X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcTyFuns.lhs;h=9a369d91f9d412a5130b68d5188b79c86d75ea6d;hb=9892daf7fac4087813c6f5fedfc3de5d19410689;hp=113ea43bd5e68c2a16e439814c9934718e9c4917;hpb=619efa4035d215c16ea657f2b038362c87b769fc;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcTyFuns.lhs b/compiler/typecheck/TcTyFuns.lhs index 113ea43..9a369d9 100644 --- a/compiler/typecheck/TcTyFuns.lhs +++ b/compiler/typecheck/TcTyFuns.lhs @@ -303,10 +303,15 @@ normaliseEqs eqs -- normaliseDicts :: Bool -> [Inst] -> TcM EqConfig normaliseDicts isWanted insts - = do { traceTc $ ptext (sLit "Entering normaliseDicts") <+> - ptext (if isWanted then sLit "[Wanted]" else sLit "[Local]") + = do { traceTc $ hang (ptext (sLit "Entering normaliseDicts") <+> + ptext (if isWanted then sLit "[Wanted] for" + else sLit "[Local] for")) + 4 (ppr insts) ; (insts', eqss, bindss, skolemss) <- mapAndUnzip4M (normDict isWanted) insts + + ; traceTc $ hang (ptext (sLit "normaliseDicts returns")) + 4 (ppr insts' $$ ppr eqss) ; return $ emptyEqConfig { eqs = concat eqss , locals = if isWanted then [] else insts' , wanteds = if isWanted then insts' else [] @@ -470,22 +475,29 @@ normEqInst :: Inst -> TcM ([RewriteInst], TyVarSet) -- Normalise one equality. normEqInst inst = ASSERT( isEqInst inst ) - go ty1 ty2 (eqInstCoercion inst) + do { traceTc $ ptext (sLit "normEqInst of ") <+> + pprEqInstCo co <+> text "::" <+> + ppr ty1 <+> text "~" <+> ppr ty2 + ; res <- go ty1 ty2 co + ; traceTc $ ptext (sLit "normEqInst returns") <+> ppr res + ; return res + } where (ty1, ty2) = eqInstTys inst + co = eqInstCoercion inst -- look through synonyms go ty1 ty2 co | Just ty1' <- tcView ty1 = go ty1' ty2 co go ty1 ty2 co | Just ty2' <- tcView ty2 = go ty1 ty2' co -- left-to-right rule with type family head - go (TyConApp con args) ty2 co - | isOpenSynTyCon con + go ty1@(TyConApp con args) ty2 co + | isOpenSynTyConApp ty1 -- only if not oversaturated = mkRewriteFam False con args ty2 co -- right-to-left rule with type family head go ty1 ty2@(TyConApp con args) co - | isOpenSynTyCon con + | isOpenSynTyConApp ty2 -- only if not oversaturated = do { co' <- mkSymEqInstCo co (ty2, ty1) ; mkRewriteFam True con args ty1 co' } @@ -573,13 +585,7 @@ checkOrientation :: Type -> Type -> EqInstCo -> Inst -> TcM [RewriteInst] -- NB: We cannot assume that the two types already have outermost type -- synonyms expanded due to the recursion in the case of type applications. checkOrientation ty1 ty2 co inst - = do { traceTc $ ptext (sLit "checkOrientation of ") <+> - pprEqInstCo co <+> text "::" <+> - ppr ty1 <+> text "~" <+> ppr ty2 - ; eqs <- go ty1 ty2 - ; traceTc $ ptext (sLit "checkOrientation returns") <+> ppr eqs - ; return eqs - } + = go ty1 ty2 where -- look through synonyms go ty1 ty2 | Just ty1' <- tcView ty1 = go ty1' ty2 @@ -669,10 +675,10 @@ flattenType inst ty go ty@(TyVarTy _) = return (ty, ty, [] , emptyVarSet) - -- type family application + -- type family application & family arity matches number of args -- => flatten to "gamma :: F t1'..tn' ~ alpha" (alpha & gamma fresh) go ty@(TyConApp con args) - | isOpenSynTyCon con + | isOpenSynTyConApp ty -- only if not oversaturated = do { (args', cargs, args_eqss, args_skolemss) <- mapAndUnzip4M go args ; alpha <- newFlexiTyVar (typeKind ty) ; let alphaTy = mkTyVarTy alpha @@ -695,6 +701,7 @@ flattenType inst ty -- data constructor application => flatten subtypes -- NB: Special cased for efficiency - could be handled as type application go ty@(TyConApp con args) + | not (isOpenSynTyCon con) -- don't match oversaturated family apps = do { (args', cargs, args_eqss, args_skolemss) <- mapAndUnzip4M go args ; if null args_eqss then -- unchanged, keep the old type with folded synonyms @@ -722,7 +729,10 @@ flattenType inst ty } -- type application => flatten subtypes - go ty@(AppTy ty_l ty_r) + go ty + | Just (ty_l, ty_r) <- repSplitAppTy_maybe ty + -- need to use the smart split as ty may be an + -- oversaturated family application = do { (ty_l', co_l, eqs_l, skolems_l) <- go ty_l ; (ty_r', co_r, eqs_r, skolems_r) <- go ty_r ; if null eqs_l && null eqs_r @@ -749,6 +759,8 @@ flattenType inst ty go (PredTy _) = panic "TcTyFuns.flattenType: unexpected PredType" + go _ = panic "TcTyFuns: suppress bogus warning" + adjustCoercions :: EqInstCo -- coercion of original equality -> Coercion -- coercion witnessing the left rewrite -> Coercion -- coercion witnessing the right rewrite @@ -802,17 +814,23 @@ mkDictBind dict isWanted rewriteCo pred where loc = tci_loc dict --- gamma :: Fam args ~ alpha --- => alpha :: Fam args ~ alpha, with alpha := Fam args +-- gamma ::^l Fam args ~ alpha +-- => gamma ::^w Fam args ~ alpha, with alpha := Fam args & gamma := Fam args -- (the update of alpha will not be apparent during propagation, as we -- never follow the indirections of meta variables; it will be revealed -- when the equality is zonked) +-- +-- NB: It's crucial to update *both* alpha and gamma, as gamma may already +-- have escaped into some other coercions during normalisation. +-- wantedToLocal :: RewriteInst -> TcM RewriteInst wantedToLocal eq@(RewriteFam {rwi_fam = fam, rwi_args = args, - rwi_right = alphaTy@(TyVarTy alpha)}) + rwi_right = TyVarTy alpha, + rwi_co = Left gamma}) = do { writeMetaTyVar alpha (mkTyConApp fam args) - ; return $ eq {rwi_co = mkGivenCo alphaTy} + ; writeMetaTyVar gamma (mkTyConApp fam args) + ; return $ eq {rwi_co = mkGivenCo $ mkTyVarTy gamma} } wantedToLocal _ = panic "TcTyFuns.wantedToLocal" \end{code} @@ -866,8 +884,11 @@ mapSubstRules eq eqs } where substRules eq1 eq2 - = do { -- try the SubstFam rule - optEqs <- applySubstFam eq1 eq2 + = do {traceTc $ hang (ptext (sLit "Trying subst rules with")) + 4 (ppr eq1 $$ ppr eq2) + + -- try the SubstFam rule + ; optEqs <- applySubstFam eq1 eq2 ; case optEqs of Just (eqs, skolems) -> return (eqs, [], skolems) Nothing -> do @@ -935,6 +956,8 @@ applySubstFam :: RewriteInst -> TcM (Maybe ([RewriteInst], TyVarSet)) applySubstFam eq1@(RewriteFam {rwi_fam = fam1, rwi_args = args1}) eq2@(RewriteFam {rwi_fam = fam2, rwi_args = args2}) + + -- rule matches => rewrite | fam1 == fam2 && tcEqTypes args1 args2 && (isWantedRewriteInst eq2 || not (isWantedRewriteInst eq1)) -- !!!TODO: tcEqTypes is insufficient as it does not look through type synonyms @@ -944,11 +967,18 @@ applySubstFam eq1@(RewriteFam {rwi_fam = fam1, rwi_args = args1}) ; eq2' <- deriveEqInst eq2 lhs rhs co2' ; liftM Just $ normEqInst eq2' } + + -- rule would match with eq1 and eq2 swapped => put eq2 into todo list + | fam1 == fam2 && tcEqTypes args1 args2 && + (isWantedRewriteInst eq1 || not (isWantedRewriteInst eq2)) + = return $ Just ([eq2], emptyVarSet) + where lhs = rwi_right eq1 rhs = rwi_right eq2 co1 = eqInstCoType (rwi_co eq1) co2 = rwi_co eq2 + applySubstFam _ _ = return Nothing \end{code} @@ -970,17 +1000,26 @@ applySubstVarVar :: RewriteInst -> TcM (Maybe ([RewriteInst], TyVarSet)) applySubstVarVar eq1@(RewriteVar {rwi_var = tv1}) eq2@(RewriteVar {rwi_var = tv2}) + + -- rule matches => rewrite | tv1 == tv2 && (isWantedRewriteInst eq2 || not (isWantedRewriteInst eq1)) = do { co2' <- mkRightTransEqInstCo co2 co1 (lhs, rhs) ; eq2' <- deriveEqInst eq2 lhs rhs co2' ; liftM Just $ normEqInst eq2' } + + -- rule would match with eq1 and eq2 swapped => put eq2 into todo list + | tv1 == tv2 && + (isWantedRewriteInst eq1 || not (isWantedRewriteInst eq2)) + = return $ Just ([eq2], emptyVarSet) + where lhs = rwi_right eq1 rhs = rwi_right eq2 co1 = eqInstCoType (rwi_co eq1) co2 = rwi_co eq2 + applySubstVarVar _ _ = return Nothing \end{code} @@ -998,6 +1037,8 @@ co2' is returned. (The equality co1 is not returned as it remain unaltered.) \begin{code} applySubstVarFam :: RewriteInst -> RewriteInst -> TcM (Maybe RewriteInst) + + -- rule matches => rewrite applySubstVarFam eq1@(RewriteVar {rwi_var = tv1}) eq2@(RewriteFam {rwi_fam = fam2, rwi_args = args2}) | tv1 `elemVarSet` tyVarsOfTypes args2 @@ -1012,6 +1053,13 @@ applySubstVarFam eq1@(RewriteVar {rwi_var = tv1}) rhs2 = rwi_right eq2 co1 = eqInstCoType (rwi_co eq1) co2 = rwi_co eq2 + + -- rule would match with eq1 and eq2 swapped => put eq2 into todo list +applySubstVarFam (RewriteFam {rwi_args = args1}) + eq2@(RewriteVar {rwi_var = tv2}) + | tv2 `elemVarSet` tyVarsOfTypes args1 + = return $ Just eq2 + applySubstVarFam _ _ = return Nothing \end{code} @@ -1149,7 +1197,9 @@ flattening was performed. \begin{code} instantiateAndExtract :: [RewriteInst] -> Bool -> TyVarSet -> TcM ([Inst], Bool) instantiateAndExtract eqs localsEmpty skolems - = do { results <- mapM inst wanteds + = do { traceTc $ hang (ptext (sLit "instantiateAndExtract:")) + 4 (ppr eqs $$ ppr skolems) + ; results <- mapM inst wanteds ; let residuals = [eq | Left eq <- results] only_skolems = and [tv `elemVarSet` skolems | Right tv <- results] ; residuals' <- mapM rewriteInstToInst residuals @@ -1160,16 +1210,19 @@ instantiateAndExtract eqs localsEmpty skolems checkingMode = length eqs > length wanteds || not localsEmpty -- no local equalities or dicts => checking mode + -- co :: alpha ~ t or co :: a ~ alpha inst eq@(RewriteVar {rwi_var = tv1, rwi_right = ty2, rwi_co = co}) - - -- co :: alpha ~ t - | isMetaTyVar tv1 - = doInst (rwi_swapped eq) tv1 ty2 co eq - - -- co :: a ~ alpha - | Just tv2 <- tcGetTyVar_maybe ty2 - , isMetaTyVar tv2 - = doInst (not $ rwi_swapped eq) tv2 (mkTyVarTy tv1) co eq + = do { flexi_tv1 <- isFlexible tv1 + ; maybe_flexi_tv2 <- isFlexibleTy ty2 + ; case (flexi_tv1, maybe_flexi_tv2) of + (True, _) + -> -- co :: alpha ~ t + doInst (rwi_swapped eq) tv1 ty2 co eq + (False, Just tv2) + -> -- co :: a ~ alpha + doInst (not $ rwi_swapped eq) tv2 (mkTyVarTy tv1) co eq + _ -> return $ Left eq + } -- co :: F args ~ alpha, and we are in checking mode (ie, no locals) inst eq@(RewriteFam {rwi_fam = fam, rwi_args = args, rwi_right = ty2, @@ -1185,6 +1238,19 @@ instantiateAndExtract eqs localsEmpty skolems inst eq = return $ Left eq + -- tv is a meta var and not filled + isFlexible tv + | isMetaTyVar tv = liftM isFlexi $ readMetaTyVar tv + | otherwise = return False + + -- type is a tv that is a meta var and not filled + isFlexibleTy ty + | Just tv <- tcGetTyVar_maybe ty = do {flexi <- isFlexible tv + ; if flexi then return $ Just tv + else return Nothing + } + | otherwise = return Nothing + doInst _swapped _tv _ty (Right ty) _eq = pprPanic "TcTyFuns.doInst: local eq: " (ppr ty) doInst swapped tv ty (Left cotv) eq