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,
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 %************************************************************************
676 \subsection{Stuff to do with the source-language types}
678 PredType and ThetaType are used in types for expressions and bindings.
679 ClassPred and ClassContext are used in class and instance declarations.
681 %************************************************************************
686 data PredType = Class Class [Type]
688 type ThetaType = [PredType]
689 type ClassPred = (Class, [Type])
690 type ClassContext = [ClassPred]
691 type SigmaType = Type
695 instance Outputable PredType where
700 mkClassPred clas tys = Class clas tys
702 getClassTys_maybe :: PredType -> Maybe ClassPred
703 getClassTys_maybe (Class clas tys) = Just (clas, tys)
704 getClassTys_maybe _ = Nothing
706 ipName_maybe :: PredType -> Maybe Name
707 ipName_maybe (IParam n _) = Just n
708 ipName_maybe _ = Nothing
710 classesToPreds cts = map (uncurry Class) cts
712 classesOfPreds theta = concatMap cvt theta
713 where cvt (Class clas tys) = [(clas, tys)]
714 cvt (IParam _ _ ) = []
717 @isTauTy@ tests for nested for-alls.
720 isTauTy :: Type -> Bool
721 isTauTy (TyVarTy v) = True
722 isTauTy (TyConApp _ tys) = all isTauTy tys
723 isTauTy (AppTy a b) = isTauTy a && isTauTy b
724 isTauTy (FunTy a b) = isTauTy a && isTauTy b
725 isTauTy (NoteTy _ ty) = isTauTy ty
726 isTauTy other = False
730 mkRhoTy :: [PredType] -> Type -> Type
731 mkRhoTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
733 splitRhoTy :: Type -> ([PredType], Type)
734 splitRhoTy ty = split ty ty []
736 split orig_ty (FunTy arg res) ts = case splitPredTy_maybe arg of
737 Just p -> split res res (p:ts)
738 Nothing -> (reverse ts, orig_ty)
739 split orig_ty (NoteTy _ ty) ts = split orig_ty ty ts
740 split orig_ty ty ts = (reverse ts, orig_ty)
746 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau)
748 splitSigmaTy :: Type -> ([TyVar], [PredType], Type)
752 (tyvars,rho) = splitForAllTys ty
753 (theta,tau) = splitRhoTy rho
757 %************************************************************************
759 \subsection{Kinds and free variables}
761 %************************************************************************
763 ---------------------------------------------------------------------
764 Finding the kind of a type
765 ~~~~~~~~~~~~~~~~~~~~~~~~~~
767 typeKind :: Type -> Kind
769 typeKind (TyVarTy tyvar) = tyVarKind tyvar
770 typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
771 typeKind (NoteTy _ ty) = typeKind ty
772 typeKind (AppTy fun arg) = funResultTy (typeKind fun)
774 typeKind (FunTy arg res) = boxedTypeKind -- A function is boxed regardless of its result type
775 -- No functions at the type level, hence we don't need
776 -- to say (typeKind res).
778 typeKind (ForAllTy tv ty) = typeKind ty
782 ---------------------------------------------------------------------
783 Free variables of a type
784 ~~~~~~~~~~~~~~~~~~~~~~~~
786 tyVarsOfType :: Type -> TyVarSet
788 tyVarsOfType (TyVarTy tv) = unitVarSet tv
789 tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
790 tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
791 tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty1
792 tyVarsOfType (NoteTy (UsgNote _) ty) = tyVarsOfType ty
793 tyVarsOfType (NoteTy (UsgForAll _) ty) = tyVarsOfType ty
794 tyVarsOfType (NoteTy (IPNote _) ty) = tyVarsOfType ty
795 tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionVarSet` tyVarsOfType res
796 tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionVarSet` tyVarsOfType arg
797 tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusVarSet` unitVarSet tyvar
799 tyVarsOfTypes :: [Type] -> TyVarSet
800 tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
802 tyVarsOfPred :: PredType -> TyVarSet
803 tyVarsOfPred (Class clas tys) = tyVarsOfTypes tys
804 tyVarsOfPred (IParam n ty) = tyVarsOfType ty
806 tyVarsOfTheta :: ThetaType -> TyVarSet
807 tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet
809 -- Add a Note with the free tyvars to the top of the type
810 -- (but under a usage if there is one)
811 addFreeTyVars :: Type -> Type
812 addFreeTyVars (NoteTy note@(UsgNote _) ty) = NoteTy note (addFreeTyVars ty)
813 addFreeTyVars (NoteTy note@(UsgForAll _) ty) = NoteTy note (addFreeTyVars ty)
814 addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty
815 addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty
817 -- Find the free names of a type, including the type constructors and classes it mentions
818 namesOfType :: Type -> NameSet
819 namesOfType (TyVarTy tv) = unitNameSet (getName tv)
820 namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets`
822 namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1
823 namesOfType (NoteTy other_note ty2) = namesOfType ty2
824 namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res
825 namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg
826 namesOfType (ForAllTy tyvar ty) = namesOfType ty `minusNameSet` unitNameSet (getName tyvar)
828 namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys
832 %************************************************************************
834 \subsection{TidyType}
836 %************************************************************************
838 tidyTy tidies up a type for printing in an error message, or in
841 It doesn't change the uniques at all, just the print names.
844 tidyTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
845 tidyTyVar env@(tidy_env, subst) tyvar
846 = case lookupVarEnv subst tyvar of
848 Just tyvar' -> -- Already substituted
851 Nothing -> -- Make a new nice name for it
853 case tidyOccName tidy_env (getOccName name) of
854 (tidy', occ') -> -- New occname reqd
855 ((tidy', subst'), tyvar')
857 subst' = extendVarEnv subst tyvar tyvar'
858 tyvar' = setTyVarName tyvar name'
859 name' = mkLocalName (getUnique name) occ' noSrcLoc
860 -- Note: make a *user* tyvar, so it printes nicely
861 -- Could extract src loc, but no need.
863 name = tyVarName tyvar
865 tidyTyVars env tyvars = mapAccumL tidyTyVar env tyvars
867 tidyType :: TidyEnv -> Type -> Type
868 tidyType env@(tidy_env, subst) ty
871 go (TyVarTy tv) = case lookupVarEnv subst tv of
872 Nothing -> TyVarTy tv
873 Just tv' -> TyVarTy tv'
874 go (TyConApp tycon tys) = let args = map go tys
875 in args `seqList` TyConApp tycon args
876 go (NoteTy note ty) = (NoteTy SAPPLY (go_note note)) SAPPLY (go ty)
877 go (AppTy fun arg) = (AppTy SAPPLY (go fun)) SAPPLY (go arg)
878 go (FunTy fun arg) = (FunTy SAPPLY (go fun)) SAPPLY (go arg)
879 go (ForAllTy tv ty) = ForAllTy tvp SAPPLY (tidyType envp ty)
881 (envp, tvp) = tidyTyVar env tv
883 go_note (SynNote ty) = SynNote SAPPLY (go ty)
884 go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars
885 go_note note@(UsgNote _) = note -- Usage annotation is already tidy
886 go_note note@(UsgForAll _) = note -- Uvar binder is already tidy
887 go_note (IPNote n) = IPNote (tidyIPName n)
889 tidyTypes env tys = map (tidyType env) tys
893 @tidyOpenType@ grabs the free type variables, tidies them
894 and then uses @tidyType@ to work over the type itself
897 tidyOpenType :: TidyEnv -> Type -> (TidyEnv, Type)
899 = (env', tidyType env' ty)
901 env' = foldl go env (varSetElems (tyVarsOfType ty))
902 go env tyvar = fst (tidyTyVar env tyvar)
904 tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type])
905 tidyOpenTypes env tys = mapAccumL tidyOpenType env tys
907 tidyTopType :: Type -> Type
908 tidyTopType ty = tidyType emptyTidyEnv ty
912 tidyIPName :: Name -> Name
914 = mkLocalName (getUnique name) (getOccName name) noSrcLoc
918 %************************************************************************
920 \subsection{Boxedness and liftedness}
922 %************************************************************************
925 isUnboxedType :: Type -> Bool
926 isUnboxedType ty = not (isFollowableRep (typePrimRep ty))
928 isUnLiftedType :: Type -> Bool
929 -- isUnLiftedType returns True for forall'd unlifted types:
930 -- x :: forall a. Int#
931 -- I found bindings like these were getting floated to the top level.
932 -- They are pretty bogus types, mind you. It would be better never to
935 isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
936 isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty
937 isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
938 isUnLiftedType other = False
940 isUnboxedTupleType :: Type -> Bool
941 isUnboxedTupleType ty = case splitTyConApp_maybe ty of
942 Just (tc, ty_args) -> isUnboxedTupleTyCon tc
945 -- Should only be applied to *types*; hence the assert
946 isAlgType :: Type -> Bool
947 isAlgType ty = case splitTyConApp_maybe ty of
948 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
952 -- Should only be applied to *types*; hence the assert
953 isDataType :: Type -> Bool
954 isDataType ty = case splitTyConApp_maybe ty of
955 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
959 isNewType :: Type -> Bool
960 isNewType ty = case splitTyConApp_maybe ty of
961 Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
967 %************************************************************************
969 \subsection{Sequencing on types
971 %************************************************************************
974 seqType :: Type -> ()
975 seqType (TyVarTy tv) = tv `seq` ()
976 seqType (AppTy t1 t2) = seqType t1 `seq` seqType t2
977 seqType (FunTy t1 t2) = seqType t1 `seq` seqType t2
978 seqType (NoteTy note t2) = seqNote note `seq` seqType t2
979 seqType (TyConApp tc tys) = tc `seq` seqTypes tys
980 seqType (ForAllTy tv ty) = tv `seq` seqType ty
982 seqTypes :: [Type] -> ()
984 seqTypes (ty:tys) = seqType ty `seq` seqTypes tys
986 seqNote :: TyNote -> ()
987 seqNote (SynNote ty) = seqType ty
988 seqNote (FTVNote set) = sizeUniqSet set `seq` ()
989 seqNote (UsgNote usg) = usg `seq` ()
990 seqNote (IPNote nm) = nm `seq` ()