2 % (c) The GRASP/AQUA Project, Glasgow University, 1998
4 \section[Type]{Type - public interface}
8 -- re-exports from TypeRep:
9 Type, PredType, ThetaType,
12 superKind, superBoxity, -- KX and BX respectively
13 liftedBoxity, unliftedBoxity, -- :: BX
15 typeCon, -- :: BX -> KX
16 liftedTypeKind, unliftedTypeKind, openTypeKind, -- :: KX
17 mkArrowKind, mkArrowKinds, -- :: KX -> KX -> KX
18 isTypeKind, isAnyTypeKind,
21 -- exports from this module:
22 hasMoreBoxityInfo, defaultKind,
24 mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
26 mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe,
28 mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys,
29 funResultTy, funArgTy, zipFunTys, isFunTy,
31 mkGenTyConApp, mkTyConApp, mkTyConTy,
32 tyConAppTyCon, tyConAppArgs,
33 splitTyConApp_maybe, splitTyConApp,
39 mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
40 applyTy, applyTys, isForAllTy, dropForAlls,
43 SourceType(..), sourceTypeRep, mkPredTy, mkPredTys,
49 isUnLiftedType, isUnboxedTupleType, isAlgType, isStrictType, isPrimitiveType,
52 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
53 typeKind, addFreeTyVars,
55 -- Tidying up for printing
57 tidyOpenType, tidyOpenTypes,
58 tidyTyVarBndr, tidyFreeTyVars,
59 tidyOpenTyVar, tidyOpenTyVars,
60 tidyTopType, tidyPred,
70 #include "HsVersions.h"
72 -- We import the representation and primitive functions from TypeRep.
73 -- Many things are reexported, but not the representation!
79 import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages
80 import {-# SOURCE #-} Subst ( substTyWith )
83 import Var ( Id, TyVar, tyVarKind, tyVarName, setTyVarName )
87 import Name ( NamedThing(..), mkInternalName, tidyOccName )
88 import Class ( Class, classTyCon )
89 import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon,
90 isUnboxedTupleTyCon, isUnLiftedTyCon,
91 isFunTyCon, isNewTyCon, newTyConRep,
92 isAlgTyCon, isSynTyCon, tyConArity,
93 tyConKind, getSynTyConDefn,
98 import CmdLineOpts ( opt_DictsStrict )
99 import SrcLoc ( noSrcLoc )
100 import PrimRep ( PrimRep(..) )
101 import Unique ( Uniquable(..) )
102 import Util ( mapAccumL, seqList, lengthIs, snocView )
104 import UniqSet ( sizeUniqSet ) -- Should come via VarSet
105 import Maybe ( isJust )
109 %************************************************************************
111 \subsection{Stuff to do with kinds.}
113 %************************************************************************
116 hasMoreBoxityInfo :: Kind -> Kind -> Bool
117 -- (k1 `hasMoreBoxityInfo` k2) checks that k1 <: k2
118 hasMoreBoxityInfo k1 k2
119 | k2 `eqKind` openTypeKind = isAnyTypeKind k1
120 | otherwise = k1 `eqKind` k2
122 isAnyTypeKind :: Kind -> Bool
123 -- True of kind * and *# and ?
124 isAnyTypeKind (TyConApp tc _) = tc == typeCon || tc == openKindCon
125 isAnyTypeKind (NoteTy _ k) = isAnyTypeKind k
126 isAnyTypeKind other = False
128 isTypeKind :: Kind -> Bool
129 -- True of kind * and *#
130 isTypeKind (TyConApp tc _) = tc == typeCon
131 isTypeKind (NoteTy _ k) = isTypeKind k
132 isTypeKind other = False
134 defaultKind :: Kind -> Kind
135 -- Used when generalising: default kind '?' to '*'
136 defaultKind kind | kind `eqKind` openTypeKind = liftedTypeKind
141 %************************************************************************
143 \subsection{Constructor-specific functions}
145 %************************************************************************
148 ---------------------------------------------------------------------
152 mkTyVarTy :: TyVar -> Type
155 mkTyVarTys :: [TyVar] -> [Type]
156 mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
158 getTyVar :: String -> Type -> TyVar
159 getTyVar msg (TyVarTy tv) = tv
160 getTyVar msg (SourceTy p) = getTyVar msg (sourceTypeRep p)
161 getTyVar msg (NoteTy _ t) = getTyVar msg t
162 getTyVar msg other = panic ("getTyVar: " ++ msg)
164 getTyVar_maybe :: Type -> Maybe TyVar
165 getTyVar_maybe (TyVarTy tv) = Just tv
166 getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t
167 getTyVar_maybe (SourceTy p) = getTyVar_maybe (sourceTypeRep p)
168 getTyVar_maybe other = Nothing
170 isTyVarTy :: Type -> Bool
171 isTyVarTy (TyVarTy tv) = True
172 isTyVarTy (NoteTy _ ty) = isTyVarTy ty
173 isTyVarTy (SourceTy p) = isTyVarTy (sourceTypeRep p)
174 isTyVarTy other = False
178 ---------------------------------------------------------------------
181 We need to be pretty careful with AppTy to make sure we obey the
182 invariant that a TyConApp is always visibly so. mkAppTy maintains the
186 mkAppTy orig_ty1 orig_ty2
187 = ASSERT( not (isSourceTy orig_ty1) ) -- Source types are of kind *
190 mk_app (NoteTy _ ty1) = mk_app ty1
191 mk_app (TyConApp tc tys) = mkGenTyConApp tc (tys ++ [orig_ty2])
192 mk_app ty1 = AppTy orig_ty1 orig_ty2
193 -- We call mkGenTyConApp because the TyConApp could be an
194 -- under-saturated type synonym. GHC allows that; e.g.
195 -- type Foo k = k a -> k a
197 -- foo :: Foo Id -> Foo Id
199 -- Here Id is partially applied in the type sig for Foo,
200 -- but once the type synonyms are expanded all is well
202 mkAppTys :: Type -> [Type] -> Type
203 mkAppTys orig_ty1 [] = orig_ty1
204 -- This check for an empty list of type arguments
205 -- avoids the needless loss of a type synonym constructor.
206 -- For example: mkAppTys Rational []
207 -- returns to (Ratio Integer), which has needlessly lost
208 -- the Rational part.
209 mkAppTys orig_ty1 orig_tys2
210 = ASSERT( not (isSourceTy orig_ty1) ) -- Source types are of kind *
213 mk_app (NoteTy _ ty1) = mk_app ty1
214 mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2)
215 mk_app ty1 = foldl AppTy orig_ty1 orig_tys2
217 splitAppTy_maybe :: Type -> Maybe (Type, Type)
218 splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
219 splitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
220 splitAppTy_maybe (NoteTy _ ty) = splitAppTy_maybe ty
221 splitAppTy_maybe (SourceTy p) = splitAppTy_maybe (sourceTypeRep p)
222 splitAppTy_maybe (TyConApp tc tys) = case snocView tys of
224 Just (tys',ty') -> Just (TyConApp tc tys', ty')
225 splitAppTy_maybe other = Nothing
227 splitAppTy :: Type -> (Type, Type)
228 splitAppTy ty = case splitAppTy_maybe ty of
230 Nothing -> panic "splitAppTy"
232 splitAppTys :: Type -> (Type, [Type])
233 splitAppTys ty = split ty ty []
235 split orig_ty (AppTy ty arg) args = split ty ty (arg:args)
236 split orig_ty (NoteTy _ ty) args = split orig_ty ty args
237 split orig_ty (SourceTy p) args = split orig_ty (sourceTypeRep p) args
238 split orig_ty (FunTy ty1 ty2) args = ASSERT( null args )
239 (TyConApp funTyCon [], [ty1,ty2])
240 split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args)
241 split orig_ty ty args = (orig_ty, args)
245 ---------------------------------------------------------------------
250 mkFunTy :: Type -> Type -> Type
251 mkFunTy arg res = FunTy arg res
253 mkFunTys :: [Type] -> Type -> Type
254 mkFunTys tys ty = foldr FunTy ty tys
256 isFunTy :: Type -> Bool
257 isFunTy ty = isJust (splitFunTy_maybe ty)
259 splitFunTy :: Type -> (Type, Type)
260 splitFunTy (FunTy arg res) = (arg, res)
261 splitFunTy (NoteTy _ ty) = splitFunTy ty
262 splitFunTy (SourceTy p) = splitFunTy (sourceTypeRep p)
264 splitFunTy_maybe :: Type -> Maybe (Type, Type)
265 splitFunTy_maybe (FunTy arg res) = Just (arg, res)
266 splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty
267 splitFunTy_maybe (SourceTy p) = splitFunTy_maybe (sourceTypeRep p)
268 splitFunTy_maybe other = Nothing
270 splitFunTys :: Type -> ([Type], Type)
271 splitFunTys ty = split [] ty ty
273 split args orig_ty (FunTy arg res) = split (arg:args) res res
274 split args orig_ty (NoteTy _ ty) = split args orig_ty ty
275 split args orig_ty (SourceTy p) = split args orig_ty (sourceTypeRep p)
276 split args orig_ty ty = (reverse args, orig_ty)
278 zipFunTys :: Outputable a => [a] -> Type -> ([(a,Type)], Type)
279 zipFunTys orig_xs orig_ty = split [] orig_xs orig_ty orig_ty
281 split acc [] nty ty = (reverse acc, nty)
282 split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res
283 split acc xs nty (NoteTy _ ty) = split acc xs nty ty
284 split acc xs nty (SourceTy p) = split acc xs nty (sourceTypeRep p)
285 split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> pprType orig_ty)
287 funResultTy :: Type -> Type
288 funResultTy (FunTy arg res) = res
289 funResultTy (NoteTy _ ty) = funResultTy ty
290 funResultTy (SourceTy p) = funResultTy (sourceTypeRep p)
291 funResultTy ty = pprPanic "funResultTy" (pprType ty)
293 funArgTy :: Type -> Type
294 funArgTy (FunTy arg res) = arg
295 funArgTy (NoteTy _ ty) = funArgTy ty
296 funArgTy (SourceTy p) = funArgTy (sourceTypeRep p)
297 funArgTy ty = pprPanic "funArgTy" (pprType ty)
301 ---------------------------------------------------------------------
304 @mkTyConApp@ is a key function, because it builds a TyConApp, FunTy or SourceTy,
308 mkGenTyConApp :: TyCon -> [Type] -> Type
310 | isSynTyCon tc = mkSynTy tc tys
311 | otherwise = mkTyConApp tc tys
313 mkTyConApp :: TyCon -> [Type] -> Type
314 -- Assumes TyCon is not a SynTyCon; use mkSynTy instead for those
316 | isFunTyCon tycon, [ty1,ty2] <- tys
319 | isNewTyCon tycon, -- A saturated newtype application;
320 not (isRecursiveTyCon tycon), -- Not recursive (we don't use SourceTypes for them)
321 tys `lengthIs` tyConArity tycon -- use the SourceType form
322 = SourceTy (NType tycon tys)
325 = ASSERT(not (isSynTyCon tycon))
328 mkTyConTy :: TyCon -> Type
329 mkTyConTy tycon = ASSERT( not (isSynTyCon tycon) )
332 -- splitTyConApp "looks through" synonyms, because they don't
333 -- mean a distinct type, but all other type-constructor applications
334 -- including functions are returned as Just ..
336 tyConAppTyCon :: Type -> TyCon
337 tyConAppTyCon ty = fst (splitTyConApp ty)
339 tyConAppArgs :: Type -> [Type]
340 tyConAppArgs ty = snd (splitTyConApp ty)
342 splitTyConApp :: Type -> (TyCon, [Type])
343 splitTyConApp ty = case splitTyConApp_maybe ty of
345 Nothing -> pprPanic "splitTyConApp" (pprType ty)
347 splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
348 splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
349 splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
350 splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty
351 splitTyConApp_maybe (SourceTy p) = splitTyConApp_maybe (sourceTypeRep p)
352 splitTyConApp_maybe other = Nothing
356 ---------------------------------------------------------------------
362 | n_args == arity -- Exactly saturated
364 | n_args > arity -- Over-saturated
365 = case splitAt arity tys of { (as,bs) -> mkAppTys (mk_syn as) bs }
366 -- Its important to use mkAppTys, rather than (foldl AppTy),
367 -- because (mk_syn as) might well return a partially-applied
368 -- type constructor; indeed, usually will!
369 | otherwise -- Un-saturated
371 -- For the un-saturated case we build TyConApp directly
372 -- (mkTyConApp ASSERTs that the tc isn't a SynTyCon).
373 -- Here we are relying on checkValidType to find
374 -- the error. What we can't do is use mkSynTy with
375 -- too few arg tys, because that is utterly bogus.
378 mk_syn tys = NoteTy (SynNote (TyConApp tycon tys))
379 (substTyWith tyvars tys body)
381 (tyvars, body) = ASSERT( isSynTyCon tycon ) getSynTyConDefn tycon
382 arity = tyConArity tycon
386 Notes on type synonyms
387 ~~~~~~~~~~~~~~~~~~~~~~
388 The various "split" functions (splitFunTy, splitRhoTy, splitForAllTy) try
389 to return type synonyms whereever possible. Thus
394 splitFunTys (a -> Foo a) = ([a], Foo a)
397 The reason is that we then get better (shorter) type signatures in
398 interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs.
403 repType looks through
407 (d) usage annotations
408 (e) [recursive] newtypes
409 It's useful in the back end.
411 Remember, non-recursive newtypes get expanded as part of the SourceTy case,
412 but recursive ones are represented by TyConApps and have to be expanded
416 repType :: Type -> Type
417 repType (ForAllTy _ ty) = repType ty
418 repType (NoteTy _ ty) = repType ty
419 repType (SourceTy p) = repType (sourceTypeRep p)
420 repType (TyConApp tc tys) | isNewTyCon tc && tys `lengthIs` tyConArity tc
421 = repType (newTypeRep tc tys)
425 typePrimRep :: Type -> PrimRep
426 typePrimRep ty = case repType ty of
427 TyConApp tc _ -> tyConPrimRep tc
429 AppTy _ _ -> PtrRep -- ??
435 ---------------------------------------------------------------------
440 mkForAllTy :: TyVar -> Type -> Type
442 = mkForAllTys [tyvar] ty
444 mkForAllTys :: [TyVar] -> Type -> Type
445 mkForAllTys tyvars ty = foldr ForAllTy ty tyvars
447 isForAllTy :: Type -> Bool
448 isForAllTy (NoteTy _ ty) = isForAllTy ty
449 isForAllTy (ForAllTy _ _) = True
450 isForAllTy other_ty = False
452 splitForAllTy_maybe :: Type -> Maybe (TyVar, Type)
453 splitForAllTy_maybe ty = splitFAT_m ty
455 splitFAT_m (NoteTy _ ty) = splitFAT_m ty
456 splitFAT_m (SourceTy p) = splitFAT_m (sourceTypeRep p)
457 splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty)
458 splitFAT_m _ = Nothing
460 splitForAllTys :: Type -> ([TyVar], Type)
461 splitForAllTys ty = split ty ty []
463 split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
464 split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs
465 split orig_ty (SourceTy p) tvs = split orig_ty (sourceTypeRep p) tvs
466 split orig_ty t tvs = (reverse tvs, orig_ty)
468 dropForAlls :: Type -> Type
469 dropForAlls ty = snd (splitForAllTys ty)
472 -- (mkPiType now in CoreUtils)
476 Instantiate a for-all type with one or more type arguments.
477 Used when we have a polymorphic function applied to type args:
479 Then we use (applyTys type-of-f [t1,t2]) to compute the type of
483 applyTy :: Type -> Type -> Type
484 applyTy (SourceTy p) arg = applyTy (sourceTypeRep p) arg
485 applyTy (NoteTy _ fun) arg = applyTy fun arg
486 applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty
487 applyTy other arg = panic "applyTy"
489 applyTys :: Type -> [Type] -> Type
490 -- This function is interesting because
491 -- a) the function may have more for-alls than there are args
492 -- b) less obviously, it may have fewer for-alls
493 -- For case (b) think of
494 -- applyTys (forall a.a) [forall b.b, Int]
495 -- This really can happen, via dressing up polymorphic types with newtype
496 -- clothing. Here's an example:
497 -- newtype R = R (forall a. a->a)
498 -- foo = case undefined :: R of
501 applyTys orig_fun_ty [] = orig_fun_ty
502 applyTys orig_fun_ty arg_tys
503 | n_tvs == n_args -- The vastly common case
504 = substTyWith tvs arg_tys rho_ty
505 | n_tvs > n_args -- Too many for-alls
506 = substTyWith (take n_args tvs) arg_tys
507 (mkForAllTys (drop n_args tvs) rho_ty)
508 | otherwise -- Too many type args
509 = ASSERT2( n_tvs > 0, pprType orig_fun_ty ) -- Zero case gives infnite loop!
510 applyTys (substTyWith tvs (take n_tvs arg_tys) rho_ty)
513 (tvs, rho_ty) = splitForAllTys orig_fun_ty
515 n_args = length arg_tys
519 %************************************************************************
521 \subsection{Source types}
523 %************************************************************************
525 A "source type" is a type that is a separate type as far as the type checker is
526 concerned, but which has low-level representation as far as the back end is concerned.
528 Source types are always lifted.
530 The key function is sourceTypeRep which gives the representation of a source type:
533 mkPredTy :: PredType -> Type
534 mkPredTy pred = SourceTy pred
536 mkPredTys :: ThetaType -> [Type]
537 mkPredTys preds = map SourceTy preds
539 sourceTypeRep :: SourceType -> Type
540 -- Convert a predicate to its "representation type";
541 -- the type of evidence for that predicate, which is actually passed at runtime
542 sourceTypeRep (IParam _ ty) = ty
543 sourceTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys
544 -- Note the mkTyConApp; the classTyCon might be a newtype!
545 sourceTypeRep (NType tc tys) = newTypeRep tc tys
546 -- ToDo: Consider caching this substitution in a NType
548 isSourceTy :: Type -> Bool
549 isSourceTy (NoteTy _ ty) = isSourceTy ty
550 isSourceTy (SourceTy sty) = True
554 splitNewType_maybe :: Type -> Maybe Type
555 -- Newtypes that are recursive are reprsented by TyConApp, just
556 -- as they always were. Occasionally we want to find their representation type.
557 -- NB: remember that in this module, non-recursive newtypes are transparent
559 splitNewType_maybe ty
560 = case splitTyConApp_maybe ty of
561 Just (tc,tys) | isNewTyCon tc -> ASSERT( tys `lengthIs` tyConArity tc )
562 -- The assert should hold because repType should
563 -- only be applied to *types* (of kind *)
564 Just (newTypeRep tc tys)
567 -- A local helper function (not exported)
568 newTypeRep new_tycon tys = case newTyConRep new_tycon of
569 (tvs, rep_ty) -> substTyWith tvs tys rep_ty
573 %************************************************************************
575 \subsection{Kinds and free variables}
577 %************************************************************************
579 ---------------------------------------------------------------------
580 Finding the kind of a type
581 ~~~~~~~~~~~~~~~~~~~~~~~~~~
583 typeKind :: Type -> Kind
585 typeKind (TyVarTy tyvar) = tyVarKind tyvar
586 typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
587 typeKind (NoteTy _ ty) = typeKind ty
588 typeKind (SourceTy _) = liftedTypeKind -- Predicates are always
589 -- represented by lifted types
590 typeKind (AppTy fun arg) = funResultTy (typeKind fun)
592 typeKind (FunTy arg res) = fix_up (typeKind res)
594 fix_up (TyConApp tycon _) | tycon == typeCon
595 || tycon == openKindCon = liftedTypeKind
596 fix_up (NoteTy _ kind) = fix_up kind
598 -- The basic story is
599 -- typeKind (FunTy arg res) = typeKind res
600 -- But a function is lifted regardless of its result type
601 -- Hence the strange fix-up.
602 -- Note that 'res', being the result of a FunTy, can't have
603 -- a strange kind like (*->*).
605 typeKind (ForAllTy tv ty) = typeKind ty
609 ---------------------------------------------------------------------
610 Free variables of a type
611 ~~~~~~~~~~~~~~~~~~~~~~~~
613 tyVarsOfType :: Type -> TyVarSet
614 tyVarsOfType (TyVarTy tv) = unitVarSet tv
615 tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
616 tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
617 tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty2 -- See note [Syn] below
618 tyVarsOfType (SourceTy sty) = tyVarsOfSourceType sty
619 tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionVarSet` tyVarsOfType res
620 tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionVarSet` tyVarsOfType arg
621 tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusVarSet` unitVarSet tyvar
626 -- What are the free tyvars of (T x)? Empty, of course!
627 -- Here's the example that Ralf Laemmel showed me:
628 -- foo :: (forall a. C u a -> C u a) -> u
629 -- mappend :: Monoid u => u -> u -> u
631 -- bar :: Monoid u => u
632 -- bar = foo (\t -> t `mappend` t)
633 -- We have to generalise at the arg to f, and we don't
634 -- want to capture the constraint (Monad (C u a)) because
635 -- it appears to mention a. Pretty silly, but it was useful to him.
638 tyVarsOfTypes :: [Type] -> TyVarSet
639 tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
641 tyVarsOfPred :: PredType -> TyVarSet
642 tyVarsOfPred = tyVarsOfSourceType -- Just a subtype
644 tyVarsOfSourceType :: SourceType -> TyVarSet
645 tyVarsOfSourceType (IParam _ ty) = tyVarsOfType ty
646 tyVarsOfSourceType (ClassP _ tys) = tyVarsOfTypes tys
647 tyVarsOfSourceType (NType _ tys) = tyVarsOfTypes tys
649 tyVarsOfTheta :: ThetaType -> TyVarSet
650 tyVarsOfTheta = foldr (unionVarSet . tyVarsOfSourceType) emptyVarSet
652 -- Add a Note with the free tyvars to the top of the type
653 addFreeTyVars :: Type -> Type
654 addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty
655 addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty
658 %************************************************************************
660 \subsection{TidyType}
662 %************************************************************************
664 tidyTy tidies up a type for printing in an error message, or in
667 It doesn't change the uniques at all, just the print names.
670 tidyTyVarBndr :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
671 tidyTyVarBndr (tidy_env, subst) tyvar
672 = case tidyOccName tidy_env (getOccName name) of
673 (tidy', occ') -> -- New occname reqd
674 ((tidy', subst'), tyvar')
676 subst' = extendVarEnv subst tyvar tyvar'
677 tyvar' = setTyVarName tyvar name'
678 name' = mkInternalName (getUnique name) occ' noSrcLoc
679 -- Note: make a *user* tyvar, so it printes nicely
680 -- Could extract src loc, but no need.
682 name = tyVarName tyvar
684 tidyFreeTyVars :: TidyEnv -> TyVarSet -> TidyEnv
685 -- Add the free tyvars to the env in tidy form,
686 -- so that we can tidy the type they are free in
687 tidyFreeTyVars env tyvars = fst (tidyOpenTyVars env (varSetElems tyvars))
689 tidyOpenTyVars :: TidyEnv -> [TyVar] -> (TidyEnv, [TyVar])
690 tidyOpenTyVars env tyvars = mapAccumL tidyOpenTyVar env tyvars
692 tidyOpenTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
693 -- Treat a new tyvar as a binder, and give it a fresh tidy name
694 tidyOpenTyVar env@(tidy_env, subst) tyvar
695 = case lookupVarEnv subst tyvar of
696 Just tyvar' -> (env, tyvar') -- Already substituted
697 Nothing -> tidyTyVarBndr env tyvar -- Treat it as a binder
699 tidyType :: TidyEnv -> Type -> Type
700 tidyType env@(tidy_env, subst) ty
703 go (TyVarTy tv) = case lookupVarEnv subst tv of
704 Nothing -> TyVarTy tv
705 Just tv' -> TyVarTy tv'
706 go (TyConApp tycon tys) = let args = map go tys
707 in args `seqList` TyConApp tycon args
708 go (NoteTy note ty) = (NoteTy $! (go_note note)) $! (go ty)
709 go (SourceTy sty) = SourceTy (tidySourceType env sty)
710 go (AppTy fun arg) = (AppTy $! (go fun)) $! (go arg)
711 go (FunTy fun arg) = (FunTy $! (go fun)) $! (go arg)
712 go (ForAllTy tv ty) = ForAllTy tvp $! (tidyType envp ty)
714 (envp, tvp) = tidyTyVarBndr env tv
716 go_note (SynNote ty) = SynNote $! (go ty)
717 go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars
719 tidyTypes env tys = map (tidyType env) tys
721 tidyPred :: TidyEnv -> SourceType -> SourceType
722 tidyPred = tidySourceType
724 tidySourceType :: TidyEnv -> SourceType -> SourceType
725 tidySourceType env (IParam n ty) = IParam n (tidyType env ty)
726 tidySourceType env (ClassP clas tys) = ClassP clas (tidyTypes env tys)
727 tidySourceType env (NType tc tys) = NType tc (tidyTypes env tys)
731 @tidyOpenType@ grabs the free type variables, tidies them
732 and then uses @tidyType@ to work over the type itself
735 tidyOpenType :: TidyEnv -> Type -> (TidyEnv, Type)
737 = (env', tidyType env' ty)
739 env' = tidyFreeTyVars env (tyVarsOfType ty)
741 tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type])
742 tidyOpenTypes env tys = mapAccumL tidyOpenType env tys
744 tidyTopType :: Type -> Type
745 tidyTopType ty = tidyType emptyTidyEnv ty
750 %************************************************************************
752 \subsection{Liftedness}
754 %************************************************************************
757 isUnLiftedType :: Type -> Bool
758 -- isUnLiftedType returns True for forall'd unlifted types:
759 -- x :: forall a. Int#
760 -- I found bindings like these were getting floated to the top level.
761 -- They are pretty bogus types, mind you. It would be better never to
764 isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
765 isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty
766 isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
767 isUnLiftedType (SourceTy _) = False -- All source types are lifted
768 isUnLiftedType other = False
770 isUnboxedTupleType :: Type -> Bool
771 isUnboxedTupleType ty = case splitTyConApp_maybe ty of
772 Just (tc, ty_args) -> isUnboxedTupleTyCon tc
775 -- Should only be applied to *types*; hence the assert
776 isAlgType :: Type -> Bool
777 isAlgType ty = case splitTyConApp_maybe ty of
778 Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
783 @isStrictType@ computes whether an argument (or let RHS) should
784 be computed strictly or lazily, based only on its type.
785 Works just like isUnLiftedType, except that it has a special case
786 for dictionaries. Since it takes account of ClassP, you might think
787 this function should be in TcType, but isStrictType is used by DataCon,
788 which is below TcType in the hierarchy, so it's convenient to put it here.
791 isStrictType (ForAllTy tv ty) = isStrictType ty
792 isStrictType (NoteTy _ ty) = isStrictType ty
793 isStrictType (TyConApp tc _) = isUnLiftedTyCon tc
794 isStrictType (SourceTy (ClassP clas _)) = opt_DictsStrict && not (isNewTyCon (classTyCon clas))
795 -- We may be strict in dictionary types, but only if it
796 -- has more than one component.
797 -- [Being strict in a single-component dictionary risks
798 -- poking the dictionary component, which is wrong.]
799 isStrictType other = False
803 isPrimitiveType :: Type -> Bool
804 -- Returns types that are opaque to Haskell.
805 -- Most of these are unlifted, but now that we interact with .NET, we
806 -- may have primtive (foreign-imported) types that are lifted
807 isPrimitiveType ty = case splitTyConApp_maybe ty of
808 Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
814 %************************************************************************
816 \subsection{Sequencing on types
818 %************************************************************************
821 seqType :: Type -> ()
822 seqType (TyVarTy tv) = tv `seq` ()
823 seqType (AppTy t1 t2) = seqType t1 `seq` seqType t2
824 seqType (FunTy t1 t2) = seqType t1 `seq` seqType t2
825 seqType (NoteTy note t2) = seqNote note `seq` seqType t2
826 seqType (SourceTy p) = seqPred p
827 seqType (TyConApp tc tys) = tc `seq` seqTypes tys
828 seqType (ForAllTy tv ty) = tv `seq` seqType ty
830 seqTypes :: [Type] -> ()
832 seqTypes (ty:tys) = seqType ty `seq` seqTypes tys
834 seqNote :: TyNote -> ()
835 seqNote (SynNote ty) = seqType ty
836 seqNote (FTVNote set) = sizeUniqSet set `seq` ()
838 seqPred :: SourceType -> ()
839 seqPred (ClassP c tys) = c `seq` seqTypes tys
840 seqPred (NType tc tys) = tc `seq` seqTypes tys
841 seqPred (IParam n ty) = n `seq` seqType ty
845 %************************************************************************
847 \subsection{Equality on types}
849 %************************************************************************
851 Comparison; don't use instances so that we know where it happens.
852 Look through newtypes but not usage types.
854 Note that eqType can respond 'False' for partial applications of newtypes.
856 newtype Parser m a = MkParser (Foogle m a)
859 Monad (Parser m) `eqType` Monad (Foogle m)
861 Well, yes, but eqType won't see that they are the same.
862 I don't think this is harmful, but it's soemthing to watch out for.
865 eqType t1 t2 = eq_ty emptyVarEnv t1 t2
866 eqKind = eqType -- No worries about looking
868 -- Look through Notes
869 eq_ty env (NoteTy _ t1) t2 = eq_ty env t1 t2
870 eq_ty env t1 (NoteTy _ t2) = eq_ty env t1 t2
872 -- Look through SourceTy. This is where the looping danger comes from
873 eq_ty env (SourceTy sty1) t2 = eq_ty env (sourceTypeRep sty1) t2
874 eq_ty env t1 (SourceTy sty2) = eq_ty env t1 (sourceTypeRep sty2)
876 -- The rest is plain sailing
877 eq_ty env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
878 Just tv1a -> tv1a == tv2
879 Nothing -> tv1 == tv2
880 eq_ty env (ForAllTy tv1 t1) (ForAllTy tv2 t2)
881 | tv1 == tv2 = eq_ty (delVarEnv env tv1) t1 t2
882 | otherwise = eq_ty (extendVarEnv env tv1 tv2) t1 t2
883 eq_ty env (AppTy s1 t1) (AppTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
884 eq_ty env (FunTy s1 t1) (FunTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
885 eq_ty env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 == tc2) && (eq_tys env tys1 tys2)
886 eq_ty env t1 t2 = False
888 eq_tys env [] [] = True
889 eq_tys env (t1:tys1) (t2:tys2) = (eq_ty env t1 t2) && (eq_tys env tys1 tys2)
890 eq_tys env tys1 tys2 = False