Trim imports, remove a cycle
[packages/base.git] / Data / Typeable.hs
1 {-# OPTIONS_GHC -fno-implicit-prelude -fallow-overlapping-instances #-}
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 )
90
91 #ifdef __GLASGOW_HASKELL__
92 import GHC.Base
93 import GHC.Show
94 import GHC.Err
95 import GHC.Num
96 import GHC.Float
97 import GHC.Real ( rem, Ratio )
98 import GHC.IOBase (IORef,newIORef,unsafePerformIO)
99
100 -- These imports are so we can define Typeable instances
101 -- It'd be better to give Typeable instances in the modules themselves
102 -- but they all have to be compiled before Typeable
103 import GHC.IOBase ( IO, MVar, Exception, ArithException, IOException,
104 ArrayException, AsyncException, Handle )
105 import GHC.ST ( ST )
106 import GHC.STRef ( STRef )
107 import GHC.Ptr ( Ptr, FunPtr )
108 import GHC.ForeignPtr ( ForeignPtr )
109 import GHC.Stable ( StablePtr, newStablePtr, freeStablePtr,
110 deRefStablePtr, castStablePtrToPtr,
111 castPtrToStablePtr )
112 import GHC.Exception ( block )
113 import GHC.Arr ( Array, STArray )
114
115 #endif
116
117 #ifdef __HUGS__
118 import Hugs.Prelude ( Key(..), TypeRep(..), TyCon(..), Ratio,
119 Exception, ArithException, IOException,
120 ArrayException, AsyncException, Handle,
121 Ptr, FunPtr, ForeignPtr, StablePtr )
122 import Hugs.IORef ( IORef, newIORef, readIORef, writeIORef )
123 import Hugs.IOExts ( unsafePerformIO, unsafeCoerce )
124 -- For the Typeable instance
125 import Hugs.Array ( Array )
126 import Hugs.ConcBase ( MVar )
127 #endif
128
129 #ifdef __GLASGOW_HASKELL__
130 unsafeCoerce :: a -> b
131 unsafeCoerce = unsafeCoerce#
132 #endif
133
134 #ifdef __NHC__
135 import NonStdUnsafeCoerce (unsafeCoerce)
136 import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
137 import IO (Handle)
138 import Ratio (Ratio)
139 -- For the Typeable instance
140 import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
141 import Array ( Array )
142 #endif
143
144 #include "Typeable.h"
145
146 #ifndef __HUGS__
147
148 -------------------------------------------------------------
149 --
150 -- Type representations
151 --
152 -------------------------------------------------------------
153
154 -- | A concrete representation of a (monomorphic) type. 'TypeRep'
155 -- supports reasonably efficient equality.
156 data TypeRep = TypeRep !Key TyCon [TypeRep]
157
158 -- Compare keys for equality
159 instance Eq TypeRep where
160 (TypeRep k1 _ _) == (TypeRep k2 _ _) = k1 == k2
161
162 -- | An abstract representation of a type constructor. 'TyCon' objects can
163 -- be built using 'mkTyCon'.
164 data TyCon = TyCon !Key String
165
166 instance Eq TyCon where
167 (TyCon t1 _) == (TyCon t2 _) = t1 == t2
168 #endif
169
170 -- | Returns a unique integer associated with a 'TypeRep'. This can
171 -- be used for making a mapping ('Data.IntMap.IntMap') with TypeReps
172 -- as the keys, for example. It is guaranteed that @t1 == t2@ if and only if
173 -- @typeRepKey t1 == typeRepKey t2@.
174 --
175 -- It is in the 'IO' monad because the actual value of the key may
176 -- vary from run to run of the program. You should only rely on
177 -- the equality property, not any actual key value. The relative ordering
178 -- of keys has no meaning either.
179 --
180 typeRepKey :: TypeRep -> IO Int
181 typeRepKey (TypeRep (Key i) _ _) = return i
182
183 --
184 -- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
185 -- [fTy,fTy,fTy])
186 --
187 -- returns "(Foo,Foo,Foo)"
188 --
189 -- The TypeRep Show instance promises to print tuple types
190 -- correctly. Tuple type constructors are specified by a
191 -- sequence of commas, e.g., (mkTyCon ",,,,") returns
192 -- the 5-tuple tycon.
193
194 ----------------- Construction --------------------
195
196 -- | Applies a type constructor to a sequence of types
197 mkTyConApp :: TyCon -> [TypeRep] -> TypeRep
198 mkTyConApp tc@(TyCon tc_k _) args
199 = TypeRep (appKeys tc_k arg_ks) tc args
200 where
201 arg_ks = [k | TypeRep k _ _ <- args]
202
203 -- | A special case of 'mkTyConApp', which applies the function
204 -- type constructor to a pair of types.
205 mkFunTy :: TypeRep -> TypeRep -> TypeRep
206 mkFunTy f a = mkTyConApp funTc [f,a]
207
208 -- | Splits a type constructor application
209 splitTyConApp :: TypeRep -> (TyCon,[TypeRep])
210 splitTyConApp (TypeRep _ tc trs) = (tc,trs)
211
212 -- | Applies a type to a function type. Returns: @'Just' u@ if the
213 -- first argument represents a function of type @t -> u@ and the
214 -- second argument represents a function of type @t@. Otherwise,
215 -- returns 'Nothing'.
216 funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep
217 funResultTy trFun trArg
218 = case splitTyConApp trFun of
219 (tc, [t1,t2]) | tc == funTc && t1 == trArg -> Just t2
220 _ -> Nothing
221
222 -- | Adds a TypeRep argument to a TypeRep.
223 mkAppTy :: TypeRep -> TypeRep -> TypeRep
224 mkAppTy (TypeRep tr_k tc trs) arg_tr
225 = let (TypeRep arg_k _ _) = arg_tr
226 in TypeRep (appKey tr_k arg_k) tc (trs++[arg_tr])
227
228 -- If we enforce the restriction that there is only one
229 -- @TyCon@ for a type & it is shared among all its uses,
230 -- we can map them onto Ints very simply. The benefit is,
231 -- of course, that @TyCon@s can then be compared efficiently.
232
233 -- Provided the implementor of other @Typeable@ instances
234 -- takes care of making all the @TyCon@s CAFs (toplevel constants),
235 -- this will work.
236
237 -- If this constraint does turn out to be a sore thumb, changing
238 -- the Eq instance for TyCons is trivial.
239
240 -- | Builds a 'TyCon' object representing a type constructor. An
241 -- implementation of "Data.Typeable" should ensure that the following holds:
242 --
243 -- > mkTyCon "a" == mkTyCon "a"
244 --
245
246 mkTyCon :: String -- ^ the name of the type constructor (should be unique
247 -- in the program, so it might be wise to use the
248 -- fully qualified name).
249 -> TyCon -- ^ A unique 'TyCon' object
250 mkTyCon str = TyCon (mkTyConKey str) str
251
252 ----------------- Observation ---------------------
253
254 -- | Observe the type constructor of a type representation
255 typeRepTyCon :: TypeRep -> TyCon
256 typeRepTyCon (TypeRep _ tc _) = tc
257
258 -- | Observe the argument types of a type representation
259 typeRepArgs :: TypeRep -> [TypeRep]
260 typeRepArgs (TypeRep _ _ args) = args
261
262 -- | Observe string encoding of a type representation
263 tyConString :: TyCon -> String
264 tyConString (TyCon _ str) = str
265
266 ----------------- Showing TypeReps --------------------
267
268 instance Show TypeRep where
269 showsPrec p (TypeRep _ tycon tys) =
270 case tys of
271 [] -> showsPrec p tycon
272 [x] | tycon == listTc -> showChar '[' . shows x . showChar ']'
273 [a,r] | tycon == funTc -> showParen (p > 8) $
274 showsPrec 9 a .
275 showString " -> " .
276 showsPrec 8 r
277 xs | isTupleTyCon tycon -> showTuple tycon xs
278 | otherwise ->
279 showParen (p > 9) $
280 showsPrec p tycon .
281 showChar ' ' .
282 showArgs tys
283
284 showsTypeRep :: TypeRep -> ShowS
285 showsTypeRep = shows
286
287 instance Show TyCon where
288 showsPrec _ (TyCon _ s) = showString s
289
290 isTupleTyCon :: TyCon -> Bool
291 isTupleTyCon (TyCon _ (',':_)) = True
292 isTupleTyCon _ = False
293
294 -- Some (Show.TypeRep) helpers:
295
296 showArgs :: Show a => [a] -> ShowS
297 showArgs [] = id
298 showArgs [a] = showsPrec 10 a
299 showArgs (a:as) = showsPrec 10 a . showString " " . showArgs as
300
301 showTuple :: TyCon -> [TypeRep] -> ShowS
302 showTuple (TyCon _ str) args = showChar '(' . go str args
303 where
304 go [] [a] = showsPrec 10 a . showChar ')'
305 go _ [] = showChar ')' -- a failure condition, really.
306 go (',':xs) (a:as) = showsPrec 10 a . showChar ',' . go xs as
307 go _ _ = showChar ')'
308
309 -------------------------------------------------------------
310 --
311 -- The Typeable class and friends
312 --
313 -------------------------------------------------------------
314
315 -- | The class 'Typeable' allows a concrete representation of a type to
316 -- be calculated.
317 class Typeable a where
318 typeOf :: a -> TypeRep
319 -- ^ Takes a value of type @a@ and returns a concrete representation
320 -- of that type. The /value/ of the argument should be ignored by
321 -- any instance of 'Typeable', so that it is safe to pass 'undefined' as
322 -- the argument.
323
324 -- | Variant for unary type constructors
325 class Typeable1 t where
326 typeOf1 :: t a -> TypeRep
327
328 -- | For defining a 'Typeable' instance from any 'Typeable1' instance.
329 typeOfDefault :: (Typeable1 t, Typeable a) => t a -> TypeRep
330 typeOfDefault x = typeOf1 x `mkAppTy` typeOf (argType x)
331 where
332 argType :: t a -> a
333 argType = undefined
334
335 -- | Variant for binary type constructors
336 class Typeable2 t where
337 typeOf2 :: t a b -> TypeRep
338
339 -- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
340 typeOf1Default :: (Typeable2 t, Typeable a) => t a b -> TypeRep
341 typeOf1Default x = typeOf2 x `mkAppTy` typeOf (argType x)
342 where
343 argType :: t a b -> a
344 argType = undefined
345
346 -- | Variant for 3-ary type constructors
347 class Typeable3 t where
348 typeOf3 :: t a b c -> TypeRep
349
350 -- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
351 typeOf2Default :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
352 typeOf2Default x = typeOf3 x `mkAppTy` typeOf (argType x)
353 where
354 argType :: t a b c -> a
355 argType = undefined
356
357 -- | Variant for 4-ary type constructors
358 class Typeable4 t where
359 typeOf4 :: t a b c d -> TypeRep
360
361 -- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
362 typeOf3Default :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
363 typeOf3Default x = typeOf4 x `mkAppTy` typeOf (argType x)
364 where
365 argType :: t a b c d -> a
366 argType = undefined
367
368 -- | Variant for 5-ary type constructors
369 class Typeable5 t where
370 typeOf5 :: t a b c d e -> TypeRep
371
372 -- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
373 typeOf4Default :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
374 typeOf4Default x = typeOf5 x `mkAppTy` typeOf (argType x)
375 where
376 argType :: t a b c d e -> a
377 argType = undefined
378
379 -- | Variant for 6-ary type constructors
380 class Typeable6 t where
381 typeOf6 :: t a b c d e f -> TypeRep
382
383 -- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
384 typeOf5Default :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
385 typeOf5Default x = typeOf6 x `mkAppTy` typeOf (argType x)
386 where
387 argType :: t a b c d e f -> a
388 argType = undefined
389
390 -- | Variant for 7-ary type constructors
391 class Typeable7 t where
392 typeOf7 :: t a b c d e f g -> TypeRep
393
394 -- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
395 typeOf6Default :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
396 typeOf6Default x = typeOf7 x `mkAppTy` typeOf (argType x)
397 where
398 argType :: t a b c d e f g -> a
399 argType = undefined
400
401 #ifdef __GLASGOW_HASKELL__
402 -- Given a @Typeable@/n/ instance for an /n/-ary type constructor,
403 -- define the instances for partial applications.
404 -- Programmers using non-GHC implementations must do this manually
405 -- for each type constructor.
406 -- (The INSTANCE_TYPEABLE/n/ macros in Typeable.h include this.)
407
408 -- | One Typeable instance for all Typeable1 instances
409 instance (Typeable1 s, Typeable a)
410 => Typeable (s a) where
411 typeOf = typeOfDefault
412
413 -- | One Typeable1 instance for all Typeable2 instances
414 instance (Typeable2 s, Typeable a)
415 => Typeable1 (s a) where
416 typeOf1 = typeOf1Default
417
418 -- | One Typeable2 instance for all Typeable3 instances
419 instance (Typeable3 s, Typeable a)
420 => Typeable2 (s a) where
421 typeOf2 = typeOf2Default
422
423 -- | One Typeable3 instance for all Typeable4 instances
424 instance (Typeable4 s, Typeable a)
425 => Typeable3 (s a) where
426 typeOf3 = typeOf3Default
427
428 -- | One Typeable4 instance for all Typeable5 instances
429 instance (Typeable5 s, Typeable a)
430 => Typeable4 (s a) where
431 typeOf4 = typeOf4Default
432
433 -- | One Typeable5 instance for all Typeable6 instances
434 instance (Typeable6 s, Typeable a)
435 => Typeable5 (s a) where
436 typeOf5 = typeOf5Default
437
438 -- | One Typeable6 instance for all Typeable7 instances
439 instance (Typeable7 s, Typeable a)
440 => Typeable6 (s a) where
441 typeOf6 = typeOf6Default
442
443 #endif /* __GLASGOW_HASKELL__ */
444
445 -------------------------------------------------------------
446 --
447 -- Type-safe cast
448 --
449 -------------------------------------------------------------
450
451 -- | The type-safe cast operation
452 cast :: (Typeable a, Typeable b) => a -> Maybe b
453 cast x = r
454 where
455 r = if typeOf x == typeOf (fromJust r)
456 then Just $ unsafeCoerce x
457 else Nothing
458
459 -- | A flexible variation parameterised in a type constructor
460 gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
461 gcast x = r
462 where
463 r = if typeOf (getArg x) == typeOf (getArg (fromJust r))
464 then Just $ unsafeCoerce x
465 else Nothing
466 getArg :: c x -> x
467 getArg = undefined
468
469 -- | Cast for * -> *
470 gcast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a))
471 gcast1 x = r
472 where
473 r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
474 then Just $ unsafeCoerce x
475 else Nothing
476 getArg :: c x -> x
477 getArg = undefined
478
479 -- | Cast for * -> * -> *
480 gcast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b))
481 gcast2 x = r
482 where
483 r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
484 then Just $ unsafeCoerce x
485 else Nothing
486 getArg :: c x -> x
487 getArg = undefined
488
489 -------------------------------------------------------------
490 --
491 -- Instances of the Typeable classes for Prelude types
492 --
493 -------------------------------------------------------------
494
495 INSTANCE_TYPEABLE0((),unitTc,"()")
496 INSTANCE_TYPEABLE1([],listTc,"[]")
497 INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
498 INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
499 INSTANCE_TYPEABLE2(Either,eitherTc,"Either")
500 INSTANCE_TYPEABLE2((->),funTc,"->")
501 INSTANCE_TYPEABLE1(IO,ioTc,"IO")
502
503 #if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
504 -- Types defined in GHC.IOBase
505 INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
506 INSTANCE_TYPEABLE0(Exception,exceptionTc,"Exception")
507 INSTANCE_TYPEABLE0(IOException,ioExceptionTc,"IOException")
508 INSTANCE_TYPEABLE0(ArithException,arithExceptionTc,"ArithException")
509 INSTANCE_TYPEABLE0(ArrayException,arrayExceptionTc,"ArrayException")
510 INSTANCE_TYPEABLE0(AsyncException,asyncExceptionTc,"AsyncException")
511 #endif
512
513 -- Types defined in GHC.Arr
514 INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
515
516 #ifdef __GLASGOW_HASKELL__
517 -- Hugs has these too, but their Typeable<n> instances are defined
518 -- elsewhere to keep this module within Haskell 98.
519 -- This is important because every invocation of runhugs or ffihugs
520 -- uses this module via Data.Dynamic.
521 INSTANCE_TYPEABLE2(ST,stTc,"ST")
522 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
523 INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
524 #endif
525
526 #ifndef __NHC__
527 INSTANCE_TYPEABLE2((,),pairTc,",")
528 INSTANCE_TYPEABLE3((,,),tup3Tc,",,")
529
530 tup4Tc :: TyCon
531 tup4Tc = mkTyCon ",,,"
532
533 instance Typeable4 (,,,) where
534 typeOf4 tu = mkTyConApp tup4Tc []
535
536 tup5Tc :: TyCon
537 tup5Tc = mkTyCon ",,,,"
538
539 instance Typeable5 (,,,,) where
540 typeOf5 tu = mkTyConApp tup5Tc []
541
542 tup6Tc :: TyCon
543 tup6Tc = mkTyCon ",,,,,"
544
545 instance Typeable6 (,,,,,) where
546 typeOf6 tu = mkTyConApp tup6Tc []
547
548 tup7Tc :: TyCon
549 tup7Tc = mkTyCon ",,,,,,"
550
551 instance Typeable7 (,,,,,,) where
552 typeOf7 tu = mkTyConApp tup7Tc []
553 #endif /* __NHC__ */
554
555 INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
556 INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
557 INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
558 INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
559 INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
560
561 -------------------------------------------------------
562 --
563 -- Generate Typeable instances for standard datatypes
564 --
565 -------------------------------------------------------
566
567 INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
568 INSTANCE_TYPEABLE0(Char,charTc,"Char")
569 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
570 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
571 INSTANCE_TYPEABLE0(Int,intTc,"Int")
572 #ifndef __NHC__
573 INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
574 #endif
575 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
576 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
577 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
578
579 INSTANCE_TYPEABLE0(Int8,int8Tc,"Int8")
580 INSTANCE_TYPEABLE0(Int16,int16Tc,"Int16")
581 INSTANCE_TYPEABLE0(Int32,int32Tc,"Int32")
582 INSTANCE_TYPEABLE0(Int64,int64Tc,"Int64")
583
584 INSTANCE_TYPEABLE0(Word8,word8Tc,"Word8" )
585 INSTANCE_TYPEABLE0(Word16,word16Tc,"Word16")
586 INSTANCE_TYPEABLE0(Word32,word32Tc,"Word32")
587 INSTANCE_TYPEABLE0(Word64,word64Tc,"Word64")
588
589 INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
590 INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
591
592 #ifdef __GLASGOW_HASKELL__
593 INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
594 #endif
595
596 ---------------------------------------------
597 --
598 -- Internals
599 --
600 ---------------------------------------------
601
602 #ifndef __HUGS__
603 newtype Key = Key Int deriving( Eq )
604 #endif
605
606 data KeyPr = KeyPr !Key !Key deriving( Eq )
607
608 hashKP :: KeyPr -> Int32
609 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
610
611 data Cache = Cache { next_key :: !(IORef Key), -- Not used by GHC (calls genSym instead)
612 tc_tbl :: !(HT.HashTable String Key),
613 ap_tbl :: !(HT.HashTable KeyPr Key) }
614
615 {-# NOINLINE cache #-}
616 #ifdef __GLASGOW_HASKELL__
617 foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
618 getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
619 #endif
620
621 cache :: Cache
622 cache = unsafePerformIO $ do
623 empty_tc_tbl <- HT.new (==) HT.hashString
624 empty_ap_tbl <- HT.new (==) hashKP
625 key_loc <- newIORef (Key 1)
626 let ret = Cache { next_key = key_loc,
627 tc_tbl = empty_tc_tbl,
628 ap_tbl = empty_ap_tbl }
629 #ifdef __GLASGOW_HASKELL__
630 block $ do
631 stable_ref <- newStablePtr ret
632 let ref = castStablePtrToPtr stable_ref
633 ref2 <- getOrSetTypeableStore ref
634 if ref==ref2
635 then deRefStablePtr stable_ref
636 else do
637 freeStablePtr stable_ref
638 deRefStablePtr
639 (castPtrToStablePtr ref2)
640 #else
641 return ret
642 #endif
643
644 newKey :: IORef Key -> IO Key
645 #ifdef __GLASGOW_HASKELL__
646 newKey kloc = do i <- genSym; return (Key i)
647 #else
648 newKey kloc = do { k@(Key i) <- readIORef kloc ;
649 writeIORef kloc (Key (i+1)) ;
650 return k }
651 #endif
652
653 #ifdef __GLASGOW_HASKELL__
654 foreign import ccall unsafe "genSymZh"
655 genSym :: IO Int
656 #endif
657
658 mkTyConKey :: String -> Key
659 mkTyConKey str
660 = unsafePerformIO $ do
661 let Cache {next_key = kloc, tc_tbl = tbl} = cache
662 mb_k <- HT.lookup tbl str
663 case mb_k of
664 Just k -> return k
665 Nothing -> do { k <- newKey kloc ;
666 HT.insert tbl str k ;
667 return k }
668
669 appKey :: Key -> Key -> Key
670 appKey k1 k2
671 = unsafePerformIO $ do
672 let Cache {next_key = kloc, ap_tbl = tbl} = cache
673 mb_k <- HT.lookup tbl kpr
674 case mb_k of
675 Just k -> return k
676 Nothing -> do { k <- newKey kloc ;
677 HT.insert tbl kpr k ;
678 return k }
679 where
680 kpr = KeyPr k1 k2
681
682 appKeys :: Key -> [Key] -> Key
683 appKeys k ks = foldl appKey k ks