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 "TypeChecker", 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, 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, isOpenTyCon,
173 synTyConDefn, tyConUnique )
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 ( 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 | FamInstSkol TyCon -- Bound at a family instance decl
348 | PatSkol DataCon -- An existential type variable bound by a pattern for
349 SrcSpan -- a data constructor with an existential type. E.g.
350 -- data T = forall a. Eq a => MkT a
352 -- The pattern MkT x will allocate an existential type
354 | ArrowSkol SrcSpan -- An arrow form (see TcArrows)
356 | GenSkol [TcTyVar] -- Bound when doing a subsumption check for
357 TcType -- (forall tvs. ty)
360 | UnkSkol -- Unhelpful info (until I improve it)
362 -------------------------------------
363 -- UserTypeCtxt describes the places where a
364 -- programmer-written type signature can occur
366 = FunSigCtxt Name -- Function type signature
367 -- Also used for types in SPECIALISE pragmas
368 | ExprSigCtxt -- Expression type signature
369 | ConArgCtxt Name -- Data constructor argument
370 | TySynCtxt Name -- RHS of a type synonym decl
371 | GenPatCtxt -- Pattern in generic decl
372 -- f{| a+b |} (Inl x) = ...
373 | LamPatSigCtxt -- Type sig in lambda pattern
375 | BindPatSigCtxt -- Type sig in pattern binding pattern
377 | ResSigCtxt -- Result type sig
379 | ForSigCtxt Name -- Foreign inport or export signature
380 | RuleSigCtxt Name -- Signature on a forall'd variable in a RULE
381 | DefaultDeclCtxt -- Types in a default declaration
382 | SpecInstCtxt -- SPECIALISE instance pragma
384 -- Notes re TySynCtxt
385 -- We allow type synonyms that aren't types; e.g. type List = []
387 -- If the RHS mentions tyvars that aren't in scope, we'll
388 -- quantify over them:
389 -- e.g. type T = a->a
390 -- will become type T = forall a. a->a
392 -- With gla-exts that's right, but for H98 we should complain.
394 ---------------------------------
397 mkKindName :: Unique -> Name
398 mkKindName unique = mkSystemName unique kind_var_occ
400 kindVarRef :: KindVar -> IORef MetaDetails
402 ASSERT ( isTcTyVar tc )
403 case tcTyVarDetails tc of
404 MetaTv TauTv ref -> ref
405 other -> pprPanic "kindVarRef" (ppr tc)
407 mkKindVar :: Unique -> IORef MetaDetails -> KindVar
409 = mkTcTyVar (mkKindName u)
410 tySuperKind -- not sure this is right,
411 -- do we need kind vars for
415 kind_var_occ :: OccName -- Just one for all KindVars
416 -- They may be jiggled by tidying
417 kind_var_occ = mkOccName tvName "k"
421 %************************************************************************
425 %************************************************************************
428 pprTcTyVarDetails :: TcTyVarDetails -> SDoc
430 pprTcTyVarDetails (SkolemTv _) = ptext SLIT("sk")
431 pprTcTyVarDetails (MetaTv BoxTv _) = ptext SLIT("box")
432 pprTcTyVarDetails (MetaTv TauTv _) = ptext SLIT("tau")
433 pprTcTyVarDetails (MetaTv (SigTv _) _) = ptext SLIT("sig")
435 pprUserTypeCtxt :: UserTypeCtxt -> SDoc
436 pprUserTypeCtxt (FunSigCtxt n) = ptext SLIT("the type signature for") <+> quotes (ppr n)
437 pprUserTypeCtxt ExprSigCtxt = ptext SLIT("an expression type signature")
438 pprUserTypeCtxt (ConArgCtxt c) = ptext SLIT("the type of the constructor") <+> quotes (ppr c)
439 pprUserTypeCtxt (TySynCtxt c) = ptext SLIT("the RHS of the type synonym") <+> quotes (ppr c)
440 pprUserTypeCtxt GenPatCtxt = ptext SLIT("the type pattern of a generic definition")
441 pprUserTypeCtxt LamPatSigCtxt = ptext SLIT("a pattern type signature")
442 pprUserTypeCtxt BindPatSigCtxt = ptext SLIT("a pattern type signature")
443 pprUserTypeCtxt ResSigCtxt = ptext SLIT("a result type signature")
444 pprUserTypeCtxt (ForSigCtxt n) = ptext SLIT("the foreign declaration for") <+> quotes (ppr n)
445 pprUserTypeCtxt (RuleSigCtxt n) = ptext SLIT("the type signature for") <+> quotes (ppr n)
446 pprUserTypeCtxt DefaultDeclCtxt = ptext SLIT("a type in a `default' declaration")
447 pprUserTypeCtxt SpecInstCtxt = ptext SLIT("a SPECIALISE instance pragma")
450 --------------------------------
451 tidySkolemTyVar :: TidyEnv -> TcTyVar -> (TidyEnv, TcTyVar)
452 -- Tidy the type inside a GenSkol, preparatory to printing it
453 tidySkolemTyVar env tv
454 = ASSERT( isSkolemTyVar tv || isSigTyVar tv )
455 (env1, mkTcTyVar (tyVarName tv) (tyVarKind tv) info1)
457 (env1, info1) = case tcTyVarDetails tv of
458 SkolemTv info -> (env1, SkolemTv info')
460 (env1, info') = tidy_skol_info env info
461 MetaTv (SigTv info) box -> (env1, MetaTv (SigTv info') box)
463 (env1, info') = tidy_skol_info env info
466 tidy_skol_info env (GenSkol tvs ty loc) = (env2, GenSkol tvs1 ty1 loc)
468 (env1, tvs1) = tidyOpenTyVars env tvs
469 (env2, ty1) = tidyOpenType env1 ty
470 tidy_skol_info env info = (env, info)
472 pprSkolTvBinding :: TcTyVar -> SDoc
473 -- Print info about the binding of a skolem tyvar,
474 -- or nothing if we don't have anything useful to say
476 = ASSERT ( isTcTyVar tv )
477 ppr_details (tcTyVarDetails tv)
479 ppr_details (MetaTv TauTv _) = quotes (ppr tv) <+> ptext SLIT("is a meta type variable")
480 ppr_details (MetaTv BoxTv _) = quotes (ppr tv) <+> ptext SLIT("is a boxy type variable")
481 ppr_details (MetaTv (SigTv info) _) = ppr_skol info
482 ppr_details (SkolemTv info) = ppr_skol info
484 ppr_skol UnkSkol = empty -- Unhelpful; omit
485 ppr_skol (SigSkol ctxt) = sep [quotes (ppr tv) <+> ptext SLIT("is bound by") <+> pprUserTypeCtxt ctxt,
486 nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]
487 ppr_skol info = quotes (ppr tv) <+> pprSkolInfo info
489 pprSkolInfo :: SkolemInfo -> SDoc
490 pprSkolInfo (SigSkol ctxt) = ptext SLIT("is bound by") <+> pprUserTypeCtxt ctxt
491 pprSkolInfo (ClsSkol cls) = ptext SLIT("is bound by the class declaration for") <+> quotes (ppr cls)
492 pprSkolInfo (InstSkol df) =
493 ptext SLIT("is bound by the instance declaration at") <+> ppr (getSrcLoc df)
494 pprSkolInfo (FamInstSkol tc) =
495 ptext SLIT("is bound by the family instance declaration at") <+>
497 pprSkolInfo (ArrowSkol loc) =
498 ptext SLIT("is bound by the arrow form at") <+> ppr loc
499 pprSkolInfo (PatSkol dc loc) = sep [ptext SLIT("is bound by the pattern for") <+> quotes (ppr dc),
500 nest 2 (ptext SLIT("at") <+> ppr loc)]
501 pprSkolInfo (GenSkol tvs ty loc) = sep [sep [ptext SLIT("is bound by the polymorphic type"),
502 nest 2 (quotes (ppr (mkForAllTys tvs ty)))],
503 nest 2 (ptext SLIT("at") <+> ppr loc)]
505 -- For type variables the others are dealt with by pprSkolTvBinding.
506 -- For Insts, these cases should not happen
507 pprSkolInfo UnkSkol = panic "UnkSkol"
509 instance Outputable MetaDetails where
510 ppr Flexi = ptext SLIT("Flexi")
511 ppr (Indirect ty) = ptext SLIT("Indirect") <+> ppr ty
515 %************************************************************************
519 %************************************************************************
522 isImmutableTyVar, isSkolemTyVar, isExistentialTyVar, isBoxyTyVar, isMetaTyVar :: TyVar -> Bool
524 | isTcTyVar tv = isSkolemTyVar tv
528 = ASSERT( isTcTyVar tv )
529 case tcTyVarDetails tv of
533 isExistentialTyVar tv -- Existential type variable, bound by a pattern
534 = ASSERT( isTcTyVar tv )
535 case tcTyVarDetails tv of
536 SkolemTv (PatSkol _ _) -> True
540 = ASSERT2( isTcTyVar tv, ppr tv )
541 case tcTyVarDetails tv of
546 = ASSERT( isTcTyVar tv )
547 case tcTyVarDetails tv of
548 MetaTv BoxTv _ -> True
552 = ASSERT( isTcTyVar tv )
553 case tcTyVarDetails tv of
554 MetaTv (SigTv _) _ -> True
557 metaTvRef :: TyVar -> IORef MetaDetails
559 = ASSERT( isTcTyVar tv )
560 case tcTyVarDetails tv of
562 other -> pprPanic "metaTvRef" (ppr tv)
564 isFlexi, isIndirect :: MetaDetails -> Bool
566 isFlexi other = False
568 isIndirect (Indirect _) = True
569 isIndirect other = False
573 %************************************************************************
575 \subsection{Tau, sigma and rho}
577 %************************************************************************
580 mkSigmaTy :: [TyVar] -> [PredType] -> Type -> Type
581 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkPhiTy theta tau)
583 mkPhiTy :: [PredType] -> Type -> Type
584 mkPhiTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
587 @isTauTy@ tests for nested for-alls. It should not be called on a boxy type.
590 isTauTy :: Type -> Bool
591 isTauTy ty | Just ty' <- tcView ty = isTauTy ty'
592 isTauTy (TyVarTy tv) = ASSERT( not (isTcTyVar tv && isBoxyTyVar tv) )
594 isTauTy (TyConApp tc tys) = all isTauTy tys && isTauTyCon tc
595 isTauTy (AppTy a b) = isTauTy a && isTauTy b
596 isTauTy (FunTy a b) = isTauTy a && isTauTy b
597 isTauTy (PredTy p) = True -- Don't look through source types
598 isTauTy other = False
601 isTauTyCon :: TyCon -> Bool
602 -- Returns False for type synonyms whose expansion is a polytype
604 | isSynTyCon tc && not (isOpenTyCon tc) = isTauTy (snd (synTyConDefn tc))
608 isBoxyTy :: TcType -> Bool
609 isBoxyTy ty = any isBoxyTyVar (varSetElems (tcTyVarsOfType ty))
611 isRigidTy :: TcType -> Bool
612 -- A type is rigid if it has no meta type variables in it
613 isRigidTy ty = all isSkolemTyVar (varSetElems (tcTyVarsOfType ty))
615 isRefineableTy :: TcType -> Bool
616 -- A type should have type refinements applied to it if it has
617 -- free type variables, and they are all rigid
618 isRefineableTy ty = not (null tc_tvs) && all isSkolemTyVar tc_tvs
620 tc_tvs = varSetElems (tcTyVarsOfType ty)
623 getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
624 -- construct a dictionary function name
625 getDFunTyKey ty | Just ty' <- tcView ty = getDFunTyKey ty'
626 getDFunTyKey (TyVarTy tv) = getOccName tv
627 getDFunTyKey (TyConApp tc _) = getOccName tc
628 getDFunTyKey (AppTy fun _) = getDFunTyKey fun
629 getDFunTyKey (FunTy arg _) = getOccName funTyCon
630 getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
631 getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty)
632 -- PredTy shouldn't happen
636 %************************************************************************
638 \subsection{Expanding and splitting}
640 %************************************************************************
642 These tcSplit functions are like their non-Tc analogues, but
643 a) they do not look through newtypes
644 b) they do not look through PredTys
645 c) [future] they ignore usage-type annotations
647 However, they are non-monadic and do not follow through mutable type
648 variables. It's up to you to make sure this doesn't matter.
651 tcSplitForAllTys :: Type -> ([TyVar], Type)
652 tcSplitForAllTys ty = split ty ty []
654 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
655 split orig_ty (ForAllTy tv ty) tvs
656 | not (isCoVar tv) = split ty ty (tv:tvs)
657 split orig_ty t tvs = (reverse tvs, orig_ty)
659 tcIsForAllTy ty | Just ty' <- tcView ty = tcIsForAllTy ty'
660 tcIsForAllTy (ForAllTy tv ty) = not (isCoVar tv)
661 tcIsForAllTy t = False
663 tcSplitPhiTy :: Type -> (ThetaType, Type)
664 tcSplitPhiTy ty = split ty ty []
666 split orig_ty ty tvs | Just ty' <- tcView ty = split orig_ty ty' tvs
668 split orig_ty (ForAllTy tv ty) ts
669 | isCoVar tv = split ty ty (eq_pred:ts)
671 PredTy eq_pred = tyVarKind tv
672 split orig_ty (FunTy arg res) ts
673 | Just p <- tcSplitPredTy_maybe arg = split res res (p:ts)
674 split orig_ty ty ts = (reverse ts, orig_ty)
676 tcSplitSigmaTy :: Type -> ([TyVar], ThetaType, Type)
677 tcSplitSigmaTy ty = case tcSplitForAllTys ty of
678 (tvs, rho) -> case tcSplitPhiTy rho of
679 (theta, tau) -> (tvs, theta, tau)
681 -----------------------
684 -> ( [([TyVar], ThetaType)], -- forall as.C => forall bs.D
685 TcSigmaType) -- The rest of the type
687 -- We need a loop here because we are now prepared to entertain
689 -- f:: forall a. Eq a => forall b. Baz b => tau
690 -- We want to instantiate this to
691 -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
693 tcMultiSplitSigmaTy sigma
694 = case (tcSplitSigmaTy sigma) of
695 ([],[],ty) -> ([], sigma)
696 (tvs, theta, ty) -> case tcMultiSplitSigmaTy ty of
697 (pairs, rest) -> ((tvs,theta):pairs, rest)
699 -----------------------
700 tcTyConAppTyCon :: Type -> TyCon
701 tcTyConAppTyCon ty = case tcSplitTyConApp_maybe ty of
703 Nothing -> pprPanic "tcTyConAppTyCon" (pprType ty)
705 tcTyConAppArgs :: Type -> [Type]
706 tcTyConAppArgs ty = case tcSplitTyConApp_maybe ty of
707 Just (_, args) -> args
708 Nothing -> pprPanic "tcTyConAppArgs" (pprType ty)
710 tcSplitTyConApp :: Type -> (TyCon, [Type])
711 tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
713 Nothing -> pprPanic "tcSplitTyConApp" (pprType ty)
715 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
716 tcSplitTyConApp_maybe ty | Just ty' <- tcView ty = tcSplitTyConApp_maybe ty'
717 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
718 tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
719 -- Newtypes are opaque, so they may be split
720 -- However, predicates are not treated
721 -- as tycon applications by the type checker
722 tcSplitTyConApp_maybe other = Nothing
724 -----------------------
725 tcSplitFunTys :: Type -> ([Type], Type)
726 tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
728 Just (arg,res) -> (arg:args, res')
730 (args,res') = tcSplitFunTys res
732 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
733 tcSplitFunTy_maybe ty | Just ty' <- tcView ty = tcSplitFunTy_maybe ty'
734 tcSplitFunTy_maybe (FunTy arg res) = Just (arg, res)
735 tcSplitFunTy_maybe other = Nothing
739 -> Arity -- N: Number of desired args
740 -> ([TcSigmaType], -- Arg types (N or fewer)
741 TcSigmaType) -- The rest of the type
743 tcSplitFunTysN ty n_args
746 | Just (arg,res) <- tcSplitFunTy_maybe ty
747 = case tcSplitFunTysN res (n_args - 1) of
748 (args, res) -> (arg:args, res)
752 tcSplitFunTy ty = expectJust "tcSplitFunTy" (tcSplitFunTy_maybe ty)
753 tcFunArgTy ty = fst (tcSplitFunTy ty)
754 tcFunResultTy ty = snd (tcSplitFunTy ty)
756 -----------------------
757 tcSplitAppTy_maybe :: Type -> Maybe (Type, Type)
758 tcSplitAppTy_maybe ty | Just ty' <- tcView ty = tcSplitAppTy_maybe ty'
759 tcSplitAppTy_maybe ty = repSplitAppTy_maybe ty
761 tcSplitAppTy :: Type -> (Type, Type)
762 tcSplitAppTy ty = case tcSplitAppTy_maybe ty of
764 Nothing -> pprPanic "tcSplitAppTy" (pprType ty)
766 tcSplitAppTys :: Type -> (Type, [Type])
770 go ty args = case tcSplitAppTy_maybe ty of
771 Just (ty', arg) -> go ty' (arg:args)
774 -----------------------
775 tcGetTyVar_maybe :: Type -> Maybe TyVar
776 tcGetTyVar_maybe ty | Just ty' <- tcView ty = tcGetTyVar_maybe ty'
777 tcGetTyVar_maybe (TyVarTy tv) = Just tv
778 tcGetTyVar_maybe other = Nothing
780 tcGetTyVar :: String -> Type -> TyVar
781 tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty)
783 tcIsTyVarTy :: Type -> Bool
784 tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty)
786 -----------------------
787 tcSplitDFunTy :: Type -> ([TyVar], [PredType], Class, [Type])
788 -- Split the type of a dictionary function
790 = case tcSplitSigmaTy ty of { (tvs, theta, tau) ->
791 case tcSplitDFunHead tau of { (clas, tys) ->
792 (tvs, theta, clas, tys) }}
794 tcSplitDFunHead :: Type -> (Class, [Type])
796 = case tcSplitPredTy_maybe tau of
797 Just (ClassP clas tys) -> (clas, tys)
798 other -> panic "tcSplitDFunHead"
800 tcValidInstHeadTy :: Type -> Bool
801 -- Used in Haskell-98 mode, for the argument types of an instance head
802 -- These must not be type synonyms, but everywhere else type synonyms
803 -- are transparent, so we need a special function here
806 NoteTy _ ty -> tcValidInstHeadTy ty
807 TyConApp tc tys -> not (isSynTyCon tc) && ok tys
808 FunTy arg res -> ok [arg, res]
811 -- Check that all the types are type variables,
812 -- and that each is distinct
813 ok tys = equalLength tvs tys && hasNoDups tvs
815 tvs = mapCatMaybes get_tv tys
817 get_tv (NoteTy _ ty) = get_tv ty -- Again, do not look
818 get_tv (TyVarTy tv) = Just tv -- through synonyms
819 get_tv other = Nothing
824 %************************************************************************
826 \subsection{Predicate types}
828 %************************************************************************
831 tcSplitPredTy_maybe :: Type -> Maybe PredType
832 -- Returns Just for predicates only
833 tcSplitPredTy_maybe ty | Just ty' <- tcView ty = tcSplitPredTy_maybe ty'
834 tcSplitPredTy_maybe (PredTy p) = Just p
835 tcSplitPredTy_maybe other = Nothing
837 predTyUnique :: PredType -> Unique
838 predTyUnique (IParam n _) = getUnique (ipNameName n)
839 predTyUnique (ClassP clas tys) = getUnique clas
841 mkPredName :: Unique -> SrcLoc -> PredType -> Name
842 mkPredName uniq loc (ClassP cls tys) = mkInternalName uniq (mkDictOcc (getOccName cls)) loc
843 mkPredName uniq loc (IParam ip ty) = mkInternalName uniq (getOccName (ipNameName ip)) loc
847 --------------------- Dictionary types ---------------------------------
850 mkClassPred clas tys = ClassP clas tys
852 isClassPred :: PredType -> Bool
853 isClassPred (ClassP clas tys) = True
854 isClassPred other = False
856 isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys
857 isTyVarClassPred other = False
859 getClassPredTys_maybe :: PredType -> Maybe (Class, [Type])
860 getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys)
861 getClassPredTys_maybe _ = Nothing
863 getClassPredTys :: PredType -> (Class, [Type])
864 getClassPredTys (ClassP clas tys) = (clas, tys)
865 getClassPredTys other = panic "getClassPredTys"
867 isEqPred :: PredType -> Bool
868 isEqPred (EqPred {}) = True
871 mkDictTy :: Class -> [Type] -> Type
872 mkDictTy clas tys = mkPredTy (ClassP clas tys)
874 isDictTy :: Type -> Bool
875 isDictTy ty | Just ty' <- tcView ty = isDictTy ty'
876 isDictTy (PredTy p) = isClassPred p
877 isDictTy other = False
880 --------------------- Implicit parameters ---------------------------------
883 isIPPred :: PredType -> Bool
884 isIPPred (IParam _ _) = True
885 isIPPred other = False
887 isInheritablePred :: PredType -> Bool
888 -- Can be inherited by a context. For example, consider
889 -- f x = let g y = (?v, y+x)
890 -- in (g 3 with ?v = 8,
892 -- The point is that g's type must be quantifed over ?v:
893 -- g :: (?v :: a) => a -> a
894 -- but it doesn't need to be quantified over the Num a dictionary
895 -- which can be free in g's rhs, and shared by both calls to g
896 isInheritablePred (ClassP _ _) = True
897 isInheritablePred other = False
900 --------------------- Equality predicates ---------------------------------
902 substEqSpec :: TvSubst -> [(TyVar,Type)] -> [(TcType,TcType)]
903 substEqSpec subst eq_spec = [ (substTyVar subst tv, substTy subst ty)
904 | (tv,ty) <- eq_spec]
907 --------------------- The stupid theta (sigh) ---------------------------------
910 dataConsStupidTheta :: [DataCon] -> ThetaType
911 -- Union the stupid thetas from all the specified constructors (non-empty)
912 -- All the constructors should have the same result type, modulo alpha conversion
913 -- The resulting ThetaType uses type variables from the *first* constructor in the list
915 -- It's here because it's used in MkId.mkRecordSelId, and in TcExpr
916 dataConsStupidTheta (con1:cons)
917 = nubBy tcEqPred all_preds
919 all_preds = dataConStupidTheta con1 ++ other_stupids
920 res_tys1 = dataConResTys con1
921 tvs1 = tyVarsOfTypes res_tys1
922 other_stupids = [ substPred subst pred
924 , let Just subst = tcMatchTys tvs1 res_tys1 (dataConResTys con)
925 , pred <- dataConStupidTheta con ]
926 dataConsStupidTheta [] = panic "dataConsStupidTheta"
930 %************************************************************************
932 \subsection{Predicates}
934 %************************************************************************
936 isSigmaTy returns true of any qualified type. It doesn't *necessarily* have
938 f :: (?x::Int) => Int -> Int
941 isSigmaTy :: Type -> Bool
942 isSigmaTy ty | Just ty' <- tcView ty = isSigmaTy ty'
943 isSigmaTy (ForAllTy tyvar ty) = True
944 isSigmaTy (FunTy a b) = isPredTy a
947 isOverloadedTy :: Type -> Bool
948 isOverloadedTy ty | Just ty' <- tcView ty = isOverloadedTy ty'
949 isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty
950 isOverloadedTy (FunTy a b) = isPredTy a
951 isOverloadedTy _ = False
953 isPredTy :: Type -> Bool -- Belongs in TcType because it does
954 -- not look through newtypes, or predtypes (of course)
955 isPredTy ty | Just ty' <- tcView ty = isPredTy ty'
956 isPredTy (PredTy sty) = True
961 isFloatTy = is_tc floatTyConKey
962 isDoubleTy = is_tc doubleTyConKey
963 isIntegerTy = is_tc integerTyConKey
964 isIntTy = is_tc intTyConKey
965 isBoolTy = is_tc boolTyConKey
966 isUnitTy = is_tc unitTyConKey
968 is_tc :: Unique -> Type -> Bool
969 -- Newtypes are opaque to this
970 is_tc uniq ty = case tcSplitTyConApp_maybe ty of
971 Just (tc, _) -> uniq == getUnique tc
976 %************************************************************************
980 %************************************************************************
983 deNoteType :: Type -> Type
984 -- Remove all *outermost* type synonyms and other notes
985 deNoteType ty | Just ty' <- tcView ty = deNoteType ty'
990 tcTyVarsOfType :: Type -> TcTyVarSet
991 -- Just the *TcTyVars* free in the type
992 -- (Types.tyVarsOfTypes finds all free TyVars)
993 tcTyVarsOfType (TyVarTy tv) = if isTcTyVar tv then unitVarSet tv
995 tcTyVarsOfType (TyConApp tycon tys) = tcTyVarsOfTypes tys
996 tcTyVarsOfType (NoteTy _ ty) = tcTyVarsOfType ty
997 tcTyVarsOfType (PredTy sty) = tcTyVarsOfPred sty
998 tcTyVarsOfType (FunTy arg res) = tcTyVarsOfType arg `unionVarSet` tcTyVarsOfType res
999 tcTyVarsOfType (AppTy fun arg) = tcTyVarsOfType fun `unionVarSet` tcTyVarsOfType arg
1000 tcTyVarsOfType (ForAllTy tyvar ty) = (tcTyVarsOfType ty `delVarSet` tyvar)
1001 `unionVarSet` tcTyVarsOfTyVar tyvar
1002 -- We do sometimes quantify over skolem TcTyVars
1004 tcTyVarsOfTyVar :: TcTyVar -> TyVarSet
1005 tcTyVarsOfTyVar tv | isCoVar tv = tcTyVarsOfType (tyVarKind tv)
1006 | otherwise = emptyVarSet
1008 tcTyVarsOfTypes :: [Type] -> TyVarSet
1009 tcTyVarsOfTypes tys = foldr (unionVarSet.tcTyVarsOfType) emptyVarSet tys
1011 tcTyVarsOfPred :: PredType -> TyVarSet
1012 tcTyVarsOfPred (IParam _ ty) = tcTyVarsOfType ty
1013 tcTyVarsOfPred (ClassP _ tys) = tcTyVarsOfTypes tys
1014 tcTyVarsOfPred (EqPred ty1 ty2) = tcTyVarsOfType ty1 `unionVarSet` tcTyVarsOfType ty2
1017 Note [Silly type synonym]
1018 ~~~~~~~~~~~~~~~~~~~~~~~~~
1021 What are the free tyvars of (T x)? Empty, of course!
1022 Here's the example that Ralf Laemmel showed me:
1023 foo :: (forall a. C u a -> C u a) -> u
1024 mappend :: Monoid u => u -> u -> u
1026 bar :: Monoid u => u
1027 bar = foo (\t -> t `mappend` t)
1028 We have to generalise at the arg to f, and we don't
1029 want to capture the constraint (Monad (C u a)) because
1030 it appears to mention a. Pretty silly, but it was useful to him.
1032 exactTyVarsOfType is used by the type checker to figure out exactly
1033 which type variables are mentioned in a type. It's also used in the
1034 smart-app checking code --- see TcExpr.tcIdApp
1037 exactTyVarsOfType :: TcType -> TyVarSet
1038 -- Find the free type variables (of any kind)
1039 -- but *expand* type synonyms. See Note [Silly type synonym] above.
1040 exactTyVarsOfType ty
1043 go ty | Just ty' <- tcView ty = go ty' -- This is the key line
1044 go (TyVarTy tv) = unitVarSet tv
1045 go (TyConApp tycon tys) = exactTyVarsOfTypes tys
1046 go (PredTy ty) = go_pred ty
1047 go (FunTy arg res) = go arg `unionVarSet` go res
1048 go (AppTy fun arg) = go fun `unionVarSet` go arg
1049 go (ForAllTy tyvar ty) = delVarSet (go ty) tyvar
1050 `unionVarSet` go_tv tyvar
1052 go_pred (IParam _ ty) = go ty
1053 go_pred (ClassP _ tys) = exactTyVarsOfTypes tys
1054 go_pred (EqPred ty1 ty2) = go ty1 `unionVarSet` go ty2
1056 go_tv tyvar | isCoVar tyvar = go (tyVarKind tyvar)
1057 | otherwise = emptyVarSet
1059 exactTyVarsOfTypes :: [TcType] -> TyVarSet
1060 exactTyVarsOfTypes tys = foldr (unionVarSet . exactTyVarsOfType) emptyVarSet tys
1063 Find the free tycons and classes of a type. This is used in the front
1064 end of the compiler.
1067 tyClsNamesOfType :: Type -> NameSet
1068 tyClsNamesOfType (TyVarTy tv) = emptyNameSet
1069 tyClsNamesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` tyClsNamesOfTypes tys
1070 tyClsNamesOfType (NoteTy _ ty2) = tyClsNamesOfType ty2
1071 tyClsNamesOfType (PredTy (IParam n ty)) = tyClsNamesOfType ty
1072 tyClsNamesOfType (PredTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` tyClsNamesOfTypes tys
1073 tyClsNamesOfType (PredTy (EqPred ty1 ty2)) = tyClsNamesOfType ty1 `unionNameSets` tyClsNamesOfType ty2
1074 tyClsNamesOfType (FunTy arg res) = tyClsNamesOfType arg `unionNameSets` tyClsNamesOfType res
1075 tyClsNamesOfType (AppTy fun arg) = tyClsNamesOfType fun `unionNameSets` tyClsNamesOfType arg
1076 tyClsNamesOfType (ForAllTy tyvar ty) = tyClsNamesOfType ty
1078 tyClsNamesOfTypes tys = foldr (unionNameSets . tyClsNamesOfType) emptyNameSet tys
1080 tyClsNamesOfDFunHead :: Type -> NameSet
1081 -- Find the free type constructors and classes
1082 -- of the head of the dfun instance type
1083 -- The 'dfun_head_type' is because of
1084 -- instance Foo a => Baz T where ...
1085 -- The decl is an orphan if Baz and T are both not locally defined,
1086 -- even if Foo *is* locally defined
1087 tyClsNamesOfDFunHead dfun_ty
1088 = case tcSplitSigmaTy dfun_ty of
1089 (tvs,_,head_ty) -> tyClsNamesOfType head_ty
1091 classesOfTheta :: ThetaType -> [Class]
1092 -- Looks just for ClassP things; maybe it should check
1093 classesOfTheta preds = [ c | ClassP c _ <- preds ]
1097 %************************************************************************
1099 \subsection[TysWiredIn-ext-type]{External types}
1101 %************************************************************************
1103 The compiler's foreign function interface supports the passing of a
1104 restricted set of types as arguments and results (the restricting factor
1108 tcSplitIOType_maybe :: Type -> Maybe (TyCon, Type)
1109 -- (isIOType t) returns (Just (IO,t')) if t is of the form (IO t'), or
1110 -- some newtype wrapping thereof
1111 -- returns Nothing otherwise
1112 tcSplitIOType_maybe ty
1113 | Just (io_tycon, [io_res_ty]) <- tcSplitTyConApp_maybe ty,
1114 -- This split absolutely has to be a tcSplit, because we must
1115 -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
1116 io_tycon `hasKey` ioTyConKey
1117 = Just (io_tycon, io_res_ty)
1119 | Just ty' <- coreView ty -- Look through non-recursive newtypes
1120 = tcSplitIOType_maybe ty'
1125 isFFITy :: Type -> Bool
1126 -- True for any TyCon that can possibly be an arg or result of an FFI call
1127 isFFITy ty = checkRepTyCon legalFFITyCon ty
1129 isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool
1130 -- Checks for valid argument type for a 'foreign import'
1131 isFFIArgumentTy dflags safety ty
1132 = checkRepTyCon (legalOutgoingTyCon dflags safety) ty
1134 isFFIExternalTy :: Type -> Bool
1135 -- Types that are allowed as arguments of a 'foreign export'
1136 isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty
1138 isFFIImportResultTy :: DynFlags -> Type -> Bool
1139 isFFIImportResultTy dflags ty
1140 = checkRepTyCon (legalFIResultTyCon dflags) ty
1142 isFFIExportResultTy :: Type -> Bool
1143 isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty
1145 isFFIDynArgumentTy :: Type -> Bool
1146 -- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr,
1147 -- or a newtype of either.
1148 isFFIDynArgumentTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1150 isFFIDynResultTy :: Type -> Bool
1151 -- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr,
1152 -- or a newtype of either.
1153 isFFIDynResultTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1155 isFFILabelTy :: Type -> Bool
1156 -- The type of a foreign label must be Ptr, FunPtr, Addr,
1157 -- or a newtype of either.
1158 isFFILabelTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
1160 isFFIDotnetTy :: DynFlags -> Type -> Bool
1161 isFFIDotnetTy dflags ty
1162 = checkRepTyCon (\ tc -> (legalFIResultTyCon dflags tc ||
1163 isFFIDotnetObjTy ty || isStringTy ty)) ty
1165 -- Support String as an argument or result from a .NET FFI call.
1167 case tcSplitTyConApp_maybe (repType ty) of
1169 | tc == listTyCon ->
1170 case tcSplitTyConApp_maybe (repType arg_ty) of
1171 Just (cc,[]) -> cc == charTyCon
1175 -- Support String as an argument or result from a .NET FFI call.
1176 isFFIDotnetObjTy ty =
1178 (_, t_ty) = tcSplitForAllTys ty
1180 case tcSplitTyConApp_maybe (repType t_ty) of
1181 Just (tc, [arg_ty]) | getName tc == objectTyConName -> True
1184 toDNType :: Type -> DNType
1186 | isStringTy ty = DNString
1187 | isFFIDotnetObjTy ty = DNObject
1188 | Just (tc,argTys) <- tcSplitTyConApp_maybe ty
1189 = case lookup (getUnique tc) dn_assoc of
1192 | tc `hasKey` ioTyConKey -> toDNType (head argTys)
1193 | otherwise -> pprPanic ("toDNType: unsupported .NET type")
1194 (pprType ty <+> parens (hcat (map pprType argTys)) <+> ppr tc)
1195 | otherwise = panic "toDNType" -- Is this right?
1197 dn_assoc :: [ (Unique, DNType) ]
1198 dn_assoc = [ (unitTyConKey, DNUnit)
1199 , (intTyConKey, DNInt)
1200 , (int8TyConKey, DNInt8)
1201 , (int16TyConKey, DNInt16)
1202 , (int32TyConKey, DNInt32)
1203 , (int64TyConKey, DNInt64)
1204 , (wordTyConKey, DNInt)
1205 , (word8TyConKey, DNWord8)
1206 , (word16TyConKey, DNWord16)
1207 , (word32TyConKey, DNWord32)
1208 , (word64TyConKey, DNWord64)
1209 , (floatTyConKey, DNFloat)
1210 , (doubleTyConKey, DNDouble)
1211 , (ptrTyConKey, DNPtr)
1212 , (funPtrTyConKey, DNPtr)
1213 , (charTyConKey, DNChar)
1214 , (boolTyConKey, DNBool)
1217 checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool
1218 -- Look through newtypes
1219 -- Non-recursive ones are transparent to splitTyConApp,
1220 -- but recursive ones aren't. Manuel had:
1221 -- newtype T = MkT (Ptr T)
1222 -- and wanted it to work...
1223 checkRepTyCon check_tc ty
1224 | Just (tc,_) <- splitTyConApp_maybe (repType ty) = check_tc tc
1227 checkRepTyConKey :: [Unique] -> Type -> Bool
1228 -- Like checkRepTyCon, but just looks at the TyCon key
1229 checkRepTyConKey keys
1230 = checkRepTyCon (\tc -> tyConUnique tc `elem` keys)
1233 ----------------------------------------------
1234 These chaps do the work; they are not exported
1235 ----------------------------------------------
1238 legalFEArgTyCon :: TyCon -> Bool
1240 -- It's illegal to make foreign exports that take unboxed
1241 -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000
1242 = boxedMarshalableTyCon tc
1244 legalFIResultTyCon :: DynFlags -> TyCon -> Bool
1245 legalFIResultTyCon dflags tc
1246 | tc == unitTyCon = True
1247 | otherwise = marshalableTyCon dflags tc
1249 legalFEResultTyCon :: TyCon -> Bool
1250 legalFEResultTyCon tc
1251 | tc == unitTyCon = True
1252 | otherwise = boxedMarshalableTyCon tc
1254 legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool
1255 -- Checks validity of types going from Haskell -> external world
1256 legalOutgoingTyCon dflags safety tc
1257 = marshalableTyCon dflags tc
1259 legalFFITyCon :: TyCon -> Bool
1260 -- True for any TyCon that can possibly be an arg or result of an FFI call
1262 = isUnLiftedTyCon tc || boxedMarshalableTyCon tc || tc == unitTyCon
1264 marshalableTyCon dflags tc
1265 = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc)
1266 || boxedMarshalableTyCon tc
1268 boxedMarshalableTyCon tc
1269 = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey
1270 , int32TyConKey, int64TyConKey
1271 , wordTyConKey, word8TyConKey, word16TyConKey
1272 , word32TyConKey, word64TyConKey
1273 , floatTyConKey, doubleTyConKey
1274 , ptrTyConKey, funPtrTyConKey