X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcTyFuns.lhs;h=4c5be1c8993ce7d226b2bcc797d1a56eb7ad36a9;hp=cb0eeae5d06656f89e89a01309a4127b470f345e;hb=ce5f2d9a39dd32b6a2b83addd4637a81d112c386;hpb=1bc34e903f0dcd9ea549524d26cd1517b2356dad diff --git a/compiler/typecheck/TcTyFuns.lhs b/compiler/typecheck/TcTyFuns.lhs index cb0eeae..4c5be1c 100644 --- a/compiler/typecheck/TcTyFuns.lhs +++ b/compiler/typecheck/TcTyFuns.lhs @@ -7,11 +7,9 @@ module TcTyFuns ( normaliseGivenEqs, normaliseGivenDicts, normaliseWantedEqs, normaliseWantedDicts, - solveWantedEqs, - substEqInDictInsts, -- errors - eqInstMisMatch, misMatchMsg, + misMatchMsg, failWithMisMatch ) where @@ -37,10 +35,11 @@ import Bag import Outputable import SrcLoc ( Located(..) ) import Maybes +import FastString -- standard import Data.List -import Control.Monad (liftM) +import Control.Monad \end{code} @@ -121,8 +120,10 @@ eqInstToRewrite :: Inst -> Maybe (Rewrite, Bool) -- True iff rewrite swapped equality eqInstToRewrite inst = ASSERT( isEqInst inst ) - go (eqInstLeftTy inst) (eqInstRightTy inst) (eqInstType inst) + go ty1 ty2 (eqInstType inst) where + (ty1,ty2) = eqInstTys 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 @@ -229,10 +230,6 @@ tcGenericNormaliseFamInst fun (ForAllTy tyvar ty1) = do { (coi,nty1) <- tcGenericNormaliseFamInst fun ty1 ; return (mkForAllTyCoI tyvar coi, mkForAllTy tyvar nty1) } -tcGenericNormaliseFamInst fun (NoteTy note ty1) - = do { (coi,nty1) <- tcGenericNormaliseFamInst fun ty1 - ; return (mkNoteTyCoI note coi, NoteTy note nty1) - } tcGenericNormaliseFamInst fun ty@(TyVarTy tv) | isTcTyVar tv = do { traceTc (text "tcGenericNormaliseFamInst" <+> ppr ty) @@ -309,38 +306,12 @@ normaliseGivenEqs givens \end{code} \begin{code} -normaliseWantedEqs :: [Inst] -> TcM [Inst] -normaliseWantedEqs insts - = do { traceTc (text "normaliseWantedEqs <-" <+> ppr insts) - ; result <- liftM fst $ rewriteToFixedPoint Nothing - [ ("(ZONK)", dontRerun $ zonkInsts) - , ("(TRIVIAL)", dontRerun $ trivialRule) - , ("(DECOMP)", decompRule) - , ("(TOP)", topRule) - , ("(UNIFY)", unifyMetaRule) -- incl. occurs check - , ("(SUBST)", substRule) -- incl. occurs check - ] insts - ; traceTc (text "normaliseWantedEqs ->" <+> ppr result) - ; return result - } -\end{code} - - -%************************************************************************ -%* * -\section{Solving of wanted constraints with respect to a given set} -%* * -%************************************************************************ - -The set of given equalities must have been normalised already. - -\begin{code} -solveWantedEqs :: [Inst] -- givens - -> [Inst] -- wanteds - -> TcM [Inst] -- irreducible wanteds -solveWantedEqs givens wanteds - = do { traceTc $ text "solveWantedEqs <-" <+> ppr wanteds <+> text "with" <+> - ppr givens +normaliseWantedEqs :: [Inst] -- givens + -> [Inst] -- wanteds + -> TcM [Inst] -- irreducible wanteds +normaliseWantedEqs givens wanteds + = do { traceTc $ text "normaliseWantedEqs <-" <+> ppr wanteds + <+> text "with" <+> ppr givens ; result <- liftM fst $ rewriteToFixedPoint Nothing [ ("(ZONK)", dontRerun $ zonkInsts) , ("(TRIVIAL)", dontRerun $ trivialRule) @@ -348,8 +319,9 @@ solveWantedEqs givens wanteds , ("(TOP)", topRule) , ("(GIVEN)", substGivens givens) -- incl. occurs check , ("(UNIFY)", unifyMetaRule) -- incl. occurs check + , ("(SUBST)", substRule) -- incl. occurs check ] wanteds - ; traceTc (text "solveWantedEqs ->" <+> ppr result) + ; traceTc (text "normaliseWantedEqs ->" <+> ppr result) ; return result } where @@ -386,14 +358,18 @@ normalise_dicts -- Fals <=> they are given -> TcM ([Inst],TcDictBinds) normalise_dicts given_eqs dicts is_wanted - = do { traceTc $ text "normalise???Dicts <-" <+> ppr dicts <+> + = do { traceTc $ let name | is_wanted = "normaliseWantedDicts <-" + | otherwise = "normaliseGivenDicts <-" + in + text name <+> ppr dicts <+> text "with" <+> ppr given_eqs ; (dicts0, binds0) <- normaliseInsts is_wanted dicts - ; (dicts1, binds1) <- substEqInDictInsts given_eqs dicts0 + ; (dicts1, binds1) <- substEqInDictInsts is_wanted given_eqs dicts0 ; let binds01 = binds0 `unionBags` binds1 ; if isEmptyBag binds1 then return (dicts1, binds01) - else do { (dicts2, binds2) <- normaliseGivenDicts given_eqs dicts1 + else do { (dicts2, binds2) <- + normalise_dicts given_eqs dicts1 is_wanted ; return (dicts2, binds01 `unionBags` binds2) } } \end{code} @@ -657,7 +633,7 @@ The following rules exploits the reflexivity of equality: \begin{code} trivialRule :: IdemRewriteRule trivialRule insts - = liftM catMaybes $ mappM trivial insts + = liftM catMaybes $ mapM trivial insts where trivial inst | ASSERT( isEqInst inst ) @@ -670,8 +646,7 @@ trivialRule insts | otherwise = return $ Just inst where - ty1 = eqInstLeftTy inst - ty2 = eqInstRightTy inst + (ty1,ty2) = eqInstTys inst \end{code} @@ -702,8 +677,9 @@ decompRule insts where decomp inst = ASSERT( isEqInst inst ) - go (eqInstLeftTy inst) (eqInstRightTy inst) + go ty1 ty2 where + (ty1,ty2) = eqInstTys inst go ty1 ty2 | Just ty1' <- tcView ty1 = go ty1' ty2 | Just ty2' <- tcView ty2 = go ty1 ty2' @@ -822,8 +798,7 @@ topRule insts } } where - ty1 = eqInstLeftTy inst - ty2 = eqInstRightTy inst + (ty1,ty2) = eqInstTys inst \end{code} @@ -921,8 +896,7 @@ substInst inst insts } } where - ty1 = eqInstLeftTy inst - ty2 = eqInstRightTy inst + (ty1,ty2) = eqInstTys inst \end{code} @@ -959,9 +933,10 @@ unifyMetaRule insts where unifyMeta inst = ASSERT( isEqInst inst ) - go (eqInstLeftTy inst) (eqInstRightTy inst) + go ty1 ty2 (fromWantedCo "unifyMetaRule" $ eqInstCoercion inst) where + (ty1,ty2) = eqInstTys inst go ty1 ty2 cotv | Just ty1' <- tcView ty1 = go ty1' ty2 cotv | Just ty2' <- tcView ty2 = go ty1 ty2' cotv @@ -981,26 +956,30 @@ unifyMetaRule insts uMeta _swapped _tv (IndirectTv _) _ty _cotv = return ([inst], False) - -- signature skolem meets non-variable type - -- => cannot update! - uMeta _swapped _tv (DoneTv (MetaTv (SigTv _) _)) ty _cotv - | not $ isTyVarTy ty - = return ([inst], False) - -- type variable meets type variable -- => check that tv2 hasn't been updated yet and choose which to update uMeta swapped tv1 (DoneTv details1) (TyVarTy tv2) cotv + | tv1 == tv2 + = return ([inst], False) -- The two types are already identical + + | otherwise = do { lookupTV2 <- lookupTcTyVar tv2 ; case lookupTV2 of - IndirectTv ty -> uMeta swapped tv1 (DoneTv details1) ty cotv - DoneTv details2 -> - uMetaVar swapped tv1 details1 tv2 details2 cotv + IndirectTv ty -> uMeta swapped tv1 (DoneTv details1) ty cotv + DoneTv details2 -> uMetaVar swapped tv1 details1 tv2 details2 cotv } + ------ Beyond this point we know that ty2 is not a type variable + + -- signature skolem meets non-variable type + -- => cannot update! + uMeta _swapped _tv (DoneTv (MetaTv (SigTv _) _)) _non_tv_ty _cotv + = return ([inst], False) + -- updatable meta variable meets non-variable type -- => occurs check, monotype check, and kinds match check, then update - uMeta swapped tv (DoneTv (MetaTv _ ref)) ty cotv - = do { mb_ty' <- checkTauTvUpdate tv ty -- occurs + monotype check + uMeta swapped tv (DoneTv (MetaTv _ ref)) non_tv_ty cotv + = do { mb_ty' <- checkTauTvUpdate tv non_tv_ty -- occurs + monotype check ; case mb_ty' of Nothing -> return ([inst], False) -- tv occurs in faminst Just ty' -> @@ -1012,6 +991,7 @@ unifyMetaRule insts uMeta _ _ _ _ _ = panic "uMeta" + -- uMetaVar: unify two type variables -- meta variable meets skolem -- => just update uMetaVar swapped tv1 (MetaTv _ ref) tv2 (SkolemTv _) cotv @@ -1079,10 +1059,11 @@ form where F is a type family. \begin{code} -substEqInDictInsts :: [Inst] -- given equalities (used as rewrite rules) +substEqInDictInsts :: Bool -- whether the *dictionaries* are wanted/given + -> [Inst] -- given equalities (used as rewrite rules) -> [Inst] -- dictinaries to be normalised -> TcM ([Inst], TcDictBinds) -substEqInDictInsts eqInsts dictInsts +substEqInDictInsts isWanted eqInsts dictInsts = do { traceTc (text "substEqInDictInst <-" <+> ppr dictInsts) ; dictInsts' <- foldlM rewriteWithOneEquality (dictInsts, emptyBag) eqInsts @@ -1096,7 +1077,7 @@ substEqInDictInsts eqInsts dictInsts tci_right = target}) | isOpenSynTyConApp pattern || isTyVarTy pattern = do { (dictInsts', moreDictBinds) <- - genericNormaliseInsts True {- wanted -} applyThisEq dictInsts + genericNormaliseInsts isWanted applyThisEq dictInsts ; return (dictInsts', dictBinds `unionBags` moreDictBinds) } where @@ -1171,11 +1152,17 @@ genericNormaliseInsts isWanted fun insts -- else -- dict' = dict `cast` co expr = HsVar $ instToId source_dict - cast_expr = HsWrap (WpCo st_co) expr + cast_expr = HsWrap (WpCast st_co) expr rhs = L (instLocSpan loc) cast_expr binds = instToDictBind target_dict rhs -- return the new inst - ; traceTc $ text "genericNormaliseInst ->" <+> ppr dict' + ; traceTc $ let name | isWanted + = "genericNormaliseInst (wanted) ->" + | otherwise + = "genericNormaliseInst (given) ->" + in + text name <+> ppr dict' <+> + text "with" <+> ppr binds ; return (dict', binds) } } @@ -1183,6 +1170,8 @@ genericNormaliseInsts isWanted fun insts -- TOMDO: What do we have to do about ImplicInst, Method, and LitInst?? normaliseOneInst _isWanted _fun inst = do { inst' <- zonkInst inst + ; traceTc $ text "*** TcTyFuns.normaliseOneInst: Skipping" <+> + ppr inst ; return (inst', emptyBag) } \end{code} @@ -1201,45 +1190,49 @@ somethingdifferent message. eqInstMisMatch :: Inst -> TcM a eqInstMisMatch inst = ASSERT( isEqInst inst ) - do { (env, msg) <- misMatchMsg ty_act ty_exp - ; setErrCtxt ctxt $ - failWithTcM (env, msg) - } + setErrCtxt ctxt $ failWithMisMatch ty_act ty_exp where - ty_act = eqInstLeftTy inst - ty_exp = eqInstRightTy inst - InstLoc _ _ ctxt = instLoc inst + (ty_act, ty_exp) = eqInstTys inst + InstLoc _ _ ctxt = instLoc inst ----------------------- -misMatchMsg :: TcType -> TcType -> TcM (TidyEnv, SDoc) +failWithMisMatch :: TcType -> TcType -> TcM a -- Generate the message when two types fail to match, -- going to some trouble to make it helpful. -- The argument order is: actual type, expected type -misMatchMsg ty_act ty_exp +failWithMisMatch ty_act ty_exp = do { env0 <- tcInitTidyEnv ; ty_exp <- zonkTcType ty_exp ; ty_act <- zonkTcType ty_act - ; (env1, pp_exp, extra_exp) <- ppr_ty env0 ty_exp - ; (env2, pp_act, extra_act) <- ppr_ty env1 ty_act - ; return (env2, - sep [sep [ptext SLIT("Couldn't match expected type") <+> pp_exp, - nest 7 $ - ptext SLIT("against inferred type") <+> pp_act], - nest 2 (extra_exp $$ extra_act)]) } - -ppr_ty :: TidyEnv -> TcType -> TcM (TidyEnv, SDoc, SDoc) -ppr_ty env ty - = do { let (env1, tidy_ty) = tidyOpenType env ty - ; (env2, extra) <- ppr_extra env1 tidy_ty - ; return (env2, quotes (ppr tidy_ty), extra) } - --- (ppr_extra env ty) shows extra info about 'ty' -ppr_extra :: TidyEnv -> Type -> TcM (TidyEnv, SDoc) -ppr_extra env (TyVarTy tv) - | isSkolemTyVar tv || isSigTyVar tv - = return (env1, pprSkolTvBinding tv1) + ; failWithTcM (misMatchMsg env0 (ty_act, ty_exp)) + } + +misMatchMsg :: TidyEnv -> (TcType, TcType) -> (TidyEnv, SDoc) +misMatchMsg env0 (ty_act, ty_exp) + = let (env1, pp_exp, extra_exp) = ppr_ty env0 ty_exp + (env2, pp_act, extra_act) = ppr_ty env1 ty_act + msg = sep [sep [ptext (sLit "Couldn't match expected type") <+> pp_exp, + nest 7 $ + ptext (sLit "against inferred type") <+> pp_act], + nest 2 (extra_exp $$ extra_act)] + in + (env2, msg) + where - (env1, tv1) = tidySkolemTyVar env tv + ppr_ty :: TidyEnv -> TcType -> (TidyEnv, SDoc, SDoc) + ppr_ty env ty + = let (env1, tidy_ty) = tidyOpenType env ty + (env2, extra) = ppr_extra env1 tidy_ty + in + (env2, quotes (ppr tidy_ty), extra) + + -- (ppr_extra env ty) shows extra info about 'ty' + ppr_extra :: TidyEnv -> Type -> (TidyEnv, SDoc) + ppr_extra env (TyVarTy tv) + | isTcTyVar tv && (isSkolemTyVar tv || isSigTyVar tv) && not (isUnk tv) + = (env1, pprSkolTvBinding tv1) + where + (env1, tv1) = tidySkolemTyVar env tv -ppr_extra env _ty = return (env, empty) -- Normal case + ppr_extra env _ty = (env, empty) -- Normal case \end{code}