsPrec 9 a .
showString " -> " .
showsPrec 8 r
- xs | isTupleTyCon tycon -> showTuple tycon xs
- | otherwise ->
- showParen (p > 9) $
- showsPrec p tycon .
- showChar ' ' .
- showArgs tys
+ xs | isTupleTyCon tycon -> showTuple xs
+ | otherwise ->
+ showParen (p > 9) $
+ showsPrec p tycon .
+ showChar ' ' .
+ showArgs tys
+
+showsTypeRep :: TypeRep -> ShowS
+showsTypeRep = shows
instance Show TyCon where
showsPrec _ (TyCon _ s) = showString s
isTupleTyCon :: TyCon -> Bool
-isTupleTyCon (TyCon _ (',':_)) = True
-isTupleTyCon _ = False
+isTupleTyCon (TyCon _ ('(':',':_)) = True
+isTupleTyCon _ = False
-- Some (Show.TypeRep) helpers:
showArgs [a] = showsPrec 10 a
showArgs (a:as) = showsPrec 10 a . showString " " . showArgs as
-showTuple :: TyCon -> [TypeRep] -> ShowS
-showTuple (TyCon _ str) args = showChar '(' . go str args
- where
- go [] [a] = showsPrec 10 a . showChar ')'
- go _ [] = showChar ')' -- a failure condition, really.
- go (',':xs) (a:as) = showsPrec 10 a . showChar ',' . go xs as
- go _ _ = showChar ')'
+showTuple :: [TypeRep] -> ShowS
+showTuple args = showChar '('
+ . (foldr (.) id $ intersperse (showChar ',')
+ $ map (showsPrec 10) args)
+ . showChar ')'
-------------------------------------------------------------
--
--- The Typeable class and friends
+-- The Typeable class and friends
--
-------------------------------------------------------------
-------------------------------------------------------------
--
--- Type-safe cast
+-- Type-safe cast
--
-------------------------------------------------------------
cast :: (Typeable a, Typeable b) => a -> Maybe b
cast x = r
where
- r = if typeOf x == typeOf (fromJust r)
+ r = if typeOf x == typeOf (fromJust r)
then Just $ unsafeCoerce x
- else Nothing
+ else Nothing
-- | A flexible variation parameterised in a type constructor
gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
-------------------------------------------------------------
--
--- Instances of the Typeable classes for Prelude types
+-- Instances of the Typeable classes for Prelude types
--
-------------------------------------------------------------
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")
#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
-- Types defined in GHC.Arr
#endif
#ifndef __NHC__
-INSTANCE_TYPEABLE2((,),pairTc,",")
-INSTANCE_TYPEABLE3((,,),tup3Tc,",,")
+INSTANCE_TYPEABLE2((,),pairTc,"(,)")
+INSTANCE_TYPEABLE3((,,),tup3Tc,"(,,)")
tup4Tc :: TyCon
-tup4Tc = mkTyCon ",,,"
+tup4Tc = mkTyCon "(,,,)"
instance Typeable4 (,,,) where
- typeOf4 tu = mkTyConApp tup4Tc []
+ typeOf4 _ = mkTyConApp tup4Tc []
tup5Tc :: TyCon
-tup5Tc = mkTyCon ",,,,"
+tup5Tc = mkTyCon "(,,,,)"
instance Typeable5 (,,,,) where
- typeOf5 tu = mkTyConApp tup5Tc []
+ typeOf5 _ = mkTyConApp tup5Tc []
tup6Tc :: TyCon
-tup6Tc = mkTyCon ",,,,,"
+tup6Tc = mkTyCon "(,,,,,)"
instance Typeable6 (,,,,,) where
- typeOf6 tu = mkTyConApp tup6Tc []
+ typeOf6 _ = mkTyConApp tup6Tc []
tup7Tc :: TyCon
-tup7Tc = mkTyCon ",,,,,,"
+tup7Tc = mkTyCon "(,,,,,,)"
instance Typeable7 (,,,,,,) where
- typeOf7 tu = mkTyConApp tup7Tc []
+ typeOf7 _ = 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")
---------------------------------------------
--
--- Internals
+-- Internals
--
---------------------------------------------
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), -- Not used by GHC (calls genSym instead)
- tc_tbl :: !(HT.HashTable String Key),
- ap_tbl :: !(HT.HashTable KeyPr 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 })
+ empty_tc_tbl <- HT.new (==) HT.hashString
+ empty_ap_tbl <- HT.new (==) hashKP
+ key_loc <- newIORef (Key 1)
+ 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__
-newKey kloc = do i <- genSym; return (Key i)
+newKey _ = do i <- genSym; return (Key i)
#else
newKey kloc = do { k@(Key i) <- readIORef kloc ;
- writeIORef kloc (Key (i+1)) ;
- return k }
+ writeIORef kloc (Key (i+1)) ;
+ return k }
#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
mkTyConKey :: String -> Key
mkTyConKey str
= unsafePerformIO $ do
- let Cache {next_key = kloc, tc_tbl = tbl} = cache
- mb_k <- HT.lookup tbl str
- case mb_k of
- Just k -> return k
- Nothing -> do { k <- newKey kloc ;
- HT.insert tbl str k ;
- return k }
+ let Cache {next_key = kloc, tc_tbl = tbl} = cache
+ mb_k <- HT.lookup tbl str
+ case mb_k of
+ Just k -> return k
+ Nothing -> do { k <- newKey kloc ;
+ HT.insert tbl str k ;
+ return k }
appKey :: Key -> Key -> Key
appKey k1 k2
= unsafePerformIO $ do
- let Cache {next_key = kloc, ap_tbl = tbl} = cache
- mb_k <- HT.lookup tbl kpr
- case mb_k of
- Just k -> return k
- Nothing -> do { k <- newKey kloc ;
- HT.insert tbl kpr k ;
- return k }
+ let Cache {next_key = kloc, ap_tbl = tbl} = cache
+ mb_k <- HT.lookup tbl kpr
+ case mb_k of
+ Just k -> return k
+ Nothing -> do { k <- newKey kloc ;
+ HT.insert tbl kpr k ;
+ return k }
where
kpr = KeyPr k1 k2
projects / ghc-base.git / blobdiff