2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[TcType]{Types used in the typechecker}
6 This module provides the Type interface for front-end parts of the
9 * treat "source types" as opaque:
10 newtypes, and predicates are meaningful.
11 * look through usage types
13 The "tc" prefix is for "typechechecker", because the type checker
14 is the principal client.
18 --------------------------------
20 TcType, TcSigmaType, TcRhoType, TcTauType, TcPredType, TcThetaType,
21 TcTyVar, TcTyVarSet, TcKind,
23 --------------------------------
26 MetaDetails(Flexi, Indirect), SkolemInfo(..), pprSkolemTyVar,
27 isImmutableTyVar, isSkolemTyVar, isMetaTyVar, isExistentialTyVar, skolemTvInfo, metaTvRef,
30 --------------------------------
32 mkPhiTy, mkSigmaTy, hoistForAllTys,
34 --------------------------------
36 -- These are important because they do not look through newtypes
37 tcSplitForAllTys, tcSplitPhiTy,
38 tcSplitFunTy_maybe, tcSplitFunTys, tcFunArgTy, tcFunResultTy,
39 tcSplitTyConApp, tcSplitTyConApp_maybe, tcTyConAppTyCon, tcTyConAppArgs,
40 tcSplitAppTy_maybe, tcSplitAppTy, tcSplitAppTys, tcSplitSigmaTy,
41 tcGetTyVar_maybe, tcGetTyVar,
43 ---------------------------------
45 -- Again, newtypes are opaque
46 tcEqType, tcEqTypes, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred, tcEqTypeX,
47 isSigmaTy, isOverloadedTy,
48 isDoubleTy, isFloatTy, isIntTy,
49 isIntegerTy, isAddrTy, isBoolTy, isUnitTy,
50 isTauTy, tcIsTyVarTy, tcIsForAllTy,
52 ---------------------------------
53 -- Misc type manipulators
54 deNoteType, classesOfTheta,
55 tyClsNamesOfType, tyClsNamesOfDFunHead,
58 ---------------------------------
60 getClassPredTys_maybe, getClassPredTys,
61 isClassPred, isTyVarClassPred,
62 mkDictTy, tcSplitPredTy_maybe,
63 isPredTy, isDictTy, tcSplitDFunTy, tcSplitDFunHead, predTyUnique,
64 mkClassPred, isInheritablePred, isLinearPred, isIPPred, mkPredName,
66 ---------------------------------
67 -- Foreign import and export
68 isFFIArgumentTy, -- :: DynFlags -> Safety -> Type -> Bool
69 isFFIImportResultTy, -- :: DynFlags -> Type -> Bool
70 isFFIExportResultTy, -- :: Type -> Bool
71 isFFIExternalTy, -- :: Type -> Bool
72 isFFIDynArgumentTy, -- :: Type -> Bool
73 isFFIDynResultTy, -- :: Type -> Bool
74 isFFILabelTy, -- :: Type -> Bool
75 isFFIDotnetTy, -- :: DynFlags -> Type -> Bool
76 isFFIDotnetObjTy, -- :: Type -> Bool
77 isFFITy, -- :: Type -> Bool
79 toDNType, -- :: Type -> DNType
81 --------------------------------
82 -- Rexported from Type
83 Kind, -- Stuff to do with kinds is insensitive to pre/post Tc
84 unliftedTypeKind, liftedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds,
85 isLiftedTypeKind, isUnliftedTypeKind, isOpenTypeKind,
86 isArgTypeKind, isSubKind, defaultKind,
88 Type, PredType(..), ThetaType,
89 mkForAllTy, mkForAllTys,
90 mkFunTy, mkFunTys, zipFunTys,
91 mkTyConApp, mkGenTyConApp, mkAppTy, mkAppTys, mkSynTy, applyTy, applyTys,
92 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys,
95 TvSubst(..), -- Representation visible to a few friends
96 TvSubstEnv, emptyTvSubst,
97 mkTvSubst, zipTvSubst, zipTopTvSubst, mkTopTvSubst,
98 getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope,
99 extendTvSubst, extendTvSubstList, isInScope,
100 substTy, substTys, substTyWith, substTheta, substTyVar, substTyVarBndr,
102 isUnLiftedType, -- Source types are always lifted
103 isUnboxedTupleType, -- Ditto
106 tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
107 tidyTyVarBndr, tidyOpenTyVar, tidyOpenTyVars,
110 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
112 pprKind, pprParendKind,
113 pprType, pprParendType, pprTyThingCategory,
114 pprPred, pprTheta, pprThetaArrow, pprClassPred
118 #include "HsVersions.h"
121 import TypeRep ( Type(..), TyNote(..), funTyCon ) -- friend
123 import Type ( -- Re-exports
124 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
125 tyVarsOfTheta, Kind, PredType(..),
126 ThetaType, unliftedTypeKind,
127 liftedTypeKind, openTypeKind, mkArrowKind,
128 isLiftedTypeKind, isUnliftedTypeKind,
129 mkArrowKinds, mkForAllTy, mkForAllTys,
130 defaultKind, isArgTypeKind, isOpenTypeKind,
131 mkFunTy, mkFunTys, zipFunTys,
132 mkTyConApp, mkGenTyConApp, mkAppTy,
133 mkAppTys, mkSynTy, applyTy, applyTys,
134 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy,
135 mkPredTys, isUnLiftedType,
136 isUnboxedTupleType, isPrimitiveType,
138 tidyTopType, tidyType, tidyPred, tidyTypes,
139 tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
140 tidyTyVarBndr, tidyOpenTyVar,
142 isSubKind, deShadowTy,
144 tcEqType, tcEqTypes, tcCmpType, tcCmpTypes,
145 tcEqPred, tcCmpPred, tcEqTypeX,
148 TvSubstEnv, emptyTvSubst,
149 mkTvSubst, zipTvSubst, zipTopTvSubst, mkTopTvSubst,
150 getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope,
151 extendTvSubst, extendTvSubstList, isInScope,
152 substTy, substTys, substTyWith, substTheta, substTyVar, substTyVarBndr,
155 pprKind, pprParendKind,
156 pprType, pprParendType, pprTyThingCategory,
157 pprPred, pprTheta, pprThetaArrow, pprClassPred
159 import TyCon ( TyCon, isUnLiftedTyCon, tyConUnique )
160 import DataCon ( DataCon )
161 import Class ( Class )
162 import Var ( TyVar, Id, isTcTyVar, tcTyVarDetails )
163 import ForeignCall ( Safety, playSafe, DNType(..) )
167 import CmdLineOpts ( DynFlags, DynFlag( Opt_GlasgowExts ), dopt )
168 import Name ( Name, NamedThing(..), mkInternalName, getSrcLoc )
170 import OccName ( OccName, mkDictOcc )
171 import PrelNames -- Lots (e.g. in isFFIArgumentTy)
172 import TysWiredIn ( unitTyCon, charTyCon, listTyCon )
173 import BasicTypes ( IPName(..), ipNameName )
174 import SrcLoc ( SrcLoc, SrcSpan )
175 import Util ( snocView )
176 import Maybes ( maybeToBool, expectJust )
182 %************************************************************************
186 %************************************************************************
188 The type checker divides the generic Type world into the
189 following more structured beasts:
191 sigma ::= forall tyvars. phi
192 -- A sigma type is a qualified type
194 -- Note that even if 'tyvars' is empty, theta
195 -- may not be: e.g. (?x::Int) => Int
197 -- Note that 'sigma' is in prenex form:
198 -- all the foralls are at the front.
199 -- A 'phi' type has no foralls to the right of
207 -- A 'tau' type has no quantification anywhere
208 -- Note that the args of a type constructor must be taus
210 | tycon tau_1 .. tau_n
214 -- In all cases, a (saturated) type synonym application is legal,
215 -- provided it expands to the required form.
218 type TcType = Type -- A TcType can have mutable type variables
219 -- Invariant on ForAllTy in TcTypes:
221 -- a cannot occur inside a MutTyVar in T; that is,
222 -- T is "flattened" before quantifying over a
224 type TcPredType = PredType
225 type TcThetaType = ThetaType
226 type TcSigmaType = TcType
227 type TcRhoType = TcType
228 type TcTauType = TcType
230 type TcTyVarSet = TyVarSet
234 %************************************************************************
236 \subsection{TyVarDetails}
238 %************************************************************************
240 TyVarDetails gives extra info about type variables, used during type
241 checking. It's attached to mutable type variables only.
242 It's knot-tied back to Var.lhs. There is no reason in principle
243 why Var.lhs shouldn't actually have the definition, but it "belongs" here.
246 type TcTyVar = TyVar -- Used only during type inference
248 -- A TyVarDetails is inside a TyVar
250 = SkolemTv SkolemInfo -- A skolem constant
251 | MetaTv (IORef MetaDetails) -- A meta type variable stands for a tau-type
254 = SigSkol Name -- Bound at a type signature
255 | ClsSkol Class -- Bound at a class decl
256 | InstSkol Id -- Bound at an instance decl
257 | PatSkol DataCon -- An existential type variable bound by a pattern for
258 SrcSpan -- a data constructor with an existential type. E.g.
259 -- data T = forall a. Eq a => MkT a
261 -- The pattern MkT x will allocate an existential type
263 | ArrowSkol SrcSpan -- An arrow form (see TcArrows)
265 | GenSkol TcType -- Bound when doing a subsumption check for this type
269 = Flexi -- Flexi type variables unify to become
272 | Indirect TcType -- Type indirections, treated as wobbly
273 -- for the purpose of GADT unification.
275 pprSkolemTyVar :: TcTyVar -> SDoc
277 = ASSERT( isSkolemTyVar tv )
278 quotes (ppr tv) <+> ptext SLIT("is bound by") <+> ppr (skolemTvInfo tv)
280 instance Outputable SkolemInfo where
281 ppr (SigSkol id) = ptext SLIT("the type signature for") <+> quotes (ppr id)
282 ppr (ClsSkol cls) = ptext SLIT("the class declaration for") <+> quotes (ppr cls)
283 ppr (InstSkol df) = ptext SLIT("the instance declaration at") <+> ppr (getSrcLoc df)
284 ppr (ArrowSkol loc) = ptext SLIT("the arrow form at") <+> ppr loc
285 ppr (PatSkol dc loc) = sep [ptext SLIT("the pattern for") <+> quotes (ppr dc),
286 nest 2 (ptext SLIT("at") <+> ppr loc)]
287 ppr (GenSkol ty loc) = sep [ptext SLIT("the polymorphic type") <+> quotes (ppr ty),
288 nest 2 (ptext SLIT("at") <+> ppr loc)]
290 instance Outputable MetaDetails where
291 ppr Flexi = ptext SLIT("Flexi")
292 ppr (Indirect ty) = ptext SLIT("Indirect") <+> ppr ty
294 isImmutableTyVar, isSkolemTyVar, isExistentialTyVar, isMetaTyVar :: TyVar -> Bool
296 | isTcTyVar tv = isSkolemTyVar tv
300 = ASSERT( isTcTyVar tv )
301 case tcTyVarDetails tv of
305 isExistentialTyVar tv -- Existential type variable, bound by a pattern
306 = ASSERT( isTcTyVar tv )
307 case tcTyVarDetails tv of
308 SkolemTv (PatSkol _ _) -> True
312 = ASSERT( isTcTyVar tv )
313 case tcTyVarDetails tv of
317 skolemTvInfo :: TyVar -> SkolemInfo
319 = ASSERT( isTcTyVar tv )
320 case tcTyVarDetails tv of
321 SkolemTv info -> info
323 metaTvRef :: TyVar -> IORef MetaDetails
325 = ASSERT( isTcTyVar tv )
326 case tcTyVarDetails tv of
329 isFlexi, isIndirect :: MetaDetails -> Bool
331 isFlexi other = False
333 isIndirect (Indirect _) = True
334 isIndirect other = False
338 %************************************************************************
340 \subsection{Tau, sigma and rho}
342 %************************************************************************
345 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkPhiTy theta tau)
347 mkPhiTy :: [PredType] -> Type -> Type
348 mkPhiTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
351 @isTauTy@ tests for nested for-alls.
354 isTauTy :: Type -> Bool
355 isTauTy (TyVarTy v) = True
356 isTauTy (TyConApp _ tys) = all isTauTy tys
357 isTauTy (AppTy a b) = isTauTy a && isTauTy b
358 isTauTy (FunTy a b) = isTauTy a && isTauTy b
359 isTauTy (PredTy p) = True -- Don't look through source types
360 isTauTy (NoteTy _ ty) = isTauTy ty
361 isTauTy other = False
365 getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
366 -- construct a dictionary function name
367 getDFunTyKey (TyVarTy tv) = getOccName tv
368 getDFunTyKey (TyConApp tc _) = getOccName tc
369 getDFunTyKey (AppTy fun _) = getDFunTyKey fun
370 getDFunTyKey (NoteTy _ t) = getDFunTyKey t
371 getDFunTyKey (FunTy arg _) = getOccName funTyCon
372 getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
373 getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty)
374 -- PredTy shouldn't happen
378 %************************************************************************
380 \subsection{Expanding and splitting}
382 %************************************************************************
384 These tcSplit functions are like their non-Tc analogues, but
385 a) they do not look through newtypes
386 b) they do not look through PredTys
387 c) [future] they ignore usage-type annotations
389 However, they are non-monadic and do not follow through mutable type
390 variables. It's up to you to make sure this doesn't matter.
393 tcSplitForAllTys :: Type -> ([TyVar], Type)
394 tcSplitForAllTys ty = split ty ty []
396 split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
397 split orig_ty (NoteTy n ty) tvs = split orig_ty ty tvs
398 split orig_ty t tvs = (reverse tvs, orig_ty)
400 tcIsForAllTy (ForAllTy tv ty) = True
401 tcIsForAllTy (NoteTy n ty) = tcIsForAllTy ty
402 tcIsForAllTy t = False
404 tcSplitPhiTy :: Type -> ([PredType], Type)
405 tcSplitPhiTy ty = split ty ty []
407 split orig_ty (FunTy arg res) ts = case tcSplitPredTy_maybe arg of
408 Just p -> split res res (p:ts)
409 Nothing -> (reverse ts, orig_ty)
410 split orig_ty (NoteTy n ty) ts = split orig_ty ty ts
411 split orig_ty ty ts = (reverse ts, orig_ty)
413 tcSplitSigmaTy ty = case tcSplitForAllTys ty of
414 (tvs, rho) -> case tcSplitPhiTy rho of
415 (theta, tau) -> (tvs, theta, tau)
417 tcTyConAppTyCon :: Type -> TyCon
418 tcTyConAppTyCon ty = fst (tcSplitTyConApp ty)
420 tcTyConAppArgs :: Type -> [Type]
421 tcTyConAppArgs ty = snd (tcSplitTyConApp ty)
423 tcSplitTyConApp :: Type -> (TyCon, [Type])
424 tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
426 Nothing -> pprPanic "tcSplitTyConApp" (pprType ty)
428 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
429 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
430 tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
431 tcSplitTyConApp_maybe (NoteTy n ty) = tcSplitTyConApp_maybe ty
432 -- Newtypes are opaque, so they may be split
433 -- However, predicates are not treated
434 -- as tycon applications by the type checker
435 tcSplitTyConApp_maybe other = Nothing
437 tcSplitFunTys :: Type -> ([Type], Type)
438 tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
440 Just (arg,res) -> (arg:args, res')
442 (args,res') = tcSplitFunTys res
444 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
445 tcSplitFunTy_maybe (FunTy arg res) = Just (arg, res)
446 tcSplitFunTy_maybe (NoteTy n ty) = tcSplitFunTy_maybe ty
447 tcSplitFunTy_maybe other = Nothing
449 tcFunArgTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> arg }
450 tcFunResultTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> res }
453 tcSplitAppTy_maybe :: Type -> Maybe (Type, Type)
454 tcSplitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
455 tcSplitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
456 tcSplitAppTy_maybe (NoteTy n ty) = tcSplitAppTy_maybe ty
457 tcSplitAppTy_maybe (TyConApp tc tys) = case snocView tys of
458 Just (tys', ty') -> Just (TyConApp tc tys', ty')
460 tcSplitAppTy_maybe other = Nothing
462 tcSplitAppTy ty = case tcSplitAppTy_maybe ty of
464 Nothing -> pprPanic "tcSplitAppTy" (pprType ty)
466 tcSplitAppTys :: Type -> (Type, [Type])
470 go ty args = case tcSplitAppTy_maybe ty of
471 Just (ty', arg) -> go ty' (arg:args)
474 tcGetTyVar_maybe :: Type -> Maybe TyVar
475 tcGetTyVar_maybe (TyVarTy tv) = Just tv
476 tcGetTyVar_maybe (NoteTy _ t) = tcGetTyVar_maybe t
477 tcGetTyVar_maybe other = Nothing
479 tcGetTyVar :: String -> Type -> TyVar
480 tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty)
482 tcIsTyVarTy :: Type -> Bool
483 tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty)
485 tcSplitDFunTy :: Type -> ([TyVar], [PredType], Class, [Type])
486 -- Split the type of a dictionary function
488 = case tcSplitSigmaTy ty of { (tvs, theta, tau) ->
489 case tcSplitDFunHead tau of { (clas, tys) ->
490 (tvs, theta, clas, tys) }}
492 tcSplitDFunHead :: Type -> (Class, [Type])
494 = case tcSplitPredTy_maybe tau of
495 Just (ClassP clas tys) -> (clas, tys)
500 %************************************************************************
502 \subsection{Predicate types}
504 %************************************************************************
507 tcSplitPredTy_maybe :: Type -> Maybe PredType
508 -- Returns Just for predicates only
509 tcSplitPredTy_maybe (NoteTy _ ty) = tcSplitPredTy_maybe ty
510 tcSplitPredTy_maybe (PredTy p) = Just p
511 tcSplitPredTy_maybe other = Nothing
513 predTyUnique :: PredType -> Unique
514 predTyUnique (IParam n _) = getUnique (ipNameName n)
515 predTyUnique (ClassP clas tys) = getUnique clas
517 mkPredName :: Unique -> SrcLoc -> PredType -> Name
518 mkPredName uniq loc (ClassP cls tys) = mkInternalName uniq (mkDictOcc (getOccName cls)) loc
519 mkPredName uniq loc (IParam ip ty) = mkInternalName uniq (getOccName (ipNameName ip)) loc
523 --------------------- Dictionary types ---------------------------------
526 mkClassPred clas tys = ClassP clas tys
528 isClassPred :: PredType -> Bool
529 isClassPred (ClassP clas tys) = True
530 isClassPred other = False
532 isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys
533 isTyVarClassPred other = False
535 getClassPredTys_maybe :: PredType -> Maybe (Class, [Type])
536 getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys)
537 getClassPredTys_maybe _ = Nothing
539 getClassPredTys :: PredType -> (Class, [Type])
540 getClassPredTys (ClassP clas tys) = (clas, tys)
542 mkDictTy :: Class -> [Type] -> Type
543 mkDictTy clas tys = mkPredTy (ClassP clas tys)
545 isDictTy :: Type -> Bool
546 isDictTy (PredTy p) = isClassPred p
547 isDictTy (NoteTy _ ty) = isDictTy ty
548 isDictTy other = False
551 --------------------- Implicit parameters ---------------------------------
554 isIPPred :: PredType -> Bool
555 isIPPred (IParam _ _) = True
556 isIPPred other = False
558 isInheritablePred :: PredType -> Bool
559 -- Can be inherited by a context. For example, consider
560 -- f x = let g y = (?v, y+x)
561 -- in (g 3 with ?v = 8,
563 -- The point is that g's type must be quantifed over ?v:
564 -- g :: (?v :: a) => a -> a
565 -- but it doesn't need to be quantified over the Num a dictionary
566 -- which can be free in g's rhs, and shared by both calls to g
567 isInheritablePred (ClassP _ _) = True
568 isInheritablePred other = False
570 isLinearPred :: TcPredType -> Bool
571 isLinearPred (IParam (Linear n) _) = True
572 isLinearPred other = False
576 %************************************************************************
578 \subsection{Predicates}
580 %************************************************************************
582 isSigmaTy returns true of any qualified type. It doesn't *necessarily* have
584 f :: (?x::Int) => Int -> Int
587 isSigmaTy :: Type -> Bool
588 isSigmaTy (ForAllTy tyvar ty) = True
589 isSigmaTy (FunTy a b) = isPredTy a
590 isSigmaTy (NoteTy n ty) = isSigmaTy ty
593 isOverloadedTy :: Type -> Bool
594 isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty
595 isOverloadedTy (FunTy a b) = isPredTy a
596 isOverloadedTy (NoteTy n ty) = isOverloadedTy ty
597 isOverloadedTy _ = False
599 isPredTy :: Type -> Bool -- Belongs in TcType because it does
600 -- not look through newtypes, or predtypes (of course)
601 isPredTy (NoteTy _ ty) = isPredTy ty
602 isPredTy (PredTy sty) = True
607 isFloatTy = is_tc floatTyConKey
608 isDoubleTy = is_tc doubleTyConKey
609 isIntegerTy = is_tc integerTyConKey
610 isIntTy = is_tc intTyConKey
611 isAddrTy = is_tc addrTyConKey
612 isBoolTy = is_tc boolTyConKey
613 isUnitTy = is_tc unitTyConKey
615 is_tc :: Unique -> Type -> Bool
616 -- Newtypes are opaque to this
617 is_tc uniq ty = case tcSplitTyConApp_maybe ty of
618 Just (tc, _) -> uniq == getUnique tc
625 %************************************************************************
629 %************************************************************************
631 hoistForAllTys is used for user-written type signatures only
632 We want to 'look through' type synonyms when doing this
633 so it's better done on the Type than the HsType
635 It moves all the foralls and constraints to the top
636 e.g. T -> forall a. a ==> forall a. T -> a
637 T -> (?x::Int) -> Int ==> (?x::Int) -> T -> Int
639 Also: it eliminates duplicate constraints. These can show up
640 when hoisting constraints, notably implicit parameters.
642 It tries hard to retain type synonyms if hoisting does not break one
643 up. Not only does this improve error messages, but there's a tricky
644 interaction with Haskell 98. H98 requires no unsaturated type
645 synonyms, which is checked by checkValidType. This runs after
646 hoisting, so we don't want hoisting to remove the SynNotes! (We can't
647 run validity checking before hoisting because in mutually-recursive
648 type definitions we postpone validity checking until after the knot is
652 hoistForAllTys :: Type -> Type
655 -- Running over ty with an empty substitution gives it the
656 -- no-shadowing property. This is important. For example:
657 -- type Foo r = forall a. a -> r
658 -- foo :: Foo (Foo ())
659 -- Here the hoisting should give
660 -- foo :: forall a a1. a -> a1 -> ()
662 -- What about type vars that are lexically in scope in the envt?
663 -- We simply rely on them having a different unique to any
664 -- binder in 'ty'. Otherwise we'd have to slurp the in-scope-tyvars
665 -- out of the envt, which is boring and (I think) not necessary.
668 go (TyVarTy tv) = TyVarTy tv
669 go (TyConApp tc tys) = TyConApp tc (map go tys)
670 go (PredTy pred) = PredTy pred -- No nested foralls
671 go (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (go ty1)) (go ty2)
672 go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard the free tyvar note
673 go (FunTy arg res) = mk_fun_ty (go arg) (go res)
674 go (AppTy fun arg) = AppTy (go fun) (go arg)
675 go (ForAllTy tv ty) = ForAllTy tv (go ty)
677 -- mk_fun_ty does all the work.
678 -- It's building t1 -> t2:
679 -- if t2 is a for-all type, push t1 inside it
680 -- if t2 is (pred -> t3), check for duplicates
682 | not (isOverloadedTy ty2) -- No forall's, or context =>
684 | PredTy p1 <- ty1 -- ty1 is a predicate
685 = if p1 `elem` theta then -- so check for duplicates
688 mkSigmaTy tvs (p1:theta) tau
690 = mkSigmaTy tvs theta (FunTy ty1 tau)
692 (tvs, theta, tau) = tcSplitSigmaTy ty2
696 %************************************************************************
700 %************************************************************************
703 deNoteType :: Type -> Type
704 -- Remove synonyms, but not predicate types
705 deNoteType ty@(TyVarTy tyvar) = ty
706 deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys)
707 deNoteType (PredTy p) = PredTy (deNotePredType p)
708 deNoteType (NoteTy _ ty) = deNoteType ty
709 deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg)
710 deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg)
711 deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty)
713 deNotePredType :: PredType -> PredType
714 deNotePredType (ClassP c tys) = ClassP c (map deNoteType tys)
715 deNotePredType (IParam n ty) = IParam n (deNoteType ty)
718 Find the free tycons and classes of a type. This is used in the front
722 tyClsNamesOfType :: Type -> NameSet
723 tyClsNamesOfType (TyVarTy tv) = emptyNameSet
724 tyClsNamesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` tyClsNamesOfTypes tys
725 tyClsNamesOfType (NoteTy (SynNote ty1) ty2) = tyClsNamesOfType ty1
726 tyClsNamesOfType (NoteTy other_note ty2) = tyClsNamesOfType ty2
727 tyClsNamesOfType (PredTy (IParam n ty)) = tyClsNamesOfType ty
728 tyClsNamesOfType (PredTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` tyClsNamesOfTypes tys
729 tyClsNamesOfType (FunTy arg res) = tyClsNamesOfType arg `unionNameSets` tyClsNamesOfType res
730 tyClsNamesOfType (AppTy fun arg) = tyClsNamesOfType fun `unionNameSets` tyClsNamesOfType arg
731 tyClsNamesOfType (ForAllTy tyvar ty) = tyClsNamesOfType ty
733 tyClsNamesOfTypes tys = foldr (unionNameSets . tyClsNamesOfType) emptyNameSet tys
735 tyClsNamesOfDFunHead :: Type -> NameSet
736 -- Find the free type constructors and classes
737 -- of the head of the dfun instance type
738 -- The 'dfun_head_type' is because of
739 -- instance Foo a => Baz T where ...
740 -- The decl is an orphan if Baz and T are both not locally defined,
741 -- even if Foo *is* locally defined
742 tyClsNamesOfDFunHead dfun_ty
743 = case tcSplitSigmaTy dfun_ty of
744 (tvs,_,head_ty) -> tyClsNamesOfType head_ty
746 classesOfTheta :: ThetaType -> [Class]
747 -- Looks just for ClassP things; maybe it should check
748 classesOfTheta preds = [ c | ClassP c _ <- preds ]
752 %************************************************************************
754 \subsection[TysWiredIn-ext-type]{External types}
756 %************************************************************************
758 The compiler's foreign function interface supports the passing of a
759 restricted set of types as arguments and results (the restricting factor
763 isFFITy :: Type -> Bool
764 -- True for any TyCon that can possibly be an arg or result of an FFI call
765 isFFITy ty = checkRepTyCon legalFFITyCon ty
767 isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool
768 -- Checks for valid argument type for a 'foreign import'
769 isFFIArgumentTy dflags safety ty
770 = checkRepTyCon (legalOutgoingTyCon dflags safety) ty
772 isFFIExternalTy :: Type -> Bool
773 -- Types that are allowed as arguments of a 'foreign export'
774 isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty
776 isFFIImportResultTy :: DynFlags -> Type -> Bool
777 isFFIImportResultTy dflags ty
778 = checkRepTyCon (legalFIResultTyCon dflags) ty
780 isFFIExportResultTy :: Type -> Bool
781 isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty
783 isFFIDynArgumentTy :: Type -> Bool
784 -- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr,
785 -- or a newtype of either.
786 isFFIDynArgumentTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey, addrTyConKey]
788 isFFIDynResultTy :: Type -> Bool
789 -- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr,
790 -- or a newtype of either.
791 isFFIDynResultTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey, addrTyConKey]
793 isFFILabelTy :: Type -> Bool
794 -- The type of a foreign label must be Ptr, FunPtr, Addr,
795 -- or a newtype of either.
796 isFFILabelTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey, addrTyConKey]
798 isFFIDotnetTy :: DynFlags -> Type -> Bool
799 isFFIDotnetTy dflags ty
800 = checkRepTyCon (\ tc -> not (isByteArrayLikeTyCon tc) &&
801 (legalFIResultTyCon dflags tc ||
802 isFFIDotnetObjTy ty || isStringTy ty)) ty
804 -- Support String as an argument or result from a .NET FFI call.
806 case tcSplitTyConApp_maybe (repType ty) of
809 case tcSplitTyConApp_maybe (repType arg_ty) of
810 Just (cc,[]) -> cc == charTyCon
814 -- Support String as an argument or result from a .NET FFI call.
815 isFFIDotnetObjTy ty =
817 (_, t_ty) = tcSplitForAllTys ty
819 case tcSplitTyConApp_maybe (repType t_ty) of
820 Just (tc, [arg_ty]) | getName tc == objectTyConName -> True
823 toDNType :: Type -> DNType
825 | isStringTy ty = DNString
826 | isFFIDotnetObjTy ty = DNObject
827 | Just (tc,argTys) <- tcSplitTyConApp_maybe ty =
828 case lookup (getUnique tc) dn_assoc of
831 | tc `hasKey` ioTyConKey -> toDNType (head argTys)
832 | otherwise -> pprPanic ("toDNType: unsupported .NET type") (pprType ty <+> parens (hcat (map pprType argTys)) <+> ppr tc)
834 dn_assoc :: [ (Unique, DNType) ]
835 dn_assoc = [ (unitTyConKey, DNUnit)
836 , (intTyConKey, DNInt)
837 , (int8TyConKey, DNInt8)
838 , (int16TyConKey, DNInt16)
839 , (int32TyConKey, DNInt32)
840 , (int64TyConKey, DNInt64)
841 , (wordTyConKey, DNInt)
842 , (word8TyConKey, DNWord8)
843 , (word16TyConKey, DNWord16)
844 , (word32TyConKey, DNWord32)
845 , (word64TyConKey, DNWord64)
846 , (floatTyConKey, DNFloat)
847 , (doubleTyConKey, DNDouble)
848 , (addrTyConKey, DNPtr)
849 , (ptrTyConKey, DNPtr)
850 , (funPtrTyConKey, DNPtr)
851 , (charTyConKey, DNChar)
852 , (boolTyConKey, DNBool)
855 checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool
856 -- Look through newtypes
857 -- Non-recursive ones are transparent to splitTyConApp,
858 -- but recursive ones aren't. Manuel had:
859 -- newtype T = MkT (Ptr T)
860 -- and wanted it to work...
861 checkRepTyCon check_tc ty
862 | Just (tc,_) <- splitTyConApp_maybe (repType ty) = check_tc tc
865 checkRepTyConKey :: [Unique] -> Type -> Bool
866 -- Like checkRepTyCon, but just looks at the TyCon key
867 checkRepTyConKey keys
868 = checkRepTyCon (\tc -> tyConUnique tc `elem` keys)
871 ----------------------------------------------
872 These chaps do the work; they are not exported
873 ----------------------------------------------
876 legalFEArgTyCon :: TyCon -> Bool
877 -- It's illegal to return foreign objects and (mutable)
878 -- bytearrays from a _ccall_ / foreign declaration
879 -- (or be passed them as arguments in foreign exported functions).
881 | isByteArrayLikeTyCon tc
883 -- It's also illegal to make foreign exports that take unboxed
884 -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000
886 = boxedMarshalableTyCon tc
888 legalFIResultTyCon :: DynFlags -> TyCon -> Bool
889 legalFIResultTyCon dflags tc
890 | isByteArrayLikeTyCon tc = False
891 | tc == unitTyCon = True
892 | otherwise = marshalableTyCon dflags tc
894 legalFEResultTyCon :: TyCon -> Bool
895 legalFEResultTyCon tc
896 | isByteArrayLikeTyCon tc = False
897 | tc == unitTyCon = True
898 | otherwise = boxedMarshalableTyCon tc
900 legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool
901 -- Checks validity of types going from Haskell -> external world
902 legalOutgoingTyCon dflags safety tc
903 | playSafe safety && isByteArrayLikeTyCon tc
906 = marshalableTyCon dflags tc
908 legalFFITyCon :: TyCon -> Bool
909 -- True for any TyCon that can possibly be an arg or result of an FFI call
911 = isUnLiftedTyCon tc || boxedMarshalableTyCon tc || tc == unitTyCon
913 marshalableTyCon dflags tc
914 = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc)
915 || boxedMarshalableTyCon tc
917 boxedMarshalableTyCon tc
918 = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey
919 , int32TyConKey, int64TyConKey
920 , wordTyConKey, word8TyConKey, word16TyConKey
921 , word32TyConKey, word64TyConKey
922 , floatTyConKey, doubleTyConKey
923 , addrTyConKey, ptrTyConKey, funPtrTyConKey
926 , byteArrayTyConKey, mutableByteArrayTyConKey
930 isByteArrayLikeTyCon :: TyCon -> Bool
931 isByteArrayLikeTyCon tc =
932 getUnique tc `elem` [byteArrayTyConKey, mutableByteArrayTyConKey]