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 TauType, RhoType, SigmaType,
22 --------------------------------
26 --------------------------------
28 -- These are important because they do not look through newtypes
29 tcSplitForAllTys, tcSplitRhoTy,
30 tcSplitFunTy_maybe, tcSplitFunTys, tcFunArgTy, tcFunResultTy,
31 tcSplitTyConApp, tcSplitTyConApp_maybe, tcTyConAppTyCon, tcTyConAppArgs,
32 tcSplitAppTy_maybe, tcSplitAppTy, tcSplitSigmaTy,
33 tcSplitMethodTy, tcGetTyVar_maybe, tcGetTyVar,
35 ---------------------------------
37 -- Again, newtypes are opaque
38 tcEqType, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred,
39 isQualifiedTy, isOverloadedTy,
40 isDoubleTy, isFloatTy, isIntTy,
41 isIntegerTy, isAddrTy, isBoolTy, isUnitTy, isForeignPtrTy,
42 isTauTy, tcIsTyVarTy, tcIsForAllTy,
44 ---------------------------------
45 -- Misc type manipulators
46 hoistForAllTys, deNoteType,
47 namesOfType, namesOfDFunHead,
50 ---------------------------------
52 PredType, getClassPredTys_maybe, getClassPredTys,
53 isPredTy, isClassPred, isTyVarClassPred, predHasFDs,
54 mkDictTy, tcSplitPredTy_maybe, predTyUnique,
55 isDictTy, tcSplitDFunTy, predTyUnique,
56 mkClassPred, predMentionsIPs, inheritablePred, isIPPred, mkPredName,
58 ---------------------------------
59 -- Foreign import and export
60 isFFIArgumentTy, -- :: DynFlags -> Safety -> Type -> Bool
61 isFFIImportResultTy, -- :: DynFlags -> Type -> Bool
62 isFFIExportResultTy, -- :: Type -> Bool
63 isFFIExternalTy, -- :: Type -> Bool
64 isFFIDynArgumentTy, -- :: Type -> Bool
65 isFFIDynResultTy, -- :: Type -> Bool
66 isFFILabelTy, -- :: Type -> Bool
68 ---------------------------------
69 -- Unifier and matcher
70 unifyTysX, unifyTyListsX, unifyExtendTysX,
72 matchTy, matchTys, match,
74 --------------------------------
75 -- Rexported from Type
76 Kind, -- Stuff to do with kinds is insensitive to pre/post Tc
77 unliftedTypeKind, liftedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds,
78 superBoxity, liftedBoxity, hasMoreBoxityInfo, defaultKind, superKind,
81 Type, SourceType(..), PredType, ThetaType,
82 mkForAllTy, mkForAllTys,
83 mkFunTy, mkFunTys, zipFunTys,
84 mkTyConApp, mkAppTy, mkAppTys, mkSynTy, applyTy, applyTys,
85 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys,
87 isUnLiftedType, -- Source types are always lifted
88 isUnboxedTupleType, -- Ditto
91 tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
92 tidyTyVar, tidyTyVars,
93 typeKind, eqKind, eqUsage,
95 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta
98 #include "HsVersions.h"
101 import {-# SOURCE #-} PprType( pprType )
104 import TypeRep ( Type(..), TyNote(..), funTyCon ) -- friend
105 import Type ( mkUTyM, unUTy ) -- Used locally
107 import Type ( -- Re-exports
108 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
109 Kind, Type, TauType, SourceType(..), PredType, ThetaType,
110 unliftedTypeKind, liftedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds,
111 mkForAllTy, mkForAllTys, defaultKind, isTypeKind,
112 mkFunTy, mkFunTys, zipFunTys,
113 mkTyConApp, mkAppTy, mkAppTys, mkSynTy, applyTy, applyTys,
114 mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys,
115 isUnLiftedType, isUnboxedTupleType, isPrimitiveType,
116 splitNewType_maybe, splitTyConApp_maybe,
117 tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes,
118 tidyTyVar, tidyTyVars, eqKind, eqUsage,
119 hasMoreBoxityInfo, liftedBoxity, superBoxity, typeKind, superKind
121 import TyCon ( TyCon, isPrimTyCon, tyConArity, isNewTyCon, isUnLiftedTyCon )
122 import Class ( classTyCon, classHasFDs, Class )
123 import Var ( TyVar, tyVarKind )
124 import ForeignCall ( Safety, playSafe )
129 import CmdLineOpts ( DynFlags, DynFlag( Opt_GlasgowExts ), dopt )
130 import Name ( Name, NamedThing(..), mkLocalName )
131 import OccName ( OccName, mkDictOcc )
133 import PrelNames -- Lots (e.g. in isFFIArgumentTy
134 import TysWiredIn ( ptrTyCon, funPtrTyCon, addrTyCon, unitTyCon )
135 import Unique ( Unique, Uniquable(..), mkTupleTyConUnique )
136 import SrcLoc ( SrcLoc )
137 import Util ( cmpList, thenCmp )
138 import Maybes ( maybeToBool, expectJust )
139 import BasicTypes ( Boxity(..) )
144 %************************************************************************
146 \subsection{Tau, sigma and rho}
148 %************************************************************************
151 type SigmaType = Type
154 mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau)
156 mkRhoTy :: [SourceType] -> Type -> Type
157 mkRhoTy theta ty = UASSERT2( not (isUTy ty), pprType ty )
158 foldr (\p r -> FunTy (mkUTyM (mkPredTy p)) (mkUTyM r)) ty theta
163 @isTauTy@ tests for nested for-alls.
166 isTauTy :: Type -> Bool
167 isTauTy (TyVarTy v) = True
168 isTauTy (TyConApp _ tys) = all isTauTy tys
169 isTauTy (AppTy a b) = isTauTy a && isTauTy b
170 isTauTy (FunTy a b) = isTauTy a && isTauTy b
171 isTauTy (SourceTy p) = True -- Don't look through source types
172 isTauTy (NoteTy _ ty) = isTauTy ty
173 isTauTy (UsageTy _ ty) = isTauTy ty
174 isTauTy other = False
178 getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
179 -- construct a dictionary function name
180 getDFunTyKey (TyVarTy tv) = getOccName tv
181 getDFunTyKey (TyConApp tc _) = getOccName tc
182 getDFunTyKey (AppTy fun _) = getDFunTyKey fun
183 getDFunTyKey (NoteTy _ t) = getDFunTyKey t
184 getDFunTyKey (FunTy arg _) = getOccName funTyCon
185 getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
186 getDFunTyKey (UsageTy _ t) = getDFunTyKey t
187 getDFunTyKey (SourceTy (NType tc _)) = getOccName tc -- Newtypes are quite reasonable
188 getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty)
189 -- SourceTy shouldn't happen
193 %************************************************************************
195 \subsection{Expanding and splitting}
197 %************************************************************************
199 These tcSplit functions are like their non-Tc analogues, but
200 a) they do not look through newtypes
201 b) they do not look through PredTys
202 c) [future] they ignore usage-type annotations
204 However, they are non-monadic and do not follow through mutable type
205 variables. It's up to you to make sure this doesn't matter.
208 tcSplitForAllTys :: Type -> ([TyVar], Type)
209 tcSplitForAllTys ty = split ty ty []
211 split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
212 split orig_ty (NoteTy n ty) tvs = split orig_ty ty tvs
213 split orig_ty (UsageTy _ ty) tvs = split orig_ty ty tvs
214 split orig_ty t tvs = (reverse tvs, orig_ty)
216 tcIsForAllTy (ForAllTy tv ty) = True
217 tcIsForAllTy (NoteTy n ty) = tcIsForAllTy ty
218 tcIsForAllTy (UsageTy n ty) = tcIsForAllTy ty
219 tcIsForAllTy t = False
221 tcSplitRhoTy :: Type -> ([PredType], Type)
222 tcSplitRhoTy ty = split ty ty []
224 split orig_ty (FunTy arg res) ts = case tcSplitPredTy_maybe arg of
225 Just p -> split res res (p:ts)
226 Nothing -> (reverse ts, orig_ty)
227 split orig_ty (NoteTy n ty) ts = split orig_ty ty ts
228 split orig_ty (UsageTy _ ty) ts = split orig_ty ty ts
229 split orig_ty ty ts = (reverse ts, orig_ty)
231 tcSplitSigmaTy ty = case tcSplitForAllTys ty of
232 (tvs, rho) -> case tcSplitRhoTy rho of
233 (theta, tau) -> (tvs, theta, tau)
235 tcTyConAppTyCon :: Type -> TyCon
236 tcTyConAppTyCon ty = fst (tcSplitTyConApp ty)
238 tcTyConAppArgs :: Type -> [Type]
239 tcTyConAppArgs ty = snd (tcSplitTyConApp ty)
241 tcSplitTyConApp :: Type -> (TyCon, [Type])
242 tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
244 Nothing -> pprPanic "tcSplitTyConApp" (pprType ty)
246 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
247 -- Newtypes are opaque, so they may be split
248 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
249 tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [unUTy arg,unUTy res])
250 tcSplitTyConApp_maybe (NoteTy n ty) = tcSplitTyConApp_maybe ty
251 tcSplitTyConApp_maybe (UsageTy _ ty) = tcSplitTyConApp_maybe ty
252 tcSplitTyConApp_maybe (SourceTy (NType tc tys)) = Just (tc,tys)
253 -- However, predicates are not treated
254 -- as tycon applications by the type checker
255 tcSplitTyConApp_maybe other = Nothing
257 tcSplitFunTys :: Type -> ([Type], Type)
258 tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
260 Just (arg,res) -> (arg:args, res')
262 (args,res') = tcSplitFunTys res
264 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
265 tcSplitFunTy_maybe (FunTy arg res) = Just (arg, res)
266 tcSplitFunTy_maybe (NoteTy n ty) = tcSplitFunTy_maybe ty
267 tcSplitFunTy_maybe (UsageTy _ ty) = tcSplitFunTy_maybe ty
268 tcSplitFunTy_maybe other = Nothing
270 tcFunArgTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> arg }
271 tcFunResultTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> res }
274 tcSplitAppTy_maybe :: Type -> Maybe (Type, Type)
275 tcSplitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [unUTy ty1], unUTy ty2)
276 tcSplitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
277 tcSplitAppTy_maybe (NoteTy n ty) = tcSplitAppTy_maybe ty
278 tcSplitAppTy_maybe (UsageTy _ ty) = tcSplitAppTy_maybe ty
279 tcSplitAppTy_maybe (SourceTy (NType tc tys)) = tc_split_app tc tys
280 --- Don't forget that newtype!
281 tcSplitAppTy_maybe (TyConApp tc tys) = tc_split_app tc tys
282 tcSplitAppTy_maybe other = Nothing
284 tc_split_app tc [] = Nothing
285 tc_split_app tc tys = split tys []
287 split [ty2] acc = Just (TyConApp tc (reverse acc), ty2)
288 split (ty:tys) acc = split tys (ty:acc)
290 tcSplitAppTy ty = case tcSplitAppTy_maybe ty of
292 Nothing -> pprPanic "tcSplitAppTy" (pprType ty)
294 tcGetTyVar_maybe :: Type -> Maybe TyVar
295 tcGetTyVar_maybe (TyVarTy tv) = Just tv
296 tcGetTyVar_maybe (NoteTy _ t) = tcGetTyVar_maybe t
297 tcGetTyVar_maybe ty@(UsageTy _ _) = pprPanic "tcGetTyVar_maybe: UTy:" (pprType ty)
298 tcGetTyVar_maybe other = Nothing
300 tcGetTyVar :: String -> Type -> TyVar
301 tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty)
303 tcIsTyVarTy :: Type -> Bool
304 tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty)
307 The type of a method for class C is always of the form:
308 Forall a1..an. C a1..an => sig_ty
309 where sig_ty is the type given by the method's signature, and thus in general
310 is a ForallTy. At the point that splitMethodTy is called, it is expected
311 that the outer Forall has already been stripped off. splitMethodTy then
312 returns (C a1..an, sig_ty') where sig_ty' is sig_ty with any Notes or
316 tcSplitMethodTy :: Type -> (PredType, Type)
317 tcSplitMethodTy ty = split ty
319 split (FunTy arg res) = case tcSplitPredTy_maybe arg of
321 Nothing -> panic "splitMethodTy"
322 split (NoteTy n ty) = split ty
323 split (UsageTy _ ty) = split ty
324 split _ = panic "splitMethodTy"
326 tcSplitDFunTy :: Type -> ([TyVar], [SourceType], Class, [Type])
327 -- Split the type of a dictionary function
329 = case tcSplitSigmaTy ty of { (tvs, theta, tau) ->
330 case tcSplitPredTy_maybe tau of { Just (ClassP clas tys) ->
331 (tvs, theta, clas, tys) }}
335 %************************************************************************
337 \subsection{Predicate types}
339 %************************************************************************
341 "Predicates" are particular source types, namelyClassP or IParams
344 isPred :: SourceType -> Bool
345 isPred (ClassP _ _) = True
346 isPred (IParam _ _) = True
347 isPred (NType _ __) = False
349 isPredTy :: Type -> Bool
350 isPredTy (NoteTy _ ty) = isPredTy ty
351 isPredTy (UsageTy _ ty) = isPredTy ty
352 isPredTy (SourceTy sty) = isPred sty
355 tcSplitPredTy_maybe :: Type -> Maybe PredType
356 -- Returns Just for predicates only
357 tcSplitPredTy_maybe (NoteTy _ ty) = tcSplitPredTy_maybe ty
358 tcSplitPredTy_maybe (UsageTy _ ty) = tcSplitPredTy_maybe ty
359 tcSplitPredTy_maybe (SourceTy p) | isPred p = Just p
360 tcSplitPredTy_maybe other = Nothing
362 predTyUnique :: PredType -> Unique
363 predTyUnique (IParam n _) = getUnique n
364 predTyUnique (ClassP clas tys) = getUnique clas
366 predHasFDs :: PredType -> Bool
367 -- True if the predicate has functional depenencies;
368 -- I.e. should participate in improvement
369 predHasFDs (IParam _ _) = True
370 predHasFDs (ClassP cls _) = classHasFDs cls
372 mkPredName :: Unique -> SrcLoc -> SourceType -> Name
373 mkPredName uniq loc (ClassP cls tys) = mkLocalName uniq (mkDictOcc (getOccName cls)) loc
374 mkPredName uniq loc (IParam name ty) = name
378 --------------------- Dictionary types ---------------------------------
381 mkClassPred clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) )
384 isClassPred :: SourceType -> Bool
385 isClassPred (ClassP clas tys) = True
386 isClassPred other = False
388 isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys
389 isTyVarClassPred other = False
391 getClassPredTys_maybe :: SourceType -> Maybe (Class, [Type])
392 getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys)
393 getClassPredTys_maybe _ = Nothing
395 getClassPredTys :: PredType -> (Class, [Type])
396 getClassPredTys (ClassP clas tys) = (clas, tys)
398 mkDictTy :: Class -> [Type] -> Type
399 mkDictTy clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) )
400 mkPredTy (ClassP clas tys)
402 isDictTy :: Type -> Bool
403 isDictTy (SourceTy p) = isClassPred p
404 isDictTy (NoteTy _ ty) = isDictTy ty
405 isDictTy (UsageTy _ ty) = isDictTy ty
406 isDictTy other = False
409 --------------------- Implicit parameters ---------------------------------
412 isIPPred :: SourceType -> Bool
413 isIPPred (IParam _ _) = True
414 isIPPred other = False
416 inheritablePred :: PredType -> Bool
417 -- Can be inherited by a context. For example, consider
418 -- f x = let g y = (?v, y+x)
419 -- in (g 3 with ?v = 8,
421 -- The point is that g's type must be quantifed over ?v:
422 -- g :: (?v :: a) => a -> a
423 -- but it doesn't need to be quantified over the Num a dictionary
424 -- which can be free in g's rhs, and shared by both calls to g
425 inheritablePred (ClassP _ _) = True
426 inheritablePred other = False
428 predMentionsIPs :: SourceType -> NameSet -> Bool
429 predMentionsIPs (IParam n _) ns = n `elemNameSet` ns
430 predMentionsIPs other ns = False
434 %************************************************************************
436 \subsection{Comparison}
438 %************************************************************************
440 Comparison, taking note of newtypes, predicates, etc,
441 But ignoring usage types
444 tcEqType :: Type -> Type -> Bool
445 tcEqType ty1 ty2 = case ty1 `tcCmpType` ty2 of { EQ -> True; other -> False }
447 tcEqPred :: PredType -> PredType -> Bool
448 tcEqPred p1 p2 = case p1 `tcCmpPred` p2 of { EQ -> True; other -> False }
451 tcCmpType :: Type -> Type -> Ordering
452 tcCmpType ty1 ty2 = cmpTy emptyVarEnv ty1 ty2
454 tcCmpTypes tys1 tys2 = cmpTys emptyVarEnv tys1 tys2
456 tcCmpPred p1 p2 = cmpSourceTy emptyVarEnv p1 p2
458 cmpTys env tys1 tys2 = cmpList (cmpTy env) tys1 tys2
461 cmpTy :: TyVarEnv TyVar -> Type -> Type -> Ordering
462 -- The "env" maps type variables in ty1 to type variables in ty2
463 -- So when comparing for-alls.. (forall tv1 . t1) (forall tv2 . t2)
464 -- we in effect substitute tv2 for tv1 in t1 before continuing
466 -- Look through NoteTy and UsageTy
467 cmpTy env (NoteTy _ ty1) ty2 = cmpTy env ty1 ty2
468 cmpTy env ty1 (NoteTy _ ty2) = cmpTy env ty1 ty2
469 cmpTy env (UsageTy _ ty1) ty2 = cmpTy env ty1 ty2
470 cmpTy env ty1 (UsageTy _ ty2) = cmpTy env ty1 ty2
472 -- Deal with equal constructors
473 cmpTy env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
474 Just tv1a -> tv1a `compare` tv2
475 Nothing -> tv1 `compare` tv2
477 cmpTy env (SourceTy p1) (SourceTy p2) = cmpSourceTy env p1 p2
478 cmpTy env (AppTy f1 a1) (AppTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
479 cmpTy env (FunTy f1 a1) (FunTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
480 cmpTy env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2)
481 cmpTy env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTy (extendVarEnv env tv1 tv2) t1 t2
483 -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < SourceTy
484 cmpTy env (AppTy _ _) (TyVarTy _) = GT
486 cmpTy env (FunTy _ _) (TyVarTy _) = GT
487 cmpTy env (FunTy _ _) (AppTy _ _) = GT
489 cmpTy env (TyConApp _ _) (TyVarTy _) = GT
490 cmpTy env (TyConApp _ _) (AppTy _ _) = GT
491 cmpTy env (TyConApp _ _) (FunTy _ _) = GT
493 cmpTy env (ForAllTy _ _) (TyVarTy _) = GT
494 cmpTy env (ForAllTy _ _) (AppTy _ _) = GT
495 cmpTy env (ForAllTy _ _) (FunTy _ _) = GT
496 cmpTy env (ForAllTy _ _) (TyConApp _ _) = GT
498 cmpTy env (SourceTy _) t2 = GT
504 cmpSourceTy :: TyVarEnv TyVar -> SourceType -> SourceType -> Ordering
505 cmpSourceTy env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` (cmpTy env ty1 ty2)
506 -- Compare types as well as names for implicit parameters
507 -- This comparison is used exclusively (I think) for the
508 -- finite map built in TcSimplify
509 cmpSourceTy env (IParam _ _) sty = LT
511 cmpSourceTy env (ClassP _ _) (IParam _ _) = GT
512 cmpSourceTy env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` (cmpTys env tys1 tys2)
513 cmpSourceTy env (ClassP _ _) (NType _ _) = LT
515 cmpSourceTy env (NType tc1 tys1) (NType tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2)
516 cmpSourceTy env (NType _ _) sty = GT
519 PredTypes are used as a FM key in TcSimplify,
520 so we take the easy path and make them an instance of Ord
523 instance Eq SourceType where { (==) = tcEqPred }
524 instance Ord SourceType where { compare = tcCmpPred }
528 %************************************************************************
530 \subsection{Predicates}
532 %************************************************************************
534 isQualifiedTy returns true of any qualified type. It doesn't *necessarily* have
536 f :: (?x::Int) => Int -> Int
539 isQualifiedTy :: Type -> Bool
540 isQualifiedTy (ForAllTy tyvar ty) = True
541 isQualifiedTy (FunTy a b) = isPredTy a
542 isQualifiedTy (NoteTy n ty) = isQualifiedTy ty
543 isQualifiedTy (UsageTy _ ty) = isQualifiedTy ty
544 isQualifiedTy _ = False
546 isOverloadedTy :: Type -> Bool
547 isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty
548 isOverloadedTy (FunTy a b) = isPredTy a
549 isOverloadedTy (NoteTy n ty) = isOverloadedTy ty
550 isOverloadedTy (UsageTy _ ty) = isOverloadedTy ty
551 isOverloadedTy _ = False
555 isFloatTy = is_tc floatTyConKey
556 isDoubleTy = is_tc doubleTyConKey
557 isForeignPtrTy = is_tc foreignPtrTyConKey
558 isIntegerTy = is_tc integerTyConKey
559 isIntTy = is_tc intTyConKey
560 isAddrTy = is_tc addrTyConKey
561 isBoolTy = is_tc boolTyConKey
562 isUnitTy = is_tc (mkTupleTyConUnique Boxed 0)
564 is_tc :: Unique -> Type -> Bool
565 -- Newtypes are opaque to this
566 is_tc uniq ty = case tcSplitTyConApp_maybe ty of
567 Just (tc, _) -> uniq == getUnique tc
572 %************************************************************************
576 %************************************************************************
579 hoistForAllTys :: Type -> Type
580 -- Move all the foralls to the top
581 -- e.g. T -> forall a. a ==> forall a. T -> a
582 -- Careful: LOSES USAGE ANNOTATIONS!
584 = case hoist ty of { (tvs, body) -> mkForAllTys tvs body }
586 hoist :: Type -> ([TyVar], Type)
587 hoist ty = case tcSplitFunTys ty of { (args, res) ->
588 case tcSplitForAllTys res of {
589 ([], body) -> ([], ty) ;
590 (tvs1, body1) -> case hoist body1 of { (tvs2,body2) ->
591 (tvs1 ++ tvs2, mkFunTys args body2)
597 deNoteType :: Type -> Type
598 -- Remove synonyms, but not source types
599 deNoteType ty@(TyVarTy tyvar) = ty
600 deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys)
601 deNoteType (SourceTy p) = SourceTy (deNoteSourceType p)
602 deNoteType (NoteTy _ ty) = deNoteType ty
603 deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg)
604 deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg)
605 deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty)
606 deNoteType (UsageTy u ty) = UsageTy u (deNoteType ty)
608 deNoteSourceType :: SourceType -> SourceType
609 deNoteSourceType (ClassP c tys) = ClassP c (map deNoteType tys)
610 deNoteSourceType (IParam n ty) = IParam n (deNoteType ty)
611 deNoteSourceType (NType tc tys) = NType tc (map deNoteType tys)
614 Find the free names of a type, including the type constructors and classes it mentions
615 This is used in the front end of the compiler
618 namesOfType :: Type -> NameSet
619 namesOfType (TyVarTy tv) = unitNameSet (getName tv)
620 namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` namesOfTypes tys
621 namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1
622 namesOfType (NoteTy other_note ty2) = namesOfType ty2
623 namesOfType (SourceTy (IParam n ty)) = namesOfType ty
624 namesOfType (SourceTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` namesOfTypes tys
625 namesOfType (SourceTy (NType tc tys)) = unitNameSet (getName tc) `unionNameSets` namesOfTypes tys
626 namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res
627 namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg
628 namesOfType (ForAllTy tyvar ty) = namesOfType ty `delFromNameSet` getName tyvar
629 namesOfType (UsageTy u ty) = namesOfType u `unionNameSets` namesOfType ty
631 namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys
633 namesOfDFunHead :: Type -> NameSet
634 -- Find the free type constructors and classes
635 -- of the head of the dfun instance type
636 -- The 'dfun_head_type' is because of
637 -- instance Foo a => Baz T where ...
638 -- The decl is an orphan if Baz and T are both not locally defined,
639 -- even if Foo *is* locally defined
640 namesOfDFunHead dfun_ty = case tcSplitSigmaTy dfun_ty of
641 (tvs,_,head_ty) -> delListFromNameSet (namesOfType head_ty)
646 %************************************************************************
648 \subsection[TysWiredIn-ext-type]{External types}
650 %************************************************************************
652 The compiler's foreign function interface supports the passing of a
653 restricted set of types as arguments and results (the restricting factor
657 isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool
658 -- Checks for valid argument type for a 'foreign import'
659 isFFIArgumentTy dflags safety ty
660 = checkRepTyCon (legalOutgoingTyCon dflags safety) ty
662 isFFIExternalTy :: Type -> Bool
663 -- Types that are allowed as arguments of a 'foreign export'
664 isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty
666 isFFIImportResultTy :: DynFlags -> Type -> Bool
667 isFFIImportResultTy dflags ty
668 = checkRepTyCon (legalFIResultTyCon dflags) ty
670 isFFIExportResultTy :: Type -> Bool
671 isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty
673 isFFIDynArgumentTy :: Type -> Bool
674 -- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr,
675 -- or a newtype of either.
676 isFFIDynArgumentTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon)
678 isFFIDynResultTy :: Type -> Bool
679 -- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr,
680 -- or a newtype of either.
681 isFFIDynResultTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon)
683 isFFILabelTy :: Type -> Bool
684 -- The type of a foreign label must be Ptr, FunPtr, Addr,
685 -- or a newtype of either.
686 isFFILabelTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon)
688 checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool
689 -- Look through newtypes
690 -- Non-recursive ones are transparent to splitTyConApp,
691 -- but recursive ones aren't; hence the splitNewType_maybe
692 checkRepTyCon check_tc ty
693 | Just ty' <- splitNewType_maybe ty = checkRepTyCon check_tc ty'
694 | Just (tc,_) <- splitTyConApp_maybe ty = check_tc tc
698 ----------------------------------------------
699 These chaps do the work; they are not exported
700 ----------------------------------------------
703 legalFEArgTyCon :: TyCon -> Bool
704 -- It's illegal to return foreign objects and (mutable)
705 -- bytearrays from a _ccall_ / foreign declaration
706 -- (or be passed them as arguments in foreign exported functions).
708 | getUnique tc `elem` [ foreignObjTyConKey, foreignPtrTyConKey,
709 byteArrayTyConKey, mutableByteArrayTyConKey ]
711 -- It's also illegal to make foreign exports that take unboxed
712 -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000
714 = boxedMarshalableTyCon tc
716 legalFIResultTyCon :: DynFlags -> TyCon -> Bool
717 legalFIResultTyCon dflags tc
718 | getUnique tc `elem`
719 [ foreignObjTyConKey, foreignPtrTyConKey,
720 byteArrayTyConKey, mutableByteArrayTyConKey ] = False
721 | tc == unitTyCon = True
722 | otherwise = marshalableTyCon dflags tc
724 legalFEResultTyCon :: TyCon -> Bool
725 legalFEResultTyCon tc
726 | getUnique tc `elem`
727 [ foreignObjTyConKey, foreignPtrTyConKey,
728 byteArrayTyConKey, mutableByteArrayTyConKey ] = False
729 | tc == unitTyCon = True
730 | otherwise = boxedMarshalableTyCon tc
732 legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool
733 -- Checks validity of types going from Haskell -> external world
734 legalOutgoingTyCon dflags safety tc
735 | playSafe safety && getUnique tc `elem` [byteArrayTyConKey, mutableByteArrayTyConKey]
738 = marshalableTyCon dflags tc
740 marshalableTyCon dflags tc
741 = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc)
742 || boxedMarshalableTyCon tc
744 boxedMarshalableTyCon tc
745 = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey
746 , int32TyConKey, int64TyConKey
747 , wordTyConKey, word8TyConKey, word16TyConKey
748 , word32TyConKey, word64TyConKey
749 , floatTyConKey, doubleTyConKey
750 , addrTyConKey, ptrTyConKey, funPtrTyConKey
751 , charTyConKey, foreignObjTyConKey
754 , byteArrayTyConKey, mutableByteArrayTyConKey
760 %************************************************************************
762 \subsection{Unification with an explicit substitution}
764 %************************************************************************
766 (allDistinctTyVars tys tvs) = True
768 all the types tys are type variables,
769 distinct from each other and from tvs.
771 This is useful when checking that unification hasn't unified signature
772 type variables. For example, if the type sig is
773 f :: forall a b. a -> b -> b
774 we want to check that 'a' and 'b' havn't
775 (a) been unified with a non-tyvar type
776 (b) been unified with each other (all distinct)
777 (c) been unified with a variable free in the environment
780 allDistinctTyVars :: [Type] -> TyVarSet -> Bool
782 allDistinctTyVars [] acc
784 allDistinctTyVars (ty:tys) acc
785 = case tcGetTyVar_maybe ty of
786 Nothing -> False -- (a)
787 Just tv | tv `elemVarSet` acc -> False -- (b) or (c)
788 | otherwise -> allDistinctTyVars tys (acc `extendVarSet` tv)
792 %************************************************************************
794 \subsection{Unification with an explicit substitution}
796 %************************************************************************
798 Unify types with an explicit substitution and no monad.
799 Ignore usage annotations.
803 = (TyVarSet, -- Set of template tyvars
804 TyVarSubstEnv) -- Not necessarily idempotent
806 unifyTysX :: TyVarSet -- Template tyvars
809 -> Maybe TyVarSubstEnv
810 unifyTysX tmpl_tyvars ty1 ty2
811 = uTysX ty1 ty2 (\(_,s) -> Just s) (tmpl_tyvars, emptySubstEnv)
813 unifyExtendTysX :: TyVarSet -- Template tyvars
814 -> TyVarSubstEnv -- Substitution to start with
817 -> Maybe TyVarSubstEnv -- Extended substitution
818 unifyExtendTysX tmpl_tyvars subst ty1 ty2
819 = uTysX ty1 ty2 (\(_,s) -> Just s) (tmpl_tyvars, subst)
821 unifyTyListsX :: TyVarSet -> [Type] -> [Type]
822 -> Maybe TyVarSubstEnv
823 unifyTyListsX tmpl_tyvars tys1 tys2
824 = uTyListsX tys1 tys2 (\(_,s) -> Just s) (tmpl_tyvars, emptySubstEnv)
829 -> (MySubst -> Maybe result)
833 uTysX (NoteTy _ ty1) ty2 k subst = uTysX ty1 ty2 k subst
834 uTysX ty1 (NoteTy _ ty2) k subst = uTysX ty1 ty2 k subst
836 -- Variables; go for uVar
837 uTysX (TyVarTy tyvar1) (TyVarTy tyvar2) k subst
840 uTysX (TyVarTy tyvar1) ty2 k subst@(tmpls,_)
841 | tyvar1 `elemVarSet` tmpls
842 = uVarX tyvar1 ty2 k subst
843 uTysX ty1 (TyVarTy tyvar2) k subst@(tmpls,_)
844 | tyvar2 `elemVarSet` tmpls
845 = uVarX tyvar2 ty1 k subst
848 uTysX (SourceTy (IParam n1 t1)) (SourceTy (IParam n2 t2)) k subst
849 | n1 == n2 = uTysX t1 t2 k subst
850 uTysX (SourceTy (ClassP c1 tys1)) (SourceTy (ClassP c2 tys2)) k subst
851 | c1 == c2 = uTyListsX tys1 tys2 k subst
852 uTysX (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) k subst
853 | tc1 == tc2 = uTyListsX tys1 tys2 k subst
855 -- Functions; just check the two parts
856 uTysX (FunTy fun1 arg1) (FunTy fun2 arg2) k subst
857 = uTysX fun1 fun2 (uTysX arg1 arg2 k) subst
859 -- Type constructors must match
860 uTysX (TyConApp con1 tys1) (TyConApp con2 tys2) k subst
861 | (con1 == con2 && length tys1 == length tys2)
862 = uTyListsX tys1 tys2 k subst
864 -- Applications need a bit of care!
865 -- They can match FunTy and TyConApp, so use splitAppTy_maybe
866 -- NB: we've already dealt with type variables and Notes,
867 -- so if one type is an App the other one jolly well better be too
868 uTysX (AppTy s1 t1) ty2 k subst
869 = case tcSplitAppTy_maybe ty2 of
870 Just (s2, t2) -> uTysX s1 s2 (uTysX t1 t2 k) subst
871 Nothing -> Nothing -- Fail
873 uTysX ty1 (AppTy s2 t2) k subst
874 = case tcSplitAppTy_maybe ty1 of
875 Just (s1, t1) -> uTysX s1 s2 (uTysX t1 t2 k) subst
876 Nothing -> Nothing -- Fail
878 -- Not expecting for-alls in unification
880 uTysX (ForAllTy _ _) ty2 k subst = panic "Unify.uTysX subst:ForAllTy (1st arg)"
881 uTysX ty1 (ForAllTy _ _) k subst = panic "Unify.uTysX subst:ForAllTy (2nd arg)"
885 uTysX (UsageTy _ t1) t2 k subst = uTysX t1 t2 k subst
886 uTysX t1 (UsageTy _ t2) k subst = uTysX t1 t2 k subst
888 -- Anything else fails
889 uTysX ty1 ty2 k subst = Nothing
892 uTyListsX [] [] k subst = k subst
893 uTyListsX (ty1:tys1) (ty2:tys2) k subst = uTysX ty1 ty2 (uTyListsX tys1 tys2 k) subst
894 uTyListsX tys1 tys2 k subst = Nothing -- Fail if the lists are different lengths
898 -- Invariant: tv1 is a unifiable variable
899 uVarX tv1 ty2 k subst@(tmpls, env)
900 = case lookupSubstEnv env tv1 of
901 Just (DoneTy ty1) -> -- Already bound
902 uTysX ty1 ty2 k subst
904 Nothing -- Not already bound
905 | typeKind ty2 `eqKind` tyVarKind tv1
906 && occur_check_ok ty2
907 -> -- No kind mismatch nor occur check
908 UASSERT( not (isUTy ty2) )
909 k (tmpls, extendSubstEnv env tv1 (DoneTy ty2))
911 | otherwise -> Nothing -- Fail if kind mis-match or occur check
913 occur_check_ok ty = all occur_check_ok_tv (varSetElems (tyVarsOfType ty))
914 occur_check_ok_tv tv | tv1 == tv = False
915 | otherwise = case lookupSubstEnv env tv of
917 Just (DoneTy ty) -> occur_check_ok ty
922 %************************************************************************
924 \subsection{Matching on types}
926 %************************************************************************
928 Matching is a {\em unidirectional} process, matching a type against a
929 template (which is just a type with type variables in it). The
930 matcher assumes that there are no repeated type variables in the
931 template, so that it simply returns a mapping of type variables to
932 types. It also fails on nested foralls.
934 @matchTys@ matches corresponding elements of a list of templates and
935 types. It and @matchTy@ both ignore usage annotations, unlike the
936 main function @match@.
939 matchTy :: TyVarSet -- Template tyvars
941 -> Type -- Proposed instance of template
942 -> Maybe TyVarSubstEnv -- Matching substitution
945 matchTys :: TyVarSet -- Template tyvars
946 -> [Type] -- Templates
947 -> [Type] -- Proposed instance of template
948 -> Maybe (TyVarSubstEnv, -- Matching substitution
949 [Type]) -- Left over instance types
951 matchTy tmpls ty1 ty2 = match ty1 ty2 tmpls (\ senv -> Just senv) emptySubstEnv
953 matchTys tmpls tys1 tys2 = match_list tys1 tys2 tmpls
954 (\ (senv,tys) -> Just (senv,tys))
958 @match@ is the main function. It takes a flag indicating whether
959 usage annotations are to be respected.
962 match :: Type -> Type -- Current match pair
963 -> TyVarSet -- Template vars
964 -> (TyVarSubstEnv -> Maybe result) -- Continuation
965 -> TyVarSubstEnv -- Current subst
968 -- When matching against a type variable, see if the variable
969 -- has already been bound. If so, check that what it's bound to
970 -- is the same as ty; if not, bind it and carry on.
972 match (TyVarTy v) ty tmpls k senv
973 | v `elemVarSet` tmpls
974 = -- v is a template variable
975 case lookupSubstEnv senv v of
976 Nothing -> UASSERT( not (isUTy ty) )
977 k (extendSubstEnv senv v (DoneTy ty))
978 Just (DoneTy ty') | ty' `tcEqType` ty -> k senv -- Succeeds
979 | otherwise -> Nothing -- Fails
982 = -- v is not a template variable; ty had better match
983 -- Can't use (==) because types differ
984 case tcGetTyVar_maybe ty of
985 Just v' | v == v' -> k senv -- Success
986 other -> Nothing -- Failure
987 -- This tcGetTyVar_maybe is *required* because it must strip Notes.
988 -- I guess the reason the Note-stripping case is *last* rather than first
989 -- is to preserve type synonyms etc., so I'm not moving it to the
990 -- top; but this means that (without the deNotetype) a type
991 -- variable may not match the pattern (TyVarTy v') as one would
992 -- expect, due to an intervening Note. KSW 2000-06.
995 match (SourceTy (IParam n1 t1)) (SourceTy (IParam n2 t2)) tmpls k senv
996 | n1 == n2 = match t1 t2 tmpls k senv
997 match (SourceTy (ClassP c1 tys1)) (SourceTy (ClassP c2 tys2)) tmpls k senv
998 | c1 == c2 = match_list_exactly tys1 tys2 tmpls k senv
999 match (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) tmpls k senv
1000 | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv
1002 -- Functions; just check the two parts
1003 match (FunTy arg1 res1) (FunTy arg2 res2) tmpls k senv
1004 = match arg1 arg2 tmpls (match res1 res2 tmpls k) senv
1006 match (AppTy fun1 arg1) ty2 tmpls k senv
1007 = case tcSplitAppTy_maybe ty2 of
1008 Just (fun2,arg2) -> match fun1 fun2 tmpls (match arg1 arg2 tmpls k) senv
1009 Nothing -> Nothing -- Fail
1011 match (TyConApp tc1 tys1) (TyConApp tc2 tys2) tmpls k senv
1012 | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv
1014 -- Newtypes are opaque; other source types should not happen
1015 match (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) tmpls k senv
1016 | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv
1018 match (UsageTy _ ty1) ty2 tmpls k senv = match ty1 ty2 tmpls k senv
1019 match ty1 (UsageTy _ ty2) tmpls k senv = match ty1 ty2 tmpls k senv
1021 -- With type synonyms, we have to be careful for the exact
1022 -- same reasons as in the unifier. Please see the
1023 -- considerable commentary there before changing anything
1024 -- here! (WDP 95/05)
1025 match (NoteTy n1 ty1) ty2 tmpls k senv = match ty1 ty2 tmpls k senv
1026 match ty1 (NoteTy n2 ty2) tmpls k senv = match ty1 ty2 tmpls k senv
1029 match _ _ _ _ _ = Nothing
1031 match_list_exactly tys1 tys2 tmpls k senv
1032 = match_list tys1 tys2 tmpls k' senv
1034 k' (senv', tys2') | null tys2' = k senv' -- Succeed
1035 | otherwise = Nothing -- Fail
1037 match_list [] tys2 tmpls k senv = k (senv, tys2)
1038 match_list (ty1:tys1) [] tmpls k senv = Nothing -- Not enough arg tys => failure
1039 match_list (ty1:tys1) (ty2:tys2) tmpls k senv
1040 = match ty1 ty2 tmpls (match_list tys1 tys2 tmpls k) senv