-- 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.
--
+-- 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
mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
- splitTyConApp, -- :: TypeRep -> (TyCon, [TypeRep])
- funResultTy, -- :: TypeRep -> TypeRep -> Maybe TypeRep
-- * Observation of type representations
- typerepTyCon, -- :: TypeRep -> TyCon
- typerepArgs, -- :: TypeRep -> [TypeRep]
- tyconString, -- :: TyCon -> String
+ 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.
#ifdef __NHC__
import NonStdUnsafeCoerce (unsafeCoerce)
import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
+import IO (Handle)
+import Ratio (Ratio)
+import NHC.FFI (Ptr,StablePtr)
#else
-#include "Typeable.h"
#endif
+#include "Typeable.h"
+
#ifndef __HUGS__
-------------------------------------------------------------
----------------- 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 --------------------
--
-------------------------------------------------------------
-#ifndef __NHC__
INSTANCE_TYPEABLE1([],listTc,"[]")
INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
INSTANCE_TYPEABLE2((->),funTc,"->")
INSTANCE_TYPEABLE1(IO,ioTc,"IO")
INSTANCE_TYPEABLE0((),unitTc,"()")
+#ifndef __NHC__
INSTANCE_TYPEABLE2((,),pairTc,",")
INSTANCE_TYPEABLE3((,,),tup3Tc,",,")
typeOf6 tu = mkTyConApp tup6Tc []
tup7Tc :: TyCon
-tup7Tc = mkTyCon ",,,,,"
+tup7Tc = mkTyCon ",,,,,,"
instance Typeable7 (,,,,,,) where
typeOf7 tu = mkTyConApp tup7Tc []
-INSTANCE_TYPEABLE1(Ptr,ptrTc,"Foreign.Ptr.Ptr")
-INSTANCE_TYPEABLE1(StablePtr,stableptrTc,"Foreign.StablePtr.StablePtr")
-INSTANCE_TYPEABLE1(IORef,iorefTc,"Data.IORef.IORef")
-#endif /* ! __NHC__ */
+#endif /* __NHC__ */
+INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
+INSTANCE_TYPEABLE1(StablePtr,stableptrTc,"StablePtr")
+INSTANCE_TYPEABLE1(IORef,iorefTc,"IORef")
-------------------------------------------------------
--
--
-------------------------------------------------------
-#ifndef __NHC__
INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
INSTANCE_TYPEABLE0(Char,charTc,"Char")
INSTANCE_TYPEABLE0(Float,floatTc,"Float")
INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
-#endif /* !__NHC__ */
#ifdef __GLASGOW_HASKELL__
INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
+INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
#endif
---------------------------------------------