SafeHaskell: Added SafeHaskell to base
[packages/base.git] / Data / Typeable.hs
1 {-# LANGUAGE CPP
2 , NoImplicitPrelude
3 , OverlappingInstances
4 , ScopedTypeVariables
5 , ForeignFunctionInterface
6 , FlexibleInstances
7 #-}
8 {-# OPTIONS_GHC -funbox-strict-fields #-}
9 #ifdef __GLASGOW_HASKELL__
10 {-# LANGUAGE DeriveDataTypeable, StandaloneDeriving #-}
11 #endif
12
13 -- The -XOverlappingInstances flag allows the user to over-ride
14 -- the instances for Typeable given here. In particular, we provide an instance
15 -- instance ... => Typeable (s a)
16 -- But a user might want to say
17 -- instance ... => Typeable (MyType a b)
18
19 -----------------------------------------------------------------------------
20 -- |
21 -- Module : Data.Typeable
22 -- Copyright : (c) The University of Glasgow, CWI 2001--2004
23 -- License : BSD-style (see the file libraries/base/LICENSE)
24 --
25 -- Maintainer : libraries@haskell.org
26 -- Stability : experimental
27 -- Portability : portable
28 --
29 -- The 'Typeable' class reifies types to some extent by associating type
30 -- representations to types. These type representations can be compared,
31 -- and one can in turn define a type-safe cast operation. To this end,
32 -- an unsafe cast is guarded by a test for type (representation)
33 -- equivalence. The module "Data.Dynamic" uses Typeable for an
34 -- implementation of dynamics. The module "Data.Data" uses Typeable
35 -- and type-safe cast (but not dynamics) to support the \"Scrap your
36 -- boilerplate\" style of generic programming.
37 --
38 -----------------------------------------------------------------------------
39
40 module Data.Typeable
41 (
42
43 -- * The Typeable class
44 Typeable( typeOf ), -- :: a -> TypeRep
45
46 -- * Type-safe cast
47 cast, -- :: (Typeable a, Typeable b) => a -> Maybe b
48 gcast, -- a generalisation of cast
49
50 -- * Type representations
51 TypeRep, -- abstract, instance of: Eq, Show, Typeable
52 TyCon, -- abstract, instance of: Eq, Show, Typeable
53 showsTypeRep,
54
55 -- * Construction of type representations
56 mkTyCon, -- :: String -> TyCon
57 mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
58 mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
59 mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
60
61 -- * Observation of type representations
62 splitTyConApp, -- :: TypeRep -> (TyCon, [TypeRep])
63 funResultTy, -- :: TypeRep -> TypeRep -> Maybe TypeRep
64 typeRepTyCon, -- :: TypeRep -> TyCon
65 typeRepArgs, -- :: TypeRep -> [TypeRep]
66 tyConString, -- :: TyCon -> String
67 typeRepKey, -- :: TypeRep -> IO Int
68
69 -- * The other Typeable classes
70 -- | /Note:/ The general instances are provided for GHC only.
71 Typeable1( typeOf1 ), -- :: t a -> TypeRep
72 Typeable2( typeOf2 ), -- :: t a b -> TypeRep
73 Typeable3( typeOf3 ), -- :: t a b c -> TypeRep
74 Typeable4( typeOf4 ), -- :: t a b c d -> TypeRep
75 Typeable5( typeOf5 ), -- :: t a b c d e -> TypeRep
76 Typeable6( typeOf6 ), -- :: t a b c d e f -> TypeRep
77 Typeable7( typeOf7 ), -- :: t a b c d e f g -> TypeRep
78 gcast1, -- :: ... => c (t a) -> Maybe (c (t' a))
79 gcast2, -- :: ... => c (t a b) -> Maybe (c (t' a b))
80
81 -- * Default instances
82 -- | /Note:/ These are not needed by GHC, for which these instances
83 -- are generated by general instance declarations.
84 typeOfDefault, -- :: (Typeable1 t, Typeable a) => t a -> TypeRep
85 typeOf1Default, -- :: (Typeable2 t, Typeable a) => t a b -> TypeRep
86 typeOf2Default, -- :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
87 typeOf3Default, -- :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
88 typeOf4Default, -- :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
89 typeOf5Default, -- :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
90 typeOf6Default -- :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
91
92 ) where
93
94 import qualified Data.HashTable as HT
95 import Data.Maybe
96 import Data.Int
97 import Data.Word
98 import Data.List( foldl, intersperse )
99 import Unsafe.Coerce
100
101 #ifdef __GLASGOW_HASKELL__
102 import GHC.Base
103 import GHC.Show (Show(..), ShowS,
104 shows, showString, showChar, showParen)
105 import GHC.Err (undefined)
106 import GHC.Num (Integer, (+))
107 import GHC.Real ( rem, Ratio )
108 import GHC.IORef (IORef,newIORef)
109 import GHC.IO (mask_, unsafePerformIO)
110
111 -- These imports are so we can define Typeable instances
112 -- It'd be better to give Typeable instances in the modules themselves
113 -- but they all have to be compiled before Typeable
114 import GHC.IOArray
115 import GHC.MVar
116 import GHC.ST ( ST )
117 import GHC.STRef ( STRef )
118 import GHC.Ptr ( Ptr, FunPtr )
119 import GHC.Stable ( StablePtr, newStablePtr, freeStablePtr,
120 deRefStablePtr, castStablePtrToPtr,
121 castPtrToStablePtr )
122 import GHC.Arr ( Array, STArray )
123
124 #endif
125
126 #ifdef __HUGS__
127 import Hugs.Prelude ( Key(..), TypeRep(..), TyCon(..), Ratio,
128 Handle, Ptr, FunPtr, ForeignPtr, StablePtr )
129 import Hugs.IORef ( IORef, newIORef, readIORef, writeIORef )
130 import Hugs.IOExts ( unsafePerformIO )
131 -- For the Typeable instance
132 import Hugs.Array ( Array )
133 import Hugs.IOArray
134 import Hugs.ConcBase ( MVar )
135 #endif
136
137 #ifdef __NHC__
138 import NHC.IOExtras (IOArray,IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
139 import IO (Handle)
140 import Ratio (Ratio)
141 -- For the Typeable instance
142 import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
143 import Array ( Array )
144 #endif
145
146 #include "Typeable.h"
147
148 #ifndef __HUGS__
149
150 -------------------------------------------------------------
151 --
152 -- Type representations
153 --
154 -------------------------------------------------------------
155
156 -- | A concrete representation of a (monomorphic) type. 'TypeRep'
157 -- supports reasonably efficient equality.
158 data TypeRep = TypeRep !Key TyCon [TypeRep]
159
160 -- Compare keys for equality
161 instance Eq TypeRep where
162 (TypeRep k1 _ _) == (TypeRep k2 _ _) = k1 == k2
163
164 -- | An abstract representation of a type constructor. 'TyCon' objects can
165 -- be built using 'mkTyCon'.
166 data TyCon = TyCon !Key String
167
168 instance Eq TyCon where
169 (TyCon t1 _) == (TyCon t2 _) = t1 == t2
170 #endif
171
172 -- | Returns a unique integer associated with a 'TypeRep'. This can
173 -- be used for making a mapping with TypeReps
174 -- as the keys, for example. It is guaranteed that @t1 == t2@ if and only if
175 -- @typeRepKey t1 == typeRepKey t2@.
176 --
177 -- It is in the 'IO' monad because the actual value of the key may
178 -- vary from run to run of the program. You should only rely on
179 -- the equality property, not any actual key value. The relative ordering
180 -- of keys has no meaning either.
181 --
182 typeRepKey :: TypeRep -> IO Int
183 typeRepKey (TypeRep (Key i) _ _) = return i
184
185 --
186 -- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
187 -- [fTy,fTy,fTy])
188 --
189 -- returns "(Foo,Foo,Foo)"
190 --
191 -- The TypeRep Show instance promises to print tuple types
192 -- correctly. Tuple type constructors are specified by a
193 -- sequence of commas, e.g., (mkTyCon ",,,,") returns
194 -- the 5-tuple tycon.
195
196 ----------------- Construction --------------------
197
198 -- | Applies a type constructor to a sequence of types
199 mkTyConApp :: TyCon -> [TypeRep] -> TypeRep
200 mkTyConApp tc@(TyCon tc_k _) args
201 = TypeRep (appKeys tc_k arg_ks) tc args
202 where
203 arg_ks = [k | TypeRep k _ _ <- args]
204
205 -- | A special case of 'mkTyConApp', which applies the function
206 -- type constructor to a pair of types.
207 mkFunTy :: TypeRep -> TypeRep -> TypeRep
208 mkFunTy f a = mkTyConApp funTc [f,a]
209
210 -- | Splits a type constructor application
211 splitTyConApp :: TypeRep -> (TyCon,[TypeRep])
212 splitTyConApp (TypeRep _ tc trs) = (tc,trs)
213
214 -- | Applies a type to a function type. Returns: @'Just' u@ if the
215 -- first argument represents a function of type @t -> u@ and the
216 -- second argument represents a function of type @t@. Otherwise,
217 -- returns 'Nothing'.
218 funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep
219 funResultTy trFun trArg
220 = case splitTyConApp trFun of
221 (tc, [t1,t2]) | tc == funTc && t1 == trArg -> Just t2
222 _ -> Nothing
223
224 -- | Adds a TypeRep argument to a TypeRep.
225 mkAppTy :: TypeRep -> TypeRep -> TypeRep
226 mkAppTy (TypeRep tr_k tc trs) arg_tr
227 = let (TypeRep arg_k _ _) = arg_tr
228 in TypeRep (appKey tr_k arg_k) tc (trs++[arg_tr])
229
230 -- If we enforce the restriction that there is only one
231 -- @TyCon@ for a type & it is shared among all its uses,
232 -- we can map them onto Ints very simply. The benefit is,
233 -- of course, that @TyCon@s can then be compared efficiently.
234
235 -- Provided the implementor of other @Typeable@ instances
236 -- takes care of making all the @TyCon@s CAFs (toplevel constants),
237 -- this will work.
238
239 -- If this constraint does turn out to be a sore thumb, changing
240 -- the Eq instance for TyCons is trivial.
241
242 -- | Builds a 'TyCon' object representing a type constructor. An
243 -- implementation of "Data.Typeable" should ensure that the following holds:
244 --
245 -- > mkTyCon "a" == mkTyCon "a"
246 --
247
248 mkTyCon :: String -- ^ the name of the type constructor (should be unique
249 -- in the program, so it might be wise to use the
250 -- fully qualified name).
251 -> TyCon -- ^ A unique 'TyCon' object
252 mkTyCon str = TyCon (mkTyConKey str) str
253
254 ----------------- Observation ---------------------
255
256 -- | Observe the type constructor of a type representation
257 typeRepTyCon :: TypeRep -> TyCon
258 typeRepTyCon (TypeRep _ tc _) = tc
259
260 -- | Observe the argument types of a type representation
261 typeRepArgs :: TypeRep -> [TypeRep]
262 typeRepArgs (TypeRep _ _ args) = args
263
264 -- | Observe string encoding of a type representation
265 tyConString :: TyCon -> String
266 tyConString (TyCon _ str) = str
267
268 ----------------- Showing TypeReps --------------------
269
270 instance Show TypeRep where
271 showsPrec p (TypeRep _ tycon tys) =
272 case tys of
273 [] -> showsPrec p tycon
274 [x] | tycon == listTc -> showChar '[' . shows x . showChar ']'
275 [a,r] | tycon == funTc -> showParen (p > 8) $
276 showsPrec 9 a .
277 showString " -> " .
278 showsPrec 8 r
279 xs | isTupleTyCon tycon -> showTuple xs
280 | otherwise ->
281 showParen (p > 9) $
282 showsPrec p tycon .
283 showChar ' ' .
284 showArgs tys
285
286 showsTypeRep :: TypeRep -> ShowS
287 showsTypeRep = shows
288
289 instance Show TyCon where
290 showsPrec _ (TyCon _ s) = showString s
291
292 isTupleTyCon :: TyCon -> Bool
293 isTupleTyCon (TyCon _ ('(':',':_)) = True
294 isTupleTyCon _ = False
295
296 -- Some (Show.TypeRep) helpers:
297
298 showArgs :: Show a => [a] -> ShowS
299 showArgs [] = id
300 showArgs [a] = showsPrec 10 a
301 showArgs (a:as) = showsPrec 10 a . showString " " . showArgs as
302
303 showTuple :: [TypeRep] -> ShowS
304 showTuple args = showChar '('
305 . (foldr (.) id $ intersperse (showChar ',')
306 $ map (showsPrec 10) args)
307 . showChar ')'
308
309 -------------------------------------------------------------
310 --
311 -- The Typeable class and friends
312 --
313 -------------------------------------------------------------
314
315 {- Note [Memoising typeOf]
316 ~~~~~~~~~~~~~~~~~~~~~~~~~~
317 IMPORTANT: we don't want to recalculate the type-rep once per
318 call to the dummy argument. This is what went wrong in Trac #3245
319 So we help GHC by manually keeping the 'rep' *outside* the value
320 lambda, thus
321
322 typeOfDefault :: forall t a. (Typeable1 t, Typeable a) => t a -> TypeRep
323 typeOfDefault = \_ -> rep
324 where
325 rep = typeOf1 (undefined :: t a) `mkAppTy`
326 typeOf (undefined :: a)
327
328 Notice the crucial use of scoped type variables here!
329 -}
330
331 -- | The class 'Typeable' allows a concrete representation of a type to
332 -- be calculated.
333 class Typeable a where
334 typeOf :: a -> TypeRep
335 -- ^ Takes a value of type @a@ and returns a concrete representation
336 -- of that type. The /value/ of the argument should be ignored by
337 -- any instance of 'Typeable', so that it is safe to pass 'undefined' as
338 -- the argument.
339
340 -- | Variant for unary type constructors
341 class Typeable1 t where
342 typeOf1 :: t a -> TypeRep
343
344 #ifdef __GLASGOW_HASKELL__
345 -- | For defining a 'Typeable' instance from any 'Typeable1' instance.
346 typeOfDefault :: forall t a. (Typeable1 t, Typeable a) => t a -> TypeRep
347 typeOfDefault = \_ -> rep
348 where
349 rep = typeOf1 (undefined :: t a) `mkAppTy`
350 typeOf (undefined :: a)
351 -- Note [Memoising typeOf]
352 #else
353 -- | For defining a 'Typeable' instance from any 'Typeable1' instance.
354 typeOfDefault :: (Typeable1 t, Typeable a) => t a -> TypeRep
355 typeOfDefault x = typeOf1 x `mkAppTy` typeOf (argType x)
356 where
357 argType :: t a -> a
358 argType = undefined
359 #endif
360
361 -- | Variant for binary type constructors
362 class Typeable2 t where
363 typeOf2 :: t a b -> TypeRep
364
365 #ifdef __GLASGOW_HASKELL__
366 -- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
367 typeOf1Default :: forall t a b. (Typeable2 t, Typeable a) => t a b -> TypeRep
368 typeOf1Default = \_ -> rep
369 where
370 rep = typeOf2 (undefined :: t a b) `mkAppTy`
371 typeOf (undefined :: a)
372 -- Note [Memoising typeOf]
373 #else
374 -- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
375 typeOf1Default :: (Typeable2 t, Typeable a) => t a b -> TypeRep
376 typeOf1Default x = typeOf2 x `mkAppTy` typeOf (argType x)
377 where
378 argType :: t a b -> a
379 argType = undefined
380 #endif
381
382 -- | Variant for 3-ary type constructors
383 class Typeable3 t where
384 typeOf3 :: t a b c -> TypeRep
385
386 #ifdef __GLASGOW_HASKELL__
387 -- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
388 typeOf2Default :: forall t a b c. (Typeable3 t, Typeable a) => t a b c -> TypeRep
389 typeOf2Default = \_ -> rep
390 where
391 rep = typeOf3 (undefined :: t a b c) `mkAppTy`
392 typeOf (undefined :: a)
393 -- Note [Memoising typeOf]
394 #else
395 -- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
396 typeOf2Default :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
397 typeOf2Default x = typeOf3 x `mkAppTy` typeOf (argType x)
398 where
399 argType :: t a b c -> a
400 argType = undefined
401 #endif
402
403 -- | Variant for 4-ary type constructors
404 class Typeable4 t where
405 typeOf4 :: t a b c d -> TypeRep
406
407 #ifdef __GLASGOW_HASKELL__
408 -- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
409 typeOf3Default :: forall t a b c d. (Typeable4 t, Typeable a) => t a b c d -> TypeRep
410 typeOf3Default = \_ -> rep
411 where
412 rep = typeOf4 (undefined :: t a b c d) `mkAppTy`
413 typeOf (undefined :: a)
414 -- Note [Memoising typeOf]
415 #else
416 -- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
417 typeOf3Default :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
418 typeOf3Default x = typeOf4 x `mkAppTy` typeOf (argType x)
419 where
420 argType :: t a b c d -> a
421 argType = undefined
422 #endif
423
424 -- | Variant for 5-ary type constructors
425 class Typeable5 t where
426 typeOf5 :: t a b c d e -> TypeRep
427
428 #ifdef __GLASGOW_HASKELL__
429 -- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
430 typeOf4Default :: forall t a b c d e. (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
431 typeOf4Default = \_ -> rep
432 where
433 rep = typeOf5 (undefined :: t a b c d e) `mkAppTy`
434 typeOf (undefined :: a)
435 -- Note [Memoising typeOf]
436 #else
437 -- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
438 typeOf4Default :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
439 typeOf4Default x = typeOf5 x `mkAppTy` typeOf (argType x)
440 where
441 argType :: t a b c d e -> a
442 argType = undefined
443 #endif
444
445 -- | Variant for 6-ary type constructors
446 class Typeable6 t where
447 typeOf6 :: t a b c d e f -> TypeRep
448
449 #ifdef __GLASGOW_HASKELL__
450 -- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
451 typeOf5Default :: forall t a b c d e f. (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
452 typeOf5Default = \_ -> rep
453 where
454 rep = typeOf6 (undefined :: t a b c d e f) `mkAppTy`
455 typeOf (undefined :: a)
456 -- Note [Memoising typeOf]
457 #else
458 -- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
459 typeOf5Default :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
460 typeOf5Default x = typeOf6 x `mkAppTy` typeOf (argType x)
461 where
462 argType :: t a b c d e f -> a
463 argType = undefined
464 #endif
465
466 -- | Variant for 7-ary type constructors
467 class Typeable7 t where
468 typeOf7 :: t a b c d e f g -> TypeRep
469
470 #ifdef __GLASGOW_HASKELL__
471 -- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
472 typeOf6Default :: forall t a b c d e f g. (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
473 typeOf6Default = \_ -> rep
474 where
475 rep = typeOf7 (undefined :: t a b c d e f g) `mkAppTy`
476 typeOf (undefined :: a)
477 -- Note [Memoising typeOf]
478 #else
479 -- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
480 typeOf6Default :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
481 typeOf6Default x = typeOf7 x `mkAppTy` typeOf (argType x)
482 where
483 argType :: t a b c d e f g -> a
484 argType = undefined
485 #endif
486
487 #ifdef __GLASGOW_HASKELL__
488 -- Given a @Typeable@/n/ instance for an /n/-ary type constructor,
489 -- define the instances for partial applications.
490 -- Programmers using non-GHC implementations must do this manually
491 -- for each type constructor.
492 -- (The INSTANCE_TYPEABLE/n/ macros in Typeable.h include this.)
493
494 -- | One Typeable instance for all Typeable1 instances
495 instance (Typeable1 s, Typeable a)
496 => Typeable (s a) where
497 typeOf = typeOfDefault
498
499 -- | One Typeable1 instance for all Typeable2 instances
500 instance (Typeable2 s, Typeable a)
501 => Typeable1 (s a) where
502 typeOf1 = typeOf1Default
503
504 -- | One Typeable2 instance for all Typeable3 instances
505 instance (Typeable3 s, Typeable a)
506 => Typeable2 (s a) where
507 typeOf2 = typeOf2Default
508
509 -- | One Typeable3 instance for all Typeable4 instances
510 instance (Typeable4 s, Typeable a)
511 => Typeable3 (s a) where
512 typeOf3 = typeOf3Default
513
514 -- | One Typeable4 instance for all Typeable5 instances
515 instance (Typeable5 s, Typeable a)
516 => Typeable4 (s a) where
517 typeOf4 = typeOf4Default
518
519 -- | One Typeable5 instance for all Typeable6 instances
520 instance (Typeable6 s, Typeable a)
521 => Typeable5 (s a) where
522 typeOf5 = typeOf5Default
523
524 -- | One Typeable6 instance for all Typeable7 instances
525 instance (Typeable7 s, Typeable a)
526 => Typeable6 (s a) where
527 typeOf6 = typeOf6Default
528
529 #endif /* __GLASGOW_HASKELL__ */
530
531 -------------------------------------------------------------
532 --
533 -- Type-safe cast
534 --
535 -------------------------------------------------------------
536
537 -- | The type-safe cast operation
538 cast :: (Typeable a, Typeable b) => a -> Maybe b
539 cast x = r
540 where
541 r = if typeOf x == typeOf (fromJust r)
542 then Just $ unsafeCoerce x
543 else Nothing
544
545 -- | A flexible variation parameterised in a type constructor
546 gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
547 gcast x = r
548 where
549 r = if typeOf (getArg x) == typeOf (getArg (fromJust r))
550 then Just $ unsafeCoerce x
551 else Nothing
552 getArg :: c x -> x
553 getArg = undefined
554
555 -- | Cast for * -> *
556 gcast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a))
557 gcast1 x = r
558 where
559 r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
560 then Just $ unsafeCoerce x
561 else Nothing
562 getArg :: c x -> x
563 getArg = undefined
564
565 -- | Cast for * -> * -> *
566 gcast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b))
567 gcast2 x = r
568 where
569 r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
570 then Just $ unsafeCoerce x
571 else Nothing
572 getArg :: c x -> x
573 getArg = undefined
574
575 -------------------------------------------------------------
576 --
577 -- Instances of the Typeable classes for Prelude types
578 --
579 -------------------------------------------------------------
580
581 INSTANCE_TYPEABLE0((),unitTc,"()")
582 INSTANCE_TYPEABLE1([],listTc,"[]")
583 #if defined(__GLASGOW_HASKELL__)
584 listTc :: TyCon
585 listTc = typeRepTyCon (typeOf [()])
586 #endif
587 INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
588 INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
589 #if defined(__GLASGOW_HASKELL__)
590 {-
591 TODO: Deriving this instance fails with:
592 libraries/base/Data/Typeable.hs:589:1:
593 Can't make a derived instance of `Typeable2 (->)':
594 The last argument of the instance must be a data or newtype application
595 In the stand-alone deriving instance for `Typeable2 (->)'
596 -}
597 instance Typeable2 (->) where { typeOf2 _ = mkTyConApp funTc [] }
598 funTc :: TyCon
599 funTc = mkTyCon "->"
600 #else
601 INSTANCE_TYPEABLE2((->),funTc,"->")
602 #endif
603 INSTANCE_TYPEABLE1(IO,ioTc,"IO")
604
605 #if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
606 -- Types defined in GHC.MVar
607 INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
608 #endif
609
610 INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
611 INSTANCE_TYPEABLE2(IOArray,iOArrayTc,"IOArray")
612
613 #ifdef __GLASGOW_HASKELL__
614 -- Hugs has these too, but their Typeable<n> instances are defined
615 -- elsewhere to keep this module within Haskell 98.
616 -- This is important because every invocation of runhugs or ffihugs
617 -- uses this module via Data.Dynamic.
618 INSTANCE_TYPEABLE2(ST,stTc,"ST")
619 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
620 INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
621 #endif
622
623 #ifndef __NHC__
624 INSTANCE_TYPEABLE2((,),pairTc,"(,)")
625 INSTANCE_TYPEABLE3((,,),tup3Tc,"(,,)")
626 INSTANCE_TYPEABLE4((,,,),tup4Tc,"(,,,)")
627 INSTANCE_TYPEABLE5((,,,,),tup5Tc,"(,,,,)")
628 INSTANCE_TYPEABLE6((,,,,,),tup6Tc,"(,,,,,)")
629 INSTANCE_TYPEABLE7((,,,,,,),tup7Tc,"(,,,,,,)")
630 #endif /* __NHC__ */
631
632 INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
633 INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
634 #ifndef __GLASGOW_HASKELL__
635 INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
636 #endif
637 INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
638 INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
639
640 -------------------------------------------------------
641 --
642 -- Generate Typeable instances for standard datatypes
643 --
644 -------------------------------------------------------
645
646 INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
647 INSTANCE_TYPEABLE0(Char,charTc,"Char")
648 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
649 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
650 INSTANCE_TYPEABLE0(Int,intTc,"Int")
651 #ifndef __NHC__
652 INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
653 #endif
654 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
655 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
656 #ifndef __GLASGOW_HASKELL__
657 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
658 #endif
659
660 INSTANCE_TYPEABLE0(Int8,int8Tc,"Int8")
661 INSTANCE_TYPEABLE0(Int16,int16Tc,"Int16")
662 INSTANCE_TYPEABLE0(Int32,int32Tc,"Int32")
663 INSTANCE_TYPEABLE0(Int64,int64Tc,"Int64")
664
665 INSTANCE_TYPEABLE0(Word8,word8Tc,"Word8" )
666 INSTANCE_TYPEABLE0(Word16,word16Tc,"Word16")
667 INSTANCE_TYPEABLE0(Word32,word32Tc,"Word32")
668 INSTANCE_TYPEABLE0(Word64,word64Tc,"Word64")
669
670 INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
671 INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
672
673 #ifdef __GLASGOW_HASKELL__
674 {-
675 TODO: This can't be derived currently:
676 libraries/base/Data/Typeable.hs:674:1:
677 Can't make a derived instance of `Typeable RealWorld':
678 The last argument of the instance must be a data or newtype application
679 In the stand-alone deriving instance for `Typeable RealWorld'
680 -}
681 realWorldTc :: TyCon; \
682 realWorldTc = mkTyCon "GHC.Base.RealWorld"; \
683 instance Typeable RealWorld where { typeOf _ = mkTyConApp realWorldTc [] }
684
685 #endif
686
687 ---------------------------------------------
688 --
689 -- Internals
690 --
691 ---------------------------------------------
692
693 #ifndef __HUGS__
694 newtype Key = Key Int deriving( Eq )
695 #endif
696
697 data KeyPr = KeyPr !Key !Key deriving( Eq )
698
699 hashKP :: KeyPr -> Int32
700 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
701
702 data Cache = Cache { next_key :: !(IORef Key), -- Not used by GHC (calls genSym instead)
703 tc_tbl :: !(HT.HashTable String Key),
704 ap_tbl :: !(HT.HashTable KeyPr Key) }
705
706 {-# NOINLINE cache #-}
707 #ifdef __GLASGOW_HASKELL__
708 foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
709 getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
710 #endif
711
712 cache :: Cache
713 cache = unsafePerformIO $ do
714 empty_tc_tbl <- HT.new (==) HT.hashString
715 empty_ap_tbl <- HT.new (==) hashKP
716 key_loc <- newIORef (Key 1)
717 let ret = Cache { next_key = key_loc,
718 tc_tbl = empty_tc_tbl,
719 ap_tbl = empty_ap_tbl }
720 #ifdef __GLASGOW_HASKELL__
721 mask_ $ do
722 stable_ref <- newStablePtr ret
723 let ref = castStablePtrToPtr stable_ref
724 ref2 <- getOrSetTypeableStore ref
725 if ref==ref2
726 then deRefStablePtr stable_ref
727 else do
728 freeStablePtr stable_ref
729 deRefStablePtr
730 (castPtrToStablePtr ref2)
731 #else
732 return ret
733 #endif
734
735 newKey :: IORef Key -> IO Key
736 #ifdef __GLASGOW_HASKELL__
737 newKey _ = do i <- genSym; return (Key i)
738 #else
739 newKey kloc = do { k@(Key i) <- readIORef kloc ;
740 writeIORef kloc (Key (i+1)) ;
741 return k }
742 #endif
743
744 #ifdef __GLASGOW_HASKELL__
745 foreign import ccall unsafe "genSymZh"
746 genSym :: IO Int
747 #endif
748
749 mkTyConKey :: String -> Key
750 mkTyConKey str
751 = unsafePerformIO $ do
752 let Cache {next_key = kloc, tc_tbl = tbl} = cache
753 mb_k <- HT.lookup tbl str
754 case mb_k of
755 Just k -> return k
756 Nothing -> do { k <- newKey kloc ;
757 HT.insert tbl str k ;
758 return k }
759
760 appKey :: Key -> Key -> Key
761 appKey k1 k2
762 = unsafePerformIO $ do
763 let Cache {next_key = kloc, ap_tbl = tbl} = cache
764 mb_k <- HT.lookup tbl kpr
765 case mb_k of
766 Just k -> return k
767 Nothing -> do { k <- newKey kloc ;
768 HT.insert tbl kpr k ;
769 return k }
770 where
771 kpr = KeyPr k1 k2
772
773 appKeys :: Key -> [Key] -> Key
774 appKeys k ks = foldl appKey k ks