FIX dynamic001, dynamic002: further fixes to tuple printing
[ghc.git] / libraries / base / Data / Typeable.hs
1 {-# OPTIONS_GHC -fno-implicit-prelude -fallow-overlapping-instances -funbox-strict-fields #-}
2
3 -- The -fallow-overlapping-instances flag allows the user to over-ride
4 -- the instances for Typeable given here. In particular, we provide an instance
5 -- instance ... => Typeable (s a)
6 -- But a user might want to say
7 -- instance ... => Typeable (MyType a b)
8
9 -----------------------------------------------------------------------------
10 -- |
11 -- Module : Data.Typeable
12 -- Copyright : (c) The University of Glasgow, CWI 2001--2004
13 -- License : BSD-style (see the file libraries/base/LICENSE)
14 --
15 -- Maintainer : libraries@haskell.org
16 -- Stability : experimental
17 -- Portability : portable
18 --
19 -- The 'Typeable' class reifies types to some extent by associating type
20 -- representations to types. These type representations can be compared,
21 -- and one can in turn define a type-safe cast operation. To this end,
22 -- an unsafe cast is guarded by a test for type (representation)
23 -- equivalence. The module "Data.Dynamic" uses Typeable for an
24 -- implementation of dynamics. The module "Data.Generics" uses Typeable
25 -- and type-safe cast (but not dynamics) to support the \"Scrap your
26 -- boilerplate\" style of generic programming.
27 --
28 -----------------------------------------------------------------------------
29
30 module Data.Typeable
31 (
32
33 -- * The Typeable class
34 Typeable( typeOf ), -- :: a -> TypeRep
35
36 -- * Type-safe cast
37 cast, -- :: (Typeable a, Typeable b) => a -> Maybe b
38 gcast, -- a generalisation of cast
39
40 -- * Type representations
41 TypeRep, -- abstract, instance of: Eq, Show, Typeable
42 TyCon, -- abstract, instance of: Eq, Show, Typeable
43 showsTypeRep,
44
45 -- * Construction of type representations
46 mkTyCon, -- :: String -> TyCon
47 mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
48 mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
49 mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
50
51 -- * Observation of type representations
52 splitTyConApp, -- :: TypeRep -> (TyCon, [TypeRep])
53 funResultTy, -- :: TypeRep -> TypeRep -> Maybe TypeRep
54 typeRepTyCon, -- :: TypeRep -> TyCon
55 typeRepArgs, -- :: TypeRep -> [TypeRep]
56 tyConString, -- :: TyCon -> String
57 typeRepKey, -- :: TypeRep -> IO Int
58
59 -- * The other Typeable classes
60 -- | /Note:/ The general instances are provided for GHC only.
61 Typeable1( typeOf1 ), -- :: t a -> TypeRep
62 Typeable2( typeOf2 ), -- :: t a b -> TypeRep
63 Typeable3( typeOf3 ), -- :: t a b c -> TypeRep
64 Typeable4( typeOf4 ), -- :: t a b c d -> TypeRep
65 Typeable5( typeOf5 ), -- :: t a b c d e -> TypeRep
66 Typeable6( typeOf6 ), -- :: t a b c d e f -> TypeRep
67 Typeable7( typeOf7 ), -- :: t a b c d e f g -> TypeRep
68 gcast1, -- :: ... => c (t a) -> Maybe (c (t' a))
69 gcast2, -- :: ... => c (t a b) -> Maybe (c (t' a b))
70
71 -- * Default instances
72 -- | /Note:/ These are not needed by GHC, for which these instances
73 -- are generated by general instance declarations.
74 typeOfDefault, -- :: (Typeable1 t, Typeable a) => t a -> TypeRep
75 typeOf1Default, -- :: (Typeable2 t, Typeable a) => t a b -> TypeRep
76 typeOf2Default, -- :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
77 typeOf3Default, -- :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
78 typeOf4Default, -- :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
79 typeOf5Default, -- :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
80 typeOf6Default -- :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
81
82 ) where
83
84 import qualified Data.HashTable as HT
85 import Data.Maybe
86 import Data.Either
87 import Data.Int
88 import Data.Word
89 import Data.List( foldl, intersperse )
90 import Unsafe.Coerce
91
92 #ifdef __GLASGOW_HASKELL__
93 import GHC.Base
94 import GHC.Show
95 import GHC.Err
96 import GHC.Num
97 import GHC.Float
98 import GHC.Real ( rem, Ratio )
99 import GHC.IOBase (IORef,newIORef,unsafePerformIO)
100
101 -- These imports are so we can define Typeable instances
102 -- It'd be better to give Typeable instances in the modules themselves
103 -- but they all have to be compiled before Typeable
104 import GHC.IOBase ( IO, MVar, Exception, ArithException, IOException,
105 ArrayException, AsyncException, Handle )
106 import GHC.ST ( ST )
107 import GHC.STRef ( STRef )
108 import GHC.Ptr ( Ptr, FunPtr )
109 import GHC.ForeignPtr ( ForeignPtr )
110 import GHC.Stable ( StablePtr, newStablePtr, freeStablePtr,
111 deRefStablePtr, castStablePtrToPtr,
112 castPtrToStablePtr )
113 import GHC.Exception ( block )
114 import GHC.Arr ( Array, STArray )
115
116 #endif
117
118 #ifdef __HUGS__
119 import Hugs.Prelude ( Key(..), TypeRep(..), TyCon(..), Ratio,
120 Exception, ArithException, IOException,
121 ArrayException, AsyncException, Handle,
122 Ptr, FunPtr, ForeignPtr, StablePtr )
123 import Hugs.IORef ( IORef, newIORef, readIORef, writeIORef )
124 import Hugs.IOExts ( unsafePerformIO )
125 -- For the Typeable instance
126 import Hugs.Array ( Array )
127 import Hugs.ConcBase ( MVar )
128 #endif
129
130 #ifdef __NHC__
131 import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
132 import IO (Handle)
133 import Ratio (Ratio)
134 -- For the Typeable instance
135 import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
136 import Array ( Array )
137 #endif
138
139 #include "Typeable.h"
140
141 #ifndef __HUGS__
142
143 -------------------------------------------------------------
144 --
145 -- Type representations
146 --
147 -------------------------------------------------------------
148
149 -- | A concrete representation of a (monomorphic) type. 'TypeRep'
150 -- supports reasonably efficient equality.
151 data TypeRep = TypeRep !Key TyCon [TypeRep]
152
153 -- Compare keys for equality
154 instance Eq TypeRep where
155 (TypeRep k1 _ _) == (TypeRep k2 _ _) = k1 == k2
156
157 -- | An abstract representation of a type constructor. 'TyCon' objects can
158 -- be built using 'mkTyCon'.
159 data TyCon = TyCon !Key String
160
161 instance Eq TyCon where
162 (TyCon t1 _) == (TyCon t2 _) = t1 == t2
163 #endif
164
165 -- | Returns a unique integer associated with a 'TypeRep'. This can
166 -- be used for making a mapping with TypeReps
167 -- as the keys, for example. It is guaranteed that @t1 == t2@ if and only if
168 -- @typeRepKey t1 == typeRepKey t2@.
169 --
170 -- It is in the 'IO' monad because the actual value of the key may
171 -- vary from run to run of the program. You should only rely on
172 -- the equality property, not any actual key value. The relative ordering
173 -- of keys has no meaning either.
174 --
175 typeRepKey :: TypeRep -> IO Int
176 typeRepKey (TypeRep (Key i) _ _) = return i
177
178 --
179 -- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
180 -- [fTy,fTy,fTy])
181 --
182 -- returns "(Foo,Foo,Foo)"
183 --
184 -- The TypeRep Show instance promises to print tuple types
185 -- correctly. Tuple type constructors are specified by a
186 -- sequence of commas, e.g., (mkTyCon ",,,,") returns
187 -- the 5-tuple tycon.
188
189 ----------------- Construction --------------------
190
191 -- | Applies a type constructor to a sequence of types
192 mkTyConApp :: TyCon -> [TypeRep] -> TypeRep
193 mkTyConApp tc@(TyCon tc_k _) args
194 = TypeRep (appKeys tc_k arg_ks) tc args
195 where
196 arg_ks = [k | TypeRep k _ _ <- args]
197
198 -- | A special case of 'mkTyConApp', which applies the function
199 -- type constructor to a pair of types.
200 mkFunTy :: TypeRep -> TypeRep -> TypeRep
201 mkFunTy f a = mkTyConApp funTc [f,a]
202
203 -- | Splits a type constructor application
204 splitTyConApp :: TypeRep -> (TyCon,[TypeRep])
205 splitTyConApp (TypeRep _ tc trs) = (tc,trs)
206
207 -- | Applies a type to a function type. Returns: @'Just' u@ if the
208 -- first argument represents a function of type @t -> u@ and the
209 -- second argument represents a function of type @t@. Otherwise,
210 -- returns 'Nothing'.
211 funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep
212 funResultTy trFun trArg
213 = case splitTyConApp trFun of
214 (tc, [t1,t2]) | tc == funTc && t1 == trArg -> Just t2
215 _ -> Nothing
216
217 -- | Adds a TypeRep argument to a TypeRep.
218 mkAppTy :: TypeRep -> TypeRep -> TypeRep
219 mkAppTy (TypeRep tr_k tc trs) arg_tr
220 = let (TypeRep arg_k _ _) = arg_tr
221 in TypeRep (appKey tr_k arg_k) tc (trs++[arg_tr])
222
223 -- If we enforce the restriction that there is only one
224 -- @TyCon@ for a type & it is shared among all its uses,
225 -- we can map them onto Ints very simply. The benefit is,
226 -- of course, that @TyCon@s can then be compared efficiently.
227
228 -- Provided the implementor of other @Typeable@ instances
229 -- takes care of making all the @TyCon@s CAFs (toplevel constants),
230 -- this will work.
231
232 -- If this constraint does turn out to be a sore thumb, changing
233 -- the Eq instance for TyCons is trivial.
234
235 -- | Builds a 'TyCon' object representing a type constructor. An
236 -- implementation of "Data.Typeable" should ensure that the following holds:
237 --
238 -- > mkTyCon "a" == mkTyCon "a"
239 --
240
241 mkTyCon :: String -- ^ the name of the type constructor (should be unique
242 -- in the program, so it might be wise to use the
243 -- fully qualified name).
244 -> TyCon -- ^ A unique 'TyCon' object
245 mkTyCon str = TyCon (mkTyConKey str) str
246
247 ----------------- Observation ---------------------
248
249 -- | Observe the type constructor of a type representation
250 typeRepTyCon :: TypeRep -> TyCon
251 typeRepTyCon (TypeRep _ tc _) = tc
252
253 -- | Observe the argument types of a type representation
254 typeRepArgs :: TypeRep -> [TypeRep]
255 typeRepArgs (TypeRep _ _ args) = args
256
257 -- | Observe string encoding of a type representation
258 tyConString :: TyCon -> String
259 tyConString (TyCon _ str) = str
260
261 ----------------- Showing TypeReps --------------------
262
263 instance Show TypeRep where
264 showsPrec p (TypeRep _ tycon tys) =
265 case tys of
266 [] -> showsPrec p tycon
267 [x] | tycon == listTc -> showChar '[' . shows x . showChar ']'
268 [a,r] | tycon == funTc -> showParen (p > 8) $
269 showsPrec 9 a .
270 showString " -> " .
271 showsPrec 8 r
272 xs | isTupleTyCon tycon -> showTuple xs
273 | otherwise ->
274 showParen (p > 9) $
275 showsPrec p tycon .
276 showChar ' ' .
277 showArgs tys
278
279 showsTypeRep :: TypeRep -> ShowS
280 showsTypeRep = shows
281
282 instance Show TyCon where
283 showsPrec _ (TyCon _ s) = showString s
284
285 isTupleTyCon :: TyCon -> Bool
286 isTupleTyCon (TyCon _ ('(':',':_)) = True
287 isTupleTyCon _ = False
288
289 -- Some (Show.TypeRep) helpers:
290
291 showArgs :: Show a => [a] -> ShowS
292 showArgs [] = id
293 showArgs [a] = showsPrec 10 a
294 showArgs (a:as) = showsPrec 10 a . showString " " . showArgs as
295
296 showTuple :: [TypeRep] -> ShowS
297 showTuple args = showChar '('
298 . (foldr (.) id $ intersperse (showChar ',')
299 $ map (showsPrec 10) args)
300 . showChar ')'
301
302 -------------------------------------------------------------
303 --
304 -- The Typeable class and friends
305 --
306 -------------------------------------------------------------
307
308 -- | The class 'Typeable' allows a concrete representation of a type to
309 -- be calculated.
310 class Typeable a where
311 typeOf :: a -> TypeRep
312 -- ^ Takes a value of type @a@ and returns a concrete representation
313 -- of that type. The /value/ of the argument should be ignored by
314 -- any instance of 'Typeable', so that it is safe to pass 'undefined' as
315 -- the argument.
316
317 -- | Variant for unary type constructors
318 class Typeable1 t where
319 typeOf1 :: t a -> TypeRep
320
321 -- | For defining a 'Typeable' instance from any 'Typeable1' instance.
322 typeOfDefault :: (Typeable1 t, Typeable a) => t a -> TypeRep
323 typeOfDefault x = typeOf1 x `mkAppTy` typeOf (argType x)
324 where
325 argType :: t a -> a
326 argType = undefined
327
328 -- | Variant for binary type constructors
329 class Typeable2 t where
330 typeOf2 :: t a b -> TypeRep
331
332 -- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
333 typeOf1Default :: (Typeable2 t, Typeable a) => t a b -> TypeRep
334 typeOf1Default x = typeOf2 x `mkAppTy` typeOf (argType x)
335 where
336 argType :: t a b -> a
337 argType = undefined
338
339 -- | Variant for 3-ary type constructors
340 class Typeable3 t where
341 typeOf3 :: t a b c -> TypeRep
342
343 -- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
344 typeOf2Default :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
345 typeOf2Default x = typeOf3 x `mkAppTy` typeOf (argType x)
346 where
347 argType :: t a b c -> a
348 argType = undefined
349
350 -- | Variant for 4-ary type constructors
351 class Typeable4 t where
352 typeOf4 :: t a b c d -> TypeRep
353
354 -- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
355 typeOf3Default :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
356 typeOf3Default x = typeOf4 x `mkAppTy` typeOf (argType x)
357 where
358 argType :: t a b c d -> a
359 argType = undefined
360
361 -- | Variant for 5-ary type constructors
362 class Typeable5 t where
363 typeOf5 :: t a b c d e -> TypeRep
364
365 -- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
366 typeOf4Default :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
367 typeOf4Default x = typeOf5 x `mkAppTy` typeOf (argType x)
368 where
369 argType :: t a b c d e -> a
370 argType = undefined
371
372 -- | Variant for 6-ary type constructors
373 class Typeable6 t where
374 typeOf6 :: t a b c d e f -> TypeRep
375
376 -- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
377 typeOf5Default :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
378 typeOf5Default x = typeOf6 x `mkAppTy` typeOf (argType x)
379 where
380 argType :: t a b c d e f -> a
381 argType = undefined
382
383 -- | Variant for 7-ary type constructors
384 class Typeable7 t where
385 typeOf7 :: t a b c d e f g -> TypeRep
386
387 -- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
388 typeOf6Default :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
389 typeOf6Default x = typeOf7 x `mkAppTy` typeOf (argType x)
390 where
391 argType :: t a b c d e f g -> a
392 argType = undefined
393
394 #ifdef __GLASGOW_HASKELL__
395 -- Given a @Typeable@/n/ instance for an /n/-ary type constructor,
396 -- define the instances for partial applications.
397 -- Programmers using non-GHC implementations must do this manually
398 -- for each type constructor.
399 -- (The INSTANCE_TYPEABLE/n/ macros in Typeable.h include this.)
400
401 -- | One Typeable instance for all Typeable1 instances
402 instance (Typeable1 s, Typeable a)
403 => Typeable (s a) where
404 typeOf = typeOfDefault
405
406 -- | One Typeable1 instance for all Typeable2 instances
407 instance (Typeable2 s, Typeable a)
408 => Typeable1 (s a) where
409 typeOf1 = typeOf1Default
410
411 -- | One Typeable2 instance for all Typeable3 instances
412 instance (Typeable3 s, Typeable a)
413 => Typeable2 (s a) where
414 typeOf2 = typeOf2Default
415
416 -- | One Typeable3 instance for all Typeable4 instances
417 instance (Typeable4 s, Typeable a)
418 => Typeable3 (s a) where
419 typeOf3 = typeOf3Default
420
421 -- | One Typeable4 instance for all Typeable5 instances
422 instance (Typeable5 s, Typeable a)
423 => Typeable4 (s a) where
424 typeOf4 = typeOf4Default
425
426 -- | One Typeable5 instance for all Typeable6 instances
427 instance (Typeable6 s, Typeable a)
428 => Typeable5 (s a) where
429 typeOf5 = typeOf5Default
430
431 -- | One Typeable6 instance for all Typeable7 instances
432 instance (Typeable7 s, Typeable a)
433 => Typeable6 (s a) where
434 typeOf6 = typeOf6Default
435
436 #endif /* __GLASGOW_HASKELL__ */
437
438 -------------------------------------------------------------
439 --
440 -- Type-safe cast
441 --
442 -------------------------------------------------------------
443
444 -- | The type-safe cast operation
445 cast :: (Typeable a, Typeable b) => a -> Maybe b
446 cast x = r
447 where
448 r = if typeOf x == typeOf (fromJust r)
449 then Just $ unsafeCoerce x
450 else Nothing
451
452 -- | A flexible variation parameterised in a type constructor
453 gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
454 gcast x = r
455 where
456 r = if typeOf (getArg x) == typeOf (getArg (fromJust r))
457 then Just $ unsafeCoerce x
458 else Nothing
459 getArg :: c x -> x
460 getArg = undefined
461
462 -- | Cast for * -> *
463 gcast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a))
464 gcast1 x = r
465 where
466 r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
467 then Just $ unsafeCoerce x
468 else Nothing
469 getArg :: c x -> x
470 getArg = undefined
471
472 -- | Cast for * -> * -> *
473 gcast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b))
474 gcast2 x = r
475 where
476 r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
477 then Just $ unsafeCoerce x
478 else Nothing
479 getArg :: c x -> x
480 getArg = undefined
481
482 -------------------------------------------------------------
483 --
484 -- Instances of the Typeable classes for Prelude types
485 --
486 -------------------------------------------------------------
487
488 INSTANCE_TYPEABLE0((),unitTc,"()")
489 INSTANCE_TYPEABLE1([],listTc,"[]")
490 INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
491 INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
492 INSTANCE_TYPEABLE2(Either,eitherTc,"Either")
493 INSTANCE_TYPEABLE2((->),funTc,"->")
494 INSTANCE_TYPEABLE1(IO,ioTc,"IO")
495
496 #if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
497 -- Types defined in GHC.IOBase
498 INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
499 INSTANCE_TYPEABLE0(Exception,exceptionTc,"Exception")
500 INSTANCE_TYPEABLE0(IOException,ioExceptionTc,"IOException")
501 INSTANCE_TYPEABLE0(ArithException,arithExceptionTc,"ArithException")
502 INSTANCE_TYPEABLE0(ArrayException,arrayExceptionTc,"ArrayException")
503 INSTANCE_TYPEABLE0(AsyncException,asyncExceptionTc,"AsyncException")
504 #endif
505
506 -- Types defined in GHC.Arr
507 INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
508
509 #ifdef __GLASGOW_HASKELL__
510 -- Hugs has these too, but their Typeable<n> instances are defined
511 -- elsewhere to keep this module within Haskell 98.
512 -- This is important because every invocation of runhugs or ffihugs
513 -- uses this module via Data.Dynamic.
514 INSTANCE_TYPEABLE2(ST,stTc,"ST")
515 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
516 INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
517 #endif
518
519 #ifndef __NHC__
520 INSTANCE_TYPEABLE2((,),pairTc,"(,)")
521 INSTANCE_TYPEABLE3((,,),tup3Tc,"(,,)")
522
523 tup4Tc :: TyCon
524 tup4Tc = mkTyCon "(,,,)"
525
526 instance Typeable4 (,,,) where
527 typeOf4 tu = mkTyConApp tup4Tc []
528
529 tup5Tc :: TyCon
530 tup5Tc = mkTyCon "(,,,,)"
531
532 instance Typeable5 (,,,,) where
533 typeOf5 tu = mkTyConApp tup5Tc []
534
535 tup6Tc :: TyCon
536 tup6Tc = mkTyCon "(,,,,,)"
537
538 instance Typeable6 (,,,,,) where
539 typeOf6 tu = mkTyConApp tup6Tc []
540
541 tup7Tc :: TyCon
542 tup7Tc = mkTyCon "(,,,,,,)"
543
544 instance Typeable7 (,,,,,,) where
545 typeOf7 tu = mkTyConApp tup7Tc []
546 #endif /* __NHC__ */
547
548 INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
549 INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
550 INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
551 INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
552 INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
553
554 -------------------------------------------------------
555 --
556 -- Generate Typeable instances for standard datatypes
557 --
558 -------------------------------------------------------
559
560 INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
561 INSTANCE_TYPEABLE0(Char,charTc,"Char")
562 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
563 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
564 INSTANCE_TYPEABLE0(Int,intTc,"Int")
565 #ifndef __NHC__
566 INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
567 #endif
568 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
569 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
570 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
571
572 INSTANCE_TYPEABLE0(Int8,int8Tc,"Int8")
573 INSTANCE_TYPEABLE0(Int16,int16Tc,"Int16")
574 INSTANCE_TYPEABLE0(Int32,int32Tc,"Int32")
575 INSTANCE_TYPEABLE0(Int64,int64Tc,"Int64")
576
577 INSTANCE_TYPEABLE0(Word8,word8Tc,"Word8" )
578 INSTANCE_TYPEABLE0(Word16,word16Tc,"Word16")
579 INSTANCE_TYPEABLE0(Word32,word32Tc,"Word32")
580 INSTANCE_TYPEABLE0(Word64,word64Tc,"Word64")
581
582 INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
583 INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
584
585 #ifdef __GLASGOW_HASKELL__
586 INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
587 #endif
588
589 ---------------------------------------------
590 --
591 -- Internals
592 --
593 ---------------------------------------------
594
595 #ifndef __HUGS__
596 newtype Key = Key Int deriving( Eq )
597 #endif
598
599 data KeyPr = KeyPr !Key !Key deriving( Eq )
600
601 hashKP :: KeyPr -> Int32
602 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
603
604 data Cache = Cache { next_key :: !(IORef Key), -- Not used by GHC (calls genSym instead)
605 tc_tbl :: !(HT.HashTable String Key),
606 ap_tbl :: !(HT.HashTable KeyPr Key) }
607
608 {-# NOINLINE cache #-}
609 #ifdef __GLASGOW_HASKELL__
610 foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
611 getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
612 #endif
613
614 cache :: Cache
615 cache = unsafePerformIO $ do
616 empty_tc_tbl <- HT.new (==) HT.hashString
617 empty_ap_tbl <- HT.new (==) hashKP
618 key_loc <- newIORef (Key 1)
619 let ret = Cache { next_key = key_loc,
620 tc_tbl = empty_tc_tbl,
621 ap_tbl = empty_ap_tbl }
622 #ifdef __GLASGOW_HASKELL__
623 block $ do
624 stable_ref <- newStablePtr ret
625 let ref = castStablePtrToPtr stable_ref
626 ref2 <- getOrSetTypeableStore ref
627 if ref==ref2
628 then deRefStablePtr stable_ref
629 else do
630 freeStablePtr stable_ref
631 deRefStablePtr
632 (castPtrToStablePtr ref2)
633 #else
634 return ret
635 #endif
636
637 newKey :: IORef Key -> IO Key
638 #ifdef __GLASGOW_HASKELL__
639 newKey kloc = do i <- genSym; return (Key i)
640 #else
641 newKey kloc = do { k@(Key i) <- readIORef kloc ;
642 writeIORef kloc (Key (i+1)) ;
643 return k }
644 #endif
645
646 #ifdef __GLASGOW_HASKELL__
647 foreign import ccall unsafe "genSymZh"
648 genSym :: IO Int
649 #endif
650
651 mkTyConKey :: String -> Key
652 mkTyConKey str
653 = unsafePerformIO $ do
654 let Cache {next_key = kloc, tc_tbl = tbl} = cache
655 mb_k <- HT.lookup tbl str
656 case mb_k of
657 Just k -> return k
658 Nothing -> do { k <- newKey kloc ;
659 HT.insert tbl str k ;
660 return k }
661
662 appKey :: Key -> Key -> Key
663 appKey k1 k2
664 = unsafePerformIO $ do
665 let Cache {next_key = kloc, ap_tbl = tbl} = cache
666 mb_k <- HT.lookup tbl kpr
667 case mb_k of
668 Just k -> return k
669 Nothing -> do { k <- newKey kloc ;
670 HT.insert tbl kpr k ;
671 return k }
672 where
673 kpr = KeyPr k1 k2
674
675 appKeys :: Key -> [Key] -> Key
676 appKeys k ks = foldl appKey k ks