X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcType.lhs;h=dbf52a6cc57954fcf5cff8ce980b73eee7e7d5e5;hb=61bfd5dd3b9d70404d6f93c030a9bb1c402b9d31;hp=038789bac742e5e180ebbff829a537cc851a3493;hpb=7e602b0a11e567fcb035d1afd34015aebcf9a577;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcType.lhs b/ghc/compiler/typecheck/TcType.lhs index 038789b..dbf52a6 100644 --- a/ghc/compiler/typecheck/TcType.lhs +++ b/ghc/compiler/typecheck/TcType.lhs @@ -3,483 +3,1108 @@ % \section[TcType]{Types used in the typechecker} -\begin{code} -module TcType ( - - TcTyVar, - TcTyVarSet, - newTyVar, - newTyVarTy, -- Kind -> NF_TcM s TcType - newTyVarTys, -- Int -> Kind -> NF_TcM s [TcType] - - newTyVarTy_OpenKind, -- NF_TcM s TcType - newOpenTypeKind, -- NF_TcM s TcKind - - ----------------------------------------- - TcType, TcTauType, TcThetaType, TcRhoType, +This module provides the Type interface for front-end parts of the +compiler. These parts - -- Find the type to which a type variable is bound - tcPutTyVar, -- :: TcTyVar -> TcType -> NF_TcM TcType - tcGetTyVar, -- :: TcTyVar -> NF_TcM (Maybe TcType) does shorting out + * treat "source types" as opaque: + newtypes, and predicates are meaningful. + * look through usage types +The "tc" prefix is for "typechechecker", because the type checker +is the principal client. - tcSplitRhoTy, - - tcInstTyVars, - tcInstTcType, - - typeToTcType, +\begin{code} +module TcType ( + -------------------------------- + -- Types + TcType, TcTauType, TcPredType, TcThetaType, TcRhoType, + TcTyVar, TcTyVarSet, TcKind, - tcTypeKind, -- :: TcType -> NF_TcM s TcKind -------------------------------- - TcKind, - newKindVar, newKindVars, - kindToTcKind, - zonkTcKind, + -- TyVarDetails + TyVarDetails(..), isUserTyVar, isSkolemTyVar, -------------------------------- - zonkTcTyVar, zonkTcTyVars, zonkTcTyVarBndr, - zonkTcType, zonkTcTypes, zonkTcThetaType, + -- Builders + mkRhoTy, mkSigmaTy, - zonkTcTypeToType, zonkTcTyVarToTyVar, - zonkTcKindToKind + -------------------------------- + -- Splitters + -- These are important because they do not look through newtypes + tcSplitForAllTys, tcSplitRhoTy, + tcSplitFunTy_maybe, tcSplitFunTys, tcFunArgTy, tcFunResultTy, + tcSplitTyConApp, tcSplitTyConApp_maybe, tcTyConAppTyCon, tcTyConAppArgs, + tcSplitAppTy_maybe, tcSplitAppTy, tcSplitSigmaTy, + tcSplitMethodTy, tcGetTyVar_maybe, tcGetTyVar, + + --------------------------------- + -- Predicates. + -- Again, newtypes are opaque + tcEqType, tcEqPred, tcCmpType, tcCmpTypes, tcCmpPred, + isQualifiedTy, isOverloadedTy, + isDoubleTy, isFloatTy, isIntTy, + isIntegerTy, isAddrTy, isBoolTy, isUnitTy, isForeignPtrTy, + isTauTy, tcIsTyVarTy, tcIsForAllTy, + + --------------------------------- + -- Misc type manipulators + hoistForAllTys, deNoteType, + namesOfType, namesOfDFunHead, + getDFunTyKey, + + --------------------------------- + -- Predicate types + PredType, getClassPredTys_maybe, getClassPredTys, + isPredTy, isClassPred, isTyVarClassPred, predHasFDs, + mkDictTy, tcSplitPredTy_maybe, predTyUnique, + isDictTy, tcSplitDFunTy, predTyUnique, + mkClassPred, inheritablePred, isIPPred, mkPredName, + + --------------------------------- + -- Foreign import and export + isFFIArgumentTy, -- :: DynFlags -> Safety -> Type -> Bool + isFFIImportResultTy, -- :: DynFlags -> Type -> Bool + isFFIExportResultTy, -- :: Type -> Bool + isFFIExternalTy, -- :: Type -> Bool + isFFIDynArgumentTy, -- :: Type -> Bool + isFFIDynResultTy, -- :: Type -> Bool + isFFILabelTy, -- :: Type -> Bool + + --------------------------------- + -- Unifier and matcher + unifyTysX, unifyTyListsX, unifyExtendTysX, + allDistinctTyVars, + matchTy, matchTys, match, + -------------------------------- + -- Rexported from Type + Kind, -- Stuff to do with kinds is insensitive to pre/post Tc + unliftedTypeKind, liftedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds, + superBoxity, liftedBoxity, hasMoreBoxityInfo, defaultKind, superKind, + isTypeKind, + + Type, SourceType(..), PredType, ThetaType, + mkForAllTy, mkForAllTys, + mkFunTy, mkFunTys, zipFunTys, + mkTyConApp, mkAppTy, mkAppTys, mkSynTy, applyTy, applyTys, + mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys, + + isUnLiftedType, -- Source types are always lifted + isUnboxedTupleType, -- Ditto + isPrimitiveType, + + tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes, + tidyTyVarBndr, tidyOpenTyVar, tidyOpenTyVars, + typeKind, eqKind, eqUsage, + + tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta ) where #include "HsVersions.h" +import {-# SOURCE #-} PprType( pprType ) + -- friends: -import PprType ( pprType ) -import Type ( Type(..), Kind, ThetaType, TyNote(..), - mkAppTy, mkTyConApp, - splitDictTy_maybe, splitForAllTys, - isTyVarTy, mkTyVarTy, mkTyVarTys, - fullSubstTy, substTopTy, - typeCon, openTypeKind, boxedTypeKind, boxedKind, superKind, superBoxity +import TypeRep ( Type(..), TyNote(..), funTyCon ) -- friend +import Type ( mkUTyM, unUTy ) -- Used locally + +import Type ( -- Re-exports + tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta, + Kind, Type, TauType, SourceType(..), PredType, ThetaType, + unliftedTypeKind, liftedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds, + mkForAllTy, mkForAllTys, defaultKind, isTypeKind, + mkFunTy, mkFunTys, zipFunTys, + mkTyConApp, mkAppTy, mkAppTys, mkSynTy, applyTy, applyTys, + mkTyVarTy, mkTyVarTys, mkTyConTy, mkPredTy, mkPredTys, + isUnLiftedType, isUnboxedTupleType, isPrimitiveType, + splitNewType_maybe, splitTyConApp_maybe, + tidyTopType, tidyType, tidyPred, tidyTypes, tidyFreeTyVars, tidyOpenType, tidyOpenTypes, + tidyTyVarBndr, tidyOpenTyVar, tidyOpenTyVars, eqKind, eqUsage, + hasMoreBoxityInfo, liftedBoxity, superBoxity, typeKind, superKind ) -import TyCon ( tyConKind ) +import TyCon ( TyCon, isUnLiftedTyCon ) +import Class ( classHasFDs, Class ) +import Var ( TyVar, tyVarKind ) +import ForeignCall ( Safety, playSafe ) import VarEnv -import VarSet ( emptyVarSet ) -import Var ( TyVar, tyVarKind, tyVarName, isTyVar, isMutTyVar, mkTyVar ) +import VarSet -- others: -import TcMonad -import TysWiredIn ( voidTy ) - -import Name ( NamedThing(..), setNameUnique, mkSysLocalName ) -import Unique ( Unique ) -import Util ( nOfThem ) +import CmdLineOpts ( DynFlags, DynFlag( Opt_GlasgowExts ), dopt ) +import Name ( Name, NamedThing(..), mkLocalName ) +import OccName ( OccName, mkDictOcc ) +import NameSet +import PrelNames -- Lots (e.g. in isFFIArgumentTy) +import TysWiredIn ( ptrTyCon, funPtrTyCon, addrTyCon, unitTyCon ) +import Unique ( Unique, Uniquable(..) ) +import SrcLoc ( SrcLoc ) +import Util ( cmpList, thenCmp, equalLength ) +import Maybes ( maybeToBool, expectJust ) import Outputable \end{code} - -Coercions -~~~~~~~~~~ -Type definitions are in TcMonad.lhs +%************************************************************************ +%* * +\subsection{Types} +%* * +%************************************************************************ \begin{code} -typeToTcType :: Type -> TcType -typeToTcType ty = ty - -kindToTcKind :: Kind -> TcKind -kindToTcKind kind = kind +type TcTyVar = TyVar -- Might be a mutable tyvar +type TcTyVarSet = TyVarSet + +type TcType = Type -- A TcType can have mutable type variables + -- Invariant on ForAllTy in TcTypes: + -- forall a. T + -- a cannot occur inside a MutTyVar in T; that is, + -- T is "flattened" before quantifying over a + +type TcPredType = PredType +type TcThetaType = ThetaType +type TcRhoType = Type +type TcTauType = TauType +type TcKind = TcType \end{code} -Utility functions -~~~~~~~~~~~~~~~~~ -These tcSplit functions are like their non-Tc analogues, but they -follow through bound type variables. -No need for tcSplitForAllTy because a type variable can't be instantiated -to a for-all type. +%************************************************************************ +%* * +\subsection{TyVarDetails} +%* * +%************************************************************************ + +TyVarDetails gives extra info about type variables, used during type +checking. It's attached to mutable type variables only. \begin{code} -tcSplitRhoTy :: TcType -> NF_TcM s (TcThetaType, TcType) -tcSplitRhoTy t - = go t t [] - where - -- A type variable is never instantiated to a dictionary type, - -- so we don't need to do a tcReadVar on the "arg". - go syn_t (FunTy arg res) ts = case splitDictTy_maybe arg of - Just pair -> go res res (pair:ts) - Nothing -> returnNF_Tc (reverse ts, syn_t) - go syn_t (NoteTy _ t) ts = go syn_t t ts - go syn_t (TyVarTy tv) ts = tcGetTyVar tv `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Just ty | not (isTyVarTy ty) -> go syn_t ty ts - other -> returnNF_Tc (reverse ts, syn_t) - go syn_t t ts = returnNF_Tc (reverse ts, syn_t) +data TyVarDetails + = SigTv -- Introduced when instantiating a type signature, + -- prior to checking that the defn of a fn does + -- have the expected type. Should not be instantiated. + -- + -- f :: forall a. a -> a + -- f = e + -- When checking e, with expected type (a->a), we + -- should not instantiate a + + | ClsTv -- Scoped type variable introduced by a class decl + -- class C a where ... + + | InstTv -- Ditto, but instance decl + + | PatSigTv -- Scoped type variable, introduced by a pattern + -- type signature + -- \ x::a -> e + + | VanillaTv -- Everything else + +isUserTyVar :: TyVarDetails -> Bool -- Avoid unifying these if possible +isUserTyVar VanillaTv = False +isUserTyVar other = True + +isSkolemTyVar :: TyVarDetails -> Bool +isSkolemTyVar SigTv = True +isSkolemTyVar other = False + +instance Outputable TyVarDetails where + ppr SigTv = ptext SLIT("type signature") + ppr ClsTv = ptext SLIT("class declaration") + ppr InstTv = ptext SLIT("instance declaration") + ppr PatSigTv = ptext SLIT("pattern type signature") + ppr VanillaTv = ptext SLIT("???") \end{code} %************************************************************************ %* * -\subsection{New type variables} +\subsection{Tau, sigma and rho} %* * %************************************************************************ \begin{code} -newTyVar :: Kind -> NF_TcM s TcTyVar -newTyVar kind - = tcGetUnique `thenNF_Tc` \ uniq -> - tcNewMutTyVar (mkSysLocalName uniq SLIT("t")) kind - -newTyVarTy :: Kind -> NF_TcM s TcType -newTyVarTy kind - = newTyVar kind `thenNF_Tc` \ tc_tyvar -> - returnNF_Tc (TyVarTy tc_tyvar) - -newTyVarTys :: Int -> Kind -> NF_TcM s [TcType] -newTyVarTys n kind = mapNF_Tc newTyVarTy (nOfThem n kind) - -newKindVar :: NF_TcM s TcKind -newKindVar - = tcGetUnique `thenNF_Tc` \ uniq -> - tcNewMutTyVar (mkSysLocalName uniq SLIT("k")) superKind `thenNF_Tc` \ kv -> - returnNF_Tc (TyVarTy kv) - -newKindVars :: Int -> NF_TcM s [TcKind] -newKindVars n = mapNF_Tc (\ _ -> newKindVar) (nOfThem n ()) - --- Returns a type variable of kind (Type bv) where bv is a new boxity var --- Used when you need a type variable that's definitely a , but you don't know --- what kind of type (boxed or unboxed). -newTyVarTy_OpenKind :: NF_TcM s TcType -newTyVarTy_OpenKind = newOpenTypeKind `thenNF_Tc` \ kind -> - newTyVarTy kind - -newOpenTypeKind :: NF_TcM s TcKind -newOpenTypeKind = newTyVarTy superBoxity `thenNF_Tc` \ bv -> - returnNF_Tc (mkTyConApp typeCon [bv]) +mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau) + +mkRhoTy :: [SourceType] -> Type -> Type +mkRhoTy theta ty = UASSERT2( not (isUTy ty), pprType ty ) + foldr (\p r -> FunTy (mkUTyM (mkPredTy p)) (mkUTyM r)) ty theta + +\end{code} + + +@isTauTy@ tests for nested for-alls. + +\begin{code} +isTauTy :: Type -> Bool +isTauTy (TyVarTy v) = True +isTauTy (TyConApp _ tys) = all isTauTy tys +isTauTy (AppTy a b) = isTauTy a && isTauTy b +isTauTy (FunTy a b) = isTauTy a && isTauTy b +isTauTy (SourceTy p) = True -- Don't look through source types +isTauTy (NoteTy _ ty) = isTauTy ty +isTauTy (UsageTy _ ty) = isTauTy ty +isTauTy other = False +\end{code} + +\begin{code} +getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to + -- construct a dictionary function name +getDFunTyKey (TyVarTy tv) = getOccName tv +getDFunTyKey (TyConApp tc _) = getOccName tc +getDFunTyKey (AppTy fun _) = getDFunTyKey fun +getDFunTyKey (NoteTy _ t) = getDFunTyKey t +getDFunTyKey (FunTy arg _) = getOccName funTyCon +getDFunTyKey (ForAllTy _ t) = getDFunTyKey t +getDFunTyKey (UsageTy _ t) = getDFunTyKey t +getDFunTyKey (SourceTy (NType tc _)) = getOccName tc -- Newtypes are quite reasonable +getDFunTyKey ty = pprPanic "getDFunTyKey" (pprType ty) +-- SourceTy shouldn't happen \end{code} %************************************************************************ %* * -\subsection{Type instantiation} +\subsection{Expanding and splitting} %* * %************************************************************************ -Instantiating a bunch of type variables +These tcSplit functions are like their non-Tc analogues, but + a) they do not look through newtypes + b) they do not look through PredTys + c) [future] they ignore usage-type annotations + +However, they are non-monadic and do not follow through mutable type +variables. It's up to you to make sure this doesn't matter. \begin{code} -tcInstTyVars :: [TyVar] - -> NF_TcM s ([TcTyVar], [TcType], TyVarEnv TcType) - -tcInstTyVars tyvars - = mapNF_Tc inst_tyvar tyvars `thenNF_Tc` \ tc_tyvars -> - let - tys = mkTyVarTys tc_tyvars - in - returnNF_Tc (tc_tyvars, tys, zipVarEnv tyvars tys) - -inst_tyvar tyvar -- Could use the name from the tyvar? - = tcGetUnique `thenNF_Tc` \ uniq -> - let - kind = tyVarKind tyvar - name = setNameUnique (tyVarName tyvar) uniq - -- Note that we don't change the print-name - -- This won't confuse the type checker but there's a chance - -- that two different tyvars will print the same way - -- in an error message. -dppr-debug will show up the difference - -- Better watch out for this. If worst comes to worst, just - -- use mkSysLocalName. - in - tcNewMutTyVar name kind +tcSplitForAllTys :: Type -> ([TyVar], Type) +tcSplitForAllTys ty = split ty ty [] + where + split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs) + split orig_ty (NoteTy n ty) tvs = split orig_ty ty tvs + split orig_ty (UsageTy _ ty) tvs = split orig_ty ty tvs + split orig_ty t tvs = (reverse tvs, orig_ty) + +tcIsForAllTy (ForAllTy tv ty) = True +tcIsForAllTy (NoteTy n ty) = tcIsForAllTy ty +tcIsForAllTy (UsageTy n ty) = tcIsForAllTy ty +tcIsForAllTy t = False + +tcSplitRhoTy :: Type -> ([PredType], Type) +tcSplitRhoTy ty = split ty ty [] + where + split orig_ty (FunTy arg res) ts = case tcSplitPredTy_maybe arg of + Just p -> split res res (p:ts) + Nothing -> (reverse ts, orig_ty) + split orig_ty (NoteTy n ty) ts = split orig_ty ty ts + split orig_ty (UsageTy _ ty) ts = split orig_ty ty ts + split orig_ty ty ts = (reverse ts, orig_ty) + +tcSplitSigmaTy ty = case tcSplitForAllTys ty of + (tvs, rho) -> case tcSplitRhoTy rho of + (theta, tau) -> (tvs, theta, tau) + +tcTyConAppTyCon :: Type -> TyCon +tcTyConAppTyCon ty = fst (tcSplitTyConApp ty) + +tcTyConAppArgs :: Type -> [Type] +tcTyConAppArgs ty = snd (tcSplitTyConApp ty) + +tcSplitTyConApp :: Type -> (TyCon, [Type]) +tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of + Just stuff -> stuff + Nothing -> pprPanic "tcSplitTyConApp" (pprType ty) + +tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type]) +-- Newtypes are opaque, so they may be split +tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys) +tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [unUTy arg,unUTy res]) +tcSplitTyConApp_maybe (NoteTy n ty) = tcSplitTyConApp_maybe ty +tcSplitTyConApp_maybe (UsageTy _ ty) = tcSplitTyConApp_maybe ty +tcSplitTyConApp_maybe (SourceTy (NType tc tys)) = Just (tc,tys) + -- However, predicates are not treated + -- as tycon applications by the type checker +tcSplitTyConApp_maybe other = Nothing + +tcSplitFunTys :: Type -> ([Type], Type) +tcSplitFunTys ty = case tcSplitFunTy_maybe ty of + Nothing -> ([], ty) + Just (arg,res) -> (arg:args, res') + where + (args,res') = tcSplitFunTys res + +tcSplitFunTy_maybe :: Type -> Maybe (Type, Type) +tcSplitFunTy_maybe (FunTy arg res) = Just (arg, res) +tcSplitFunTy_maybe (NoteTy n ty) = tcSplitFunTy_maybe ty +tcSplitFunTy_maybe (UsageTy _ ty) = tcSplitFunTy_maybe ty +tcSplitFunTy_maybe other = Nothing + +tcFunArgTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> arg } +tcFunResultTy ty = case tcSplitFunTy_maybe ty of { Just (arg,res) -> res } + + +tcSplitAppTy_maybe :: Type -> Maybe (Type, Type) +tcSplitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [unUTy ty1], unUTy ty2) +tcSplitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2) +tcSplitAppTy_maybe (NoteTy n ty) = tcSplitAppTy_maybe ty +tcSplitAppTy_maybe (UsageTy _ ty) = tcSplitAppTy_maybe ty +tcSplitAppTy_maybe (SourceTy (NType tc tys)) = tc_split_app tc tys + --- Don't forget that newtype! +tcSplitAppTy_maybe (TyConApp tc tys) = tc_split_app tc tys +tcSplitAppTy_maybe other = Nothing + +tc_split_app tc [] = Nothing +tc_split_app tc tys = split tys [] + where + split [ty2] acc = Just (TyConApp tc (reverse acc), ty2) + split (ty:tys) acc = split tys (ty:acc) + +tcSplitAppTy ty = case tcSplitAppTy_maybe ty of + Just stuff -> stuff + Nothing -> pprPanic "tcSplitAppTy" (pprType ty) + +tcGetTyVar_maybe :: Type -> Maybe TyVar +tcGetTyVar_maybe (TyVarTy tv) = Just tv +tcGetTyVar_maybe (NoteTy _ t) = tcGetTyVar_maybe t +tcGetTyVar_maybe ty@(UsageTy _ _) = pprPanic "tcGetTyVar_maybe: UTy:" (pprType ty) +tcGetTyVar_maybe other = Nothing + +tcGetTyVar :: String -> Type -> TyVar +tcGetTyVar msg ty = expectJust msg (tcGetTyVar_maybe ty) + +tcIsTyVarTy :: Type -> Bool +tcIsTyVarTy ty = maybeToBool (tcGetTyVar_maybe ty) \end{code} -@tcInstTcType@ instantiates the outer-level for-alls of a TcType with -fresh type variables, returning them and the instantiated body of the for-all. +The type of a method for class C is always of the form: + Forall a1..an. C a1..an => sig_ty +where sig_ty is the type given by the method's signature, and thus in general +is a ForallTy. At the point that splitMethodTy is called, it is expected +that the outer Forall has already been stripped off. splitMethodTy then +returns (C a1..an, sig_ty') where sig_ty' is sig_ty with any Notes or +Usages stripped off. \begin{code} -tcInstTcType :: TcType -> NF_TcM s ([TcTyVar], TcType) -tcInstTcType ty - = case splitForAllTys ty of - ([], _) -> returnNF_Tc ([], ty) -- Nothing to do - (tyvars, rho) -> tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', _, tenv) -> - returnNF_Tc (tyvars', fullSubstTy tenv emptyVarSet rho) - -- Since the tyvars are freshly made, - -- they cannot possibly be captured by - -- any existing for-alls. Hence emptyVarSet +tcSplitMethodTy :: Type -> (PredType, Type) +tcSplitMethodTy ty = split ty + where + split (FunTy arg res) = case tcSplitPredTy_maybe arg of + Just p -> (p, res) + Nothing -> panic "splitMethodTy" + split (NoteTy n ty) = split ty + split (UsageTy _ ty) = split ty + split _ = panic "splitMethodTy" + +tcSplitDFunTy :: Type -> ([TyVar], [SourceType], Class, [Type]) +-- Split the type of a dictionary function +tcSplitDFunTy ty + = case tcSplitSigmaTy ty of { (tvs, theta, tau) -> + case tcSplitPredTy_maybe tau of { Just (ClassP clas tys) -> + (tvs, theta, clas, tys) }} \end{code} - %************************************************************************ %* * -\subsection{Putting and getting mutable type variables} +\subsection{Predicate types} %* * %************************************************************************ +"Predicates" are particular source types, namelyClassP or IParams + \begin{code} -tcPutTyVar :: TcTyVar -> TcType -> NF_TcM s TcType -tcGetTyVar :: TcTyVar -> NF_TcM s (Maybe TcType) +isPred :: SourceType -> Bool +isPred (ClassP _ _) = True +isPred (IParam _ _) = True +isPred (NType _ __) = False + +isPredTy :: Type -> Bool +isPredTy (NoteTy _ ty) = isPredTy ty +isPredTy (UsageTy _ ty) = isPredTy ty +isPredTy (SourceTy sty) = isPred sty +isPredTy _ = False + +tcSplitPredTy_maybe :: Type -> Maybe PredType + -- Returns Just for predicates only +tcSplitPredTy_maybe (NoteTy _ ty) = tcSplitPredTy_maybe ty +tcSplitPredTy_maybe (UsageTy _ ty) = tcSplitPredTy_maybe ty +tcSplitPredTy_maybe (SourceTy p) | isPred p = Just p +tcSplitPredTy_maybe other = Nothing + +predTyUnique :: PredType -> Unique +predTyUnique (IParam n _) = getUnique n +predTyUnique (ClassP clas tys) = getUnique clas + +predHasFDs :: PredType -> Bool +-- True if the predicate has functional depenencies; +-- I.e. should participate in improvement +predHasFDs (IParam _ _) = True +predHasFDs (ClassP cls _) = classHasFDs cls + +mkPredName :: Unique -> SrcLoc -> SourceType -> Name +mkPredName uniq loc (ClassP cls tys) = mkLocalName uniq (mkDictOcc (getOccName cls)) loc +mkPredName uniq loc (IParam name ty) = name \end{code} -Putting is easy: + +--------------------- Dictionary types --------------------------------- \begin{code} -tcPutTyVar tyvar ty = tcWriteMutTyVar tyvar (Just ty) `thenNF_Tc_` - returnNF_Tc ty -\end{code} +mkClassPred clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) ) + ClassP clas tys + +isClassPred :: SourceType -> Bool +isClassPred (ClassP clas tys) = True +isClassPred other = False + +isTyVarClassPred (ClassP clas tys) = all tcIsTyVarTy tys +isTyVarClassPred other = False + +getClassPredTys_maybe :: SourceType -> Maybe (Class, [Type]) +getClassPredTys_maybe (ClassP clas tys) = Just (clas, tys) +getClassPredTys_maybe _ = Nothing -Getting is more interesting. The easy thing to do is just to read, thus: +getClassPredTys :: PredType -> (Class, [Type]) +getClassPredTys (ClassP clas tys) = (clas, tys) -\begin{verbatim} -tcGetTyVar tyvar = tcReadMutTyVar tyvar -\end{verbatim} +mkDictTy :: Class -> [Type] -> Type +mkDictTy clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) ) + mkPredTy (ClassP clas tys) -But it's more fun to short out indirections on the way: If this -version returns a TyVar, then that TyVar is unbound. If it returns -any other type, then there might be bound TyVars embedded inside it. +isDictTy :: Type -> Bool +isDictTy (SourceTy p) = isClassPred p +isDictTy (NoteTy _ ty) = isDictTy ty +isDictTy (UsageTy _ ty) = isDictTy ty +isDictTy other = False +\end{code} -We return Nothing iff the original box was unbound. +--------------------- Implicit parameters --------------------------------- \begin{code} -tcGetTyVar tyvar - = ASSERT2( isMutTyVar tyvar, ppr tyvar ) - tcReadMutTyVar tyvar `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Just ty -> short_out ty `thenNF_Tc` \ ty' -> - tcWriteMutTyVar tyvar (Just ty') `thenNF_Tc_` - returnNF_Tc (Just ty') +isIPPred :: SourceType -> Bool +isIPPred (IParam _ _) = True +isIPPred other = False + +inheritablePred :: PredType -> Bool +-- Can be inherited by a context. For example, consider +-- f x = let g y = (?v, y+x) +-- in (g 3 with ?v = 8, +-- g 4 with ?v = 9) +-- The point is that g's type must be quantifed over ?v: +-- g :: (?v :: a) => a -> a +-- but it doesn't need to be quantified over the Num a dictionary +-- which can be free in g's rhs, and shared by both calls to g +inheritablePred (ClassP _ _) = True +inheritablePred other = False +\end{code} - Nothing -> returnNF_Tc Nothing -short_out :: TcType -> NF_TcM s TcType -short_out ty@(TyVarTy tyvar) - | not (isMutTyVar tyvar) - = returnNF_Tc ty +%************************************************************************ +%* * +\subsection{Comparison} +%* * +%************************************************************************ - | otherwise - = tcReadMutTyVar tyvar `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Just ty' -> short_out ty' `thenNF_Tc` \ ty' -> - tcWriteMutTyVar tyvar (Just ty') `thenNF_Tc_` - returnNF_Tc ty' +Comparison, taking note of newtypes, predicates, etc, +But ignoring usage types - other -> returnNF_Tc ty +\begin{code} +tcEqType :: Type -> Type -> Bool +tcEqType ty1 ty2 = case ty1 `tcCmpType` ty2 of { EQ -> True; other -> False } + +tcEqPred :: PredType -> PredType -> Bool +tcEqPred p1 p2 = case p1 `tcCmpPred` p2 of { EQ -> True; other -> False } + +------------- +tcCmpType :: Type -> Type -> Ordering +tcCmpType ty1 ty2 = cmpTy emptyVarEnv ty1 ty2 + +tcCmpTypes tys1 tys2 = cmpTys emptyVarEnv tys1 tys2 + +tcCmpPred p1 p2 = cmpSourceTy emptyVarEnv p1 p2 +------------- +cmpTys env tys1 tys2 = cmpList (cmpTy env) tys1 tys2 + +------------- +cmpTy :: TyVarEnv TyVar -> Type -> Type -> Ordering + -- The "env" maps type variables in ty1 to type variables in ty2 + -- So when comparing for-alls.. (forall tv1 . t1) (forall tv2 . t2) + -- we in effect substitute tv2 for tv1 in t1 before continuing + + -- Look through NoteTy and UsageTy +cmpTy env (NoteTy _ ty1) ty2 = cmpTy env ty1 ty2 +cmpTy env ty1 (NoteTy _ ty2) = cmpTy env ty1 ty2 +cmpTy env (UsageTy _ ty1) ty2 = cmpTy env ty1 ty2 +cmpTy env ty1 (UsageTy _ ty2) = cmpTy env ty1 ty2 + + -- Deal with equal constructors +cmpTy env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of + Just tv1a -> tv1a `compare` tv2 + Nothing -> tv1 `compare` tv2 + +cmpTy env (SourceTy p1) (SourceTy p2) = cmpSourceTy env p1 p2 +cmpTy env (AppTy f1 a1) (AppTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2 +cmpTy env (FunTy f1 a1) (FunTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2 +cmpTy env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2) +cmpTy env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTy (extendVarEnv env tv1 tv2) t1 t2 + + -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < SourceTy +cmpTy env (AppTy _ _) (TyVarTy _) = GT + +cmpTy env (FunTy _ _) (TyVarTy _) = GT +cmpTy env (FunTy _ _) (AppTy _ _) = GT + +cmpTy env (TyConApp _ _) (TyVarTy _) = GT +cmpTy env (TyConApp _ _) (AppTy _ _) = GT +cmpTy env (TyConApp _ _) (FunTy _ _) = GT + +cmpTy env (ForAllTy _ _) (TyVarTy _) = GT +cmpTy env (ForAllTy _ _) (AppTy _ _) = GT +cmpTy env (ForAllTy _ _) (FunTy _ _) = GT +cmpTy env (ForAllTy _ _) (TyConApp _ _) = GT + +cmpTy env (SourceTy _) t2 = GT + +cmpTy env _ _ = LT +\end{code} + +\begin{code} +cmpSourceTy :: TyVarEnv TyVar -> SourceType -> SourceType -> Ordering +cmpSourceTy env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` (cmpTy env ty1 ty2) + -- Compare types as well as names for implicit parameters + -- This comparison is used exclusively (I think) for the + -- finite map built in TcSimplify +cmpSourceTy env (IParam _ _) sty = LT + +cmpSourceTy env (ClassP _ _) (IParam _ _) = GT +cmpSourceTy env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` (cmpTys env tys1 tys2) +cmpSourceTy env (ClassP _ _) (NType _ _) = LT + +cmpSourceTy env (NType tc1 tys1) (NType tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2) +cmpSourceTy env (NType _ _) sty = GT +\end{code} + +PredTypes are used as a FM key in TcSimplify, +so we take the easy path and make them an instance of Ord -short_out other_ty = returnNF_Tc other_ty +\begin{code} +instance Eq SourceType where { (==) = tcEqPred } +instance Ord SourceType where { compare = tcCmpPred } \end{code} %************************************************************************ %* * -\subsection{Zonking -- the exernal interfaces} +\subsection{Predicates} %* * %************************************************************************ ------------------ Type variables +isQualifiedTy returns true of any qualified type. It doesn't *necessarily* have +any foralls. E.g. + f :: (?x::Int) => Int -> Int \begin{code} -zonkTcTyVars :: [TcTyVar] -> NF_TcM s [TcType] -zonkTcTyVars tyvars = mapNF_Tc zonkTcTyVar tyvars +isQualifiedTy :: Type -> Bool +isQualifiedTy (ForAllTy tyvar ty) = True +isQualifiedTy (FunTy a b) = isPredTy a +isQualifiedTy (NoteTy n ty) = isQualifiedTy ty +isQualifiedTy (UsageTy _ ty) = isQualifiedTy ty +isQualifiedTy _ = False + +isOverloadedTy :: Type -> Bool +isOverloadedTy (ForAllTy tyvar ty) = isOverloadedTy ty +isOverloadedTy (FunTy a b) = isPredTy a +isOverloadedTy (NoteTy n ty) = isOverloadedTy ty +isOverloadedTy (UsageTy _ ty) = isOverloadedTy ty +isOverloadedTy _ = False +\end{code} -zonkTcTyVarBndr :: TcTyVar -> NF_TcM s TcTyVar -zonkTcTyVarBndr tyvar - = zonkTcTyVar tyvar `thenNF_Tc` \ (TyVarTy tyvar') -> - returnNF_Tc tyvar' - -zonkTcTyVar :: TcTyVar -> NF_TcM s TcType -zonkTcTyVar tyvar = zonkTyVar (\ tv -> returnNF_Tc (TyVarTy tv)) tyvar +\begin{code} +isFloatTy = is_tc floatTyConKey +isDoubleTy = is_tc doubleTyConKey +isForeignPtrTy = is_tc foreignPtrTyConKey +isIntegerTy = is_tc integerTyConKey +isIntTy = is_tc intTyConKey +isAddrTy = is_tc addrTyConKey +isBoolTy = is_tc boolTyConKey +isUnitTy = is_tc unitTyConKey + +is_tc :: Unique -> Type -> Bool +-- Newtypes are opaque to this +is_tc uniq ty = case tcSplitTyConApp_maybe ty of + Just (tc, _) -> uniq == getUnique tc + Nothing -> False \end{code} ------------------ Types -\begin{code} -zonkTcType :: TcType -> NF_TcM s TcType -zonkTcType ty = zonkType (\ tv -> returnNF_Tc (TyVarTy tv)) ty +%************************************************************************ +%* * +\subsection{Misc} +%* * +%************************************************************************ -zonkTcTypes :: [TcType] -> NF_TcM s [TcType] -zonkTcTypes tys = mapNF_Tc zonkTcType tys +\begin{code} +hoistForAllTys :: Type -> Type + -- Move all the foralls to the top + -- e.g. T -> forall a. a ==> forall a. T -> a + -- Careful: LOSES USAGE ANNOTATIONS! +hoistForAllTys ty + = case hoist ty of { (tvs, body) -> mkForAllTys tvs body } + where + hoist :: Type -> ([TyVar], Type) + hoist ty = case tcSplitFunTys ty of { (args, res) -> + case tcSplitForAllTys res of { + ([], body) -> ([], ty) ; + (tvs1, body1) -> case hoist body1 of { (tvs2,body2) -> + (tvs1 ++ tvs2, mkFunTys args body2) + }}} +\end{code} -zonkTcThetaType :: TcThetaType -> NF_TcM s TcThetaType -zonkTcThetaType theta = mapNF_Tc zonk theta - where - zonk (c,ts) = zonkTcTypes ts `thenNF_Tc` \ new_ts -> - returnNF_Tc (c, new_ts) -zonkTcKind :: TcKind -> NF_TcM s TcKind -zonkTcKind = zonkTcType +\begin{code} +deNoteType :: Type -> Type + -- Remove synonyms, but not source types +deNoteType ty@(TyVarTy tyvar) = ty +deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys) +deNoteType (SourceTy p) = SourceTy (deNoteSourceType p) +deNoteType (NoteTy _ ty) = deNoteType ty +deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg) +deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg) +deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty) +deNoteType (UsageTy u ty) = UsageTy u (deNoteType ty) + +deNoteSourceType :: SourceType -> SourceType +deNoteSourceType (ClassP c tys) = ClassP c (map deNoteType tys) +deNoteSourceType (IParam n ty) = IParam n (deNoteType ty) +deNoteSourceType (NType tc tys) = NType tc (map deNoteType tys) \end{code} -------------------- These ...ToType, ...ToKind versions - are used at the end of type checking +Find the free names of a type, including the type constructors and classes it mentions +This is used in the front end of the compiler \begin{code} -zonkTcKindToKind :: TcKind -> NF_TcM s Kind -zonkTcKindToKind kind = zonkType zonk_unbound_kind_var kind - where - -- Zonk a mutable but unbound kind variable to - -- (Type Boxed) if it has kind superKind - -- Boxed if it has kind superBoxity - zonk_unbound_kind_var kv - | super_kind == superKind = tcPutTyVar kv boxedTypeKind - | otherwise = ASSERT( super_kind == superBoxity ) - tcPutTyVar kv boxedKind - where - super_kind = tyVarKind kv - - -zonkTcTypeToType :: TcType -> NF_TcM s Type -zonkTcTypeToType ty = zonkType zonk_unbound_tyvar ty - where - -- Zonk a mutable but unbound type variable to - -- Void if it has kind (Type Boxed) - -- Voidxxx otherwise - zonk_unbound_tyvar tv - = zonkTcKindToKind (tyVarKind tv) `thenNF_Tc` \ kind -> - if kind == boxedTypeKind then - tcPutTyVar tv voidTy -- Just to creating a new tycon in - -- this vastly common case - else - tcPutTyVar tv (TyConApp (mk_void_tycon tv) []) - - mk_void_tycon tv -- Make a new TyCon with the same kind as the - -- type variable tv. Same name too, apart from - -- making it start with a capital letter (sigh) - -- I can't quite bring myself to write the Name-fiddling - -- code yet. ToDo. SLPJ Nov 98 - = pprPanic "zonkTcTypeToType: free type variable with non-* type:" (ppr tv) - - --- zonkTcTyVarToTyVar is applied to the *binding* occurrence --- of a type variable, at the *end* of type checking. --- It zonks the type variable, to get a mutable, but unbound, tyvar, tv; --- zonks its kind, and then makes an immutable version of tv and binds tv to it. --- Now any bound occurences of the original type variable will get --- zonked to the immutable version. - -zonkTcTyVarToTyVar :: TcTyVar -> NF_TcM s TyVar -zonkTcTyVarToTyVar tv - = zonkTcKindToKind (tyVarKind tv) `thenNF_Tc` \ kind -> - let - -- Make an immutable version - immut_tv = mkTyVar (tyVarName tv) kind - immut_tv_ty = mkTyVarTy immut_tv - - zap tv = tcPutTyVar tv immut_tv_ty - -- Bind the mutable version to the immutable one - in - -- If the type variable is mutable, then bind it to immut_tv_ty - -- so that all other occurrences of the tyvar will get zapped too - zonkTyVar zap tv `thenNF_Tc` \ ty2 -> - ASSERT2( immut_tv_ty == ty2, ppr tv $$ ppr immut_tv $$ ppr ty2 ) - - returnNF_Tc immut_tv +namesOfType :: Type -> NameSet +namesOfType (TyVarTy tv) = unitNameSet (getName tv) +namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` namesOfTypes tys +namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1 +namesOfType (NoteTy other_note ty2) = namesOfType ty2 +namesOfType (SourceTy (IParam n ty)) = namesOfType ty +namesOfType (SourceTy (ClassP cl tys)) = unitNameSet (getName cl) `unionNameSets` namesOfTypes tys +namesOfType (SourceTy (NType tc tys)) = unitNameSet (getName tc) `unionNameSets` namesOfTypes tys +namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res +namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg +namesOfType (ForAllTy tyvar ty) = namesOfType ty `delFromNameSet` getName tyvar +namesOfType (UsageTy u ty) = namesOfType u `unionNameSets` namesOfType ty + +namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys + +namesOfDFunHead :: Type -> NameSet +-- Find the free type constructors and classes +-- of the head of the dfun instance type +-- The 'dfun_head_type' is because of +-- instance Foo a => Baz T where ... +-- The decl is an orphan if Baz and T are both not locally defined, +-- even if Foo *is* locally defined +namesOfDFunHead dfun_ty = case tcSplitSigmaTy dfun_ty of + (tvs,_,head_ty) -> delListFromNameSet (namesOfType head_ty) + (map getName tvs) \end{code} %************************************************************************ %* * -\subsection{Zonking -- the main work-horses: zonkType, zonkTyVar} -%* * -%* For internal use only! * +\subsection[TysWiredIn-ext-type]{External types} %* * %************************************************************************ +The compiler's foreign function interface supports the passing of a +restricted set of types as arguments and results (the restricting factor +being the ) + \begin{code} --- zonkType is used for Kinds as well - --- For unbound, mutable tyvars, zonkType uses the function given to it --- For tyvars bound at a for-all, zonkType zonks them to an immutable --- type variable and zonks the kind too - -zonkType :: (TcTyVar -> NF_TcM s Type) -- What to do with unbound mutable type variables - -- see zonkTcType, and zonkTcTypeToType - -> TcType - -> NF_TcM s Type -zonkType unbound_var_fn ty - = go ty - where - go (TyConApp tycon tys) = mapNF_Tc go tys `thenNF_Tc` \ tys' -> - returnNF_Tc (TyConApp tycon tys') +isFFIArgumentTy :: DynFlags -> Safety -> Type -> Bool +-- Checks for valid argument type for a 'foreign import' +isFFIArgumentTy dflags safety ty + = checkRepTyCon (legalOutgoingTyCon dflags safety) ty + +isFFIExternalTy :: Type -> Bool +-- Types that are allowed as arguments of a 'foreign export' +isFFIExternalTy ty = checkRepTyCon legalFEArgTyCon ty + +isFFIImportResultTy :: DynFlags -> Type -> Bool +isFFIImportResultTy dflags ty + = checkRepTyCon (legalFIResultTyCon dflags) ty + +isFFIExportResultTy :: Type -> Bool +isFFIExportResultTy ty = checkRepTyCon legalFEResultTyCon ty + +isFFIDynArgumentTy :: Type -> Bool +-- The argument type of a foreign import dynamic must be Ptr, FunPtr, Addr, +-- or a newtype of either. +isFFIDynArgumentTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon) + +isFFIDynResultTy :: Type -> Bool +-- The result type of a foreign export dynamic must be Ptr, FunPtr, Addr, +-- or a newtype of either. +isFFIDynResultTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon) + +isFFILabelTy :: Type -> Bool +-- The type of a foreign label must be Ptr, FunPtr, Addr, +-- or a newtype of either. +isFFILabelTy = checkRepTyCon (\tc -> tc == ptrTyCon || tc == funPtrTyCon || tc == addrTyCon) + +checkRepTyCon :: (TyCon -> Bool) -> Type -> Bool + -- Look through newtypes + -- Non-recursive ones are transparent to splitTyConApp, + -- but recursive ones aren't; hence the splitNewType_maybe +checkRepTyCon check_tc ty + | Just ty' <- splitNewType_maybe ty = checkRepTyCon check_tc ty' + | Just (tc,_) <- splitTyConApp_maybe ty = check_tc tc + | otherwise = False +\end{code} + +---------------------------------------------- +These chaps do the work; they are not exported +---------------------------------------------- + +\begin{code} +legalFEArgTyCon :: TyCon -> Bool +-- It's illegal to return foreign objects and (mutable) +-- bytearrays from a _ccall_ / foreign declaration +-- (or be passed them as arguments in foreign exported functions). +legalFEArgTyCon tc + | getUnique tc `elem` [ foreignObjTyConKey, foreignPtrTyConKey, + byteArrayTyConKey, mutableByteArrayTyConKey ] + = False + -- It's also illegal to make foreign exports that take unboxed + -- arguments. The RTS API currently can't invoke such things. --SDM 7/2000 + | otherwise + = boxedMarshalableTyCon tc + +legalFIResultTyCon :: DynFlags -> TyCon -> Bool +legalFIResultTyCon dflags tc + | getUnique tc `elem` + [ foreignObjTyConKey, foreignPtrTyConKey, + byteArrayTyConKey, mutableByteArrayTyConKey ] = False + | tc == unitTyCon = True + | otherwise = marshalableTyCon dflags tc + +legalFEResultTyCon :: TyCon -> Bool +legalFEResultTyCon tc + | getUnique tc `elem` + [ foreignObjTyConKey, foreignPtrTyConKey, + byteArrayTyConKey, mutableByteArrayTyConKey ] = False + | tc == unitTyCon = True + | otherwise = boxedMarshalableTyCon tc + +legalOutgoingTyCon :: DynFlags -> Safety -> TyCon -> Bool +-- Checks validity of types going from Haskell -> external world +legalOutgoingTyCon dflags safety tc + | playSafe safety && getUnique tc `elem` [byteArrayTyConKey, mutableByteArrayTyConKey] + = False + | otherwise + = marshalableTyCon dflags tc + +marshalableTyCon dflags tc + = (dopt Opt_GlasgowExts dflags && isUnLiftedTyCon tc) + || boxedMarshalableTyCon tc + +boxedMarshalableTyCon tc + = getUnique tc `elem` [ intTyConKey, int8TyConKey, int16TyConKey + , int32TyConKey, int64TyConKey + , wordTyConKey, word8TyConKey, word16TyConKey + , word32TyConKey, word64TyConKey + , floatTyConKey, doubleTyConKey + , addrTyConKey, ptrTyConKey, funPtrTyConKey + , charTyConKey, foreignObjTyConKey + , foreignPtrTyConKey + , stablePtrTyConKey + , byteArrayTyConKey, mutableByteArrayTyConKey + , boolTyConKey + ] +\end{code} - go (NoteTy (SynNote ty1) ty2) = go ty1 `thenNF_Tc` \ ty1' -> - go ty2 `thenNF_Tc` \ ty2' -> - returnNF_Tc (NoteTy (SynNote ty1') ty2') - go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard free-tyvar annotations +%************************************************************************ +%* * +\subsection{Unification with an explicit substitution} +%* * +%************************************************************************ - go (FunTy arg res) = go arg `thenNF_Tc` \ arg' -> - go res `thenNF_Tc` \ res' -> - returnNF_Tc (FunTy arg' res') - - go (AppTy fun arg) = go fun `thenNF_Tc` \ fun' -> - go arg `thenNF_Tc` \ arg' -> - returnNF_Tc (mkAppTy fun' arg') +(allDistinctTyVars tys tvs) = True + iff +all the types tys are type variables, +distinct from each other and from tvs. - -- The two interesting cases! - go (TyVarTy tyvar) = zonkTyVar unbound_var_fn tyvar +This is useful when checking that unification hasn't unified signature +type variables. For example, if the type sig is + f :: forall a b. a -> b -> b +we want to check that 'a' and 'b' havn't + (a) been unified with a non-tyvar type + (b) been unified with each other (all distinct) + (c) been unified with a variable free in the environment - go (ForAllTy tyvar ty) - = zonkTcTyVarToTyVar tyvar `thenNF_Tc` \ tyvar' -> - go ty `thenNF_Tc` \ ty' -> - returnNF_Tc (ForAllTy tyvar' ty') +\begin{code} +allDistinctTyVars :: [Type] -> TyVarSet -> Bool +allDistinctTyVars [] acc + = True +allDistinctTyVars (ty:tys) acc + = case tcGetTyVar_maybe ty of + Nothing -> False -- (a) + Just tv | tv `elemVarSet` acc -> False -- (b) or (c) + | otherwise -> allDistinctTyVars tys (acc `extendVarSet` tv) +\end{code} -zonkTyVar :: (TcTyVar -> NF_TcM s Type) -- What to do for an unbound mutable variable - -> TcTyVar -> NF_TcM s TcType -zonkTyVar unbound_var_fn tyvar - | not (isMutTyVar tyvar) -- Not a mutable tyvar. This can happen when - -- zonking a forall type, when the bound type variable - -- needn't be mutable - = ASSERT( isTyVar tyvar ) -- Should not be any immutable kind vars - returnNF_Tc (TyVarTy tyvar) - | otherwise - = tcGetTyVar tyvar `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Nothing -> unbound_var_fn tyvar -- Mutable and unbound - Just other_ty -> zonkType unbound_var_fn other_ty -- Bound +%************************************************************************ +%* * +\subsection{Unification with an explicit substitution} +%* * +%************************************************************************ + +Unify types with an explicit substitution and no monad. +Ignore usage annotations. + +\begin{code} +type MySubst + = (TyVarSet, -- Set of template tyvars + TyVarSubstEnv) -- Not necessarily idempotent + +unifyTysX :: TyVarSet -- Template tyvars + -> Type + -> Type + -> Maybe TyVarSubstEnv +unifyTysX tmpl_tyvars ty1 ty2 + = uTysX ty1 ty2 (\(_,s) -> Just s) (tmpl_tyvars, emptySubstEnv) + +unifyExtendTysX :: TyVarSet -- Template tyvars + -> TyVarSubstEnv -- Substitution to start with + -> Type + -> Type + -> Maybe TyVarSubstEnv -- Extended substitution +unifyExtendTysX tmpl_tyvars subst ty1 ty2 + = uTysX ty1 ty2 (\(_,s) -> Just s) (tmpl_tyvars, subst) + +unifyTyListsX :: TyVarSet -> [Type] -> [Type] + -> Maybe TyVarSubstEnv +unifyTyListsX tmpl_tyvars tys1 tys2 + = uTyListsX tys1 tys2 (\(_,s) -> Just s) (tmpl_tyvars, emptySubstEnv) + + +uTysX :: Type + -> Type + -> (MySubst -> Maybe result) + -> MySubst + -> Maybe result + +uTysX (NoteTy _ ty1) ty2 k subst = uTysX ty1 ty2 k subst +uTysX ty1 (NoteTy _ ty2) k subst = uTysX ty1 ty2 k subst + + -- Variables; go for uVar +uTysX (TyVarTy tyvar1) (TyVarTy tyvar2) k subst + | tyvar1 == tyvar2 + = k subst +uTysX (TyVarTy tyvar1) ty2 k subst@(tmpls,_) + | tyvar1 `elemVarSet` tmpls + = uVarX tyvar1 ty2 k subst +uTysX ty1 (TyVarTy tyvar2) k subst@(tmpls,_) + | tyvar2 `elemVarSet` tmpls + = uVarX tyvar2 ty1 k subst + + -- Predicates +uTysX (SourceTy (IParam n1 t1)) (SourceTy (IParam n2 t2)) k subst + | n1 == n2 = uTysX t1 t2 k subst +uTysX (SourceTy (ClassP c1 tys1)) (SourceTy (ClassP c2 tys2)) k subst + | c1 == c2 = uTyListsX tys1 tys2 k subst +uTysX (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) k subst + | tc1 == tc2 = uTyListsX tys1 tys2 k subst + + -- Functions; just check the two parts +uTysX (FunTy fun1 arg1) (FunTy fun2 arg2) k subst + = uTysX fun1 fun2 (uTysX arg1 arg2 k) subst + + -- Type constructors must match +uTysX (TyConApp con1 tys1) (TyConApp con2 tys2) k subst + | (con1 == con2 && equalLength tys1 tys2) + = uTyListsX tys1 tys2 k subst + + -- Applications need a bit of care! + -- They can match FunTy and TyConApp, so use splitAppTy_maybe + -- NB: we've already dealt with type variables and Notes, + -- so if one type is an App the other one jolly well better be too +uTysX (AppTy s1 t1) ty2 k subst + = case tcSplitAppTy_maybe ty2 of + Just (s2, t2) -> uTysX s1 s2 (uTysX t1 t2 k) subst + Nothing -> Nothing -- Fail + +uTysX ty1 (AppTy s2 t2) k subst + = case tcSplitAppTy_maybe ty1 of + Just (s1, t1) -> uTysX s1 s2 (uTysX t1 t2 k) subst + Nothing -> Nothing -- Fail + + -- Not expecting for-alls in unification +#ifdef DEBUG +uTysX (ForAllTy _ _) ty2 k subst = panic "Unify.uTysX subst:ForAllTy (1st arg)" +uTysX ty1 (ForAllTy _ _) k subst = panic "Unify.uTysX subst:ForAllTy (2nd arg)" +#endif + + -- Ignore usages +uTysX (UsageTy _ t1) t2 k subst = uTysX t1 t2 k subst +uTysX t1 (UsageTy _ t2) k subst = uTysX t1 t2 k subst + + -- Anything else fails +uTysX ty1 ty2 k subst = Nothing + + +uTyListsX [] [] k subst = k subst +uTyListsX (ty1:tys1) (ty2:tys2) k subst = uTysX ty1 ty2 (uTyListsX tys1 tys2 k) subst +uTyListsX tys1 tys2 k subst = Nothing -- Fail if the lists are different lengths \end{code} +\begin{code} +-- Invariant: tv1 is a unifiable variable +uVarX tv1 ty2 k subst@(tmpls, env) + = case lookupSubstEnv env tv1 of + Just (DoneTy ty1) -> -- Already bound + uTysX ty1 ty2 k subst + + Nothing -- Not already bound + | typeKind ty2 `eqKind` tyVarKind tv1 + && occur_check_ok ty2 + -> -- No kind mismatch nor occur check + UASSERT( not (isUTy ty2) ) + k (tmpls, extendSubstEnv env tv1 (DoneTy ty2)) + + | otherwise -> Nothing -- Fail if kind mis-match or occur check + where + occur_check_ok ty = all occur_check_ok_tv (varSetElems (tyVarsOfType ty)) + occur_check_ok_tv tv | tv1 == tv = False + | otherwise = case lookupSubstEnv env tv of + Nothing -> True + Just (DoneTy ty) -> occur_check_ok ty +\end{code} + + + %************************************************************************ %* * -\subsection{tcTypeKind} +\subsection{Matching on types} %* * %************************************************************************ -Sadly, we need a Tc version of typeKind, that looks though mutable -kind variables. See the notes with Type.typeKind for the typeKindF nonsense +Matching is a {\em unidirectional} process, matching a type against a +template (which is just a type with type variables in it). The +matcher assumes that there are no repeated type variables in the +template, so that it simply returns a mapping of type variables to +types. It also fails on nested foralls. -This is pretty gruesome. +@matchTys@ matches corresponding elements of a list of templates and +types. It and @matchTy@ both ignore usage annotations, unlike the +main function @match@. \begin{code} -tcTypeKind :: TcType -> NF_TcM s TcKind - -tcTypeKind (TyVarTy tyvar) = returnNF_Tc (tyVarKind tyvar) -tcTypeKind (TyConApp tycon tys) = foldlTc (\k _ -> tcFunResultTy k) (tyConKind tycon) tys -tcTypeKind (NoteTy _ ty) = tcTypeKind ty -tcTypeKind (AppTy fun arg) = tcTypeKind fun `thenNF_Tc` \ fun_kind -> - tcFunResultTy fun_kind -tcTypeKind (FunTy fun arg) = tcTypeKindF arg -tcTypeKind (ForAllTy _ ty) = tcTypeKindF ty - -tcTypeKindF :: TcType -> NF_TcM s TcKind -tcTypeKindF (NoteTy _ ty) = tcTypeKindF ty -tcTypeKindF (FunTy _ ty) = tcTypeKindF ty -tcTypeKindF (ForAllTy _ ty) = tcTypeKindF ty -tcTypeKindF other = tcTypeKind other `thenNF_Tc` \ kind -> - fix_up kind +matchTy :: TyVarSet -- Template tyvars + -> Type -- Template + -> Type -- Proposed instance of template + -> Maybe TyVarSubstEnv -- Matching substitution + + +matchTys :: TyVarSet -- Template tyvars + -> [Type] -- Templates + -> [Type] -- Proposed instance of template + -> Maybe (TyVarSubstEnv, -- Matching substitution + [Type]) -- Left over instance types + +matchTy tmpls ty1 ty2 = match ty1 ty2 tmpls (\ senv -> Just senv) emptySubstEnv + +matchTys tmpls tys1 tys2 = match_list tys1 tys2 tmpls + (\ (senv,tys) -> Just (senv,tys)) + emptySubstEnv +\end{code} + +@match@ is the main function. It takes a flag indicating whether +usage annotations are to be respected. + +\begin{code} +match :: Type -> Type -- Current match pair + -> TyVarSet -- Template vars + -> (TyVarSubstEnv -> Maybe result) -- Continuation + -> TyVarSubstEnv -- Current subst + -> Maybe result + +-- When matching against a type variable, see if the variable +-- has already been bound. If so, check that what it's bound to +-- is the same as ty; if not, bind it and carry on. + +match (TyVarTy v) ty tmpls k senv + | v `elemVarSet` tmpls + = -- v is a template variable + case lookupSubstEnv senv v of + Nothing -> UASSERT( not (isUTy ty) ) + k (extendSubstEnv senv v (DoneTy ty)) + Just (DoneTy ty') | ty' `tcEqType` ty -> k senv -- Succeeds + | otherwise -> Nothing -- Fails + + | otherwise + = -- v is not a template variable; ty had better match + -- Can't use (==) because types differ + case tcGetTyVar_maybe ty of + Just v' | v == v' -> k senv -- Success + other -> Nothing -- Failure + -- This tcGetTyVar_maybe is *required* because it must strip Notes. + -- I guess the reason the Note-stripping case is *last* rather than first + -- is to preserve type synonyms etc., so I'm not moving it to the + -- top; but this means that (without the deNotetype) a type + -- variable may not match the pattern (TyVarTy v') as one would + -- expect, due to an intervening Note. KSW 2000-06. + + -- Predicates +match (SourceTy (IParam n1 t1)) (SourceTy (IParam n2 t2)) tmpls k senv + | n1 == n2 = match t1 t2 tmpls k senv +match (SourceTy (ClassP c1 tys1)) (SourceTy (ClassP c2 tys2)) tmpls k senv + | c1 == c2 = match_list_exactly tys1 tys2 tmpls k senv +match (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) tmpls k senv + | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv + + -- Functions; just check the two parts +match (FunTy arg1 res1) (FunTy arg2 res2) tmpls k senv + = match arg1 arg2 tmpls (match res1 res2 tmpls k) senv + +match (AppTy fun1 arg1) ty2 tmpls k senv + = case tcSplitAppTy_maybe ty2 of + Just (fun2,arg2) -> match fun1 fun2 tmpls (match arg1 arg2 tmpls k) senv + Nothing -> Nothing -- Fail + +match (TyConApp tc1 tys1) (TyConApp tc2 tys2) tmpls k senv + | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv + +-- Newtypes are opaque; other source types should not happen +match (SourceTy (NType tc1 tys1)) (SourceTy (NType tc2 tys2)) tmpls k senv + | tc1 == tc2 = match_list_exactly tys1 tys2 tmpls k senv + +match (UsageTy _ ty1) ty2 tmpls k senv = match ty1 ty2 tmpls k senv +match ty1 (UsageTy _ ty2) tmpls k senv = match ty1 ty2 tmpls k senv + + -- With type synonyms, we have to be careful for the exact + -- same reasons as in the unifier. Please see the + -- considerable commentary there before changing anything + -- here! (WDP 95/05) +match (NoteTy n1 ty1) ty2 tmpls k senv = match ty1 ty2 tmpls k senv +match ty1 (NoteTy n2 ty2) tmpls k senv = match ty1 ty2 tmpls k senv + +-- Catch-all fails +match _ _ _ _ _ = Nothing + +match_list_exactly tys1 tys2 tmpls k senv + = match_list tys1 tys2 tmpls k' senv where - fix_up (TyConApp kc _) | kc == typeCon = returnNF_Tc boxedTypeKind - -- Functions at the type level are always boxed - fix_up (NoteTy _ kind) = fix_up kind - fix_up kind@(TyVarTy tv) = tcGetTyVar tv `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Just kind' -> fix_up kind' - Nothing -> returnNF_Tc kind - fix_up kind = returnNF_Tc kind - -tcFunResultTy (NoteTy _ ty) = tcFunResultTy ty -tcFunResultTy (FunTy arg res) = returnNF_Tc res -tcFunResultTy (TyVarTy tv) = tcGetTyVar tv `thenNF_Tc` \ maybe_ty -> - case maybe_ty of - Just ty' -> tcFunResultTy ty' - -- The Nothing case, and the other cases for tcFunResultTy - -- should never happen... pattern match failure + k' (senv', tys2') | null tys2' = k senv' -- Succeed + | otherwise = Nothing -- Fail + +match_list [] tys2 tmpls k senv = k (senv, tys2) +match_list (ty1:tys1) [] tmpls k senv = Nothing -- Not enough arg tys => failure +match_list (ty1:tys1) (ty2:tys2) tmpls k senv + = match ty1 ty2 tmpls (match_list tys1 tys2 tmpls k) senv \end{code}