X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=8768e202505aacb50fb35ec6a0f8ff06cffdbadb;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=2eaac288510167299ed02edae90cafb3def0b9d7;hpb=550421384b8364cdaf3135f7859c9f7d7ee1fff1;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index 2eaac28..8768e20 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -5,29 +5,29 @@ \begin{code} module Inst ( - showLIE, - Inst, - pprInst, pprInsts, pprInstsInFull, pprDFuns, + + pprInstances, pprDictsTheta, pprDictsInFull, -- User error messages + showLIE, pprInst, pprInsts, pprInstInFull, -- Debugging messages + tidyInsts, tidyMoreInsts, - newDictsFromOld, newDicts, cloneDict, - newOverloadedLit, newIPDict, + newDicts, newDictAtLoc, newDictsAtLoc, cloneDict, + shortCutFracLit, shortCutIntLit, newIPDict, newMethod, newMethodFromName, newMethodWithGivenTy, - tcInstClassOp, tcInstCall, tcInstDataCon, - tcSyntaxName, tcStdSyntaxName, + tcInstClassOp, tcInstStupidTheta, + tcSyntaxName, isHsVar, tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, instLoc, getDictClassTys, dictPred, - lookupInst, LookupInstResult(..), - tcExtendLocalInstEnv, tcGetInstEnvs, + lookupInst, LookupInstResult(..), lookupPred, + tcExtendLocalInstEnv, tcGetInstEnvs, getOverlapFlag, isDict, isClassDict, isMethod, isLinearInst, linearInstType, isIPDict, isInheritableInst, - isTyVarDict, isStdClassTyVarDict, isMethodFor, - instBindingRequired, + isTyVarDict, isMethodFor, zonkInst, zonkInsts, instToId, instName, @@ -37,51 +37,56 @@ module Inst ( #include "HsVersions.h" -import {-# SOURCE #-} TcExpr( tcCheckSigma ) +import {-# SOURCE #-} TcExpr( tcPolyExpr ) -import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, nlHsVar, mkHsApp ) -import TcHsSyn ( TcId, TcIdSet, - mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, - mkCoercion, ExprCoFn - ) +import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp, + nlHsLit, nlHsVar ) +import TcHsSyn ( mkHsTyApp, mkHsDictApp, zonkId ) import TcRnMonad import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy ) -import InstEnv ( DFunId, InstEnv, lookupInstEnv, checkFunDeps, extendInstEnv ) -import TcIface ( loadImportedInsts ) -import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, - zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars +import InstEnv ( DFunId, InstEnv, Instance(..), OverlapFlag(..), + lookupInstEnv, extendInstEnv, pprInstances, + instanceHead, instanceDFunId, setInstanceDFunId ) +import FunDeps ( checkFunDeps ) +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType, + tcInstTyVar, tcInstSkolType ) -import TcType ( Type, TcType, TcThetaType, TcTyVarSet, - PredType(..), TyVarDetails(VanillaTv), - tcSplitForAllTys, tcSplitForAllTys, mkTyConApp, - tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy, +import TcType ( Type, TcType, TcThetaType, TcTyVarSet, TcPredType, + BoxyRhoType, + PredType(..), SkolemInfo(..), typeKind, mkSigmaTy, + tcSplitForAllTys, applyTys, + tcSplitPhiTy, tcSplitDFunHead, isIntTy,isFloatTy, isIntegerTy, isDoubleTy, - tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys, + mkPredTy, mkTyVarTys, tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred, isClassPred, isTyVarClassPred, isLinearPred, - getClassPredTys, getClassPredTys_maybe, mkPredName, - isInheritablePred, isIPPred, matchTys, + getClassPredTys, mkPredName, + isInheritablePred, isIPPred, tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy, - pprPred, pprParendType, pprThetaArrow, pprClassPred + pprPred, pprParendType, pprTheta ) +import Type ( TvSubst, substTy, substTyVar, substTyWith, substTheta, zipTopTvSubst, + notElemTvSubst, extendTvSubstList ) +import Unify ( tcMatchTys ) +import Kind ( isSubKind ) +import Packages ( isHomeModule ) import HscTypes ( ExternalPackageState(..) ) import CoreFVs ( idFreeTyVars ) -import DataCon ( DataCon,dataConSig ) -import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique ) -import PrelInfo ( isStandardClass, isNoDictClass ) -import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, isHomePackageName, isInternalName ) +import DataCon ( DataCon, dataConTyVars, dataConStupidTheta, dataConName, dataConWrapId ) +import Id ( Id, idName, idType, mkUserLocal, mkLocalId ) +import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, nameModule, + isInternalName, setNameUnique ) import NameSet ( addOneToNameSet ) -import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst ) import Literal ( inIntRange ) -import Var ( TyVar ) -import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) ) +import Var ( TyVar, tyVarKind, setIdType ) +import VarEnv ( TidyEnv, emptyTidyEnv ) import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet ) import TysWiredIn ( floatDataCon, doubleDataCon ) import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName ) import BasicTypes( IPName(..), mapIPName, ipNameName ) import UniqSupply( uniqsFromSupply ) import SrcLoc ( mkSrcSpan, noLoc, unLoc, Located(..) ) -import CmdLineOpts( DynFlags, DynFlag( Opt_AllowUndecidableInstances ), dopt ) +import DynFlags ( DynFlag(..), dopt ) import Maybes ( isJust ) import Outputable \end{code} @@ -94,13 +99,13 @@ instName :: Inst -> Name instName inst = idName (instToId inst) instToId :: Inst -> TcId -instToId (Dict id _ _) = id -instToId (Method id _ _ _ _ _) = id -instToId (LitInst id _ _ _) = id +instToId (LitInst nm _ ty _) = mkLocalId nm ty +instToId (Dict nm pred _) = mkLocalId nm (mkPredTy pred) +instToId (Method id _ _ _ _) = id -instLoc (Dict _ _ loc) = loc -instLoc (Method _ _ _ _ _ loc) = loc -instLoc (LitInst _ _ _ loc) = loc +instLoc (Dict _ _ loc) = loc +instLoc (Method _ _ _ _ loc) = loc +instLoc (LitInst _ _ _ loc) = loc dictPred (Dict _ pred _ ) = pred dictPred inst = pprPanic "dictPred" (ppr inst) @@ -113,16 +118,16 @@ getDictClassTys (Dict _ pred _) = getClassPredTys pred -- Leaving these in is really important for the call to fdPredsOfInsts -- in TcSimplify.inferLoop, because the result is fed to 'grow', -- which is supposed to be conservative -fdPredsOfInst (Dict _ pred _) = [pred] -fdPredsOfInst (Method _ _ _ theta _ _) = theta -fdPredsOfInst other = [] -- LitInsts etc +fdPredsOfInst (Dict _ pred _) = [pred] +fdPredsOfInst (Method _ _ _ theta _) = theta +fdPredsOfInst other = [] -- LitInsts etc fdPredsOfInsts :: [Inst] -> [PredType] fdPredsOfInsts insts = concatMap fdPredsOfInst insts -isInheritableInst (Dict _ pred _) = isInheritablePred pred -isInheritableInst (Method _ _ _ theta _ _) = all isInheritablePred theta -isInheritableInst other = True +isInheritableInst (Dict _ pred _) = isInheritablePred pred +isInheritableInst (Method _ _ _ theta _) = all isInheritablePred theta +isInheritableInst other = True ipNamesOfInsts :: [Inst] -> [Name] @@ -131,14 +136,14 @@ ipNamesOfInst :: Inst -> [Name] -- NB: ?x and %x get different Names ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst] -ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n] -ipNamesOfInst (Method _ _ _ theta _ _) = [ipNameName n | IParam n _ <- theta] -ipNamesOfInst other = [] +ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n] +ipNamesOfInst (Method _ _ _ theta _) = [ipNameName n | IParam n _ <- theta] +ipNamesOfInst other = [] tyVarsOfInst :: Inst -> TcTyVarSet -tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty -tyVarsOfInst (Dict _ pred _) = tyVarsOfPred pred -tyVarsOfInst (Method _ id tys _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id +tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty +tyVarsOfInst (Dict _ pred _) = tyVarsOfPred pred +tyVarsOfInst (Method _ id tys _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id -- The id might have free type variables; in the case of -- locally-overloaded class methods, for example @@ -167,12 +172,12 @@ isIPDict (Dict _ pred _) = isIPPred pred isIPDict other = False isMethod :: Inst -> Bool -isMethod (Method _ _ _ _ _ _) = True -isMethod other = False +isMethod (Method {}) = True +isMethod other = False isMethodFor :: TcIdSet -> Inst -> Bool -isMethodFor ids (Method uniq id tys _ _ loc) = id `elemVarSet` ids -isMethodFor ids inst = False +isMethodFor ids (Method uniq id tys _ loc) = id `elemVarSet` ids +isMethodFor ids inst = False isLinearInst :: Inst -> Bool isLinearInst (Dict _ pred _) = isLinearPred pred @@ -184,23 +189,8 @@ isLinearInst other = False linearInstType :: Inst -> TcType -- %x::t --> t linearInstType (Dict _ (IParam _ ty) _) = ty - - -isStdClassTyVarDict (Dict _ pred _) = case getClassPredTys_maybe pred of - Just (clas, [ty]) -> isStandardClass clas && tcIsTyVarTy ty - other -> False \end{code} -Two predicates which deal with the case where class constraints don't -necessarily result in bindings. The first tells whether an @Inst@ -must be witnessed by an actual binding; the second tells whether an -@Inst@ can be generalised over. - -\begin{code} -instBindingRequired :: Inst -> Bool -instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas) -instBindingRequired other = True -\end{code} %************************************************************************ @@ -218,24 +208,23 @@ newDicts orig theta newDictsAtLoc loc theta cloneDict :: Inst -> TcM Inst -cloneDict (Dict id ty loc) = newUnique `thenM` \ uniq -> - returnM (Dict (setIdUnique id uniq) ty loc) +cloneDict (Dict nm ty loc) = newUnique `thenM` \ uniq -> + returnM (Dict (setNameUnique nm uniq) ty loc) -newDictsFromOld :: Inst -> TcThetaType -> TcM [Inst] -newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta +newDictAtLoc :: InstLoc -> TcPredType -> TcM Inst +newDictAtLoc inst_loc pred + = do { uniq <- newUnique + ; return (mkDict inst_loc uniq pred) } --- Local function, similar to newDicts, --- but with slightly different interface -newDictsAtLoc :: InstLoc - -> TcThetaType - -> TcM [Inst] +newDictsAtLoc :: InstLoc -> TcThetaType -> TcM [Inst] newDictsAtLoc inst_loc theta = newUniqueSupply `thenM` \ us -> - returnM (zipWith mk_dict (uniqsFromSupply us) theta) + returnM (zipWith (mkDict inst_loc) (uniqsFromSupply us) theta) + +mkDict inst_loc uniq pred + = Dict name pred inst_loc where - mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) - pred inst_loc - loc = instLocSrcLoc inst_loc + name = mkPredName uniq (instLocSrcLoc inst_loc) pred -- For vanilla implicit parameters, there is only one in scope -- at any time, so we used to use the name of the implicit parameter itself @@ -249,9 +238,9 @@ newIPDict orig ip_name ty let pred = IParam ip_name ty name = mkPredName uniq (instLocSrcLoc inst_loc) pred - id = mkLocalId name (mkPredTy pred) + dict = Dict name pred inst_loc in - returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) + returnM (mapIPName (\n -> instToId dict) ip_name, dict) \end{code} @@ -264,48 +253,21 @@ newIPDict orig ip_name ty \begin{code} -tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, TcType) -tcInstCall orig fun_ty -- fun_ty is usually a sigma-type - = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) -> - newDicts orig theta `thenM` \ dicts -> - extendLIEs dicts `thenM_` - let - inst_fn e = DictApp (mkHsTyApp (noLoc e) (mkTyVarTys tyvars)) (map instToId dicts) - in - returnM (mkCoercion inst_fn, tau) - -tcInstDataCon :: InstOrigin -> DataCon - -> TcM ([TcType], -- Types to instantiate at - [Inst], -- Existential dictionaries to apply to - [TcType], -- Argument types of constructor - TcType, -- Result type - [TyVar]) -- Existential tyvars -tcInstDataCon orig data_con - = let - (tvs, stupid_theta, ex_tvs, ex_theta, arg_tys, tycon) = dataConSig data_con - -- We generate constraints for the stupid theta even when - -- pattern matching (as the Report requires) - in - tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (all_tvs', ty_args', tenv) -> - let - stupid_theta' = substTheta tenv stupid_theta - ex_theta' = substTheta tenv ex_theta - arg_tys' = map (substTy tenv) arg_tys - - n_normal_tvs = length tvs - ex_tvs' = drop n_normal_tvs all_tvs' - result_ty = mkTyConApp tycon (take n_normal_tvs ty_args') - in - newDicts orig stupid_theta' `thenM` \ stupid_dicts -> - newDicts orig ex_theta' `thenM` \ ex_dicts -> - - -- Note that we return the stupid theta *only* in the LIE; - -- we don't otherwise use it at all - extendLIEs stupid_dicts `thenM_` - - returnM (ty_args', ex_dicts, arg_tys', result_ty, ex_tvs') +tcInstStupidTheta :: DataCon -> [TcType] -> TcM () +-- Instantiate the "stupid theta" of the data con, and throw +-- the constraints into the constraint set +tcInstStupidTheta data_con inst_tys + | null stupid_theta + = return () + | otherwise + = do { stupid_dicts <- newDicts (OccurrenceOf (dataConName data_con)) + (substTheta tenv stupid_theta) + ; extendLIEs stupid_dicts } + where + stupid_theta = dataConStupidTheta data_con + tenv = zipTopTvSubst (dataConTyVars data_con) inst_tys -newMethodFromName :: InstOrigin -> TcType -> Name -> TcM TcId +newMethodFromName :: InstOrigin -> BoxyRhoType -> Name -> TcM TcId newMethodFromName origin ty name = tcLookupId name `thenM` \ id -> -- Use tcLookupId not tcLookupGlobalId; the method is almost @@ -317,10 +279,10 @@ newMethodFromName origin ty name extendLIE inst `thenM_` returnM (instToId inst) -newMethodWithGivenTy orig id tys theta tau - = getInstLoc orig `thenM` \ loc -> - newMethod loc id tys theta tau `thenM` \ inst -> - extendLIE inst `thenM_` +newMethodWithGivenTy orig id tys + = getInstLoc orig `thenM` \ loc -> + newMethod loc id tys `thenM` \ inst -> + extendLIE inst `thenM_` returnM (instToId inst) -------------------------------------------- @@ -329,90 +291,66 @@ newMethodWithGivenTy orig id tys theta tau -- This is important because they are used by TcSimplify -- to simplify Insts +-- NB: the kind of the type variable to be instantiated +-- might be a sub-kind of the type to which it is applied, +-- notably when the latter is a type variable of kind ?? +-- Hence the call to checkKind +-- A worry: is this needed anywhere else? tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst tcInstClassOp inst_loc sel_id tys = let - (tyvars,rho) = tcSplitForAllTys (idType sel_id) - rho_ty = ASSERT( length tyvars == length tys ) - substTyWith tyvars tys rho - (preds,tau) = tcSplitPhiTy rho_ty + (tyvars, _rho) = tcSplitForAllTys (idType sel_id) in - newMethod inst_loc sel_id tys preds tau + zipWithM_ checkKind tyvars tys `thenM_` + newMethod inst_loc sel_id tys + +checkKind :: TyVar -> TcType -> TcM () +-- Ensure that the type has a sub-kind of the tyvar +checkKind tv ty + = do { let ty1 = ty + -- ty1 <- zonkTcType ty + ; if typeKind ty1 `isSubKind` tyVarKind tv + then return () + else + + pprPanic "checkKind: adding kind constraint" + (vcat [ppr tv <+> ppr (tyVarKind tv), + ppr ty <+> ppr ty1 <+> ppr (typeKind ty1)]) + } +-- do { tv1 <- tcInstTyVar tv +-- ; unifyType ty1 (mkTyVarTy tv1) } } + --------------------------- -newMethod inst_loc id tys theta tau +newMethod inst_loc id tys = newUnique `thenM` \ new_uniq -> let - meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc - inst = Method meth_id id tys theta tau inst_loc - loc = instLocSrcLoc inst_loc + (theta,tau) = tcSplitPhiTy (applyTys (idType id) tys) + meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc + inst = Method meth_id id tys theta inst_loc + loc = instLocSrcLoc inst_loc in returnM inst \end{code} -In newOverloadedLit we convert directly to an Int or Integer if we -know that's what we want. This may save some time, by not -temporarily generating overloaded literals, but it won't catch all -cases (the rest are caught in lookupInst). - \begin{code} -newOverloadedLit :: InstOrigin - -> HsOverLit - -> TcType - -> TcM (LHsExpr TcId) -newOverloadedLit orig lit@(HsIntegral i fi) expected_ty - | fi /= fromIntegerName -- Do not generate a LitInst for rebindable syntax. - -- Reason: tcSyntaxName does unification - -- which is very inconvenient in tcSimplify - -- ToDo: noLoc sadness - = tcSyntaxName orig expected_ty (fromIntegerName, noLoc (HsVar fi)) `thenM` \ (_,expr) -> - mkIntegerLit i `thenM` \ integer_lit -> - returnM (mkHsApp expr integer_lit) - - | Just expr <- shortCutIntLit i expected_ty - = returnM expr - - | otherwise - = newLitInst orig lit expected_ty - -newOverloadedLit orig lit@(HsFractional r fr) expected_ty - | fr /= fromRationalName -- c.f. HsIntegral case - = tcSyntaxName orig expected_ty (fromRationalName, noLoc (HsVar fr)) `thenM` \ (_,expr) -> - mkRatLit r `thenM` \ rat_lit -> - returnM (mkHsApp expr rat_lit) - - | Just expr <- shortCutFracLit r expected_ty - = returnM expr - - | otherwise - = newLitInst orig lit expected_ty - -newLitInst :: InstOrigin -> HsOverLit -> TcType -> TcM (LHsExpr TcId) -newLitInst orig lit expected_ty - = getInstLoc orig `thenM` \ loc -> - newUnique `thenM` \ new_uniq -> - let - lit_inst = LitInst lit_id lit expected_ty loc - lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty - in - extendLIE lit_inst `thenM_` - returnM (L (instLocSrcSpan loc) (HsVar (instToId lit_inst))) - -shortCutIntLit :: Integer -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-) +shortCutIntLit :: Integer -> TcType -> Maybe (HsExpr TcId) shortCutIntLit i ty | isIntTy ty && inIntRange i -- Short cut for Int - = Just (noLoc (HsLit (HsInt i))) + = Just (HsLit (HsInt i)) | isIntegerTy ty -- Short cut for Integer - = Just (noLoc (HsLit (HsInteger i ty))) + = Just (HsLit (HsInteger i ty)) | otherwise = Nothing -shortCutFracLit :: Rational -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-) +shortCutFracLit :: Rational -> TcType -> Maybe (HsExpr TcId) shortCutFracLit f ty | isFloatTy ty - = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)]) + = Just (mk_lit floatDataCon (HsFloatPrim f)) | isDoubleTy ty - = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)]) + = Just (mk_lit doubleDataCon (HsDoublePrim f)) | otherwise = Nothing + where + mk_lit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit) mkIntegerLit :: Integer -> TcM (LHsExpr TcId) mkIntegerLit i @@ -425,6 +363,10 @@ mkRatLit r = tcMetaTy rationalTyConName `thenM` \ rat_ty -> getSrcSpanM `thenM` \ span -> returnM (L span $ HsLit (HsRat r rat_ty)) + +isHsVar :: HsExpr Name -> Name -> Bool +isHsVar (HsVar f) g = f==g +isHsVar other g = False \end{code} @@ -434,17 +376,15 @@ mkRatLit r %* * %************************************************************************ -Zonking makes sure that the instance types are fully zonked, -but doesn't do the same for any of the Ids in an Inst. There's no -need, and it's a lot of extra work. +Zonking makes sure that the instance types are fully zonked. \begin{code} zonkInst :: Inst -> TcM Inst -zonkInst (Dict id pred loc) +zonkInst (Dict name pred loc) = zonkTcPredType pred `thenM` \ new_pred -> - returnM (Dict id new_pred loc) + returnM (Dict name new_pred loc) -zonkInst (Method m id tys theta tau loc) +zonkInst (Method m id tys theta loc) = zonkId id `thenM` \ new_id -> -- Essential to zonk the id in case it's a local variable -- Can't use zonkIdOcc because the id might itself be @@ -452,12 +392,11 @@ zonkInst (Method m id tys theta tau loc) zonkTcTypes tys `thenM` \ new_tys -> zonkTcThetaType theta `thenM` \ new_theta -> - zonkTcType tau `thenM` \ new_tau -> - returnM (Method m new_id new_tys new_theta new_tau loc) + returnM (Method m new_id new_tys new_theta loc) -zonkInst (LitInst id lit ty loc) +zonkInst (LitInst nm lit ty loc) = zonkTcType ty `thenM` \ new_ty -> - returnM (LitInst id lit new_ty loc) + returnM (LitInst nm lit new_ty loc) zonkInsts insts = mappM zonkInst insts \end{code} @@ -476,43 +415,38 @@ relevant in error messages. instance Outputable Inst where ppr inst = pprInst inst -pprInsts :: [Inst] -> SDoc -pprInsts insts = parens (sep (punctuate comma (map pprInst insts))) +pprDictsTheta :: [Inst] -> SDoc +-- Print in type-like fashion (Eq a, Show b) +pprDictsTheta dicts = pprTheta (map dictPred dicts) -pprInstsInFull insts - = vcat (map go insts) +pprDictsInFull :: [Inst] -> SDoc +-- Print in type-like fashion, but with source location +pprDictsInFull dicts + = vcat (map go dicts) where - go inst = sep [quotes (ppr inst), nest 2 (pprInstLoc (instLoc inst))] - -pprInst (LitInst u lit ty loc) - = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u] - -pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u + go dict = sep [quotes (ppr (dictPred dict)), nest 2 (pprInstLoc (instLoc dict))] -pprInst m@(Method u id tys theta tau loc) - = hsep [ppr id, ptext SLIT("at"), - brackets (sep (map pprParendType tys)) {- , - ptext SLIT("theta"), ppr theta, - ptext SLIT("tau"), ppr tau - show_uniq u, - ppr (instToId m) -}] +pprInsts :: [Inst] -> SDoc +-- Debugging: print the evidence :: type +pprInsts insts = brackets (interpp'SP insts) +pprInst, pprInstInFull :: Inst -> SDoc +-- Debugging: print the evidence :: type +pprInst (LitInst nm lit ty loc) = ppr nm <+> dcolon <+> ppr ty +pprInst (Dict nm pred loc) = ppr nm <+> dcolon <+> pprPred pred -pprDFuns :: [DFunId] -> SDoc --- Prints the dfun as an instance declaration -pprDFuns dfuns = vcat [ hang (ppr (getSrcLoc dfun) <> colon) - 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, - pprClassPred clas tys]) - | dfun <- dfuns - , let (_, theta, clas, tys) = tcSplitDFunTy (idType dfun) ] - -- Print without the for-all, which the programmer doesn't write +pprInst m@(Method inst_id id tys theta loc) + = ppr inst_id <+> dcolon <+> + braces (sep [ppr id <+> ptext SLIT("at"), + brackets (sep (map pprParendType tys))]) -show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}") +pprInstInFull inst + = sep [quotes (pprInst inst), nest 2 (pprInstLoc (instLoc inst))] tidyInst :: TidyEnv -> Inst -> Inst -tidyInst env (LitInst u lit ty loc) = LitInst u lit (tidyType env ty) loc -tidyInst env (Dict u pred loc) = Dict u (tidyPred env pred) loc -tidyInst env (Method u id tys theta tau loc) = Method u id (tidyTypes env tys) theta tau loc +tidyInst env (LitInst nm lit ty loc) = LitInst nm lit (tidyType env ty) loc +tidyInst env (Dict nm pred loc) = Dict nm (tidyPred env pred) loc +tidyInst env (Method u id tys theta loc) = Method u id (tidyTypes env tys) theta loc tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst]) -- This function doesn't assume that the tyvars are in scope @@ -529,7 +463,7 @@ showLIE :: SDoc -> TcM () -- Debugging showLIE str = do { lie_var <- getLIEVar ; lie <- readMutVar lie_var ; - traceTc (str <+> pprInstsInFull (lieToList lie)) } + traceTc (str <+> vcat (map pprInstInFull (lieToList lie))) } \end{code} @@ -540,64 +474,90 @@ showLIE str %************************************************************************ \begin{code} -tcExtendLocalInstEnv :: [DFunId] -> TcM a -> TcM a +tcExtendLocalInstEnv :: [Instance] -> TcM a -> TcM a -- Add new locally-defined instances tcExtendLocalInstEnv dfuns thing_inside = do { traceDFuns dfuns ; env <- getGblEnv - ; dflags <- getDOpts - ; inst_env' <- foldlM (addInst dflags) (tcg_inst_env env) dfuns + ; inst_env' <- foldlM addLocalInst (tcg_inst_env env) dfuns ; let env' = env { tcg_insts = dfuns ++ tcg_insts env, tcg_inst_env = inst_env' } ; setGblEnv env' thing_inside } -addInst :: DynFlags -> InstEnv -> DFunId -> TcM InstEnv +addLocalInst :: InstEnv -> Instance -> TcM InstEnv -- Check that the proposed new instance is OK, -- and then add it to the home inst env -addInst dflags home_ie dfun - = do { -- Load imported instances, so that we report +addLocalInst home_ie ispec + = do { -- Instantiate the dfun type so that we extend the instance + -- envt with completely fresh template variables + -- This is important because the template variables must + -- not overlap with anything in the things being looked up + -- (since we do unification). + -- We use tcInstSkolType because we don't want to allocate fresh + -- *meta* type variables. + let dfun = instanceDFunId ispec + ; (tvs', theta', tau') <- tcInstSkolType (InstSkol dfun) (idType dfun) + ; let (cls, tys') = tcSplitDFunHead tau' + dfun' = setIdType dfun (mkSigmaTy tvs' theta' tau') + ispec' = setInstanceDFunId ispec dfun' + + -- Load imported instances, so that we report -- duplicates correctly - pkg_ie <- loadImportedInsts cls tys + ; eps <- getEps + ; let inst_envs = (eps_inst_env eps, home_ie) -- Check functional dependencies - ; case checkFunDeps (pkg_ie, home_ie) dfun of - Just dfuns -> funDepErr dfun dfuns + ; case checkFunDeps inst_envs ispec' of + Just specs -> funDepErr ispec' specs Nothing -> return () -- Check for duplicate instance decls - ; let { (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys - ; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches, - isJust (matchTys (mkVarSet tvs) tys dup_tys)] } - -- Find memebers of the match list which - -- dfun itself matches. If the match is 2-way, it's a duplicate - ; case dup_dfuns of - dup_dfun : _ -> dupInstErr dfun dup_dfun - [] -> return () + ; let { (matches, _) = lookupInstEnv inst_envs cls tys' + ; dup_ispecs = [ dup_ispec + | (_, dup_ispec) <- matches + , let (_,_,_,dup_tys) = instanceHead dup_ispec + , isJust (tcMatchTys (mkVarSet tvs') tys' dup_tys)] } + -- Find memebers of the match list which ispec itself matches. + -- If the match is 2-way, it's a duplicate + ; case dup_ispecs of + dup_ispec : _ -> dupInstErr ispec' dup_ispec + [] -> return () -- OK, now extend the envt - ; return (extendInstEnv home_ie dfun) } - where - (tvs, _, cls, tys) = tcSplitDFunTy (idType dfun) - -traceDFuns dfuns - = traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) + ; return (extendInstEnv home_ie ispec') } + +getOverlapFlag :: TcM OverlapFlag +getOverlapFlag + = do { dflags <- getDOpts + ; let overlap_ok = dopt Opt_AllowOverlappingInstances dflags + incoherent_ok = dopt Opt_AllowIncoherentInstances dflags + overlap_flag | incoherent_ok = Incoherent + | overlap_ok = OverlapOk + | otherwise = NoOverlap + + ; return overlap_flag } + +traceDFuns ispecs + = traceTc (hang (text "Adding instances:") 2 (vcat (map pp ispecs))) where - pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun) + pp ispec = ppr (instanceDFunId ispec) <+> colon <+> ppr ispec + -- Print the dfun name itself too -funDepErr dfun dfuns - = addDictLoc dfun $ +funDepErr ispec ispecs + = addDictLoc ispec $ addErr (hang (ptext SLIT("Functional dependencies conflict between instance declarations:")) - 2 (pprDFuns (dfun:dfuns))) -dupInstErr dfun dup_dfun - = addDictLoc dfun $ + 2 (pprInstances (ispec:ispecs))) +dupInstErr ispec dup_ispec + = addDictLoc ispec $ addErr (hang (ptext SLIT("Duplicate instance declarations:")) - 2 (pprDFuns [dfun, dup_dfun])) + 2 (pprInstances [ispec, dup_ispec])) -addDictLoc dfun thing_inside - = addSrcSpan (mkSrcSpan loc loc) thing_inside +addDictLoc ispec thing_inside + = setSrcSpan (mkSrcSpan loc loc) thing_inside where - loc = getSrcLoc dfun + loc = getSrcLoc ispec \end{code} + %************************************************************************ %* * @@ -606,12 +566,12 @@ addDictLoc dfun thing_inside %************************************************************************ \begin{code} -data LookupInstResult s +data LookupInstResult = NoInstance | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts -lookupInst :: Inst -> TcM (LookupInstResult s) +lookupInst :: Inst -> TcM LookupInstResult -- It's important that lookupInst does not put any new stuff into -- the LIE. Instead, any Insts needed by the lookup are returned in -- the LookupInstResult, where they can be further processed by tcSimplify @@ -619,7 +579,7 @@ lookupInst :: Inst -> TcM (LookupInstResult s) -- Methods -lookupInst inst@(Method _ id tys theta _ loc) +lookupInst inst@(Method _ id tys theta loc) = newDictsAtLoc loc theta `thenM` \ dicts -> returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (L span (HsVar id)) tys) (map instToId dicts))) where @@ -629,17 +589,16 @@ lookupInst inst@(Method _ id tys theta _ loc) -- Look for short cuts first: if the literal is *definitely* a -- int, integer, float or a double, generate the real thing here. --- This is essential (see nofib/spectral/nucleic). +-- This is essential (see nofib/spectral/nucleic). -- [Same shortcut as in newOverloadedLit, but we -- may have done some unification by now] - -lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc) +lookupInst inst@(LitInst _nm (HsIntegral i from_integer_name) ty loc) | Just expr <- shortCutIntLit i ty - = returnM (GenInst [] expr) -- GenInst, not SimpleInst, because + = returnM (GenInst [] (noLoc expr)) -- GenInst, not SimpleInst, because -- expr may be a constructor application | otherwise - = ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant + = ASSERT( from_integer_name `isHsVar` fromIntegerName ) -- A LitInst invariant tcLookupId fromIntegerName `thenM` \ from_integer -> tcInstClassOp loc from_integer [ty] `thenM` \ method_inst -> mkIntegerLit i `thenM` \ integer_lit -> @@ -647,12 +606,12 @@ lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc) (mkHsApp (L (instLocSrcSpan loc) (HsVar (instToId method_inst))) integer_lit)) -lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) +lookupInst inst@(LitInst _nm (HsFractional f from_rat_name) ty loc) | Just expr <- shortCutFracLit f ty - = returnM (GenInst [] expr) + = returnM (GenInst [] (noLoc expr)) | otherwise - = ASSERT( from_rat_name == fromRationalName ) -- A LitInst invariant + = ASSERT( from_rat_name `isHsVar` fromRationalName ) -- A LitInst invariant tcLookupId fromRationalName `thenM` \ from_rational -> tcInstClassOp loc from_rational [ty] `thenM` \ method_inst -> mkRatLit f `thenM` \ rat_lit -> @@ -660,85 +619,101 @@ lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) (HsVar (instToId method_inst))) rat_lit)) -- Dictionaries -lookupInst dict@(Dict _ pred@(ClassP clas tys) loc) - = do { dflags <- getDOpts - ; if all tcIsTyVarTy tys && - not (dopt Opt_AllowUndecidableInstances dflags) - -- Common special case; no lookup - -- NB: tcIsTyVarTy... don't look through newtypes! - -- Don't take this short cut if we allow undecidable instances - -- because we might have "instance T a where ...". - -- [That means we need -fallow-undecidable-instances in the - -- client module, as well as the module with the instance decl.] - then return NoInstance - - else do - { pkg_ie <- loadImportedInsts clas tys - -- Suck in any instance decls that may be relevant +lookupInst (Dict _ pred loc) + = do { mb_result <- lookupPred pred + ; case mb_result of { + Nothing -> return NoInstance ; + Just (tenv, dfun_id) -> do + + -- tenv is a substitution that instantiates the dfun_id + -- to match the requested result type. + -- + -- We ASSUME that the dfun is quantified over the very same tyvars + -- that are bound by the tenv. + -- + -- However, the dfun + -- might have some tyvars that *only* appear in arguments + -- dfun :: forall a b. C a b, Ord b => D [a] + -- We instantiate b to a flexi type variable -- it'll presumably + -- become fixed later via functional dependencies + { use_stage <- getStage + ; checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred)) + (topIdLvl dfun_id) use_stage + + -- It's possible that not all the tyvars are in + -- the substitution, tenv. For example: + -- instance C X a => D X where ... + -- (presumably there's a functional dependency in class C) + -- Hence the open_tvs to instantiate any un-substituted tyvars. + ; let (tyvars, rho) = tcSplitForAllTys (idType dfun_id) + open_tvs = filter (`notElemTvSubst` tenv) tyvars + ; open_tvs' <- mappM tcInstTyVar open_tvs + ; let + tenv' = extendTvSubstList tenv open_tvs (mkTyVarTys open_tvs') + -- Since the open_tvs' are freshly made, they cannot possibly be captured by + -- any nested for-alls in rho. So the in-scope set is unchanged + dfun_rho = substTy tenv' rho + (theta, _) = tcSplitPhiTy dfun_rho + ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id)) + (map (substTyVar tenv') tyvars) + ; if null theta then + returnM (SimpleInst ty_app) + else do + { dicts <- newDictsAtLoc loc theta + ; let rhs = mkHsDictApp ty_app (map instToId dicts) + ; returnM (GenInst dicts rhs) + }}}} + +--------------- +lookupPred :: TcPredType -> TcM (Maybe (TvSubst, DFunId)) +-- Look up a class constraint in the instance environment +lookupPred pred@(ClassP clas tys) + = do { eps <- getEps ; tcg_env <- getGblEnv - ; case lookupInstEnv dflags (pkg_ie, tcg_inst_env tcg_env) clas tys of { - ([(tenv, (_,_,dfun_id))], []) -> instantiate_dfun tenv dfun_id pred loc ; - (matches, unifs) -> do - { traceTc (text "lookupInst" <+> vcat [text "matches" <+> ppr matches, - text "unifs" <+> ppr unifs]) - ; return NoInstance } } } } + ; let inst_envs = (eps_inst_env eps, tcg_inst_env tcg_env) + ; case lookupInstEnv inst_envs clas tys of { + ([(tenv, ispec)], []) + -> do { let dfun_id = is_dfun ispec + ; traceTc (text "lookupInst success" <+> + vcat [text "dict" <+> ppr pred, + text "witness" <+> ppr dfun_id + <+> ppr (idType dfun_id) ]) + -- Record that this dfun is needed + ; record_dfun_usage dfun_id + ; return (Just (tenv, dfun_id)) } ; + + (matches, unifs) + -> do { traceTc (text "lookupInst fail" <+> + vcat [text "dict" <+> ppr pred, + text "matches" <+> ppr matches, + text "unifs" <+> ppr unifs]) -- In the case of overlap (multiple matches) we report -- NoInstance here. That has the effect of making the -- context-simplifier return the dict as an irreducible one. -- Then it'll be given to addNoInstanceErrs, which will do another -- lookupInstEnv to get the detailed info about what went wrong. + ; return Nothing } + }} -lookupInst (Dict _ _ _) = returnM NoInstance +lookupPred ip_pred = return Nothing ------------------ -instantiate_dfun tenv dfun_id pred loc - = -- Record that this dfun is needed - record_dfun_usage dfun_id `thenM_` +record_dfun_usage dfun_id + = do { gbl <- getGblEnv + ; let dfun_name = idName dfun_id + dfun_mod = nameModule dfun_name + ; if isInternalName dfun_name || -- Internal name => defined in this module + not (isHomeModule (tcg_home_mods gbl) dfun_mod) + then return () -- internal, or in another package + else do { tcg_env <- getGblEnv + ; updMutVar (tcg_inst_uses tcg_env) + (`addOneToNameSet` idName dfun_id) }} - -- It's possible that not all the tyvars are in - -- the substitution, tenv. For example: - -- instance C X a => D X where ... - -- (presumably there's a functional dependency in class C) - -- Hence the mk_ty_arg to instantiate any un-substituted tyvars. - getStage `thenM` \ use_stage -> - checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred)) - (topIdLvl dfun_id) use_stage `thenM_` - let - (tyvars, rho) = tcSplitForAllTys (idType dfun_id) - mk_ty_arg tv = case lookupSubstEnv tenv tv of - Just (DoneTy ty) -> returnM ty - Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv -> - returnM (mkTyVarTy tc_tv) - in - mappM mk_ty_arg tyvars `thenM` \ ty_args -> - let - dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho - (theta, _) = tcSplitPhiTy dfun_rho - ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id)) ty_args - in - if null theta then - returnM (SimpleInst ty_app) - else - newDictsAtLoc loc theta `thenM` \ dicts -> - let - rhs = mkHsDictApp ty_app (map instToId dicts) - in - returnM (GenInst dicts rhs) - -record_dfun_usage dfun_id - | isInternalName dfun_name = return () -- From this module - | not (isHomePackageName dfun_name) = return () -- From another package package - | otherwise = getGblEnv `thenM` \ tcg_env -> - updMutVar (tcg_inst_uses tcg_env) - (`addOneToNameSet` idName dfun_id) - where - dfun_name = idName dfun_id tcGetInstEnvs :: TcM (InstEnv, InstEnv) --- Gets both the home-pkg inst env (includes module being compiled) --- and the external-package inst-env +-- Gets both the external-package inst-env +-- and the home-pkg inst env (includes module being compiled) tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv; - return (tcg_inst_env env, eps_inst_env eps) } + return (eps_inst_env eps, tcg_inst_env env) } \end{code} @@ -749,7 +724,6 @@ tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv; %* * %************************************************************************ - Suppose we are doing the -fno-implicit-prelude thing, and we encounter a do-expression. We have to find (>>) in the current environment, which is done by the rename. Then we have to check that it has the same type as @@ -775,41 +749,34 @@ just use the expression inline. \begin{code} tcSyntaxName :: InstOrigin -> TcType -- Type to instantiate it at - -> (Name, LHsExpr Name) -- (Standard name, user name) - -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression) - + -> (Name, HsExpr Name) -- (Standard name, user name) + -> TcM (Name, HsExpr TcId) -- (Standard name, suitable expression) +-- *** NOW USED ONLY FOR CmdTop (sigh) *** -- NB: tcSyntaxName calls tcExpr, and hence can do unification. -- So we do not call it from lookupInst, which is called from tcSimplify -tcSyntaxName orig ty (std_nm, L span (HsVar user_nm)) +tcSyntaxName orig ty (std_nm, HsVar user_nm) | std_nm == user_nm - = addSrcSpan span (tcStdSyntaxName orig ty std_nm) + = newMethodFromName orig ty std_nm `thenM` \ id -> + returnM (std_nm, HsVar id) tcSyntaxName orig ty (std_nm, user_nm_expr) = tcLookupId std_nm `thenM` \ std_id -> let -- C.f. newMethodAtLoc ([tv], _, tau) = tcSplitSigmaTy (idType std_id) - tau1 = substTyWith [tv] [ty] tau + sigma1 = substTyWith [tv] [ty] tau -- Actually, the "tau-type" might be a sigma-type in the -- case of locally-polymorphic methods. in - addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $ + addErrCtxtM (syntaxNameCtxt user_nm_expr orig sigma1) $ -- Check that the user-supplied thing has the - -- same type as the standard one - tcCheckSigma user_nm_expr tau1 `thenM` \ expr -> - returnM (std_nm, expr) - -tcStdSyntaxName :: InstOrigin - -> TcType -- Type to instantiate it at - -> Name -- Standard name - -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression) - -tcStdSyntaxName orig ty std_nm - = newMethodFromName orig ty std_nm `thenM` \ id -> - getSrcSpanM `thenM` \ span -> - returnM (std_nm, L span (HsVar id)) + -- same type as the standard one. + -- Tiresome jiggling because tcCheckSigma takes a located expression + getSrcSpanM `thenM` \ span -> + tcPolyExpr (L span user_nm_expr) sigma1 `thenM` \ expr -> + returnM (std_nm, unLoc expr) syntaxNameCtxt name orig ty tidy_env = getInstLoc orig `thenM` \ inst_loc ->