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 BoxyTyVar, BoxySigmaType, BoxyRhoType, BoxyThetaType, BoxyType,
25 --------------------------------
27 UserTypeCtxt(..), pprUserTypeCtxt,
28 TcTyVarDetails(..), BoxInfo(..), pprTcTyVarDetails,
29 MetaDetails(Flexi, Indirect), SkolemInfo(..), pprSkolTvBinding, pprSkolInfo,
30 isImmutableTyVar, isSkolemTyVar, isMetaTyVar, isBoxyTyVar, isSigTyVar, isExistentialTyVar,
34 --------------------------------
38 --------------------------------
40 -- These are important because they do not look through newtypes
42 tcSplitForAllTys, tcSplitPhiTy,
43 tcSplitFunTy_maybe, tcSplitFunTys, tcFunArgTy, tcFunResultTy, tcSplitFunTysN,
44 tcSplitTyConApp, tcSplitTyConApp_maybe, tcTyConAppTyCon, tcTyConAppArgs,
45 tcSplitAppTy_maybe, tcSplitAppTy, tcSplitAppTys, repSplitAppTy_maybe,
46 tcValidInstHeadTy, tcGetTyVar_maybe, tcGetTyVar,
47 tcSplitSigmaTy, tcMultiSplitSigmaTy,
49 ---------------------------------
51 -- Again, newtypes are opaque
52 tcEqType, tcEqTypes, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred, tcEqTypeX,
54 isSigmaTy, isOverloadedTy, isRigidTy, isBoxyTy,
55 isDoubleTy, isFloatTy, isIntTy, isStringTy,
56 isIntegerTy, isBoolTy, isUnitTy,
57 isTauTy, isTauTyCon, tcIsTyVarTy, tcIsForAllTy,
59 ---------------------------------
60 -- Misc type manipulators
61 deNoteType, classesOfTheta,
62 tyClsNamesOfType, tyClsNamesOfDFunHead,
65 ---------------------------------
67 getClassPredTys_maybe, getClassPredTys,
68 isClassPred, isTyVarClassPred, isEqPred,
69 mkDictTy, tcSplitPredTy_maybe,
70 isPredTy, isDictTy, tcSplitDFunTy, tcSplitDFunHead, predTyUnique,
71 mkClassPred, isInheritablePred, isLinearPred, isIPPred, mkPredName,
72 dataConsStupidTheta, isRefineableTy,
74 ---------------------------------
75 -- Foreign import and export
76 isFFIArgumentTy, -- :: DynFlags -> Safety -> Type -> Bool
77 isFFIImportResultTy, -- :: DynFlags -> Type -> Bool
78 isFFIExportResultTy, -- :: Type -> Bool
79 isFFIExternalTy, -- :: Type -> Bool
80 isFFIDynArgumentTy, -- :: Type -> Bool
81 isFFIDynResultTy, -- :: Type -> Bool
82 isFFILabelTy, -- :: Type -> Bool
83 isFFIDotnetTy, -- :: DynFlags -> Type -> Bool
84 isFFIDotnetObjTy, -- :: Type -> Bool
85 isFFITy, -- :: Type -> Bool
86 tcSplitIOType_maybe, -- :: Type -> Maybe Type
87 toDNType, -- :: Type -> DNType
89 --------------------------------
90 -- Rexported from Type
91 Kind, -- Stuff to do with kinds is insensitive to pre/post Tc
92 unliftedTypeKind, liftedTypeKind, argTypeKind,
93 openTypeKind, mkArrowKind, mkArrowKinds,
94 isLiftedTypeKind, isUnliftedTypeKind, isSubOpenTypeKind,
95 isSubArgTypeKind, isSubKind, defaultKind,
96 kindVarRef, mkKindVar,
98 Type, PredType(..), ThetaType,
99 mkForAllTy, mkForAllTys,
100 mkFunTy, mkFunTys, zipFunTys,
101 mkTyConApp, mkAppTy, mkAppTys, applyTy, applyTys,
102 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys,
104 -- Type substitutions
105 TvSubst(..), -- Representation visible to a few friends
106 TvSubstEnv, emptyTvSubst, substEqSpec,
107 mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst,
108 getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope, lookupTyVar,
109 extendTvSubst, extendTvSubstList, isInScope, mkTvSubst, zipTyEnv,
110 substTy, substTys, substTyWith, substTheta, substTyVar, substTyVarBndr,
112 isUnLiftedType, -- Source types are always lifted
113 isUnboxedTupleType, -- Ditto
116 tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
117 tidyTyVarBndr, tidyOpenTyVar, tidyOpenTyVars, tidySkolemTyVar,
120 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
121 tcTyVarsOfType, tcTyVarsOfTypes, exactTyVarsOfType, exactTyVarsOfTypes,
123 pprKind, pprParendKind,
124 pprType, pprParendType, pprTyThingCategory,
125 pprPred, pprTheta, pprThetaArrow, pprClassPred
129 #include "HsVersions.h"
132 import TypeRep ( Type(..), funTyCon, Kind ) -- friend
134 import Type ( -- Re-exports
135 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
136 tyVarsOfTheta, Kind, PredType(..), KindVar,
137 ThetaType, isUnliftedTypeKind, unliftedTypeKind,
139 liftedTypeKind, openTypeKind, mkArrowKind,
140 tySuperKind, isLiftedTypeKind,
141 mkArrowKinds, mkForAllTy, mkForAllTys,
142 defaultKind, isSubArgTypeKind, isSubOpenTypeKind,
143 mkFunTy, mkFunTys, zipFunTys,
145 mkAppTys, applyTy, applyTys,
146 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy,
147 mkPredTys, isUnLiftedType,
148 isUnboxedTupleType, isPrimitiveType,
150 tidyTopType, tidyType, tidyPred, tidyTypes,
151 tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
152 tidyTyVarBndr, tidyOpenTyVar,
153 tidyOpenTyVars, tidyKind,
156 tcEqType, tcEqTypes, tcCmpType, tcCmpTypes,
157 tcEqPred, tcCmpPred, tcEqTypeX, eqKind,
160 TvSubstEnv, emptyTvSubst, mkTvSubst, zipTyEnv,
161 mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst,
162 getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope,
163 extendTvSubst, extendTvSubstList, isInScope, notElemTvSubst,
164 substTy, substTys, substTyWith, substTheta,
165 substTyVar, substTyVarBndr, substPred, lookupTyVar,
167 typeKind, repType, coreView, repSplitAppTy_maybe,
168 pprKind, pprParendKind,
169 pprType, pprParendType, pprTyThingCategory,
170 pprPred, pprTheta, pprThetaArrow, pprClassPred
172 import TyCon ( TyCon, isUnLiftedTyCon, isSynTyCon, synTyConDefn, tyConUnique )
173 import Coercion ( splitForAllCo_maybe )
174 import DataCon ( DataCon, dataConStupidTheta, dataConResTys )
175 import Class ( Class )
176 import Var ( TyVar, Id, isCoVar, isTcTyVar, mkTcTyVar, tyVarName, tyVarKind, tcTyVarDetails )
177 import ForeignCall ( Safety, DNType(..) )
178 import Unify ( tcMatchTys )
182 import DynFlags ( DynFlags, DynFlag( Opt_GlasgowExts ), dopt )
183 import Name ( Name, NamedThing(..), mkInternalName, getSrcLoc, mkSystemName )
185 import VarEnv ( TidyEnv )
186 import OccName ( OccName, mkDictOcc, mkOccName, tvName )
187 import PrelNames -- Lots (e.g. in isFFIArgumentTy)
188 import TysWiredIn ( unitTyCon, charTyCon, listTyCon )
189 import BasicTypes ( IPName(..), Arity, ipNameName )
190 import SrcLoc ( SrcLoc, SrcSpan )
191 import Util ( equalLength )
192 import Maybes ( maybeToBool, expectJust, mapCatMaybes )
193 import ListSetOps ( hasNoDups )
194 import List ( nubBy )
200 %************************************************************************
204 %************************************************************************
206 The type checker divides the generic Type world into the
207 following more structured beasts:
209 sigma ::= forall tyvars. phi
210 -- A sigma type is a qualified type
212 -- Note that even if 'tyvars' is empty, theta
213 -- may not be: e.g. (?x::Int) => Int
215 -- Note that 'sigma' is in prenex form:
216 -- all the foralls are at the front.
217 -- A 'phi' type has no foralls to the right of
225 -- A 'tau' type has no quantification anywhere
226 -- Note that the args of a type constructor must be taus
228 | tycon tau_1 .. tau_n
232 -- In all cases, a (saturated) type synonym application is legal,
233 -- provided it expands to the required form.
236 type TcTyVar = TyVar -- Used only during type inference
237 type TcType = Type -- A TcType can have mutable type variables
238 -- Invariant on ForAllTy in TcTypes:
240 -- a cannot occur inside a MutTyVar in T; that is,
241 -- T is "flattened" before quantifying over a
243 -- These types do not have boxy type variables in them
244 type TcPredType = PredType
245 type TcThetaType = ThetaType
246 type TcSigmaType = TcType
247 type TcRhoType = TcType
248 type TcTauType = TcType
250 type TcTyVarSet = TyVarSet
252 -- These types may have boxy type variables in them
253 type BoxyTyVar = TcTyVar
254 type BoxyRhoType = TcType
255 type BoxyThetaType = TcThetaType
256 type BoxySigmaType = TcType
257 type BoxyType = TcType
261 %************************************************************************
263 \subsection{TyVarDetails}
265 %************************************************************************
267 TyVarDetails gives extra info about type variables, used during type
268 checking. It's attached to mutable type variables only.
269 It's knot-tied back to Var.lhs. There is no reason in principle
270 why Var.lhs shouldn't actually have the definition, but it "belongs" here.
273 Note [Signature skolems]
274 ~~~~~~~~~~~~~~~~~~~~~~~~
279 (x,y,z) = ([y,z], z, head x)
281 Here, x and y have type sigs, which go into the environment. We used to
282 instantiate their types with skolem constants, and push those types into
283 the RHS, so we'd typecheck the RHS with type
285 where a*, b* are skolem constants, and c is an ordinary meta type varible.
287 The trouble is that the occurrences of z in the RHS force a* and b* to
288 be the *same*, so we can't make them into skolem constants that don't unify
289 with each other. Alas.
291 One solution would be insist that in the above defn the programmer uses
292 the same type variable in both type signatures. But that takes explanation.
294 The alternative (currently implemented) is to have a special kind of skolem
295 constant, SigTv, which can unify with other SigTvs. These are *not* treated
296 as righd for the purposes of GADTs. And they are used *only* for pattern
297 bindings and mutually recursive function bindings. See the function
298 TcBinds.tcInstSig, and its use_skols parameter.
302 -- A TyVarDetails is inside a TyVar
304 = SkolemTv SkolemInfo -- A skolem constant
306 | MetaTv BoxInfo (IORef MetaDetails)
309 = BoxTv -- The contents is a (non-boxy) sigma-type
310 -- That is, this MetaTv is a "box"
312 | TauTv -- The contents is a (non-boxy) tau-type
313 -- That is, this MetaTv is an ordinary unification variable
315 | SigTv SkolemInfo -- A variant of TauTv, except that it should not be
316 -- unified with a type, only with a type variable
317 -- SigTvs are only distinguished to improve error messages
318 -- see Note [Signature skolems]
319 -- The MetaDetails, if filled in, will
320 -- always be another SigTv or a SkolemTv
323 -- A TauTv is always filled in with a tau-type, which
324 -- never contains any BoxTvs, nor any ForAlls
326 -- However, a BoxTv can contain a type that contains further BoxTvs
327 -- Notably, when typechecking an explicit list, say [e1,e2], with
328 -- expected type being a box b1, we fill in b1 with (List b2), where
329 -- b2 is another (currently empty) box.
332 = Flexi -- Flexi type variables unify to become
335 | Indirect TcType -- INVARIANT:
336 -- For a BoxTv, this type must be non-boxy
337 -- For a TauTv, this type must be a tau-type
340 = SigSkol UserTypeCtxt -- A skolem that is created by instantiating
341 -- a programmer-supplied type signature
342 -- Location of the binding site is on the TyVar
344 -- The rest are for non-scoped skolems
345 | ClsSkol Class -- Bound at a class decl
346 | InstSkol Id -- Bound at an instance decl
347 | PatSkol DataCon -- An existential type variable bound by a pattern for
348 SrcSpan -- a data constructor with an existential type. E.g.
349 -- data T = forall a. Eq a => MkT a
351 -- The pattern MkT x will allocate an existential type
353 | ArrowSkol SrcSpan -- An arrow form (see TcArrows)
355 | GenSkol [TcTyVar] -- Bound when doing a subsumption check for
356 TcType -- (forall tvs. ty)
359 | UnkSkol -- Unhelpful info (until I improve it)
361 -------------------------------------
362 -- UserTypeCtxt describes the places where a
363 -- programmer-written type signature can occur
365 = FunSigCtxt Name -- Function type signature
366 -- Also used for types in SPECIALISE pragmas
367 | ExprSigCtxt -- Expression type signature
368 | ConArgCtxt Name -- Data constructor argument
369 | TySynCtxt Name -- RHS of a type synonym decl
370 | GenPatCtxt -- Pattern in generic decl
371 -- f{| a+b |} (Inl x) = ...
372 | LamPatSigCtxt -- Type sig in lambda pattern
374 | BindPatSigCtxt -- Type sig in pattern binding pattern
376 | ResSigCtxt -- Result type sig
378 | ForSigCtxt Name -- Foreign inport or export signature
379 | RuleSigCtxt Name -- Signature on a forall'd variable in a RULE
380 | DefaultDeclCtxt -- Types in a default declaration
381 | SpecInstCtxt -- SPECIALISE instance pragma
383 -- Notes re TySynCtxt
384 -- We allow type synonyms that aren't types; e.g. type List = []
386 -- If the RHS mentions tyvars that aren't in scope, we'll
387 -- quantify over them:
388 -- e.g. type T = a->a
389 -- will become type T = forall a. a->a
391 -- With gla-exts that's right, but for H98 we should complain.
393 ---------------------------------
396 mkKindName :: Unique -> Name
397 mkKindName unique = mkSystemName unique kind_var_occ
399 kindVarRef :: KindVar -> IORef MetaDetails
401 case tcTyVarDetails tc of
402 MetaTv TauTv ref -> ref
403 other -> pprPanic "kindVarRef" (ppr tc)
405 mkKindVar :: Unique -> IORef MetaDetails -> KindVar
407 = mkTcTyVar (mkKindName u)
408 tySuperKind -- not sure this is right,
409 -- do we need kind vars for
413 kind_var_occ :: OccName -- Just one for all KindVars
414 -- They may be jiggled by tidying
415 kind_var_occ = mkOccName tvName "k"
419 %************************************************************************
423 %************************************************************************
426 pprTcTyVarDetails :: TcTyVarDetails -> SDoc
428 pprTcTyVarDetails (SkolemTv _) = ptext SLIT("sk")
429 pprTcTyVarDetails (MetaTv BoxTv _) = ptext SLIT("box")
430 pprTcTyVarDetails (MetaTv TauTv _) = ptext SLIT("tau")
431 pprTcTyVarDetails (MetaTv (SigTv _) _) = ptext SLIT("sig")
433 pprUserTypeCtxt :: UserTypeCtxt -> SDoc
434 pprUserTypeCtxt (FunSigCtxt n) = ptext SLIT("the type signature for") <+> quotes (ppr n)
435 pprUserTypeCtxt ExprSigCtxt = ptext SLIT("an expression type signature")
436 pprUserTypeCtxt (ConArgCtxt c) = ptext SLIT("the type of the constructor") <+> quotes (ppr c)
437 pprUserTypeCtxt (TySynCtxt c) = ptext SLIT("the RHS of the type synonym") <+> quotes (ppr c)
438 pprUserTypeCtxt GenPatCtxt = ptext SLIT("the type pattern of a generic definition")
439 pprUserTypeCtxt LamPatSigCtxt = ptext SLIT("a pattern type signature")
440 pprUserTypeCtxt BindPatSigCtxt = ptext SLIT("a pattern type signature")
441 pprUserTypeCtxt ResSigCtxt = ptext SLIT("a result type signature")
442 pprUserTypeCtxt (ForSigCtxt n) = ptext SLIT("the foreign declaration for") <+> quotes (ppr n)
443 pprUserTypeCtxt (RuleSigCtxt n) = ptext SLIT("the type signature for") <+> quotes (ppr n)
444 pprUserTypeCtxt DefaultDeclCtxt = ptext SLIT("a type in a `default' declaration")
445 pprUserTypeCtxt SpecInstCtxt = ptext SLIT("a SPECIALISE instance pragma")
448 --------------------------------
449 tidySkolemTyVar :: TidyEnv -> TcTyVar -> (TidyEnv, TcTyVar)
450 -- Tidy the type inside a GenSkol, preparatory to printing it
451 tidySkolemTyVar env tv
452 = ASSERT( isSkolemTyVar tv || isSigTyVar tv )
453 (env1, mkTcTyVar (tyVarName tv) (tyVarKind tv) info1)
455 (env1, info1) = case tcTyVarDetails tv of
456 SkolemTv info -> (env1, SkolemTv info')
458 (env1, info') = tidy_skol_info env info
459 MetaTv (SigTv info) box -> (env1, MetaTv (SigTv info') box)
461 (env1, info') = tidy_skol_info env info
464 tidy_skol_info env (GenSkol tvs ty loc) = (env2, GenSkol tvs1 ty1 loc)
466 (env1, tvs1) = tidyOpenTyVars env tvs
467 (env2, ty1) = tidyOpenType env1 ty
468 tidy_skol_info env info = (env, info)
470 pprSkolTvBinding :: TcTyVar -> SDoc
471 -- Print info about the binding of a skolem tyvar,
472 -- or nothing if we don't have anything useful to say
474 = ppr_details (tcTyVarDetails tv)
476 ppr_details (MetaTv TauTv _) = quotes (ppr tv) <+> ptext SLIT("is a meta type variable")
477 ppr_details (MetaTv BoxTv _) = quotes (ppr tv) <+> ptext SLIT("is a boxy type variable")
478 ppr_details (MetaTv (SigTv info) _) = ppr_skol info
479 ppr_details (SkolemTv info) = ppr_skol info
481 ppr_skol UnkSkol = empty -- Unhelpful; omit
482 ppr_skol (SigSkol ctxt) = sep [quotes (ppr tv) <+> ptext SLIT("is bound by") <+> pprUserTypeCtxt ctxt,
483 nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]
484 ppr_skol info = quotes (ppr tv) <+> pprSkolInfo info
486 pprSkolInfo :: SkolemInfo -> SDoc
487 pprSkolInfo (SigSkol ctxt) = ptext SLIT("is bound by") <+> pprUserTypeCtxt ctxt
488 pprSkolInfo (ClsSkol cls) = ptext SLIT("is bound by the class declaration for") <+> quotes (ppr cls)
489 pprSkolInfo (InstSkol df) = ptext SLIT("is bound by the instance declaration at") <+> ppr (getSrcLoc df)
490 pprSkolInfo (ArrowSkol loc) = ptext SLIT("is bound by the arrow form at") <+> ppr loc
491 pprSkolInfo (PatSkol dc loc) = sep [ptext SLIT("is bound by the pattern for") <+> quotes (ppr dc),
492 nest 2 (ptext SLIT("at") <+> ppr loc)]
493 pprSkolInfo (GenSkol tvs ty loc) = sep [sep [ptext SLIT("is bound by the polymorphic type"),
494 nest 2 (quotes (ppr (mkForAllTys tvs ty)))],
495 nest 2 (ptext SLIT("at") <+> ppr loc)]
497 -- For type variables the others are dealt with by pprSkolTvBinding.
498 -- For Insts, these cases should not happen
499 pprSkolInfo UnkSkol = panic "UnkSkol"
501 instance Outputable MetaDetails where
502 ppr Flexi = ptext SLIT("Flexi")
503 ppr (Indirect ty) = ptext SLIT("Indirect") <+> ppr ty
507 %************************************************************************
511 %************************************************************************
514 isImmutableTyVar, isSkolemTyVar, isExistentialTyVar, isBoxyTyVar, isMetaTyVar :: TyVar -> Bool
516 | isTcTyVar tv = isSkolemTyVar tv
520 = ASSERT( isTcTyVar tv )
521 case tcTyVarDetails tv of
525 isExistentialTyVar tv -- Existential type variable, bound by a pattern
526 = ASSERT( isTcTyVar tv )
527 case tcTyVarDetails tv of
528 SkolemTv (PatSkol _ _) -> True
532 = ASSERT2( isTcTyVar tv, ppr tv )
533 case tcTyVarDetails tv of
538 = ASSERT( isTcTyVar tv )
539 case tcTyVarDetails tv of
540 MetaTv BoxTv _ -> True
544 = ASSERT( isTcTyVar tv )
545 case tcTyVarDetails tv of
546 MetaTv (SigTv _) _ -> True
549 metaTvRef :: TyVar -> IORef MetaDetails
551 = ASSERT( isTcTyVar tv )
552 case tcTyVarDetails tv of
554 other -> pprPanic "metaTvRef" (ppr tv)
556 isFlexi, isIndirect :: MetaDetails -> Bool
558 isFlexi other = False
560 isIndirect (Indirect _) = True
561 isIndirect other = False
565 %************************************************************************
567 \subsection{Tau, sigma and rho}
569 %************************************************************************
572 mkSigmaTy :: [TyVar] -> [PredType] -> Type -> Type
573 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkPhiTy theta tau)
575 mkPhiTy :: [PredType] -> Type -> Type
576 mkPhiTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
579 @isTauTy@ tests for nested for-alls. It should not be called on a boxy type.
582 isTauTy :: Type -> Bool
583 isTauTy ty | Just ty' <- tcView ty = isTauTy ty'
584 isTauTy (TyVarTy tv) = ASSERT( not (isTcTyVar tv && isBoxyTyVar tv) )
586 isTauTy (TyConApp tc tys) = all isTauTy tys && isTauTyCon tc
587 isTauTy (AppTy a b) = isTauTy a && isTauTy b
588 isTauTy (FunTy a b) = isTauTy a && isTauTy b
589 isTauTy (PredTy p) = True -- Don't look through source types
590 isTauTy other = False
593 isTauTyCon :: TyCon -> Bool
594 -- Returns False for type synonyms whose expansion is a polytype
595 isTauTyCon tc | isSynTyCon tc = isTauTy (snd (synTyConDefn tc))
599 isBoxyTy :: TcType -> Bool
600 isBoxyTy ty = any isBoxyTyVar (varSetElems (tcTyVarsOfType ty))
602 isRigidTy :: TcType -> Bool
603 -- A type is rigid if it has no meta type variables in it
604 isRigidTy ty = all isSkolemTyVar (varSetElems (tcTyVarsOfType ty))
606 isRefineableTy :: TcType -> Bool
607 -- A type should have type refinements applied to it if it has
608 -- free type variables, and they are all rigid
609 isRefineableTy ty = not (null tc_tvs) && all isSkolemTyVar tc_tvs
611 tc_tvs = varSetElems (tcTyVarsOfType ty)
614 getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
615 -- construct a dictionary function name
616 getDFunTyKey ty | Just ty' <- tcView ty = getDFunTyKey ty'
617 getDFunTyKey (TyVarTy tv) = getOccName tv
618 getDFunTyKey (TyConApp tc _) = getOccName tc
619 getDFunTyKey (AppTy fun _) = getDFunTyKey fun
620 getDFunTyKey (FunTy arg _) = getOccName funTyCon
621 getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
622 getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty)
623 -- PredTy shouldn't happen
627 %************************************************************************
629 \subsection{Expanding and splitting}
631 %************************************************************************
633 These tcSplit functions are like their non-Tc analogues, but
634 a) they do not look through newtypes
635 b) they do not look through PredTys
636 c) [future] they ignore usage-type annotations
638 However, they are non-monadic and do not follow through mutable type
639 variables. It's up to you to make sure this doesn't matter.
642 tcSplitForAllTys :: Type -> ([TyVar], Type)
643 tcSplitForAllTys ty = split ty ty []
645 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
646 split orig_ty (ForAllTy tv ty) tvs
647 | not (isCoVar tv) = split ty ty (tv:tvs)
648 split orig_ty t tvs = (reverse tvs, orig_ty)
650 tcIsForAllTy ty | Just ty' <- tcView ty = tcIsForAllTy ty'
651 tcIsForAllTy (ForAllTy tv ty) = True
652 tcIsForAllTy t = False
654 tcSplitPhiTy :: Type -> (ThetaType, Type)
655 tcSplitPhiTy ty = split ty ty []
657 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
658 split orig_ty (FunTy arg res) ts
659 | Just p <- tcSplitPredTy_maybe arg = split res res (p:ts)
661 | Just (p, ty') <- splitForAllCo_maybe ty = split ty' ty' (p:ts)
662 split orig_ty ty ts = (reverse ts, orig_ty)
664 tcSplitSigmaTy :: Type -> ([TyVar], ThetaType, Type)
665 tcSplitSigmaTy ty = case tcSplitForAllTys ty of
666 (tvs, rho) -> case tcSplitPhiTy rho of
667 (theta, tau) -> (tvs, theta, tau)
669 -----------------------
672 -> ( [([TyVar], ThetaType)], -- forall as.C => forall bs.D
673 TcSigmaType) -- The rest of the type
675 -- We need a loop here because we are now prepared to entertain
677 -- f:: forall a. Eq a => forall b. Baz b => tau
678 -- We want to instantiate this to
679 -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
681 tcMultiSplitSigmaTy sigma
682 = case (tcSplitSigmaTy sigma) of
683 ([],[],ty) -> ([], sigma)
684 (tvs, theta, ty) -> case tcMultiSplitSigmaTy ty of
685 (pairs, rest) -> ((tvs,theta):pairs, rest)
687 -----------------------
688 tcTyConAppTyCon :: Type -> TyCon
689 tcTyConAppTyCon ty = fst (tcSplitTyConApp ty)
691 tcTyConAppArgs :: Type -> [Type]
692 tcTyConAppArgs ty = snd (tcSplitTyConApp ty)
694 tcSplitTyConApp :: Type -> (TyCon, [Type])
695 tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
697 Nothing -> pprPanic "tcSplitTyConApp" (pprType ty)
699 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
700 tcSplitTyConApp_maybe ty | Just ty' <- tcView ty = tcSplitTyConApp_maybe ty'
701 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
702 tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
703 -- Newtypes are opaque, so they may be split
704 -- However, predicates are not treated
705 -- as tycon applications by the type checker
706 tcSplitTyConApp_maybe other = Nothing
708 -----------------------
709 tcSplitFunTys :: Type -> ([Type], Type)
710 tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
712 Just (arg,res) -> (arg:args, res')
714 (args,res') = tcSplitFunTys res
716 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
717 tcSplitFunTy_maybe ty | Just ty' <- tcView ty = tcSplitFunTy_maybe ty'
718 tcSplitFunTy_maybe (FunTy arg res) = Just (arg, res)
719 tcSplitFunTy_maybe other = Nothing
723 -> Arity -- N: Number of desired args
724 -> ([TcSigmaType], -- Arg types (N or fewer)
725 TcSigmaType) -- The rest of the type
727 tcSplitFunTysN ty n_args
730 | Just (arg,res) <- tcSplitFunTy_maybe ty
731 = case tcSplitFunTysN res (n_args - 1) of
732 (args, res) -> (arg:args, res)
736 tcSplitFunTy ty = expectJust "tcSplitFunTy" (tcSplitFunTy_maybe ty)
737 tcFunArgTy ty = fst (tcSplitFunTy ty)
738 tcFunResultTy ty = snd (tcSplitFunTy ty)
740 -----------------------
741 tcSplitAppTy_maybe :: Type -> Maybe (Type, Type)
742 tcSplitAppTy_maybe ty | Just ty' <- tcView ty = tcSplitAppTy_maybe ty'
743 tcSplitAppTy_maybe ty = repSplitAppTy_maybe ty
745 tcSplitAppTy :: Type -> (Type, Type)
746 tcSplitAppTy ty = case tcSplitAppTy_maybe ty of
748 Nothing -> pprPanic "tcSplitAppTy" (pprType ty)
750 tcSplitAppTys :: Type -> (Type, [Type])
754 go ty args = case tcSplitAppTy_maybe ty of
755 Just (ty', arg) -> go ty' (arg:args)
758 -----------------------
759 tcGetTyVar_maybe :: Type -> Maybe TyVar
760 tcGetTyVar_maybe ty | Just ty' <- tcView ty = tcGetTyVar_maybe ty'
761 tcGetTyVar_maybe (TyVarTy tv) = Just tv
762 tcGetTyVar_maybe other = Nothing
764 tcGetTyVar :: String -> Type -> TyVar
765 tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty)
767 tcIsTyVarTy :: Type -> Bool
768 tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty)
770 -----------------------
771 tcSplitDFunTy :: Type -> ([TyVar], [PredType], Class, [Type])
772 -- Split the type of a dictionary function
774 = case tcSplitSigmaTy ty of { (tvs, theta, tau) ->
775 case tcSplitDFunHead tau of { (clas, tys) ->
776 (tvs, theta, clas, tys) }}
778 tcSplitDFunHead :: Type -> (Class, [Type])
780 = case tcSplitPredTy_maybe tau of
781 Just (ClassP clas tys) -> (clas, tys)
782 other -> panic "tcSplitDFunHead"
784 tcValidInstHeadTy :: Type -> Bool
785 -- Used in Haskell-98 mode, for the argument types of an instance head
786 -- These must not be type synonyms, but everywhere else type synonyms
787 -- are transparent, so we need a special function here
790 NoteTy _ ty -> tcValidInstHeadTy ty
791 TyConApp tc tys -> not (isSynTyCon tc) && ok tys
792 FunTy arg res -> ok [arg, res]
795 -- Check that all the types are type variables,
796 -- and that each is distinct
797 ok tys = equalLength tvs tys && hasNoDups tvs
799 tvs = mapCatMaybes get_tv tys
801 get_tv (NoteTy _ ty) = get_tv ty -- Again, do not look
802 get_tv (TyVarTy tv) = Just tv -- through synonyms
803 get_tv other = Nothing
808 %************************************************************************
810 \subsection{Predicate types}
812 %************************************************************************
815 tcSplitPredTy_maybe :: Type -> Maybe PredType
816 -- Returns Just for predicates only
817 tcSplitPredTy_maybe ty | Just ty' <- tcView ty = tcSplitPredTy_maybe ty'
818 tcSplitPredTy_maybe (PredTy p) = Just p
819 tcSplitPredTy_maybe other = Nothing
821 predTyUnique :: PredType -> Unique
822 predTyUnique (IParam n _) = getUnique (ipNameName n)
823 predTyUnique (ClassP clas tys) = getUnique clas
825 mkPredName :: Unique -> SrcLoc -> PredType -> Name
826 mkPredName uniq loc (ClassP cls tys) = mkInternalName uniq (mkDictOcc (getOccName cls)) loc
827 mkPredName uniq loc (IParam ip ty) = mkInternalName uniq (getOccName (ipNameName ip)) loc
831 --------------------- Dictionary types ---------------------------------
834 mkClassPred clas tys = ClassP clas tys
836 isClassPred :: PredType -> Bool
837 isClassPred (ClassP clas tys) = True
838 isClassPred other = False
840 isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys
841 isTyVarClassPred other = False
843 getClassPredTys_maybe :: PredType -> Maybe (Class, [Type])
844 getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys)
845 getClassPredTys_maybe _ = Nothing
847 getClassPredTys :: PredType -> (Class, [Type])
848 getClassPredTys (ClassP clas tys) = (clas, tys)
849 getClassPredTys other = panic "getClassPredTys"
851 isEqPred :: PredType -> Bool
852 isEqPred (EqPred {}) = True
855 mkDictTy :: Class -> [Type] -> Type
856 mkDictTy clas tys = mkPredTy (ClassP clas tys)
858 isDictTy :: Type -> Bool
859 isDictTy ty | Just ty' <- tcView ty = isDictTy ty'
860 isDictTy (PredTy p) = isClassPred p
861 isDictTy other = False
864 --------------------- Implicit parameters ---------------------------------
867 isIPPred :: PredType -> Bool
868 isIPPred (IParam _ _) = True
869 isIPPred other = False
871 isInheritablePred :: PredType -> Bool
872 -- Can be inherited by a context. For example, consider
873 -- f x = let g y = (?v, y+x)
874 -- in (g 3 with ?v = 8,
876 -- The point is that g's type must be quantifed over ?v:
877 -- g :: (?v :: a) => a -> a
878 -- but it doesn't need to be quantified over the Num a dictionary
879 -- which can be free in g's rhs, and shared by both calls to g
880 isInheritablePred (ClassP _ _) = True
881 isInheritablePred other = False
883 isLinearPred :: TcPredType -> Bool
884 isLinearPred (IParam (Linear n) _) = True
885 isLinearPred other = False
888 --------------------- Equality predicates ---------------------------------
890 substEqSpec :: TvSubst -> [(TyVar,Type)] -> [(TcType,TcType)]
891 substEqSpec subst eq_spec = [ (substTyVar subst tv, substTy subst ty)
892 | (tv,ty) <- eq_spec]
895 --------------------- The stupid theta (sigh) ---------------------------------
898 dataConsStupidTheta :: [DataCon] -> ThetaType
899 -- Union the stupid thetas from all the specified constructors (non-empty)
900 -- All the constructors should have the same result type, modulo alpha conversion
901 -- The resulting ThetaType uses type variables from the *first* constructor in the list
903 -- It's here because it's used in MkId.mkRecordSelId, and in TcExpr
904 dataConsStupidTheta (con1:cons)
905 = nubBy tcEqPred all_preds
907 all_preds = dataConStupidTheta con1 ++ other_stupids
908 res_tys1 = dataConResTys con1
909 tvs1 = tyVarsOfTypes res_tys1
910 other_stupids = [ substPred subst pred
912 , let Just subst = tcMatchTys tvs1 res_tys1 (dataConResTys con)
913 , pred <- dataConStupidTheta con ]
914 dataConsStupidTheta [] = panic "dataConsStupidTheta"
918 %************************************************************************
920 \subsection{Predicates}
922 %************************************************************************
924 isSigmaTy returns true of any qualified type. It doesn't *necessarily* have
926 f :: (?x::Int) => Int -> Int
929 isSigmaTy :: Type -> Bool
930 isSigmaTy ty | Just ty' <- tcView ty = isSigmaTy ty'
931 isSigmaTy (ForAllTy tyvar ty) = True
932 isSigmaTy (FunTy a b) = isPredTy a
935 isOverloadedTy :: Type -> Bool
936 isOverloadedTy ty | Just ty' <- tcView ty = isOverloadedTy ty'
937 isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty
938 isOverloadedTy (FunTy a b) = isPredTy a
939 isOverloadedTy _ = False
941 isPredTy :: Type -> Bool -- Belongs in TcType because it does
942 -- not look through newtypes, or predtypes (of course)
943 isPredTy ty | Just ty' <- tcView ty = isPredTy ty'
944 isPredTy (PredTy sty) = True
949 isFloatTy = is_tc floatTyConKey
950 isDoubleTy = is_tc doubleTyConKey
951 isIntegerTy = is_tc integerTyConKey
952 isIntTy = is_tc intTyConKey
953 isBoolTy = is_tc boolTyConKey
954 isUnitTy = is_tc unitTyConKey
956 is_tc :: Unique -> Type -> Bool
957 -- Newtypes are opaque to this
958 is_tc uniq ty = case tcSplitTyConApp_maybe ty of
959 Just (tc, _) -> uniq == getUnique tc
964 %************************************************************************
968 %************************************************************************
971 deNoteType :: Type -> Type
972 -- Remove all *outermost* type synonyms and other notes
973 deNoteType ty | Just ty' <- tcView ty = deNoteType ty'
978 tcTyVarsOfType :: Type -> TcTyVarSet
979 -- Just the *TcTyVars* free in the type
980 -- (Types.tyVarsOfTypes finds all free TyVars)
981 tcTyVarsOfType (TyVarTy tv) = if isTcTyVar tv then unitVarSet tv
983 tcTyVarsOfType (TyConApp tycon tys) = tcTyVarsOfTypes tys
984 tcTyVarsOfType (NoteTy _ ty) = tcTyVarsOfType ty
985 tcTyVarsOfType (PredTy sty) = tcTyVarsOfPred sty
986 tcTyVarsOfType (FunTy arg res) = tcTyVarsOfType arg `unionVarSet` tcTyVarsOfType res
987 tcTyVarsOfType (AppTy fun arg) = tcTyVarsOfType fun `unionVarSet` tcTyVarsOfType arg
988 tcTyVarsOfType (ForAllTy tyvar ty) = tcTyVarsOfType ty `delVarSet` tyvar
989 -- We do sometimes quantify over skolem TcTyVars
991 tcTyVarsOfTypes :: [Type] -> TyVarSet
992 tcTyVarsOfTypes tys = foldr (unionVarSet.tcTyVarsOfType) emptyVarSet tys
994 tcTyVarsOfPred :: PredType -> TyVarSet
995 tcTyVarsOfPred (IParam _ ty) = tcTyVarsOfType ty
996 tcTyVarsOfPred (ClassP _ tys) = tcTyVarsOfTypes tys
997 tcTyVarsOfPred (EqPred ty1 ty2) = tcTyVarsOfType ty1 `unionVarSet` tcTyVarsOfType ty2
1000 Note [Silly type synonym]
1001 ~~~~~~~~~~~~~~~~~~~~~~~~~
1004 What are the free tyvars of (T x)? Empty, of course!
1005 Here's the example that Ralf Laemmel showed me:
1006 foo :: (forall a. C u a -> C u a) -> u
1007 mappend :: Monoid u => u -> u -> u
1009 bar :: Monoid u => u
1010 bar = foo (\t -> t `mappend` t)
1011 We have to generalise at the arg to f, and we don't
1012 want to capture the constraint (Monad (C u a)) because
1013 it appears to mention a. Pretty silly, but it was useful to him.
1015 exactTyVarsOfType is used by the type checker to figure out exactly
1016 which type variables are mentioned in a type. It's also used in the
1017 smart-app checking code --- see TcExpr.tcIdApp
1020 exactTyVarsOfType :: TcType -> TyVarSet
1021 -- Find the free type variables (of any kind)
1022 -- but *expand* type synonyms. See Note [Silly type synonym] above.
1023 exactTyVarsOfType ty
1026 go ty | Just ty' <- tcView ty = go ty' -- This is the key line
1027 go (TyVarTy tv) = unitVarSet tv
1028 go (TyConApp tycon tys) = exactTyVarsOfTypes tys
1029 go (PredTy ty) = go_pred ty
1030 go (FunTy arg res) = go arg `unionVarSet` go res
1031 go (AppTy fun arg) = go fun `unionVarSet` go arg
1032 go (ForAllTy tyvar ty) = delVarSet (go ty) tyvar
1034 go_pred (IParam _ ty) = go ty
1035 go_pred (ClassP _ tys) = exactTyVarsOfTypes tys
1036 go_pred (EqPred ty1 ty2) = go ty1 `unionVarSet` go ty2
1038 exactTyVarsOfTypes :: [TcType] -> TyVarSet
1039 exactTyVarsOfTypes tys = foldr (unionVarSet . exactTyVarsOfType) emptyVarSet tys
1042 Find the free tycons and classes of a type. This is used in the front
1043 end of the compiler.
1046 tyClsNamesOfType :: Type -> NameSet
1047 tyClsNamesOfType (TyVarTy tv) = emptyNameSet
1048 tyClsNamesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` tyClsNamesOfTypes tys
1049 tyClsNamesOfType (NoteTy _ ty2) = tyClsNamesOfType ty2
1050 tyClsNamesOfType (PredTy (IParam n ty)) = tyClsNamesOfType ty
1051 tyClsNamesOfType (PredTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` tyClsNamesOfTypes tys
1052 tyClsNamesOfType (PredTy (EqPred ty1 ty2)) = tyClsNamesOfType ty1 `unionNameSets` tyClsNamesOfType ty2
1053 tyClsNamesOfType (FunTy arg res) = tyClsNamesOfType arg `unionNameSets` tyClsNamesOfType res
1054 tyClsNamesOfType (AppTy fun arg) = tyClsNamesOfType fun `unionNameSets` tyClsNamesOfType arg
1055 tyClsNamesOfType (ForAllTy tyvar ty) = tyClsNamesOfType ty
1057 tyClsNamesOfTypes tys = foldr (unionNameSets . tyClsNamesOfType) emptyNameSet tys
1059 tyClsNamesOfDFunHead :: Type -> NameSet
1060 -- Find the free type constructors and classes
1061 -- of the head of the dfun instance type
1062 -- The 'dfun_head_type' is because of
1063 -- instance Foo a => Baz T where ...
1064 -- The decl is an orphan if Baz and T are both not locally defined,
1065 -- even if Foo *is* locally defined
1066 tyClsNamesOfDFunHead dfun_ty
1067 = case tcSplitSigmaTy dfun_ty of
1068 (tvs,_,head_ty) -> tyClsNamesOfType head_ty
1070 classesOfTheta :: ThetaType -> [Class]
1071 -- Looks just for ClassP things; maybe it should check
1072 classesOfTheta preds = [ c | ClassP c _ <- preds ]
1076 %************************************************************************
1078 \subsection[TysWiredIn-ext-type]{External types}
1080 %************************************************************************
1082 The compiler's foreign function interface supports the passing of a
1083 restricted set of types as arguments and results (the restricting factor
1087 tcSplitIOType_maybe :: Type -> Maybe (TyCon, Type)
1088 -- (isIOType t) returns (Just (IO,t')) if t is of the form (IO t'), or
1089 -- some newtype wrapping thereof
1090 -- returns Nothing otherwise
1091 tcSplitIOType_maybe ty
1092 | Just (io_tycon, [io_res_ty]) <- tcSplitTyConApp_maybe ty,
1093 -- This split absolutely has to be a tcSplit, because we must
1094 -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
1095 io_tycon `hasKey` ioTyConKey
1096 = Just (io_tycon, io_res_ty)
1098 | Just ty' <- coreView ty -- Look through non-recursive newtypes
1099 = tcSplitIOType_maybe ty'
1104 isFFITy :: Type -> Bool
1105 -- True for any TyCon that can possibly be an arg or result of an FFI call
1106 isFFITy ty = checkRepTyCon legalFFITyCon ty
1108 isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool
1109 -- Checks for valid argument type for a 'foreign import'
1110 isFFIArgumentTy dflags safety ty
1111 = checkRepTyCon (legalOutgoingTyCon dflags safety) ty
1113 isFFIExternalTy :: Type -> Bool
1114 -- Types that are allowed as arguments of a 'foreign export'
1115 isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty
1117 isFFIImportResultTy :: DynFlags -> Type -> Bool
1118 isFFIImportResultTy dflags ty
1119 = checkRepTyCon (legalFIResultTyCon dflags) ty
1121 isFFIExportResultTy :: Type -> Bool
1122 isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty
1124 isFFIDynArgumentTy :: Type -> Bool
1125 -- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr,
1126 -- or a newtype of either.
1127 isFFIDynArgumentTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1129 isFFIDynResultTy :: Type -> Bool
1130 -- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr,
1131 -- or a newtype of either.
1132 isFFIDynResultTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1134 isFFILabelTy :: Type -> Bool
1135 -- The type of a foreign label must be Ptr, FunPtr, Addr,
1136 -- or a newtype of either.
1137 isFFILabelTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1139 isFFIDotnetTy :: DynFlags -> Type -> Bool
1140 isFFIDotnetTy dflags ty
1141 = checkRepTyCon (\ tc -> (legalFIResultTyCon dflags tc ||
1142 isFFIDotnetObjTy ty || isStringTy ty)) ty
1144 -- Support String as an argument or result from a .NET FFI call.
1146 case tcSplitTyConApp_maybe (repType ty) of
1148 | tc == listTyCon ->
1149 case tcSplitTyConApp_maybe (repType arg_ty) of
1150 Just (cc,[]) -> cc == charTyCon
1154 -- Support String as an argument or result from a .NET FFI call.
1155 isFFIDotnetObjTy ty =
1157 (_, t_ty) = tcSplitForAllTys ty
1159 case tcSplitTyConApp_maybe (repType t_ty) of
1160 Just (tc, [arg_ty]) | getName tc == objectTyConName -> True
1163 toDNType :: Type -> DNType
1165 | isStringTy ty = DNString
1166 | isFFIDotnetObjTy ty = DNObject
1167 | Just (tc,argTys) <- tcSplitTyConApp_maybe ty
1168 = case lookup (getUnique tc) dn_assoc of
1171 | tc `hasKey` ioTyConKey -> toDNType (head argTys)
1172 | otherwise -> pprPanic ("toDNType: unsupported .NET type")
1173 (pprType ty <+> parens (hcat (map pprType argTys)) <+> ppr tc)
1174 | otherwise = panic "toDNType" -- Is this right?
1176 dn_assoc :: [ (Unique, DNType) ]
1177 dn_assoc = [ (unitTyConKey, DNUnit)
1178 , (intTyConKey, DNInt)
1179 , (int8TyConKey, DNInt8)
1180 , (int16TyConKey, DNInt16)
1181 , (int32TyConKey, DNInt32)
1182 , (int64TyConKey, DNInt64)
1183 , (wordTyConKey, DNInt)
1184 , (word8TyConKey, DNWord8)
1185 , (word16TyConKey, DNWord16)
1186 , (word32TyConKey, DNWord32)
1187 , (word64TyConKey, DNWord64)
1188 , (floatTyConKey, DNFloat)
1189 , (doubleTyConKey, DNDouble)
1190 , (ptrTyConKey, DNPtr)
1191 , (funPtrTyConKey, DNPtr)
1192 , (charTyConKey, DNChar)
1193 , (boolTyConKey, DNBool)
1196 checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool
1197 -- Look through newtypes
1198 -- Non-recursive ones are transparent to splitTyConApp,
1199 -- but recursive ones aren't. Manuel had:
1200 -- newtype T = MkT (Ptr T)
1201 -- and wanted it to work...
1202 checkRepTyCon check_tc ty
1203 | Just (tc,_) <- splitTyConApp_maybe (repType ty) = check_tc tc
1206 checkRepTyConKey :: [Unique] -> Type -> Bool
1207 -- Like checkRepTyCon, but just looks at the TyCon key
1208 checkRepTyConKey keys
1209 = checkRepTyCon (\tc -> tyConUnique tc `elem` keys)
1212 ----------------------------------------------
1213 These chaps do the work; they are not exported
1214 ----------------------------------------------
1217 legalFEArgTyCon :: TyCon -> Bool
1219 -- It's illegal to make foreign exports that take unboxed
1220 -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000
1221 = boxedMarshalableTyCon tc
1223 legalFIResultTyCon :: DynFlags -> TyCon -> Bool
1224 legalFIResultTyCon dflags tc
1225 | tc == unitTyCon = True
1226 | otherwise = marshalableTyCon dflags tc
1228 legalFEResultTyCon :: TyCon -> Bool
1229 legalFEResultTyCon tc
1230 | tc == unitTyCon = True
1231 | otherwise = boxedMarshalableTyCon tc
1233 legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool
1234 -- Checks validity of types going from Haskell -> external world
1235 legalOutgoingTyCon dflags safety tc
1236 = marshalableTyCon dflags tc
1238 legalFFITyCon :: TyCon -> Bool
1239 -- True for any TyCon that can possibly be an arg or result of an FFI call
1241 = isUnLiftedTyCon tc || boxedMarshalableTyCon tc || tc == unitTyCon
1243 marshalableTyCon dflags tc
1244 = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc)
1245 || boxedMarshalableTyCon tc
1247 boxedMarshalableTyCon tc
1248 = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey
1249 , int32TyConKey, int64TyConKey
1250 , wordTyConKey, word8TyConKey, word16TyConKey
1251 , word32TyConKey, word64TyConKey
1252 , floatTyConKey, doubleTyConKey
1253 , ptrTyConKey, funPtrTyConKey