X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcPat.lhs;h=984b2e5481b9e9d5f6547c93a1ab2a0b6c96264b;hb=d7b36bbbcd56ee14656223d02e32f5a1f52ea17b;hp=f64dcb25cd3bfc1717b57110cf2ac227757aae0b;hpb=ecdaf6bc29d23bd704df8c65442ee08032a585fc;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs index f64dcb2..984b2e5 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) } @@ -144,7 +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 @@ -166,7 +161,7 @@ data PatCtxt patSigCtxt :: PatState -> UserTypeCtxt patSigCtxt (PS { pat_ctxt = LetPat _ }) = BindPatSigCtxt -patSigCtxt other = LamPatSigCtxt +patSigCtxt _ = LamPatSigCtxt \end{code} @@ -214,8 +209,13 @@ bindInstsOfPatId id thing_inside ; return (res, binds) } ------------------- +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 @@ -422,12 +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) ------------------------ @@ -474,7 +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 } @@ -486,7 +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 @@ -495,7 +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) @@ -508,7 +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 @@ -566,7 +568,7 @@ the split arguments for the representation tycon :R123Map as {Int, c, w} In other words, boxySplitTyConAppWithFamily implicitly takes the coercion - Co123Map a b v :: {Map (a, b) v :=: :R123Map a b v} + Co123Map a b v :: {Map (a, b) v ~ :R123Map a b v} moving between representation and family type into account. To produce type correct Core, this coercion needs to be used to case the type of the scrutinee @@ -592,7 +594,7 @@ to express the local scope of GADT refinements. \begin{code} -- Running example: --- MkT :: forall a b c. (a:=:[b]) => b -> c -> T a +-- MkT :: forall a b c. (a~[b]) => b -> c -> T a -- with scrutinee of type (T ty) tcConPat :: PatState -> SrcSpan -> DataCon -> TyCon @@ -609,18 +611,16 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside -- Instantiate the constructor type variables [a->ty] -- This may involve doing a family-instance coercion, and building a -- wrapper - ; (ctxt_res_tys, coi) <- boxySplitTyConAppWithFamily tycon pat_ty + ; (ctxt_res_tys, coi, unwrap_ty) <- boxySplitTyConAppWithFamily tycon + pat_ty ; let sym_coi = mkSymCoI coi -- boxy split coercion oriented wrongly pat_ty' = mkTyConApp tycon ctxt_res_tys -- pat_ty' /= pat_ty iff coi /= IdCo wrap_res_pat res_pat = mkCoPatCoI sym_coi uwScrut pat_ty 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 + uwScrut = unwrapFamInstScrutinee tycon ctxt_res_tys + unwrap_ty res_pat -- Add the stupid theta ; addDataConStupidTheta data_con ctxt_res_tys @@ -647,7 +647,7 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside else do -- The general case, with existential, and local equality -- constraints - { checkTc (case pat_ctxt pstate 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 @@ -656,7 +656,7 @@ 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. ; let eq_preds = [mkEqPred (mkTyVarTy tv, ty) | (tv, ty) <- eq_spec] theta' = substTheta tenv (eq_preds ++ full_theta) @@ -666,8 +666,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside pstate' | no_equalities = pstate | otherwise = pstate { pat_eqs = True } - ; unless no_equalities (checkTc (isRigidTy pat_ty) - (nonRigidMatch data_con)) + ; 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 @@ -689,12 +689,26 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside boxySplitTyConAppWithFamily tycon pat_ty = traceTc traceMsg >> case tyConFamInst_maybe tycon of - Nothing -> boxySplitTyConApp tycon pat_ty + Nothing -> + do { (scrutinee_arg_tys, coi1) <- boxySplitTyConApp tycon pat_ty + ; return (scrutinee_arg_tys, coi1, pat_ty) + } Just (fam_tycon, instTys) -> - do { (scrutinee_arg_tys, coi) <- boxySplitTyConApp fam_tycon pat_ty + do { (scrutinee_arg_tys, coi1) <- boxySplitTyConApp fam_tycon pat_ty ; (_, freshTvs, subst) <- tcInstTyVars (tyConTyVars tycon) - ; boxyUnifyList (substTys subst instTys) scrutinee_arg_tys - ; return (freshTvs, coi) + ; let instTys' = substTys subst instTys + ; cois <- boxyUnifyList instTys' scrutinee_arg_tys + ; let coi = if isIdentityCoercion coi1 + then -- pat_ty was splittable + -- => boxyUnifyList had real work to do + mkTyConAppCoI fam_tycon instTys' cois + else -- pat_ty was not splittable + -- => scrutinee_arg_tys are fresh tvs and + -- boxyUnifyList just instantiated those + coi1 + ; return (freshTvs, coi, mkTyConApp fam_tycon instTys') + -- this is /= pat_ty + -- iff cois is non-trivial } where traceMsg = sep [ text "tcConPat:boxySplitTyConAppWithFamily:" <+> @@ -706,8 +720,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside -- Wraps the pattern (which must be a ConPatOut pattern) in a coercion -- pattern if the tycon is an instance of a family. -- - unwrapFamInstScrutinee :: TyCon -> [Type] -> Pat Id -> Pat Id - unwrapFamInstScrutinee tycon args pat + unwrapFamInstScrutinee :: TyCon -> [Type] -> Type -> Pat Id -> Pat Id + unwrapFamInstScrutinee tycon args unwrap_ty pat | Just co_con <- tyConFamilyCoercion_maybe tycon -- , not (isNewTyCon tycon) -- newtypes are explicitly unwrapped by -- the desugarer @@ -716,11 +730,10 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside -- wants a located pattern. = 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 + unwrap_ty -- family inst type | otherwise = pat - tcConArgs :: DataCon -> [TcSigmaType] -> Checker (HsConPatDetails Name) (HsConPatDetails Id) @@ -745,9 +758,6 @@ 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) } @@ -803,7 +813,9 @@ 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} @@ -959,6 +971,7 @@ patCtxt pat = Just (hang (ptext (sLit "In the pattern:")) ----------------------------------------------- +existentialExplode :: LPat Name -> SDoc existentialExplode pat = hang (vcat [text "My brain just exploded.", text "I can't handle pattern bindings for existentially-quantified constructors.", @@ -966,6 +979,8 @@ 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 @@ -996,6 +1011,11 @@ polyPatSig sig_ty = hang (ptext (sLit "Illegal polymorphic type signature in pattern:")) 2 (ppr sig_ty) +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 @@ -1003,15 +1023,18 @@ 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")) -lazyPatErr pat tvs +lazyPatErr :: Pat name -> [TcTyVar] -> TcM () +lazyPatErr _ tvs = failWithTc $ 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")) +nonRigidResult :: Type -> TcM a nonRigidResult res_ty = do { env0 <- tcInitTidyEnv ; let (env1, res_ty') = tidyOpenType env0 res_ty @@ -1019,7 +1042,4 @@ nonRigidResult res_ty <+> quotes (ppr res_ty')) 2 (ptext (sLit "Solution: add a type signature")) ; failWithTcM (env1, msg) } - -inaccessibleAlt msg - = hang (ptext (sLit "Inaccessible case alternative:")) 2 msg \end{code}