2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
5 \section[TcType]{Types used in the typechecker}
7 This module provides the Type interface for front-end parts of the
10 * treat "source types" as opaque:
11 newtypes, and predicates are meaningful.
12 * look through usage types
14 The "tc" prefix is for "TypeChecker", because the type checker
15 is the principal client.
19 --------------------------------
21 TcType, TcSigmaType, TcRhoType, TcTauType, TcPredType, TcThetaType,
22 TcTyVar, TcTyVarSet, TcKind,
24 BoxyTyVar, BoxySigmaType, BoxyRhoType, BoxyThetaType, BoxyType,
26 --------------------------------
28 UserTypeCtxt(..), pprUserTypeCtxt,
29 TcTyVarDetails(..), BoxInfo(..), pprTcTyVarDetails,
30 MetaDetails(Flexi, Indirect), SkolemInfo(..), pprSkolTvBinding, pprSkolInfo,
31 isImmutableTyVar, isSkolemTyVar, isMetaTyVar, isBoxyTyVar,
32 isSigTyVar, isExistentialTyVar, isTyConableTyVar,
36 --------------------------------
40 --------------------------------
42 -- These are important because they do not look through newtypes
44 tcSplitForAllTys, tcSplitPhiTy,
45 tcSplitFunTy_maybe, tcSplitFunTys, tcFunArgTy, tcFunResultTy, tcSplitFunTysN,
46 tcSplitTyConApp, tcSplitTyConApp_maybe, tcTyConAppTyCon, tcTyConAppArgs,
47 tcSplitAppTy_maybe, tcSplitAppTy, tcSplitAppTys, repSplitAppTy_maybe,
48 tcValidInstHeadTy, tcGetTyVar_maybe, tcGetTyVar,
49 tcSplitSigmaTy, tcMultiSplitSigmaTy,
51 ---------------------------------
53 -- Again, newtypes are opaque
54 tcEqType, tcEqTypes, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred, tcEqTypeX,
56 isSigmaTy, isOverloadedTy, isRigidTy, isBoxyTy,
57 isDoubleTy, isFloatTy, isIntTy, isStringTy,
58 isIntegerTy, isBoolTy, isUnitTy, isCharTy,
59 isTauTy, isTauTyCon, tcIsTyVarTy, tcIsForAllTy,
61 ---------------------------------
62 -- Misc type manipulators
64 tyClsNamesOfType, tyClsNamesOfDFunHead,
67 ---------------------------------
69 getClassPredTys_maybe, getClassPredTys,
70 isClassPred, isTyVarClassPred, isEqPred,
71 mkDictTy, tcSplitPredTy_maybe,
72 isPredTy, isDictTy, tcSplitDFunTy, tcSplitDFunHead, predTyUnique,
73 mkClassPred, isInheritablePred, isIPPred,
74 dataConsStupidTheta, isRefineableTy, isRefineablePred,
76 ---------------------------------
77 -- Foreign import and export
78 isFFIArgumentTy, -- :: DynFlags -> Safety -> Type -> Bool
79 isFFIImportResultTy, -- :: DynFlags -> Type -> Bool
80 isFFIExportResultTy, -- :: Type -> Bool
81 isFFIExternalTy, -- :: Type -> Bool
82 isFFIDynArgumentTy, -- :: Type -> Bool
83 isFFIDynResultTy, -- :: Type -> Bool
84 isFFILabelTy, -- :: Type -> Bool
85 isFFIDotnetTy, -- :: DynFlags -> Type -> Bool
86 isFFIDotnetObjTy, -- :: Type -> Bool
87 isFFITy, -- :: Type -> Bool
88 tcSplitIOType_maybe, -- :: Type -> Maybe Type
89 toDNType, -- :: Type -> DNType
91 --------------------------------
92 -- Rexported from Type
93 Kind, -- Stuff to do with kinds is insensitive to pre/post Tc
94 unliftedTypeKind, liftedTypeKind, argTypeKind,
95 openTypeKind, mkArrowKind, mkArrowKinds,
96 isLiftedTypeKind, isUnliftedTypeKind, isSubOpenTypeKind,
97 isSubArgTypeKind, isSubKind, defaultKind,
98 kindVarRef, mkKindVar,
100 Type, PredType(..), ThetaType,
101 mkForAllTy, mkForAllTys,
102 mkFunTy, mkFunTys, zipFunTys,
103 mkTyConApp, mkAppTy, mkAppTys, applyTy, applyTys,
104 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys,
106 -- Type substitutions
107 TvSubst(..), -- Representation visible to a few friends
108 TvSubstEnv, emptyTvSubst, substEqSpec,
109 mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst,
110 getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope, lookupTyVar,
111 extendTvSubst, extendTvSubstList, isInScope, mkTvSubst, zipTyEnv,
112 substTy, substTys, substTyWith, substTheta, substTyVar, substTyVars, substTyVarBndr,
114 isUnLiftedType, -- Source types are always lifted
115 isUnboxedTupleType, -- Ditto
118 tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
119 tidyTyVarBndr, tidyOpenTyVar, tidyOpenTyVars, tidySkolemTyVar,
122 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
123 tcTyVarsOfType, tcTyVarsOfTypes, exactTyVarsOfType, exactTyVarsOfTypes,
125 pprKind, pprParendKind,
126 pprType, pprParendType, pprTypeApp, pprTyThingCategory,
127 pprPred, pprTheta, pprThetaArrow, pprClassPred
131 #include "HsVersions.h"
164 %************************************************************************
168 %************************************************************************
170 The type checker divides the generic Type world into the
171 following more structured beasts:
173 sigma ::= forall tyvars. phi
174 -- A sigma type is a qualified type
176 -- Note that even if 'tyvars' is empty, theta
177 -- may not be: e.g. (?x::Int) => Int
179 -- Note that 'sigma' is in prenex form:
180 -- all the foralls are at the front.
181 -- A 'phi' type has no foralls to the right of
189 -- A 'tau' type has no quantification anywhere
190 -- Note that the args of a type constructor must be taus
192 | tycon tau_1 .. tau_n
196 -- In all cases, a (saturated) type synonym application is legal,
197 -- provided it expands to the required form.
200 type TcTyVar = TyVar -- Used only during type inference
201 type TcType = Type -- A TcType can have mutable type variables
202 -- Invariant on ForAllTy in TcTypes:
204 -- a cannot occur inside a MutTyVar in T; that is,
205 -- T is "flattened" before quantifying over a
207 -- These types do not have boxy type variables in them
208 type TcPredType = PredType
209 type TcThetaType = ThetaType
210 type TcSigmaType = TcType
211 type TcRhoType = TcType
212 type TcTauType = TcType
214 type TcTyVarSet = TyVarSet
216 -- These types may have boxy type variables in them
217 type BoxyTyVar = TcTyVar
218 type BoxyRhoType = TcType
219 type BoxyThetaType = TcThetaType
220 type BoxySigmaType = TcType
221 type BoxyType = TcType
225 %************************************************************************
227 \subsection{TyVarDetails}
229 %************************************************************************
231 TyVarDetails gives extra info about type variables, used during type
232 checking. It's attached to mutable type variables only.
233 It's knot-tied back to Var.lhs. There is no reason in principle
234 why Var.lhs shouldn't actually have the definition, but it "belongs" here.
237 Note [Signature skolems]
238 ~~~~~~~~~~~~~~~~~~~~~~~~
243 (x,y,z) = ([y,z], z, head x)
245 Here, x and y have type sigs, which go into the environment. We used to
246 instantiate their types with skolem constants, and push those types into
247 the RHS, so we'd typecheck the RHS with type
249 where a*, b* are skolem constants, and c is an ordinary meta type varible.
251 The trouble is that the occurrences of z in the RHS force a* and b* to
252 be the *same*, so we can't make them into skolem constants that don't unify
253 with each other. Alas.
255 One solution would be insist that in the above defn the programmer uses
256 the same type variable in both type signatures. But that takes explanation.
258 The alternative (currently implemented) is to have a special kind of skolem
259 constant, SigTv, which can unify with other SigTvs. These are *not* treated
260 as righd for the purposes of GADTs. And they are used *only* for pattern
261 bindings and mutually recursive function bindings. See the function
262 TcBinds.tcInstSig, and its use_skols parameter.
266 -- A TyVarDetails is inside a TyVar
268 = SkolemTv SkolemInfo -- A skolem constant
270 | MetaTv BoxInfo (IORef MetaDetails)
273 = BoxTv -- The contents is a (non-boxy) sigma-type
274 -- That is, this MetaTv is a "box"
276 | TauTv -- The contents is a (non-boxy) tau-type
277 -- That is, this MetaTv is an ordinary unification variable
279 | SigTv SkolemInfo -- A variant of TauTv, except that it should not be
280 -- unified with a type, only with a type variable
281 -- SigTvs are only distinguished to improve error messages
282 -- see Note [Signature skolems]
283 -- The MetaDetails, if filled in, will
284 -- always be another SigTv or a SkolemTv
287 -- A TauTv is always filled in with a tau-type, which
288 -- never contains any BoxTvs, nor any ForAlls
290 -- However, a BoxTv can contain a type that contains further BoxTvs
291 -- Notably, when typechecking an explicit list, say [e1,e2], with
292 -- expected type being a box b1, we fill in b1 with (List b2), where
293 -- b2 is another (currently empty) box.
296 = Flexi -- Flexi type variables unify to become
299 | Indirect TcType -- INVARIANT:
300 -- For a BoxTv, this type must be non-boxy
301 -- For a TauTv, this type must be a tau-type
303 -- Generally speaking, SkolemInfo should not contain location info
304 -- that is contained in the Name of the tyvar with this SkolemInfo
306 = SigSkol UserTypeCtxt -- A skolem that is created by instantiating
307 -- a programmer-supplied type signature
308 -- Location of the binding site is on the TyVar
310 -- The rest are for non-scoped skolems
311 | ClsSkol Class -- Bound at a class decl
312 | InstSkol -- Bound at an instance decl
313 | FamInstSkol -- Bound at a family instance decl
314 | PatSkol DataCon -- An existential type variable bound by a pattern for
315 -- a data constructor with an existential type. E.g.
316 -- data T = forall a. Eq a => MkT a
318 -- The pattern MkT x will allocate an existential type
320 | ArrowSkol -- An arrow form (see TcArrows)
322 | RuleSkol RuleName -- The LHS of a RULE
323 | GenSkol [TcTyVar] -- Bound when doing a subsumption check for
324 TcType -- (forall tvs. ty)
326 | RuntimeUnkSkol -- a type variable used to represent an unknown
327 -- runtime type (used in the GHCi debugger)
329 | UnkSkol -- Unhelpful info (until I improve it)
331 -------------------------------------
332 -- UserTypeCtxt describes the places where a
333 -- programmer-written type signature can occur
334 -- Like SkolemInfo, no location info
336 = FunSigCtxt Name -- Function type signature
337 -- Also used for types in SPECIALISE pragmas
338 | ExprSigCtxt -- Expression type signature
339 | ConArgCtxt Name -- Data constructor argument
340 | TySynCtxt Name -- RHS of a type synonym decl
341 | GenPatCtxt -- Pattern in generic decl
342 -- f{| a+b |} (Inl x) = ...
343 | LamPatSigCtxt -- Type sig in lambda pattern
345 | BindPatSigCtxt -- Type sig in pattern binding pattern
347 | ResSigCtxt -- Result type sig
349 | ForSigCtxt Name -- Foreign inport or export signature
350 | DefaultDeclCtxt -- Types in a default declaration
351 | SpecInstCtxt -- SPECIALISE instance pragma
353 -- Notes re TySynCtxt
354 -- We allow type synonyms that aren't types; e.g. type List = []
356 -- If the RHS mentions tyvars that aren't in scope, we'll
357 -- quantify over them:
358 -- e.g. type T = a->a
359 -- will become type T = forall a. a->a
361 -- With gla-exts that's right, but for H98 we should complain.
363 ---------------------------------
366 mkKindName :: Unique -> Name
367 mkKindName unique = mkSystemName unique kind_var_occ
369 kindVarRef :: KindVar -> IORef MetaDetails
371 ASSERT ( isTcTyVar tc )
372 case tcTyVarDetails tc of
373 MetaTv TauTv ref -> ref
374 other -> pprPanic "kindVarRef" (ppr tc)
376 mkKindVar :: Unique -> IORef MetaDetails -> KindVar
378 = mkTcTyVar (mkKindName u)
379 tySuperKind -- not sure this is right,
380 -- do we need kind vars for
384 kind_var_occ :: OccName -- Just one for all KindVars
385 -- They may be jiggled by tidying
386 kind_var_occ = mkOccName tvName "k"
390 %************************************************************************
394 %************************************************************************
397 pprTcTyVarDetails :: TcTyVarDetails -> SDoc
399 pprTcTyVarDetails (SkolemTv _) = ptext SLIT("sk")
400 pprTcTyVarDetails (MetaTv BoxTv _) = ptext SLIT("box")
401 pprTcTyVarDetails (MetaTv TauTv _) = ptext SLIT("tau")
402 pprTcTyVarDetails (MetaTv (SigTv _) _) = ptext SLIT("sig")
404 pprUserTypeCtxt :: UserTypeCtxt -> SDoc
405 pprUserTypeCtxt (FunSigCtxt n) = ptext SLIT("the type signature for") <+> quotes (ppr n)
406 pprUserTypeCtxt ExprSigCtxt = ptext SLIT("an expression type signature")
407 pprUserTypeCtxt (ConArgCtxt c) = ptext SLIT("the type of the constructor") <+> quotes (ppr c)
408 pprUserTypeCtxt (TySynCtxt c) = ptext SLIT("the RHS of the type synonym") <+> quotes (ppr c)
409 pprUserTypeCtxt GenPatCtxt = ptext SLIT("the type pattern of a generic definition")
410 pprUserTypeCtxt LamPatSigCtxt = ptext SLIT("a pattern type signature")
411 pprUserTypeCtxt BindPatSigCtxt = ptext SLIT("a pattern type signature")
412 pprUserTypeCtxt ResSigCtxt = ptext SLIT("a result type signature")
413 pprUserTypeCtxt (ForSigCtxt n) = ptext SLIT("the foreign declaration for") <+> quotes (ppr n)
414 pprUserTypeCtxt DefaultDeclCtxt = ptext SLIT("a type in a `default' declaration")
415 pprUserTypeCtxt SpecInstCtxt = ptext SLIT("a SPECIALISE instance pragma")
418 --------------------------------
419 tidySkolemTyVar :: TidyEnv -> TcTyVar -> (TidyEnv, TcTyVar)
420 -- Tidy the type inside a GenSkol, preparatory to printing it
421 tidySkolemTyVar env tv
422 = ASSERT( isSkolemTyVar tv || isSigTyVar tv )
423 (env1, mkTcTyVar (tyVarName tv) (tyVarKind tv) info1)
425 (env1, info1) = case tcTyVarDetails tv of
426 SkolemTv info -> (env1, SkolemTv info')
428 (env1, info') = tidy_skol_info env info
429 MetaTv (SigTv info) box -> (env1, MetaTv (SigTv info') box)
431 (env1, info') = tidy_skol_info env info
434 tidy_skol_info env (GenSkol tvs ty) = (env2, GenSkol tvs1 ty1)
436 (env1, tvs1) = tidyOpenTyVars env tvs
437 (env2, ty1) = tidyOpenType env1 ty
438 tidy_skol_info env info = (env, info)
440 pprSkolTvBinding :: TcTyVar -> SDoc
441 -- Print info about the binding of a skolem tyvar,
442 -- or nothing if we don't have anything useful to say
444 = ASSERT ( isTcTyVar tv )
445 quotes (ppr tv) <+> ppr_details (tcTyVarDetails tv)
447 ppr_details (MetaTv TauTv _) = ptext SLIT("is a meta type variable")
448 ppr_details (MetaTv BoxTv _) = ptext SLIT("is a boxy type variable")
449 ppr_details (MetaTv (SigTv info) _) = ppr_skol info
450 ppr_details (SkolemTv info) = ppr_skol info
452 ppr_skol UnkSkol = empty -- Unhelpful; omit
453 ppr_skol RuntimeUnkSkol = ptext SLIT("is an unknown runtime type")
454 ppr_skol info = sep [ptext SLIT("is a rigid type variable bound by"),
455 sep [pprSkolInfo info,
456 nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]]
458 pprSkolInfo :: SkolemInfo -> SDoc
459 pprSkolInfo (SigSkol ctxt) = pprUserTypeCtxt ctxt
460 pprSkolInfo (ClsSkol cls) = ptext SLIT("the class declaration for") <+> quotes (ppr cls)
461 pprSkolInfo InstSkol = ptext SLIT("the instance declaration")
462 pprSkolInfo FamInstSkol = ptext SLIT("the family instance declaration")
463 pprSkolInfo (RuleSkol name) = ptext SLIT("the RULE") <+> doubleQuotes (ftext name)
464 pprSkolInfo ArrowSkol = ptext SLIT("the arrow form")
465 pprSkolInfo (PatSkol dc) = sep [ptext SLIT("the constructor") <+> quotes (ppr dc)]
466 pprSkolInfo (GenSkol tvs ty) = sep [ptext SLIT("the polymorphic type"),
467 nest 2 (quotes (ppr (mkForAllTys tvs ty)))]
470 -- For type variables the others are dealt with by pprSkolTvBinding.
471 -- For Insts, these cases should not happen
472 pprSkolInfo UnkSkol = panic "UnkSkol"
473 pprSkolInfo RuntimeUnkSkol = panic "RuntimeUnkSkol"
475 instance Outputable MetaDetails where
476 ppr Flexi = ptext SLIT("Flexi")
477 ppr (Indirect ty) = ptext SLIT("Indirect") <+> ppr ty
481 %************************************************************************
485 %************************************************************************
488 isImmutableTyVar :: TyVar -> Bool
491 | isTcTyVar tv = isSkolemTyVar tv
494 isTyConableTyVar, isSkolemTyVar, isExistentialTyVar,
495 isBoxyTyVar, isMetaTyVar :: TcTyVar -> Bool
498 -- True of a meta-type variable tha can be filled in
499 -- with a type constructor application; in particular,
501 = ASSERT( isTcTyVar tv)
502 case tcTyVarDetails tv of
503 MetaTv BoxTv _ -> True
504 MetaTv TauTv _ -> True
505 MetaTv (SigTv {}) _ -> False
509 = ASSERT( isTcTyVar tv )
510 case tcTyVarDetails tv of
514 isExistentialTyVar tv -- Existential type variable, bound by a pattern
515 = ASSERT( isTcTyVar tv )
516 case tcTyVarDetails tv of
517 SkolemTv (PatSkol {}) -> True
521 = ASSERT2( isTcTyVar tv, ppr tv )
522 case tcTyVarDetails tv of
527 = ASSERT( isTcTyVar tv )
528 case tcTyVarDetails tv of
529 MetaTv BoxTv _ -> True
533 = ASSERT( isTcTyVar tv )
534 case tcTyVarDetails tv of
535 MetaTv (SigTv _) _ -> True
538 metaTvRef :: TyVar -> IORef MetaDetails
540 = ASSERT( isTcTyVar tv )
541 case tcTyVarDetails tv of
543 other -> pprPanic "metaTvRef" (ppr tv)
545 isFlexi, isIndirect :: MetaDetails -> Bool
547 isFlexi other = False
549 isIndirect (Indirect _) = True
550 isIndirect other = False
554 %************************************************************************
556 \subsection{Tau, sigma and rho}
558 %************************************************************************
561 mkSigmaTy :: [TyVar] -> [PredType] -> Type -> Type
562 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkPhiTy theta tau)
564 mkPhiTy :: [PredType] -> Type -> Type
565 mkPhiTy theta ty = foldr (\p r -> mkFunTy (mkPredTy p) r) ty theta
568 @isTauTy@ tests for nested for-alls. It should not be called on a boxy type.
571 isTauTy :: Type -> Bool
572 isTauTy ty | Just ty' <- tcView ty = isTauTy ty'
573 isTauTy (TyVarTy tv) = ASSERT( not (isTcTyVar tv && isBoxyTyVar tv) )
575 isTauTy (TyConApp tc tys) = all isTauTy tys && isTauTyCon tc
576 isTauTy (AppTy a b) = isTauTy a && isTauTy b
577 isTauTy (FunTy a b) = isTauTy a && isTauTy b
578 isTauTy (PredTy p) = True -- Don't look through source types
579 isTauTy other = False
582 isTauTyCon :: TyCon -> Bool
583 -- Returns False for type synonyms whose expansion is a polytype
585 | isClosedSynTyCon tc = isTauTy (snd (synTyConDefn tc))
589 isBoxyTy :: TcType -> Bool
590 isBoxyTy ty = any isBoxyTyVar (varSetElems (tcTyVarsOfType ty))
592 isRigidTy :: TcType -> Bool
593 -- A type is rigid if it has no meta type variables in it
594 isRigidTy ty = all isImmutableTyVar (varSetElems (tcTyVarsOfType ty))
596 isRefineableTy :: TcType -> Bool
597 -- A type should have type refinements applied to it if it has
598 -- free type variables, and they are all rigid
599 isRefineableTy ty = not (null tc_tvs) && all isImmutableTyVar tc_tvs
601 tc_tvs = varSetElems (tcTyVarsOfType ty)
603 isRefineablePred :: TcPredType -> Bool
604 isRefineablePred pred = not (null tc_tvs) && all isImmutableTyVar tc_tvs
606 tc_tvs = varSetElems (tcTyVarsOfPred pred)
609 getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
610 -- construct a dictionary function name
611 getDFunTyKey ty | Just ty' <- tcView ty = getDFunTyKey ty'
612 getDFunTyKey (TyVarTy tv) = getOccName tv
613 getDFunTyKey (TyConApp tc _) = getOccName tc
614 getDFunTyKey (AppTy fun _) = getDFunTyKey fun
615 getDFunTyKey (FunTy arg _) = getOccName funTyCon
616 getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
617 getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty)
618 -- PredTy shouldn't happen
622 %************************************************************************
624 \subsection{Expanding and splitting}
626 %************************************************************************
628 These tcSplit functions are like their non-Tc analogues, but
629 a) they do not look through newtypes
630 b) they do not look through PredTys
631 c) [future] they ignore usage-type annotations
633 However, they are non-monadic and do not follow through mutable type
634 variables. It's up to you to make sure this doesn't matter.
637 tcSplitForAllTys :: Type -> ([TyVar], Type)
638 tcSplitForAllTys ty = split ty ty []
640 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
641 split orig_ty (ForAllTy tv ty) tvs
642 | not (isCoVar tv) = split ty ty (tv:tvs)
643 split orig_ty t tvs = (reverse tvs, orig_ty)
645 tcIsForAllTy ty | Just ty' <- tcView ty = tcIsForAllTy ty'
646 tcIsForAllTy (ForAllTy tv ty) = not (isCoVar tv)
647 tcIsForAllTy t = False
649 tcSplitPhiTy :: Type -> (ThetaType, Type)
650 tcSplitPhiTy ty = split ty ty []
652 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
654 split orig_ty (ForAllTy tv ty) ts
655 | isCoVar tv = split ty ty (eq_pred:ts)
657 PredTy eq_pred = tyVarKind tv
658 split orig_ty (FunTy arg res) ts
659 | Just p <- tcSplitPredTy_maybe arg = split res res (p:ts)
660 split orig_ty ty ts = (reverse ts, orig_ty)
662 tcSplitSigmaTy :: Type -> ([TyVar], ThetaType, Type)
663 tcSplitSigmaTy ty = case tcSplitForAllTys ty of
664 (tvs, rho) -> case tcSplitPhiTy rho of
665 (theta, tau) -> (tvs, theta, tau)
667 -----------------------
670 -> ( [([TyVar], ThetaType)], -- forall as.C => forall bs.D
671 TcSigmaType) -- The rest of the type
673 -- We need a loop here because we are now prepared to entertain
675 -- f:: forall a. Eq a => forall b. Baz b => tau
676 -- We want to instantiate this to
677 -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
679 tcMultiSplitSigmaTy sigma
680 = case (tcSplitSigmaTy sigma) of
681 ([],[],ty) -> ([], sigma)
682 (tvs, theta, ty) -> case tcMultiSplitSigmaTy ty of
683 (pairs, rest) -> ((tvs,theta):pairs, rest)
685 -----------------------
686 tcTyConAppTyCon :: Type -> TyCon
687 tcTyConAppTyCon ty = case tcSplitTyConApp_maybe ty of
689 Nothing -> pprPanic "tcTyConAppTyCon" (pprType ty)
691 tcTyConAppArgs :: Type -> [Type]
692 tcTyConAppArgs ty = case tcSplitTyConApp_maybe ty of
693 Just (_, args) -> args
694 Nothing -> pprPanic "tcTyConAppArgs" (pprType ty)
696 tcSplitTyConApp :: Type -> (TyCon, [Type])
697 tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
699 Nothing -> pprPanic "tcSplitTyConApp" (pprType ty)
701 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
702 tcSplitTyConApp_maybe ty | Just ty' <- tcView ty = tcSplitTyConApp_maybe ty'
703 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
704 tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
705 -- Newtypes are opaque, so they may be split
706 -- However, predicates are not treated
707 -- as tycon applications by the type checker
708 tcSplitTyConApp_maybe other = Nothing
710 -----------------------
711 tcSplitFunTys :: Type -> ([Type], Type)
712 tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
714 Just (arg,res) -> (arg:args, res')
716 (args,res') = tcSplitFunTys res
718 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
719 tcSplitFunTy_maybe ty | Just ty' <- tcView ty = tcSplitFunTy_maybe ty'
720 tcSplitFunTy_maybe (FunTy arg res) | not (isPredTy arg) = Just (arg, res)
721 tcSplitFunTy_maybe other = Nothing
722 -- Note the (not (isPredTy arg)) guard
723 -- Consider (?x::Int) => Bool
724 -- We don't want to treat this as a function type!
725 -- A concrete example is test tc230:
726 -- f :: () -> (?p :: ()) => () -> ()
732 -> Arity -- N: Number of desired args
733 -> ([TcSigmaType], -- Arg types (N or fewer)
734 TcSigmaType) -- The rest of the type
736 tcSplitFunTysN ty n_args
739 | Just (arg,res) <- tcSplitFunTy_maybe ty
740 = case tcSplitFunTysN res (n_args - 1) of
741 (args, res) -> (arg:args, res)
745 tcSplitFunTy ty = expectJust "tcSplitFunTy" (tcSplitFunTy_maybe ty)
746 tcFunArgTy ty = fst (tcSplitFunTy ty)
747 tcFunResultTy ty = snd (tcSplitFunTy ty)
749 -----------------------
750 tcSplitAppTy_maybe :: Type -> Maybe (Type, Type)
751 tcSplitAppTy_maybe ty | Just ty' <- tcView ty = tcSplitAppTy_maybe ty'
752 tcSplitAppTy_maybe ty = repSplitAppTy_maybe ty
754 tcSplitAppTy :: Type -> (Type, Type)
755 tcSplitAppTy ty = case tcSplitAppTy_maybe ty of
757 Nothing -> pprPanic "tcSplitAppTy" (pprType ty)
759 tcSplitAppTys :: Type -> (Type, [Type])
763 go ty args = case tcSplitAppTy_maybe ty of
764 Just (ty', arg) -> go ty' (arg:args)
767 -----------------------
768 tcGetTyVar_maybe :: Type -> Maybe TyVar
769 tcGetTyVar_maybe ty | Just ty' <- tcView ty = tcGetTyVar_maybe ty'
770 tcGetTyVar_maybe (TyVarTy tv) = Just tv
771 tcGetTyVar_maybe other = Nothing
773 tcGetTyVar :: String -> Type -> TyVar
774 tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty)
776 tcIsTyVarTy :: Type -> Bool
777 tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty)
779 -----------------------
780 tcSplitDFunTy :: Type -> ([TyVar], [PredType], Class, [Type])
781 -- Split the type of a dictionary function
783 = case tcSplitSigmaTy ty of { (tvs, theta, tau) ->
784 case tcSplitDFunHead tau of { (clas, tys) ->
785 (tvs, theta, clas, tys) }}
787 tcSplitDFunHead :: Type -> (Class, [Type])
789 = case tcSplitPredTy_maybe tau of
790 Just (ClassP clas tys) -> (clas, tys)
791 other -> panic "tcSplitDFunHead"
793 tcValidInstHeadTy :: Type -> Bool
794 -- Used in Haskell-98 mode, for the argument types of an instance head
795 -- These must not be type synonyms, but everywhere else type synonyms
796 -- are transparent, so we need a special function here
799 NoteTy _ ty -> tcValidInstHeadTy ty
800 TyConApp tc tys -> not (isSynTyCon tc) && ok tys
801 FunTy arg res -> ok [arg, res]
804 -- Check that all the types are type variables,
805 -- and that each is distinct
806 ok tys = equalLength tvs tys && hasNoDups tvs
808 tvs = mapCatMaybes get_tv tys
810 get_tv (NoteTy _ ty) = get_tv ty -- Again, do not look
811 get_tv (TyVarTy tv) = Just tv -- through synonyms
812 get_tv other = Nothing
817 %************************************************************************
819 \subsection{Predicate types}
821 %************************************************************************
824 tcSplitPredTy_maybe :: Type -> Maybe PredType
825 -- Returns Just for predicates only
826 tcSplitPredTy_maybe ty | Just ty' <- tcView ty = tcSplitPredTy_maybe ty'
827 tcSplitPredTy_maybe (PredTy p) = Just p
828 tcSplitPredTy_maybe other = Nothing
830 predTyUnique :: PredType -> Unique
831 predTyUnique (IParam n _) = getUnique (ipNameName n)
832 predTyUnique (ClassP clas tys) = getUnique clas
836 --------------------- Dictionary types ---------------------------------
839 mkClassPred clas tys = ClassP clas tys
841 isClassPred :: PredType -> Bool
842 isClassPred (ClassP clas tys) = True
843 isClassPred other = False
845 isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys
846 isTyVarClassPred other = False
848 getClassPredTys_maybe :: PredType -> Maybe (Class, [Type])
849 getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys)
850 getClassPredTys_maybe _ = Nothing
852 getClassPredTys :: PredType -> (Class, [Type])
853 getClassPredTys (ClassP clas tys) = (clas, tys)
854 getClassPredTys other = panic "getClassPredTys"
856 mkDictTy :: Class -> [Type] -> Type
857 mkDictTy clas tys = mkPredTy (ClassP clas tys)
859 isDictTy :: Type -> Bool
860 isDictTy ty | Just ty' <- tcView ty = isDictTy ty'
861 isDictTy (PredTy p) = isClassPred p
862 isDictTy other = False
865 --------------------- Implicit parameters ---------------------------------
868 isIPPred :: PredType -> Bool
869 isIPPred (IParam _ _) = True
870 isIPPred other = False
872 isInheritablePred :: PredType -> Bool
873 -- Can be inherited by a context. For example, consider
874 -- f x = let g y = (?v, y+x)
875 -- in (g 3 with ?v = 8,
877 -- The point is that g's type must be quantifed over ?v:
878 -- g :: (?v :: a) => a -> a
879 -- but it doesn't need to be quantified over the Num a dictionary
880 -- which can be free in g's rhs, and shared by both calls to g
881 isInheritablePred (ClassP _ _) = True
882 isInheritablePred (EqPred _ _) = True
883 isInheritablePred other = False
886 --------------------- Equality predicates ---------------------------------
888 substEqSpec :: TvSubst -> [(TyVar,Type)] -> [(TcType,TcType)]
889 substEqSpec subst eq_spec = [ (substTyVar subst tv, substTy subst ty)
890 | (tv,ty) <- eq_spec]
893 --------------------- The stupid theta (sigh) ---------------------------------
896 dataConsStupidTheta :: [DataCon] -> ThetaType
897 -- Union the stupid thetas from all the specified constructors (non-empty)
898 -- All the constructors should have the same result type, modulo alpha conversion
899 -- The resulting ThetaType uses type variables from the *first* constructor in the list
901 -- It's here because it's used in MkId.mkRecordSelId, and in TcExpr
902 dataConsStupidTheta (con1:cons)
903 = nubBy tcEqPred all_preds
905 all_preds = dataConStupidTheta con1 ++ other_stupids
906 res_ty1 = dataConOrigResTy con1
907 other_stupids = [ substPred subst pred
909 , let (tvs, _, _, res_ty) = dataConSig con
910 Just subst = tcMatchTy (mkVarSet tvs) res_ty res_ty1
911 , pred <- dataConStupidTheta con ]
912 dataConsStupidTheta [] = panic "dataConsStupidTheta"
916 %************************************************************************
918 \subsection{Predicates}
920 %************************************************************************
922 isSigmaTy returns true of any qualified type. It doesn't *necessarily* have
924 f :: (?x::Int) => Int -> Int
927 isSigmaTy :: Type -> Bool
928 isSigmaTy ty | Just ty' <- tcView ty = isSigmaTy ty'
929 isSigmaTy (ForAllTy tyvar ty) = True
930 isSigmaTy (FunTy a b) = isPredTy a
933 isOverloadedTy :: Type -> Bool
934 isOverloadedTy ty | Just ty' <- tcView ty = isOverloadedTy ty'
935 isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty
936 isOverloadedTy (FunTy a b) = isPredTy a
937 isOverloadedTy _ = False
939 isPredTy :: Type -> Bool -- Belongs in TcType because it does
940 -- not look through newtypes, or predtypes (of course)
941 isPredTy ty | Just ty' <- tcView ty = isPredTy ty'
942 isPredTy (PredTy sty) = True
947 isFloatTy = is_tc floatTyConKey
948 isDoubleTy = is_tc doubleTyConKey
949 isIntegerTy = is_tc integerTyConKey
950 isIntTy = is_tc intTyConKey
951 isBoolTy = is_tc boolTyConKey
952 isUnitTy = is_tc unitTyConKey
953 isCharTy = is_tc charTyConKey
956 = case tcSplitTyConApp_maybe ty of
957 Just (tc, [arg_ty]) -> tc == listTyCon && isCharTy arg_ty
960 is_tc :: Unique -> Type -> Bool
961 -- Newtypes are opaque to this
962 is_tc uniq ty = case tcSplitTyConApp_maybe ty of
963 Just (tc, _) -> uniq == getUnique tc
968 %************************************************************************
972 %************************************************************************
975 deNoteType :: Type -> Type
976 -- Remove all *outermost* type synonyms and other notes
977 deNoteType ty | Just ty' <- tcView ty = deNoteType ty'
982 tcTyVarsOfType :: Type -> TcTyVarSet
983 -- Just the *TcTyVars* free in the type
984 -- (Types.tyVarsOfTypes finds all free TyVars)
985 tcTyVarsOfType (TyVarTy tv) = if isTcTyVar tv then unitVarSet tv
987 tcTyVarsOfType (TyConApp tycon tys) = tcTyVarsOfTypes tys
988 tcTyVarsOfType (NoteTy _ ty) = tcTyVarsOfType ty
989 tcTyVarsOfType (PredTy sty) = tcTyVarsOfPred sty
990 tcTyVarsOfType (FunTy arg res) = tcTyVarsOfType arg `unionVarSet` tcTyVarsOfType res
991 tcTyVarsOfType (AppTy fun arg) = tcTyVarsOfType fun `unionVarSet` tcTyVarsOfType arg
992 tcTyVarsOfType (ForAllTy tyvar ty) = (tcTyVarsOfType ty `delVarSet` tyvar)
993 `unionVarSet` tcTyVarsOfTyVar tyvar
994 -- We do sometimes quantify over skolem TcTyVars
996 tcTyVarsOfTyVar :: TcTyVar -> TyVarSet
997 tcTyVarsOfTyVar tv | isCoVar tv = tcTyVarsOfType (tyVarKind tv)
998 | otherwise = emptyVarSet
1000 tcTyVarsOfTypes :: [Type] -> TyVarSet
1001 tcTyVarsOfTypes tys = foldr (unionVarSet.tcTyVarsOfType) emptyVarSet tys
1003 tcTyVarsOfPred :: PredType -> TyVarSet
1004 tcTyVarsOfPred (IParam _ ty) = tcTyVarsOfType ty
1005 tcTyVarsOfPred (ClassP _ tys) = tcTyVarsOfTypes tys
1006 tcTyVarsOfPred (EqPred ty1 ty2) = tcTyVarsOfType ty1 `unionVarSet` tcTyVarsOfType ty2
1009 Note [Silly type synonym]
1010 ~~~~~~~~~~~~~~~~~~~~~~~~~
1013 What are the free tyvars of (T x)? Empty, of course!
1014 Here's the example that Ralf Laemmel showed me:
1015 foo :: (forall a. C u a -> C u a) -> u
1016 mappend :: Monoid u => u -> u -> u
1018 bar :: Monoid u => u
1019 bar = foo (\t -> t `mappend` t)
1020 We have to generalise at the arg to f, and we don't
1021 want to capture the constraint (Monad (C u a)) because
1022 it appears to mention a. Pretty silly, but it was useful to him.
1024 exactTyVarsOfType is used by the type checker to figure out exactly
1025 which type variables are mentioned in a type. It's also used in the
1026 smart-app checking code --- see TcExpr.tcIdApp
1029 exactTyVarsOfType :: TcType -> TyVarSet
1030 -- Find the free type variables (of any kind)
1031 -- but *expand* type synonyms. See Note [Silly type synonym] above.
1032 exactTyVarsOfType ty
1035 go ty | Just ty' <- tcView ty = go ty' -- This is the key line
1036 go (TyVarTy tv) = unitVarSet tv
1037 go (TyConApp tycon tys) = exactTyVarsOfTypes tys
1038 go (PredTy ty) = go_pred ty
1039 go (FunTy arg res) = go arg `unionVarSet` go res
1040 go (AppTy fun arg) = go fun `unionVarSet` go arg
1041 go (ForAllTy tyvar ty) = delVarSet (go ty) tyvar
1042 `unionVarSet` go_tv tyvar
1044 go_pred (IParam _ ty) = go ty
1045 go_pred (ClassP _ tys) = exactTyVarsOfTypes tys
1046 go_pred (EqPred ty1 ty2) = go ty1 `unionVarSet` go ty2
1048 go_tv tyvar | isCoVar tyvar = go (tyVarKind tyvar)
1049 | otherwise = emptyVarSet
1051 exactTyVarsOfTypes :: [TcType] -> TyVarSet
1052 exactTyVarsOfTypes tys = foldr (unionVarSet . exactTyVarsOfType) emptyVarSet tys
1055 Find the free tycons and classes of a type. This is used in the front
1056 end of the compiler.
1059 tyClsNamesOfType :: Type -> NameSet
1060 tyClsNamesOfType (TyVarTy tv) = emptyNameSet
1061 tyClsNamesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` tyClsNamesOfTypes tys
1062 tyClsNamesOfType (NoteTy _ ty2) = tyClsNamesOfType ty2
1063 tyClsNamesOfType (PredTy (IParam n ty)) = tyClsNamesOfType ty
1064 tyClsNamesOfType (PredTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` tyClsNamesOfTypes tys
1065 tyClsNamesOfType (PredTy (EqPred ty1 ty2)) = tyClsNamesOfType ty1 `unionNameSets` tyClsNamesOfType ty2
1066 tyClsNamesOfType (FunTy arg res) = tyClsNamesOfType arg `unionNameSets` tyClsNamesOfType res
1067 tyClsNamesOfType (AppTy fun arg) = tyClsNamesOfType fun `unionNameSets` tyClsNamesOfType arg
1068 tyClsNamesOfType (ForAllTy tyvar ty) = tyClsNamesOfType ty
1070 tyClsNamesOfTypes tys = foldr (unionNameSets . tyClsNamesOfType) emptyNameSet tys
1072 tyClsNamesOfDFunHead :: Type -> NameSet
1073 -- Find the free type constructors and classes
1074 -- of the head of the dfun instance type
1075 -- The 'dfun_head_type' is because of
1076 -- instance Foo a => Baz T where ...
1077 -- The decl is an orphan if Baz and T are both not locally defined,
1078 -- even if Foo *is* locally defined
1079 tyClsNamesOfDFunHead dfun_ty
1080 = case tcSplitSigmaTy dfun_ty of
1081 (tvs,_,head_ty) -> tyClsNamesOfType head_ty
1085 %************************************************************************
1087 \subsection[TysWiredIn-ext-type]{External types}
1089 %************************************************************************
1091 The compiler's foreign function interface supports the passing of a
1092 restricted set of types as arguments and results (the restricting factor
1096 tcSplitIOType_maybe :: Type -> Maybe (TyCon, Type)
1097 -- (isIOType t) returns (Just (IO,t')) if t is of the form (IO t'), or
1098 -- some newtype wrapping thereof
1099 -- returns Nothing otherwise
1100 tcSplitIOType_maybe ty
1101 | Just (io_tycon, [io_res_ty]) <- tcSplitTyConApp_maybe ty,
1102 -- This split absolutely has to be a tcSplit, because we must
1103 -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
1104 io_tycon `hasKey` ioTyConKey
1105 = Just (io_tycon, io_res_ty)
1107 | Just ty' <- coreView ty -- Look through non-recursive newtypes
1108 = tcSplitIOType_maybe ty'
1113 isFFITy :: Type -> Bool
1114 -- True for any TyCon that can possibly be an arg or result of an FFI call
1115 isFFITy ty = checkRepTyCon legalFFITyCon ty
1117 isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool
1118 -- Checks for valid argument type for a 'foreign import'
1119 isFFIArgumentTy dflags safety ty
1120 = checkRepTyCon (legalOutgoingTyCon dflags safety) ty
1122 isFFIExternalTy :: Type -> Bool
1123 -- Types that are allowed as arguments of a 'foreign export'
1124 isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty
1126 isFFIImportResultTy :: DynFlags -> Type -> Bool
1127 isFFIImportResultTy dflags ty
1128 = checkRepTyCon (legalFIResultTyCon dflags) ty
1130 isFFIExportResultTy :: Type -> Bool
1131 isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty
1133 isFFIDynArgumentTy :: Type -> Bool
1134 -- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr,
1135 -- or a newtype of either.
1136 isFFIDynArgumentTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1138 isFFIDynResultTy :: Type -> Bool
1139 -- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr,
1140 -- or a newtype of either.
1141 isFFIDynResultTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1143 isFFILabelTy :: Type -> Bool
1144 -- The type of a foreign label must be Ptr, FunPtr, Addr,
1145 -- or a newtype of either.
1146 isFFILabelTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1148 isFFIDotnetTy :: DynFlags -> Type -> Bool
1149 isFFIDotnetTy dflags ty
1150 = checkRepTyCon (\ tc -> (legalFIResultTyCon dflags tc ||
1151 isFFIDotnetObjTy ty || isStringTy ty)) ty
1152 -- NB: isStringTy used to look through newtypes, but
1153 -- it no longer does so. May need to adjust isFFIDotNetTy
1154 -- if we do want to look through newtypes.
1156 isFFIDotnetObjTy ty =
1158 (_, t_ty) = tcSplitForAllTys ty
1160 case tcSplitTyConApp_maybe (repType t_ty) of
1161 Just (tc, [arg_ty]) | getName tc == objectTyConName -> True
1164 toDNType :: Type -> DNType
1166 | isStringTy ty = DNString
1167 | isFFIDotnetObjTy ty = DNObject
1168 | Just (tc,argTys) <- tcSplitTyConApp_maybe ty
1169 = case lookup (getUnique tc) dn_assoc of
1172 | tc `hasKey` ioTyConKey -> toDNType (head argTys)
1173 | otherwise -> pprPanic ("toDNType: unsupported .NET type")
1174 (pprType ty <+> parens (hcat (map pprType argTys)) <+> ppr tc)
1175 | otherwise = panic "toDNType" -- Is this right?
1177 dn_assoc :: [ (Unique, DNType) ]
1178 dn_assoc = [ (unitTyConKey, DNUnit)
1179 , (intTyConKey, DNInt)
1180 , (int8TyConKey, DNInt8)
1181 , (int16TyConKey, DNInt16)
1182 , (int32TyConKey, DNInt32)
1183 , (int64TyConKey, DNInt64)
1184 , (wordTyConKey, DNInt)
1185 , (word8TyConKey, DNWord8)
1186 , (word16TyConKey, DNWord16)
1187 , (word32TyConKey, DNWord32)
1188 , (word64TyConKey, DNWord64)
1189 , (floatTyConKey, DNFloat)
1190 , (doubleTyConKey, DNDouble)
1191 , (ptrTyConKey, DNPtr)
1192 , (funPtrTyConKey, DNPtr)
1193 , (charTyConKey, DNChar)
1194 , (boolTyConKey, DNBool)
1197 checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool
1198 -- Look through newtypes
1199 -- Non-recursive ones are transparent to splitTyConApp,
1200 -- but recursive ones aren't. Manuel had:
1201 -- newtype T = MkT (Ptr T)
1202 -- and wanted it to work...
1203 checkRepTyCon check_tc ty
1204 | Just (tc,_) <- splitTyConApp_maybe (repType ty) = check_tc tc
1207 checkRepTyConKey :: [Unique] -> Type -> Bool
1208 -- Like checkRepTyCon, but just looks at the TyCon key
1209 checkRepTyConKey keys
1210 = checkRepTyCon (\tc -> tyConUnique tc `elem` keys)
1213 ----------------------------------------------
1214 These chaps do the work; they are not exported
1215 ----------------------------------------------
1218 legalFEArgTyCon :: TyCon -> Bool
1220 -- It's illegal to make foreign exports that take unboxed
1221 -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000
1222 = boxedMarshalableTyCon tc
1224 legalFIResultTyCon :: DynFlags -> TyCon -> Bool
1225 legalFIResultTyCon dflags tc
1226 | tc == unitTyCon = True
1227 | otherwise = marshalableTyCon dflags tc
1229 legalFEResultTyCon :: TyCon -> Bool
1230 legalFEResultTyCon tc
1231 | tc == unitTyCon = True
1232 | otherwise = boxedMarshalableTyCon tc
1234 legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool
1235 -- Checks validity of types going from Haskell -> external world
1236 legalOutgoingTyCon dflags safety tc
1237 = marshalableTyCon dflags tc
1239 legalFFITyCon :: TyCon -> Bool
1240 -- True for any TyCon that can possibly be an arg or result of an FFI call
1242 = isUnLiftedTyCon tc || boxedMarshalableTyCon tc || tc == unitTyCon
1244 marshalableTyCon dflags tc
1245 = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc)
1246 || boxedMarshalableTyCon tc
1248 boxedMarshalableTyCon tc
1249 = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey
1250 , int32TyConKey, int64TyConKey
1251 , wordTyConKey, word8TyConKey, word16TyConKey
1252 , word32TyConKey, word64TyConKey
1253 , floatTyConKey, doubleTyConKey
1254 , ptrTyConKey, funPtrTyConKey