X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcPat.lhs;h=fd284552af49377a21e0cc9ac86b7cbc00ed7cd2;hb=ebec49fed627b7dd17e297ddc79a9c677a2ce538;hp=61ee9382d21ccbd27600c2a5566202a28c42236b;hpb=288213d7c2c65fa68ca466c1a1a3378e24fa1151;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs index 61ee938..fd28455 100644 --- a/compiler/typecheck/TcPat.lhs +++ b/compiler/typecheck/TcPat.lhs @@ -6,13 +6,6 @@ TcPat: Typechecking patterns \begin{code} -{-# OPTIONS -w #-} --- The above warning supression flag is a temporary kludge. --- While working on this module you are encouraged to remove it and fix --- any warnings in the module. See --- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings --- for details - module TcPat ( tcLetPat, tcLamPat, tcLamPats, tcProcPat, tcOverloadedLit, addDataConStupidTheta, badFieldCon, polyPatSig ) where @@ -32,6 +25,7 @@ import TcSimplify import TcEnv import TcMType import TcType +import VarEnv import VarSet import TcUnify import TcHsType @@ -41,7 +35,6 @@ import Coercion import StaticFlags import TyCon import DataCon -import DynFlags import PrelNames import BasicTypes hiding (SuccessFlag(..)) import SrcLoc @@ -98,14 +91,16 @@ tcLamPats pats tys res_ty thing_inside = tc_lam_pats LamPat (zipEqual "tcLamPats" pats tys) res_ty thing_inside -tcLamPat :: LPat Name -> BoxySigmaType - -> BoxyRhoType -- Result type - -> (BoxyRhoType -> TcM a) -- Checker for body, given its result type - -> TcM (LPat TcId, a) - -tcProcPat = tc_lam_pat ProcPat +tcLamPat, tcProcPat :: LPat Name -> BoxySigmaType + -> BoxyRhoType -- Result type + -> (BoxyRhoType -> TcM a) -- Checker for body, given + -- its result type + -> TcM (LPat TcId, a) tcLamPat = tc_lam_pat LamPat +tcProcPat = tc_lam_pat ProcPat +tc_lam_pat :: PatCtxt -> LPat Name -> BoxySigmaType -> BoxyRhoType + -> (BoxyRhoType -> TcM a) -> TcM (LPat TcId, a) tc_lam_pat ctxt pat pat_ty res_ty thing_inside = do { ([pat'],thing) <- tc_lam_pats ctxt [(pat, pat_ty)] res_ty thing_inside ; return (pat', thing) } @@ -119,10 +114,11 @@ tc_lam_pats :: PatCtxt tc_lam_pats ctxt pat_ty_prs res_ty thing_inside = do { let init_state = PS { pat_ctxt = ctxt, pat_eqs = False } - ; (pats', ex_tvs, res) <- tcMultiple tc_lpat_pr pat_ty_prs init_state $ \ pstate' -> - if (pat_eqs pstate' && (not $ isRigidTy res_ty)) - then failWithTc (nonRigidResult res_ty) - else thing_inside res_ty + ; (pats', ex_tvs, res) <- do { traceTc (text "tc_lam_pats" <+> (ppr pat_ty_prs $$ ppr res_ty)) + ; tcMultiple tc_lpat_pr pat_ty_prs init_state $ \ pstate' -> + if (pat_eqs pstate' && (not $ isRigidTy res_ty)) + then nonRigidResult res_ty + else thing_inside res_ty } ; let tys = map snd pat_ty_prs ; tcCheckExistentialPat pats' ex_tvs tys res_ty @@ -143,7 +139,7 @@ tcCheckExistentialPat :: [LPat TcId] -- Patterns (just for error message) -- f (C g) x = g x -- Here, result_ty will be simply Int, but expected_ty is (C -> a -> Int). -tcCheckExistentialPat pats [] pat_tys body_ty +tcCheckExistentialPat _ [] _ _ = return () -- Short cut for case when there are no existentials tcCheckExistentialPat pats ex_tvs pat_tys body_ty @@ -152,8 +148,9 @@ tcCheckExistentialPat pats ex_tvs pat_tys body_ty data PatState = PS { pat_ctxt :: PatCtxt, - pat_eqs :: Bool -- <=> there are GADT equational constraints - -- for refinement + pat_eqs :: Bool -- <=> there are any equational constraints + -- Used at the end to say whether the result + -- type must be rigid } data PatCtxt @@ -164,7 +161,7 @@ data PatCtxt patSigCtxt :: PatState -> UserTypeCtxt patSigCtxt (PS { pat_ctxt = LetPat _ }) = BindPatSigCtxt -patSigCtxt other = LamPatSigCtxt +patSigCtxt _ = LamPatSigCtxt \end{code} @@ -212,9 +209,14 @@ bindInstsOfPatId id thing_inside ; return (res, binds) } ------------------- -unBoxPatBndrType ty name = unBoxArgType ty (ptext SLIT("The variable") <+> quotes (ppr name)) -unBoxWildCardType ty = unBoxArgType ty (ptext SLIT("A wild-card pattern")) -unBoxViewPatType ty pat = unBoxArgType ty (ptext SLIT("The view pattern") <+> ppr pat) +unBoxPatBndrType :: BoxyType -> Name -> TcM TcType +unBoxPatBndrType ty name = unBoxArgType ty (ptext (sLit "The variable") <+> quotes (ppr name)) + +unBoxWildCardType :: BoxyType -> TcM TcType +unBoxWildCardType ty = unBoxArgType ty (ptext (sLit "A wild-card pattern")) + +unBoxViewPatType :: BoxyType -> Pat Name -> TcM TcType +unBoxViewPatType ty pat = unBoxArgType ty (ptext (sLit "The view pattern") <+> ppr pat) unBoxArgType :: BoxyType -> SDoc -> TcM TcType -- In addition to calling unbox, unBoxArgType ensures that the type is of ArgTypeKind; @@ -235,7 +237,7 @@ unBoxArgType ty pp_this ; unifyType ty' ty2 ; return ty' }} where - msg = pp_this <+> ptext SLIT("cannot be bound to an unboxed tuple") + msg = pp_this <+> ptext (sLit "cannot be bound to an unboxed tuple") \end{code} @@ -420,12 +422,15 @@ tc_pat pstate (orig@(ViewPat expr pat _)) overall_pat_ty thing_inside -- Type signatures in patterns -- See Note [Pattern coercions] below tc_pat pstate (SigPatIn pat sig_ty) pat_ty thing_inside - = do { (inner_ty, tv_binds) <- tcPatSig (patSigCtxt pstate) sig_ty pat_ty + = do { (inner_ty, tv_binds, coi) <- tcPatSig (patSigCtxt pstate) sig_ty + pat_ty + ; unless (isIdentityCoercion coi) $ + failWithTc (badSigPat pat_ty) ; (pat', tvs, res) <- tcExtendTyVarEnv2 tv_binds $ tc_lpat pat inner_ty pstate thing_inside ; return (SigPatOut pat' inner_ty, tvs, res) } -tc_pat pstate pat@(TypePat ty) pat_ty thing_inside +tc_pat _ pat@(TypePat _) _ _ = failWithTc (badTypePat pat) ------------------------ @@ -472,7 +477,7 @@ tc_pat pstate (TuplePat pats boxity _) pat_ty thing_inside ------------------------ -- Data constructors -tc_pat pstate pat_in@(ConPatIn (L con_span con_name) arg_pats) pat_ty thing_inside +tc_pat pstate (ConPatIn (L con_span con_name) arg_pats) pat_ty thing_inside = do { data_con <- tcLookupDataCon con_name ; let tycon = dataConTyCon data_con ; tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside } @@ -484,7 +489,6 @@ tc_pat pstate (LitPat simple_lit) pat_ty thing_inside ; coi <- boxyUnify lit_ty pat_ty -- coi is of kind: lit_ty ~ pat_ty ; res <- thing_inside pstate - ; span <- getSrcSpanM -- pattern coercions have to -- be of kind: pat_ty ~ lit_ty -- hence, sym coi @@ -493,7 +497,7 @@ tc_pat pstate (LitPat simple_lit) pat_ty thing_inside ------------------------ -- Overloaded patterns: n, and n+k -tc_pat pstate pat@(NPat over_lit mb_neg eq) pat_ty thing_inside +tc_pat pstate (NPat over_lit mb_neg eq) pat_ty thing_inside = do { let orig = LiteralOrigin over_lit ; lit' <- tcOverloadedLit orig over_lit pat_ty ; eq' <- tcSyntaxOp orig eq (mkFunTys [pat_ty, pat_ty] boolTy) @@ -506,7 +510,7 @@ tc_pat pstate pat@(NPat over_lit mb_neg eq) pat_ty thing_inside ; res <- thing_inside pstate ; return (NPat lit' mb_neg' eq', [], res) } -tc_pat pstate pat@(NPlusKPat (L nm_loc name) lit ge minus) pat_ty thing_inside +tc_pat pstate (NPlusKPat (L nm_loc name) lit ge minus) pat_ty thing_inside = do { bndr_id <- setSrcSpan nm_loc (tcPatBndr pstate name pat_ty) ; let pat_ty' = idType bndr_id orig = LiteralOrigin lit @@ -616,10 +620,6 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside where uwScrut = unwrapFamInstScrutinee tycon ctxt_res_tys res_pat - ; traceTc $ case sym_coi of - IdCo -> text "sym_coi:IdCo" - ACo co -> text "sym_coi: ACoI" <+> ppr co - -- Add the stupid theta ; addDataConStupidTheta data_con ctxt_res_tys @@ -645,12 +645,7 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside else do -- The general case, with existential, and local equality -- constraints - { let eq_preds = [mkEqPred (mkTyVarTy tv, ty) | (tv, ty) <- eq_spec] - theta' = substTheta tenv (eq_preds ++ full_theta) - -- order is *important* as we generate the list of - -- dictionary binders from theta' - ctxt = pat_ctxt pstate - ; checkTc (case ctxt of { ProcPat -> False; other -> True }) + { checkTc (case pat_ctxt pstate of { ProcPat -> False; _ -> True }) (existentialProcPat data_con) -- Need to test for rigidity if *any* constraints in theta as class @@ -659,13 +654,21 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside -- ex_tvs was non-null. -- ; unless (null theta') $ -- FIXME: AT THE MOMENT WE CHEAT! We only perform the rigidity test - -- if we explicit or implicit (by a GADT def) have equality + -- if we explicitly or implicitly (by a GADT def) have equality -- constraints. - ; unless (all (not . isEqPred) theta') $ + ; let eq_preds = [mkEqPred (mkTyVarTy tv, ty) | (tv, ty) <- eq_spec] + theta' = substTheta tenv (eq_preds ++ full_theta) + -- order is *important* as we generate the list of + -- dictionary binders from theta' + no_equalities = not (any isEqPred theta') + pstate' | no_equalities = pstate + | otherwise = pstate { pat_eqs = True } + + ; unless no_equalities $ checkTc (isRigidTy pat_ty) (nonRigidMatch data_con) ; ((arg_pats', inner_tvs, res), lie_req) <- getLIE $ - tcConArgs data_con arg_tys' arg_pats pstate thing_inside + tcConArgs data_con arg_tys' arg_pats pstate' thing_inside ; loc <- getInstLoc origin ; dicts <- newDictBndrs loc theta' @@ -709,13 +712,12 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside -- NB: We can use CoPat directly, rather than mkCoPat, as we know the -- coercion is not the identity; mkCoPat is inconvenient as it -- wants a located pattern. - = CoPat (WpCo $ mkTyConApp co_con args) -- co fam ty to repr ty + = CoPat (WpCast $ mkTyConApp co_con args) -- co fam ty to repr ty (pat {pat_ty = mkTyConApp tycon args}) -- representation type pat_ty -- family inst type | otherwise = pat - tcConArgs :: DataCon -> [TcSigmaType] -> Checker (HsConPatDetails Name) (HsConPatDetails Id) @@ -740,9 +742,6 @@ tcConArgs data_con arg_tys (InfixCon p1 p2) pstate thing_inside where con_arity = dataConSourceArity data_con -tcConArgs data_con other_args (InfixCon p1 p2) pstate thing_inside - = pprPanic "tcConArgs" (ppr data_con) -- InfixCon always has two arguments - tcConArgs data_con arg_tys (RecCon (HsRecFields rpats dd)) pstate thing_inside = do { (rpats', tvs, res) <- tcMultiple tc_field rpats pstate thing_inside ; return (RecCon (HsRecFields rpats' dd), tvs, res) } @@ -798,7 +797,9 @@ addDataConStupidTheta data_con inst_tys -- The origin should always report "occurrence of C" -- even when C occurs in a pattern stupid_theta = dataConStupidTheta data_con - tenv = zipTopTvSubst (dataConUnivTyVars data_con) inst_tys + tenv = mkTopTvSubst (dataConUnivTyVars data_con `zip` inst_tys) + -- NB: inst_tys can be longer than the univ tyvars + -- because the constructor might have existentials inst_theta = substTheta tenv stupid_theta \end{code} @@ -843,63 +844,37 @@ tcOverloadedLit :: InstOrigin -> HsOverLit Name -> BoxyRhoType -> TcM (HsOverLit TcId) -tcOverloadedLit orig lit@(HsIntegral i fi _) res_ty - | not (fi `isHsVar` fromIntegerName) -- Do not generate a LitInst for rebindable syntax. +tcOverloadedLit orig lit@(OverLit { ol_val = val, ol_rebindable = rebindable + , ol_witness = meth_name }) res_ty + | rebindable + -- Do not generate a LitInst for rebindable syntax. -- Reason: If we do, tcSimplify will call lookupInst, which -- will call tcSyntaxName, which does unification, -- which tcSimplify doesn't like -- ToDo: noLoc sadness - = do { integer_ty <- tcMetaTy integerTyConName - ; fi' <- tcSyntaxOp orig fi (mkFunTy integer_ty res_ty) - ; return (HsIntegral i (HsApp (noLoc fi') (nlHsLit (HsInteger i integer_ty))) res_ty) } - - | Just expr <- shortCutIntLit i res_ty - = return (HsIntegral i expr res_ty) - - | otherwise - = do { expr <- newLitInst orig lit res_ty - ; return (HsIntegral i expr res_ty) } - -tcOverloadedLit orig lit@(HsFractional r fr _) res_ty - | not (fr `isHsVar` fromRationalName) -- c.f. HsIntegral case - = do { rat_ty <- tcMetaTy rationalTyConName - ; fr' <- tcSyntaxOp orig fr (mkFunTy rat_ty res_ty) + = do { hs_lit <- mkOverLit val + ; let lit_ty = hsLitType hs_lit + ; fi' <- tcSyntaxOp orig meth_name (mkFunTy lit_ty res_ty) -- Overloaded literals must have liftedTypeKind, because -- we're instantiating an overloaded function here, -- whereas res_ty might be openTypeKind. This was a bug in 6.2.2 -- However this'll be picked up by tcSyntaxOp if necessary - ; return (HsFractional r (HsApp (noLoc fr') (nlHsLit (HsRat r rat_ty))) res_ty) } + ; let witness = HsApp (noLoc fi') (noLoc (HsLit hs_lit)) + ; return (lit { ol_witness = witness, ol_type = res_ty }) } - | Just expr <- shortCutFracLit r res_ty - = return (HsFractional r expr res_ty) + | Just expr <- shortCutLit val res_ty + = return (lit { ol_witness = expr, ol_type = res_ty }) | otherwise - = do { expr <- newLitInst orig lit res_ty - ; return (HsFractional r expr res_ty) } - -tcOverloadedLit orig lit@(HsIsString s fr _) res_ty - | not (fr `isHsVar` fromStringName) -- c.f. HsIntegral case - = do { str_ty <- tcMetaTy stringTyConName - ; fr' <- tcSyntaxOp orig fr (mkFunTy str_ty res_ty) - ; return (HsIsString s (HsApp (noLoc fr') (nlHsLit (HsString s))) res_ty) } - - | Just expr <- shortCutStringLit s res_ty - = return (HsIsString s expr res_ty) - - | otherwise - = do { expr <- newLitInst orig lit res_ty - ; return (HsIsString s expr res_ty) } - -newLitInst :: InstOrigin -> HsOverLit Name -> BoxyRhoType -> TcM (HsExpr TcId) -newLitInst orig lit res_ty -- Make a LitInst = do { loc <- getInstLoc orig ; res_tau <- zapToMonotype res_ty ; new_uniq <- newUnique - ; let lit_nm = mkSystemVarName new_uniq FSLIT("lit") + ; let lit_nm = mkSystemVarName new_uniq (fsLit "lit") lit_inst = LitInst {tci_name = lit_nm, tci_lit = lit, tci_ty = res_tau, tci_loc = loc} + witness = HsVar (instToId lit_inst) ; extendLIE lit_inst - ; return (HsVar (instToId lit_inst)) } + ; return (lit { ol_witness = witness, ol_type = res_ty }) } \end{code} @@ -975,11 +950,12 @@ patCtxt :: Pat Name -> Maybe Message -- Not all patterns are worth pushing a con patCtxt (VarPat _) = Nothing patCtxt (ParPat _) = Nothing patCtxt (AsPat _ _) = Nothing -patCtxt pat = Just (hang (ptext SLIT("In the pattern:")) +patCtxt pat = Just (hang (ptext (sLit "In the pattern:")) 4 (ppr pat)) ----------------------------------------------- +existentialExplode :: LPat Name -> SDoc existentialExplode pat = hang (vcat [text "My brain just exploded.", text "I can't handle pattern bindings for existentially-quantified constructors.", @@ -987,6 +963,8 @@ existentialExplode pat text "In the binding group for"]) 4 (ppr pat) +sigPatCtxt :: [LPat Var] -> [Var] -> [TcType] -> TcType -> TidyEnv + -> TcM (TidyEnv, SDoc) sigPatCtxt pats bound_tvs pat_tys body_ty tidy_env = do { pat_tys' <- mapM zonkTcType pat_tys ; body_ty' <- zonkTcType body_ty @@ -994,10 +972,10 @@ sigPatCtxt pats bound_tvs pat_tys body_ty tidy_env (env2, tidy_pat_tys) = tidyOpenTypes env1 pat_tys' (env3, tidy_body_ty) = tidyOpenType env2 body_ty' ; return (env3, - sep [ptext SLIT("When checking an existential match that binds"), + sep [ptext (sLit "When checking an existential match that binds"), nest 4 (vcat (zipWith ppr_id show_ids tidy_tys)), - ptext SLIT("The pattern(s) have type(s):") <+> vcat (map ppr tidy_pat_tys), - ptext SLIT("The body has type:") <+> ppr tidy_body_ty + ptext (sLit "The pattern(s) have type(s):") <+> vcat (map ppr tidy_pat_tys), + ptext (sLit "The body has type:") <+> ppr tidy_body_ty ]) } where bound_ids = collectPatsBinders pats @@ -1009,34 +987,43 @@ sigPatCtxt pats bound_tvs pat_tys body_ty tidy_env badFieldCon :: DataCon -> Name -> SDoc badFieldCon con field - = hsep [ptext SLIT("Constructor") <+> quotes (ppr con), - ptext SLIT("does not have field"), quotes (ppr field)] + = hsep [ptext (sLit "Constructor") <+> quotes (ppr con), + ptext (sLit "does not have field"), quotes (ppr field)] polyPatSig :: TcType -> SDoc polyPatSig sig_ty - = hang (ptext SLIT("Illegal polymorphic type signature in pattern:")) + = hang (ptext (sLit "Illegal polymorphic type signature in pattern:")) 2 (ppr sig_ty) -badTypePat pat = ptext SLIT("Illegal type pattern") <+> ppr pat +badSigPat :: TcType -> SDoc +badSigPat pat_ty = ptext (sLit "Pattern signature must exactly match:") <+> + ppr pat_ty + +badTypePat :: Pat Name -> SDoc +badTypePat pat = ptext (sLit "Illegal type pattern") <+> ppr pat existentialProcPat :: DataCon -> SDoc existentialProcPat con - = hang (ptext SLIT("Illegal constructor") <+> quotes (ppr con) <+> ptext SLIT("in a 'proc' pattern")) - 2 (ptext SLIT("Proc patterns cannot use existentials or GADTs")) + = hang (ptext (sLit "Illegal constructor") <+> quotes (ppr con) <+> ptext (sLit "in a 'proc' pattern")) + 2 (ptext (sLit "Proc patterns cannot use existentials or GADTs")) -lazyPatErr pat tvs +lazyPatErr :: Pat name -> [TcTyVar] -> TcM () +lazyPatErr _ tvs = failWithTc $ - hang (ptext SLIT("A lazy (~) pattern cannot bind existential type variables")) + hang (ptext (sLit "A lazy (~) pattern cannot bind existential type variables")) 2 (vcat (map pprSkolTvBinding tvs)) +nonRigidMatch :: DataCon -> SDoc nonRigidMatch con - = hang (ptext SLIT("GADT pattern match in non-rigid context for") <+> quotes (ppr con)) - 2 (ptext SLIT("Solution: add a type signature")) + = hang (ptext (sLit "GADT pattern match in non-rigid context for") <+> quotes (ppr con)) + 2 (ptext (sLit "Solution: add a type signature")) +nonRigidResult :: Type -> TcM a nonRigidResult res_ty - = hang (ptext SLIT("GADT pattern match with non-rigid result type") <+> quotes (ppr res_ty)) - 2 (ptext SLIT("Solution: add a type signature")) - -inaccessibleAlt msg - = hang (ptext SLIT("Inaccessible case alternative:")) 2 msg + = do { env0 <- tcInitTidyEnv + ; let (env1, res_ty') = tidyOpenType env0 res_ty + msg = hang (ptext (sLit "GADT pattern match with non-rigid result type") + <+> quotes (ppr res_ty')) + 2 (ptext (sLit "Solution: add a type signature")) + ; failWithTcM (env1, msg) } \end{code}