2 % (c) The GRASP/AQUA Project, Glasgow University, 1998
4 \section[Type]{Type - public interface}
8 -- re-exports from TypeRep:
12 superKind, superBoxity, -- :: SuperKind
14 boxedKind, -- :: Kind :: BX
15 anyBoxKind, -- :: Kind :: BX
16 typeCon, -- :: KindCon :: BX -> KX
17 anyBoxCon, -- :: KindCon :: BX
19 boxedTypeKind, unboxedTypeKind, openTypeKind, -- Kind :: superKind
21 mkArrowKind, mkArrowKinds, -- mentioned below: hasMoreBoxityInfo,
25 -- exports from this module:
28 mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
30 mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe,
32 mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, splitFunTysN,
33 funResultTy, funArgTy, zipFunTys,
35 mkTyConApp, mkTyConTy, splitTyConApp_maybe,
36 splitAlgTyConApp_maybe, splitAlgTyConApp,
37 mkDictTy, mkPredTy, splitPredTy_maybe, splitDictTy_maybe, isDictTy,
39 mkSynTy, isSynTy, deNoteType,
41 repType, splitRepFunTys, splitNewType_maybe, typePrimRep,
43 UsageAnn(..), mkUsgTy, isUsgTy{- dont use -}, isNotUsgTy, splitUsgTy, unUsgTy, tyUsg,
44 mkUsForAllTy, mkUsForAllTys, splitUsForAllTys, substUsTy,
46 mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
47 isForAllTy, applyTy, applyTys, mkPiType, hoistForAllTys,
49 TauType, RhoType, SigmaType, PredType(..), ThetaType,
50 ClassPred, ClassContext, mkClassPred,
51 getClassTys_maybe, ipName_maybe, classesToPreds, classesOfPreds,
52 isTauTy, mkRhoTy, splitRhoTy,
53 mkSigmaTy, splitSigmaTy,
56 isUnLiftedType, isUnboxedType, isUnboxedTupleType, isAlgType, isDataType, isNewType,
59 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
60 namesOfType, typeKind, addFreeTyVars,
62 -- Tidying up for printing
64 tidyOpenType, tidyOpenTypes,
65 tidyTyVar, tidyTyVars,
73 #include "HsVersions.h"
75 -- We import the representation and primitive functions from TypeRep.
76 -- Many things are reexported, but not the representation!
82 import {-# SOURCE #-} DataCon( DataCon, dataConRepType )
83 import {-# SOURCE #-} PprType( pprType, pprPred ) -- Only called in debug messages
84 import {-# SOURCE #-} Subst ( mkTyVarSubst, substTy )
87 import Var ( TyVar, Var, UVar,
88 tyVarKind, tyVarName, setTyVarName, isId, idType,
93 import Name ( Name, NamedThing(..), mkLocalName, tidyOccName
96 import Class ( classTyCon, Class )
98 isUnboxedTupleTyCon, isUnLiftedTyCon,
99 isFunTyCon, isDataTyCon, isNewTyCon,
100 isAlgTyCon, isSynTyCon, tyConArity,
101 tyConKind, tyConDataCons, getSynTyConDefn,
102 tyConPrimRep, tyConClass_maybe
106 import SrcLoc ( noSrcLoc )
107 import Maybes ( maybeToBool )
108 import PrimRep ( PrimRep(..), isFollowableRep )
109 import Unique ( Uniquable(..) )
110 import Util ( mapAccumL, seqList )
112 import UniqSet ( sizeUniqSet ) -- Should come via VarSet
116 %************************************************************************
118 \subsection{Stuff to do with kinds.}
120 %************************************************************************
123 hasMoreBoxityInfo :: Kind -> Kind -> Bool
124 hasMoreBoxityInfo k1 k2
125 | k2 == openTypeKind = ASSERT( is_type_kind k1) True
126 | otherwise = k1 == k2
128 -- Returns true for things of form (Type x)
129 is_type_kind k = case splitTyConApp_maybe k of
130 Just (tc,[_]) -> tc == typeCon
135 %************************************************************************
137 \subsection{Constructor-specific functions}
139 %************************************************************************
142 ---------------------------------------------------------------------
146 mkTyVarTy :: TyVar -> Type
149 mkTyVarTys :: [TyVar] -> [Type]
150 mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
152 getTyVar :: String -> Type -> TyVar
153 getTyVar msg (TyVarTy tv) = tv
154 getTyVar msg (NoteTy _ t) = getTyVar msg t
155 getTyVar msg other = panic ("getTyVar: " ++ msg)
157 getTyVar_maybe :: Type -> Maybe TyVar
158 getTyVar_maybe (TyVarTy tv) = Just tv
159 getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t
160 getTyVar_maybe other = Nothing
162 isTyVarTy :: Type -> Bool
163 isTyVarTy (TyVarTy tv) = True
164 isTyVarTy (NoteTy _ ty) = isTyVarTy ty
165 isTyVarTy other = False
169 ---------------------------------------------------------------------
172 We need to be pretty careful with AppTy to make sure we obey the
173 invariant that a TyConApp is always visibly so. mkAppTy maintains the
177 mkAppTy orig_ty1 orig_ty2 = ASSERT2( isNotUsgTy orig_ty1 && isNotUsgTy orig_ty2, pprType orig_ty1 <+> text "to" <+> pprType orig_ty2 )
180 mk_app (NoteTy _ ty1) = mk_app ty1
181 mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ [orig_ty2])
182 mk_app ty1 = AppTy orig_ty1 orig_ty2
184 mkAppTys :: Type -> [Type] -> Type
185 mkAppTys orig_ty1 [] = orig_ty1
186 -- This check for an empty list of type arguments
187 -- avoids the needless of a type synonym constructor.
188 -- For example: mkAppTys Rational []
189 -- returns to (Ratio Integer), which has needlessly lost
190 -- the Rational part.
191 mkAppTys orig_ty1 orig_tys2 = ASSERT2( isNotUsgTy orig_ty1, pprType orig_ty1 )
194 mk_app (NoteTy _ ty1) = mk_app ty1
195 mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2)
196 mk_app ty1 = ASSERT2( all isNotUsgTy orig_tys2, pprType orig_ty1 <+> text "to" <+> hsep (map pprType orig_tys2) )
197 foldl AppTy orig_ty1 orig_tys2
199 splitAppTy_maybe :: Type -> Maybe (Type, Type)
200 splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
201 splitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
202 splitAppTy_maybe (NoteTy _ ty) = splitAppTy_maybe ty
203 splitAppTy_maybe (TyConApp tc []) = Nothing
204 splitAppTy_maybe (TyConApp tc tys) = split tys []
206 split [ty2] acc = Just (TyConApp tc (reverse acc), ty2)
207 split (ty:tys) acc = split tys (ty:acc)
209 splitAppTy_maybe other = Nothing
211 splitAppTy :: Type -> (Type, Type)
212 splitAppTy ty = case splitAppTy_maybe ty of
214 Nothing -> panic "splitAppTy"
216 splitAppTys :: Type -> (Type, [Type])
217 splitAppTys ty = split ty ty []
219 split orig_ty (AppTy ty arg) args = split ty ty (arg:args)
220 split orig_ty (NoteTy _ ty) args = split orig_ty ty args
221 split orig_ty (FunTy ty1 ty2) args = ASSERT( null args )
222 (TyConApp funTyCon [], [ty1,ty2])
223 split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args)
224 split orig_ty ty args = (orig_ty, args)
228 ---------------------------------------------------------------------
233 mkFunTy :: Type -> Type -> Type
234 mkFunTy arg res = FunTy arg res
236 mkFunTys :: [Type] -> Type -> Type
237 mkFunTys tys ty = foldr FunTy ty tys
239 splitFunTy :: Type -> (Type, Type)
240 splitFunTy (FunTy arg res) = (arg, res)
241 splitFunTy (NoteTy _ ty) = splitFunTy ty
243 splitFunTy_maybe :: Type -> Maybe (Type, Type)
244 splitFunTy_maybe (FunTy arg res) = Just (arg, res)
245 splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty
246 splitFunTy_maybe other = Nothing
248 splitFunTys :: Type -> ([Type], Type)
249 splitFunTys ty = split [] ty ty
251 split args orig_ty (FunTy arg res) = split (arg:args) res res
252 split args orig_ty (NoteTy _ ty) = split args orig_ty ty
253 split args orig_ty ty = (reverse args, orig_ty)
255 splitFunTysN :: String -> Int -> Type -> ([Type], Type)
256 splitFunTysN msg orig_n orig_ty = split orig_n [] orig_ty orig_ty
258 split 0 args syn_ty ty = (reverse args, syn_ty)
259 split n args syn_ty (FunTy arg res) = split (n-1) (arg:args) res res
260 split n args syn_ty (NoteTy _ ty) = split n args syn_ty ty
261 split n args syn_ty ty = pprPanic ("splitFunTysN: " ++ msg) (int orig_n <+> pprType orig_ty)
263 zipFunTys :: Outputable a => [a] -> Type -> ([(a,Type)], Type)
264 zipFunTys orig_xs orig_ty = split [] orig_xs orig_ty orig_ty
266 split acc [] nty ty = (reverse acc, nty)
267 split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res
268 split acc xs nty (NoteTy _ ty) = split acc xs nty ty
269 split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> pprType orig_ty)
271 funResultTy :: Type -> Type
272 funResultTy (FunTy arg res) = res
273 funResultTy (NoteTy _ ty) = funResultTy ty
274 funResultTy ty = pprPanic "funResultTy" (pprType ty)
276 funArgTy :: Type -> Type
277 funArgTy (FunTy arg res) = arg
278 funArgTy (NoteTy _ ty) = funArgTy ty
279 funArgTy ty = pprPanic "funArgTy" (pprType ty)
283 ---------------------------------------------------------------------
288 mkTyConApp :: TyCon -> [Type] -> Type
290 | isFunTyCon tycon && length tys == 2
292 (ty1:ty2:_) -> FunTy ty1 ty2
295 = ASSERT(not (isSynTyCon tycon))
298 mkTyConTy :: TyCon -> Type
299 mkTyConTy tycon = ASSERT( not (isSynTyCon tycon) )
302 -- splitTyConApp "looks through" synonyms, because they don't
303 -- mean a distinct type, but all other type-constructor applications
304 -- including functions are returned as Just ..
306 splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
307 splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
308 splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
309 splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty
310 splitTyConApp_maybe other = Nothing
312 -- splitAlgTyConApp_maybe looks for
313 -- *saturated* applications of *algebraic* data types
314 -- "Algebraic" => newtype, data type, or dictionary (not function types)
315 -- We return the constructors too.
317 splitAlgTyConApp_maybe :: Type -> Maybe (TyCon, [Type], [DataCon])
318 splitAlgTyConApp_maybe (TyConApp tc tys)
320 tyConArity tc == length tys = Just (tc, tys, tyConDataCons tc)
321 splitAlgTyConApp_maybe (NoteTy _ ty) = splitAlgTyConApp_maybe ty
322 splitAlgTyConApp_maybe other = Nothing
324 splitAlgTyConApp :: Type -> (TyCon, [Type], [DataCon])
325 -- Here the "algebraic" property is an *assertion*
326 splitAlgTyConApp (TyConApp tc tys) = ASSERT( isAlgTyCon tc && tyConArity tc == length tys )
327 (tc, tys, tyConDataCons tc)
328 splitAlgTyConApp (NoteTy _ ty) = splitAlgTyConApp ty
331 "Dictionary" types are just ordinary data types, but you can
332 tell from the type constructor whether it's a dictionary or not.
335 mkDictTy :: Class -> [Type] -> Type
336 mkDictTy clas tys = TyConApp (classTyCon clas) tys
338 mkPredTy :: PredType -> Type
339 mkPredTy (Class clas tys) = TyConApp (classTyCon clas) tys
340 mkPredTy (IParam n ty) = NoteTy (IPNote n) ty
343 splitDictTy_maybe :: Type -> Maybe (Class, [Type])
344 splitDictTy_maybe (TyConApp tc tys)
345 | maybeToBool maybe_class
346 && tyConArity tc == length tys = Just (clas, tys)
348 maybe_class = tyConClass_maybe tc
349 Just clas = maybe_class
351 splitDictTy_maybe (NoteTy _ ty) = splitDictTy_maybe ty
352 splitDictTy_maybe other = Nothing
355 splitPredTy_maybe :: Type -> Maybe PredType
356 splitPredTy_maybe (TyConApp tc tys)
357 | maybeToBool maybe_class
358 && tyConArity tc == length tys = Just (Class clas tys)
360 maybe_class = tyConClass_maybe tc
361 Just clas = maybe_class
363 splitPredTy_maybe (NoteTy (IPNote n) ty)
365 splitPredTy_maybe (NoteTy _ ty) = splitPredTy_maybe ty
366 splitPredTy_maybe other = Nothing
368 splitDictTy_maybe :: Type -> Maybe (Class, [Type])
370 = case splitPredTy_maybe ty of
371 Just p -> getClassTys_maybe p
374 isDictTy :: Type -> Bool
375 -- This version is slightly more efficient than (maybeToBool . splitDictTy)
376 isDictTy (TyConApp tc tys)
377 | maybeToBool (tyConClass_maybe tc)
378 && tyConArity tc == length tys
380 isDictTy (NoteTy _ ty) = isDictTy ty
381 isDictTy other = False
384 ---------------------------------------------------------------------
389 mkSynTy syn_tycon tys
390 = ASSERT( isSynTyCon syn_tycon )
391 ASSERT( isNotUsgTy body )
392 ASSERT( length tyvars == length tys )
393 NoteTy (SynNote (TyConApp syn_tycon tys))
394 (substTy (mkTyVarSubst tyvars tys) body)
396 (tyvars, body) = getSynTyConDefn syn_tycon
398 isSynTy (NoteTy (SynNote _) _) = True
399 isSynTy other = False
401 deNoteType :: Type -> Type
402 -- Sorry for the cute name
403 deNoteType ty@(TyVarTy tyvar) = ty
404 deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys)
405 deNoteType (NoteTy _ ty) = deNoteType ty
406 deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg)
407 deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg)
408 deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty)
411 Notes on type synonyms
412 ~~~~~~~~~~~~~~~~~~~~~~
413 The various "split" functions (splitFunTy, splitRhoTy, splitForAllTy) try
414 to return type synonyms whereever possible. Thus
419 splitFunTys (a -> Foo a) = ([a], Foo a)
422 The reason is that we then get better (shorter) type signatures in
423 interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs.
429 repType looks through
432 in addition to synonyms. It's useful in the back end where we're not
433 interested in newtypes anymore.
436 repType :: Type -> Type
437 repType (NoteTy _ ty) = repType ty
438 repType (ForAllTy _ ty) = repType ty
439 repType (TyConApp tc tys) | isNewTyCon tc = repType (new_type_rep tc tys)
440 repType other_ty = other_ty
443 typePrimRep :: Type -> PrimRep
444 typePrimRep ty = case splitTyConApp_maybe (repType ty) of
445 Just (tc, ty_args) -> tyConPrimRep tc
448 splitNewType_maybe :: Type -> Maybe Type
449 -- Find the representation of a newtype, if it is one
450 -- Looks through multiple levels of newtype
451 splitNewType_maybe (NoteTy _ ty) = splitNewType_maybe ty
452 splitNewType_maybe (TyConApp tc tys) | isNewTyCon tc = case splitNewType_maybe rep_ty of
453 Just rep_ty' -> Just rep_ty'
454 Nothing -> Just rep_ty
456 rep_ty = new_type_rep tc tys
458 splitNewType_maybe other = Nothing
460 new_type_rep :: TyCon -> [Type] -> Type
461 -- The representation type for (T t1 .. tn), where T is a newtype
462 -- Looks through one layer only
464 = ASSERT( isNewTyCon tc )
465 case splitFunTy_maybe (applyTys (dataConRepType (head (tyConDataCons tc))) tys) of
466 Just (rep_ty, _) -> rep_ty
468 splitRepFunTys :: Type -> ([Type], Type)
469 -- Like splitFunTys, but looks through newtypes and for-alls
470 splitRepFunTys ty = split [] (repType ty)
472 split args (FunTy arg res) = split (arg:args) (repType res)
473 split args ty = (reverse args, ty)
478 ---------------------------------------------------------------------
482 NB: Invariant: if present, usage note is at the very top of the type.
483 This should be carefully preserved.
485 In some parts of the compiler, comments use the _Once Upon a
486 Polymorphic Type_ (POPL'99) usage of "rho = generalised
487 usage-annotated type; sigma = usage-annotated type; tau =
488 usage-annotated type except on top"; unfortunately this conflicts with
489 the rho/tau/theta/sigma usage in the rest of the compiler. (KSW
493 mkUsgTy :: UsageAnn -> Type -> Type
495 mkUsgTy UsMany ty = ASSERT2( isNotUsgTy ty, pprType ty )
498 mkUsgTy usg ty = ASSERT2( isNotUsgTy ty, pprType ty )
499 NoteTy (UsgNote usg) ty
501 -- The isUsgTy function is utterly useless if UsManys are omitted.
502 -- Be warned! KSW 1999-04.
503 isUsgTy :: Type -> Bool
507 isUsgTy (NoteTy (UsgForAll _) ty) = isUsgTy ty
508 isUsgTy (NoteTy (UsgNote _) _ ) = True
509 isUsgTy other = False
512 -- The isNotUsgTy function may return a false True if UsManys are omitted;
513 -- in other words, A SSERT( isNotUsgTy ty ) may be useful but
514 -- A SSERT( not (isNotUsg ty) ) is asking for trouble. KSW 1999-04.
515 isNotUsgTy :: Type -> Bool
516 isNotUsgTy (NoteTy (UsgForAll _) _) = False
517 isNotUsgTy (NoteTy (UsgNote _) _) = False
518 isNotUsgTy other = True
520 -- splitUsgTy_maybe is not exported, since it is meaningless if
521 -- UsManys are omitted. It is used in several places in this module,
522 -- however. KSW 1999-04.
523 splitUsgTy_maybe :: Type -> Maybe (UsageAnn,Type)
524 splitUsgTy_maybe (NoteTy (UsgNote usg) ty2) = ASSERT( isNotUsgTy ty2 )
526 splitUsgTy_maybe ty@(NoteTy (UsgForAll _) _) = pprPanic "splitUsgTy_maybe:" $ pprType ty
527 splitUsgTy_maybe ty = Nothing
529 splitUsgTy :: Type -> (UsageAnn,Type)
530 splitUsgTy ty = case splitUsgTy_maybe ty of
536 pprPanic "splitUsgTy: no usage annot:" $ pprType ty
539 tyUsg :: Type -> UsageAnn
540 tyUsg = fst . splitUsgTy
542 unUsgTy :: Type -> Type
543 -- strip outer usage annotation if present
544 unUsgTy ty = case splitUsgTy_maybe ty of
545 Just (_,ty1) -> ASSERT2( isNotUsgTy ty1, pprType ty )
549 mkUsForAllTy :: UVar -> Type -> Type
550 mkUsForAllTy uv ty = NoteTy (UsgForAll uv) ty
552 mkUsForAllTys :: [UVar] -> Type -> Type
553 mkUsForAllTys uvs ty = foldr (NoteTy . UsgForAll) ty uvs
555 splitUsForAllTys :: Type -> ([UVar],Type)
556 splitUsForAllTys ty = split ty []
557 where split (NoteTy (UsgForAll u) ty) uvs = split ty (u:uvs)
558 split other_ty uvs = (reverse uvs, other_ty)
560 substUsTy :: VarEnv UsageAnn -> Type -> Type
561 -- assumes range is fresh uvars, so no conflicts
562 substUsTy ve (NoteTy note@(UsgNote (UsVar u))
563 ty ) = NoteTy (case lookupVarEnv ve u of
564 Just ua -> UsgNote ua
567 substUsTy ve (NoteTy note@(UsgNote _) ty ) = NoteTy note (substUsTy ve ty)
568 substUsTy ve (NoteTy note@(UsgForAll _) ty ) = NoteTy note (substUsTy ve ty)
569 substUsTy ve (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (substUsTy ve ty1))
571 substUsTy ve (NoteTy note@(FTVNote _) ty ) = NoteTy note (substUsTy ve ty)
572 substUsTy ve ty@(TyVarTy _ ) = ty
573 substUsTy ve (AppTy ty1 ty2) = AppTy (substUsTy ve ty1)
575 substUsTy ve (FunTy ty1 ty2) = FunTy (substUsTy ve ty1)
577 substUsTy ve (TyConApp tyc tys) = TyConApp tyc (map (substUsTy ve) tys)
578 substUsTy ve (ForAllTy yv ty ) = ForAllTy yv (substUsTy ve ty)
582 ---------------------------------------------------------------------
586 We need to be clever here with usage annotations; they need to be
587 lifted or lowered through the forall as appropriate.
590 mkForAllTy :: TyVar -> Type -> Type
591 mkForAllTy tyvar ty = case splitUsgTy_maybe ty of
592 Just (usg,ty') -> NoteTy (UsgNote usg)
594 Nothing -> ForAllTy tyvar ty
596 mkForAllTys :: [TyVar] -> Type -> Type
597 mkForAllTys tyvars ty = case splitUsgTy_maybe ty of
598 Just (usg,ty') -> NoteTy (UsgNote usg)
599 (foldr ForAllTy ty' tyvars)
600 Nothing -> foldr ForAllTy ty tyvars
602 splitForAllTy_maybe :: Type -> Maybe (TyVar, Type)
603 splitForAllTy_maybe ty = case splitUsgTy_maybe ty of
604 Just (usg,ty') -> do (tyvar,ty'') <- splitFAT_m ty'
605 return (tyvar, NoteTy (UsgNote usg) ty'')
606 Nothing -> splitFAT_m ty
608 splitFAT_m (NoteTy _ ty) = splitFAT_m ty
609 splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty)
610 splitFAT_m _ = Nothing
612 isForAllTy :: Type -> Bool
613 isForAllTy (NoteTy _ ty) = isForAllTy ty
614 isForAllTy (ForAllTy tyvar ty) = True
617 splitForAllTys :: Type -> ([TyVar], Type)
618 splitForAllTys ty = case splitUsgTy_maybe ty of
619 Just (usg,ty') -> let (tvs,ty'') = split ty' ty' []
620 in (tvs, NoteTy (UsgNote usg) ty'')
621 Nothing -> split ty ty []
623 split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
624 split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs
625 split orig_ty t tvs = (reverse tvs, orig_ty)
628 @mkPiType@ makes a (->) type or a forall type, depending on whether
629 it is given a type variable or a term variable.
632 mkPiType :: Var -> Type -> Type -- The more polymorphic version doesn't work...
633 mkPiType v ty | isId v = mkFunTy (idType v) ty
634 | otherwise = mkForAllTy v ty
637 Applying a for-all to its arguments
640 applyTy :: Type -> Type -> Type
641 applyTy (NoteTy note@(UsgNote _) fun) arg = NoteTy note (applyTy fun arg)
642 applyTy (NoteTy note@(UsgForAll _) fun) arg = NoteTy note (applyTy fun arg)
643 applyTy (NoteTy _ fun) arg = applyTy fun arg
644 applyTy (ForAllTy tv ty) arg = ASSERT( isNotUsgTy arg )
645 substTy (mkTyVarSubst [tv] [arg]) ty
646 applyTy other arg = panic "applyTy"
648 applyTys :: Type -> [Type] -> Type
649 applyTys fun_ty arg_tys
650 = substTy (mkTyVarSubst tvs arg_tys) ty
652 (tvs, ty) = split fun_ty arg_tys
654 split fun_ty [] = ([], fun_ty)
655 split (NoteTy note@(UsgNote _) fun_ty)
656 args = case split fun_ty args of
657 (tvs, ty) -> (tvs, NoteTy note ty)
658 split (NoteTy note@(UsgForAll _) fun_ty)
659 args = case split fun_ty args of
660 (tvs, ty) -> (tvs, NoteTy note ty)
661 split (NoteTy _ fun_ty) args = split fun_ty args
662 split (ForAllTy tv fun_ty) (arg:args) = ASSERT2( isNotUsgTy arg, vcat (map pprType arg_tys) $$
663 text "in application of" <+> pprType fun_ty)
664 case split fun_ty args of
665 (tvs, ty) -> (tv:tvs, ty)
666 split other_ty args = panic "applyTys"
669 Note that we allow applications to be of usage-annotated- types, as an
670 extension: we handle them by lifting the annotation outside. The
671 argument, however, must still be unannotated.
674 hoistForAllTys :: Type -> Type
675 -- Move all the foralls to the top
676 -- e.g. T -> forall a. a ==> forall a. T -> a
678 = case hoist ty of { (tvs, body) -> mkForAllTys tvs body }
680 hoist :: Type -> ([TyVar], Type)
681 hoist ty = case splitFunTys ty of { (args, res) ->
682 case splitForAllTys res of {
683 ([], body) -> ([], ty) ;
684 (tvs1, body1) -> case hoist body1 of { (tvs2,body2) ->
685 (tvs1 ++ tvs2, mkFunTys args body2)
690 %************************************************************************
692 \subsection{Stuff to do with the source-language types}
694 PredType and ThetaType are used in types for expressions and bindings.
695 ClassPred and ClassContext are used in class and instance declarations.
697 %************************************************************************
702 data PredType = Class Class [Type]
704 type ThetaType = [PredType]
705 type ClassPred = (Class, [Type])
706 type ClassContext = [ClassPred]
707 type SigmaType = Type
711 instance Outputable PredType where
716 mkClassPred clas tys = Class clas tys
718 getClassTys_maybe :: PredType -> Maybe ClassPred
719 getClassTys_maybe (Class clas tys) = Just (clas, tys)
720 getClassTys_maybe _ = Nothing
722 ipName_maybe :: PredType -> Maybe Name
723 ipName_maybe (IParam n _) = Just n
724 ipName_maybe _ = Nothing
726 classesToPreds cts = map (uncurry Class) cts
728 classesOfPreds theta = concatMap cvt theta
729 where cvt (Class clas tys) = [(clas, tys)]
730 cvt (IParam _ _ ) = []
733 @isTauTy@ tests for nested for-alls.
736 isTauTy :: Type -> Bool
737 isTauTy (TyVarTy v) = True
738 isTauTy (TyConApp _ tys) = all isTauTy tys
739 isTauTy (AppTy a b) = isTauTy a && isTauTy b
740 isTauTy (FunTy a b) = isTauTy a && isTauTy b
741 isTauTy (NoteTy _ ty) = isTauTy ty
742 isTauTy other = False
746 mkRhoTy :: [PredType] -> Type -> Type
747 mkRhoTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
749 splitRhoTy :: Type -> ([PredType], Type)
750 splitRhoTy ty = split ty ty []
752 split orig_ty (FunTy arg res) ts = case splitPredTy_maybe arg of
753 Just p -> split res res (p:ts)
754 Nothing -> (reverse ts, orig_ty)
755 split orig_ty (NoteTy _ ty) ts = split orig_ty ty ts
756 split orig_ty ty ts = (reverse ts, orig_ty)
762 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau)
764 splitSigmaTy :: Type -> ([TyVar], [PredType], Type)
768 (tyvars,rho) = splitForAllTys ty
769 (theta,tau) = splitRhoTy rho
773 %************************************************************************
775 \subsection{Kinds and free variables}
777 %************************************************************************
779 ---------------------------------------------------------------------
780 Finding the kind of a type
781 ~~~~~~~~~~~~~~~~~~~~~~~~~~
783 typeKind :: Type -> Kind
785 typeKind (TyVarTy tyvar) = tyVarKind tyvar
786 typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
787 typeKind (NoteTy _ ty) = typeKind ty
788 typeKind (AppTy fun arg) = funResultTy (typeKind fun)
790 typeKind (FunTy arg res) = boxedTypeKind -- A function is boxed regardless of its result type
791 -- No functions at the type level, hence we don't need
792 -- to say (typeKind res).
794 typeKind (ForAllTy tv ty) = typeKind ty
798 ---------------------------------------------------------------------
799 Free variables of a type
800 ~~~~~~~~~~~~~~~~~~~~~~~~
802 tyVarsOfType :: Type -> TyVarSet
804 tyVarsOfType (TyVarTy tv) = unitVarSet tv
805 tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
806 tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
807 tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty1
808 tyVarsOfType (NoteTy (UsgNote _) ty) = tyVarsOfType ty
809 tyVarsOfType (NoteTy (UsgForAll _) ty) = tyVarsOfType ty
810 tyVarsOfType (NoteTy (IPNote _) ty) = tyVarsOfType ty
811 tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionVarSet` tyVarsOfType res
812 tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionVarSet` tyVarsOfType arg
813 tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusVarSet` unitVarSet tyvar
815 tyVarsOfTypes :: [Type] -> TyVarSet
816 tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
818 tyVarsOfPred :: PredType -> TyVarSet
819 tyVarsOfPred (Class clas tys) = tyVarsOfTypes tys
820 tyVarsOfPred (IParam n ty) = tyVarsOfType ty
822 tyVarsOfTheta :: ThetaType -> TyVarSet
823 tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet
825 -- Add a Note with the free tyvars to the top of the type
826 -- (but under a usage if there is one)
827 addFreeTyVars :: Type -> Type
828 addFreeTyVars (NoteTy note@(UsgNote _) ty) = NoteTy note (addFreeTyVars ty)
829 addFreeTyVars (NoteTy note@(UsgForAll _) ty) = NoteTy note (addFreeTyVars ty)
830 addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty
831 addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty
833 -- Find the free names of a type, including the type constructors and classes it mentions
834 namesOfType :: Type -> NameSet
835 namesOfType (TyVarTy tv) = unitNameSet (getName tv)
836 namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets`
838 namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1
839 namesOfType (NoteTy other_note ty2) = namesOfType ty2
840 namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res
841 namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg
842 namesOfType (ForAllTy tyvar ty) = namesOfType ty `minusNameSet` unitNameSet (getName tyvar)
844 namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys
848 %************************************************************************
850 \subsection{TidyType}
852 %************************************************************************
854 tidyTy tidies up a type for printing in an error message, or in
857 It doesn't change the uniques at all, just the print names.
860 tidyTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
861 tidyTyVar env@(tidy_env, subst) tyvar
862 = case lookupVarEnv subst tyvar of
864 Just tyvar' -> -- Already substituted
867 Nothing -> -- Make a new nice name for it
869 case tidyOccName tidy_env (getOccName name) of
870 (tidy', occ') -> -- New occname reqd
871 ((tidy', subst'), tyvar')
873 subst' = extendVarEnv subst tyvar tyvar'
874 tyvar' = setTyVarName tyvar name'
875 name' = mkLocalName (getUnique name) occ' noSrcLoc
876 -- Note: make a *user* tyvar, so it printes nicely
877 -- Could extract src loc, but no need.
879 name = tyVarName tyvar
881 tidyTyVars env tyvars = mapAccumL tidyTyVar env tyvars
883 tidyType :: TidyEnv -> Type -> Type
884 tidyType env@(tidy_env, subst) ty
887 go (TyVarTy tv) = case lookupVarEnv subst tv of
888 Nothing -> TyVarTy tv
889 Just tv' -> TyVarTy tv'
890 go (TyConApp tycon tys) = let args = map go tys
891 in args `seqList` TyConApp tycon args
892 go (NoteTy note ty) = (NoteTy SAPPLY (go_note note)) SAPPLY (go ty)
893 go (AppTy fun arg) = (AppTy SAPPLY (go fun)) SAPPLY (go arg)
894 go (FunTy fun arg) = (FunTy SAPPLY (go fun)) SAPPLY (go arg)
895 go (ForAllTy tv ty) = ForAllTy tvp SAPPLY (tidyType envp ty)
897 (envp, tvp) = tidyTyVar env tv
899 go_note (SynNote ty) = SynNote SAPPLY (go ty)
900 go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars
901 go_note note@(UsgNote _) = note -- Usage annotation is already tidy
902 go_note note@(UsgForAll _) = note -- Uvar binder is already tidy
903 go_note (IPNote n) = IPNote (tidyIPName n)
905 tidyTypes env tys = map (tidyType env) tys
909 @tidyOpenType@ grabs the free type variables, tidies them
910 and then uses @tidyType@ to work over the type itself
913 tidyOpenType :: TidyEnv -> Type -> (TidyEnv, Type)
915 = (env', tidyType env' ty)
917 env' = foldl go env (varSetElems (tyVarsOfType ty))
918 go env tyvar = fst (tidyTyVar env tyvar)
920 tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type])
921 tidyOpenTypes env tys = mapAccumL tidyOpenType env tys
923 tidyTopType :: Type -> Type
924 tidyTopType ty = tidyType emptyTidyEnv ty
928 tidyIPName :: Name -> Name
930 = mkLocalName (getUnique name) (getOccName name) noSrcLoc
934 %************************************************************************
936 \subsection{Boxedness and liftedness}
938 %************************************************************************
941 isUnboxedType :: Type -> Bool
942 isUnboxedType ty = not (isFollowableRep (typePrimRep ty))
944 isUnLiftedType :: Type -> Bool
945 -- isUnLiftedType returns True for forall'd unlifted types:
946 -- x :: forall a. Int#
947 -- I found bindings like these were getting floated to the top level.
948 -- They are pretty bogus types, mind you. It would be better never to
951 isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
952 isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty
953 isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
954 isUnLiftedType other = False
956 isUnboxedTupleType :: Type -> Bool
957 isUnboxedTupleType ty = case splitTyConApp_maybe ty of
958 Just (tc, ty_args) -> isUnboxedTupleTyCon tc
961 -- Should only be applied to *types*; hence the assert
962 isAlgType :: Type -> Bool
963 isAlgType ty = case splitTyConApp_maybe ty of
964 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
968 -- Should only be applied to *types*; hence the assert
969 isDataType :: Type -> Bool
970 isDataType ty = case splitTyConApp_maybe ty of
971 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
975 isNewType :: Type -> Bool
976 isNewType ty = case splitTyConApp_maybe ty of
977 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
983 %************************************************************************
985 \subsection{Sequencing on types
987 %************************************************************************
990 seqType :: Type -> ()
991 seqType (TyVarTy tv) = tv `seq` ()
992 seqType (AppTy t1 t2) = seqType t1 `seq` seqType t2
993 seqType (FunTy t1 t2) = seqType t1 `seq` seqType t2
994 seqType (NoteTy note t2) = seqNote note `seq` seqType t2
995 seqType (TyConApp tc tys) = tc `seq` seqTypes tys
996 seqType (ForAllTy tv ty) = tv `seq` seqType ty
998 seqTypes :: [Type] -> ()
1000 seqTypes (ty:tys) = seqType ty `seq` seqTypes tys
1002 seqNote :: TyNote -> ()
1003 seqNote (SynNote ty) = seqType ty
1004 seqNote (FTVNote set) = sizeUniqSet set `seq` ()
1005 seqNote (UsgNote usg) = usg `seq` ()
1006 seqNote (IPNote nm) = nm `seq` ()