X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyDecls.lhs;h=a0a00b040a7e532b50eb109ab7cfbf098c695a48;hb=b4775e5e760111e2d71fba3c44882dce390edfb2;hp=a45e600030054392076681d5cade7f2ab719c640;hpb=26741ec416bae2c502ef00a2ba0e79050a32cb67;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyDecls.lhs b/ghc/compiler/typecheck/TcTyDecls.lhs index a45e600..a0a00b0 100644 --- a/ghc/compiler/typecheck/TcTyDecls.lhs +++ b/ghc/compiler/typecheck/TcTyDecls.lhs @@ -1,419 +1,177 @@ % -% (c) The AQUA Project, Glasgow University, 1996 +% (c) The AQUA Project, Glasgow University, 1996-1998 % \section[TcTyDecls]{Typecheck type declarations} \begin{code} -#include "HsVersions.h" - module TcTyDecls ( - tcTyDecl, - tcConDecl, - mkDataBinds + tcTyDecl1, kcConDetails, mkNewTyConRep ) where -IMP_Ubiq(){-uitous-} +#include "HsVersions.h" -import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..), - Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..), - HsBinds(..), HsLit, Stmt, Qualifier, ArithSeqInfo, - PolyType, Fake, InPat, - Bind(..), MonoBinds(..), Sig, - MonoType ) -import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..), - RnName{-instance Outputable-} +import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..), BangType(..), + getBangType, getBangStrictness, conDetailsTys ) -import TcHsSyn ( mkHsTyLam, mkHsDictLam, tcIdType, - TcHsBinds(..), TcIdOcc(..) - ) -import Inst ( newDicts, InstOrigin(..), Inst ) -import TcMonoType ( tcMonoTypeKind, tcMonoType, tcPolyType, tcContext ) -import TcSimplify ( tcSimplifyThetas ) -import TcType ( tcInstTyVars, tcInstType, tcInstId ) -import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass, - newLocalId, newLocalIds, tcLookupClassByKey +import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext ) +import BasicTypes ( NewOrData(..), RecFlag, isRec ) + +import TcMonoType ( tcHsRecType, tcHsTyVars, tcRecTheta, + kcHsContext, kcHsSigType, kcHsLiftedSigType ) -import TcMonad hiding ( rnMtoTcM ) -import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind ) - -import PprType ( GenClass, GenType{-instance Outputable-} ) -import Class ( GenClass{-instance Eq-}, classInstEnv ) -import Id ( mkDataCon, dataConSig, mkRecordSelId, idType, - dataConFieldLabels, dataConStrictMarks, - StrictnessMark(..), - GenId{-instance NamedThing-} +import TcEnv ( tcExtendTyVarEnv, + tcLookupTyCon, tcLookupRecId, + TyThingDetails(..), RecTcEnv ) +import TcMonad + +import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConRepType ) +import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId ) import FieldLabel -import Kind ( Kind, mkArrowKind, mkBoxedTypeKind ) -import SpecEnv ( SYN_IE(SpecEnv), nullSpecEnv ) -import Name ( nameSrcLoc, isLocallyDefinedName, getSrcLoc, - Name{-instance Ord3-} +import Var ( TyVar ) +import Name ( Name, NamedThing(..) ) +import Outputable +import TyCon ( TyCon, isNewTyCon, tyConTyVars ) +import Type ( tyVarsOfTypes, tyVarsOfPred, splitFunTy, applyTys, + mkTyConApp, mkTyVarTys, mkForAllTys, + splitAlgTyConApp_maybe, Type, ThetaType ) -import Outputable ( Outputable(..), interpp'SP ) -import Pretty -import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, isDataTyCon, - isNewTyCon, isSynTyCon, tyConDataCons - ) -import Type ( GenType, -- instances - typeKind, getTyVar, tyVarsOfTypes, eqTy, splitSigmaTy, - applyTyCon, mkTyVarTys, mkForAllTys, mkFunTy, - splitFunTy, mkTyVarTy, getTyVar_maybe - ) -import PprType ( GenTyVar{-instance Outputable-}{-ToDo:possibly rm-} ) -import TyVar ( tyVarKind, elementOfTyVarSet, GenTyVar{-instance Eq-} ) -import Unique ( Unique {- instance Eq -}, evalClassKey ) -import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, SYN_IE(UniqSet) ) -import Util ( equivClasses, zipEqual, nOfThem, panic, assertPanic ) -\end{code} - -\begin{code} -tcTyDecl :: RenamedTyDecl -> TcM s TyCon +import TysWiredIn ( unitTy ) +import VarSet ( intersectVarSet, isEmptyVarSet ) +import PrelNames ( unpackCStringName, unpackCStringUtf8Name ) +import ListSetOps ( equivClasses ) \end{code} -Type synonym decls -~~~~~~~~~~~~~~~~~~ +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ \begin{code} -tcTyDecl (TySynonym tycon_name tyvar_names rhs src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (tySynCtxt tycon_name) $ - - -- Look up the pieces - tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) -> - mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) -> - - -- Look at the rhs - tcMonoTypeKind rhs `thenTc` \ (rhs_kind, rhs_ty) -> - - -- Unify tycon kind with (k1->...->kn->rhs) - unifyKind tycon_kind - (foldr mkTcArrowKind rhs_kind tyvar_kinds) - `thenTc_` - let - -- Getting the TyCon's kind is a bit of a nuisance. We can't use the tycon_kind, - -- because that's a TcKind and may not yet be fully unified with other kinds. - -- We could have augmented the tycon environment with a knot-tied kind, - -- but the simplest thing to do seems to be to get the Kind by (lazily) - -- looking at the tyvars and rhs_ty. - result_kind, final_tycon_kind :: Kind -- NB not TcKind! - result_kind = typeKind rhs_ty - final_tycon_kind = foldr (mkArrowKind . tyVarKind) result_kind rec_tyvars - - -- Construct the tycon - tycon = mkSynTyCon (getName tycon_name) - final_tycon_kind - (length tyvar_names) - rec_tyvars - rhs_ty - in - returnTc tycon -\end{code} - -Algebraic data and newtype decls -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -\begin{code} -tcTyDecl (TyData context tycon_name tyvar_names con_decls derivings pragmas src_loc) - = tcTyDataOrNew DataType context tycon_name tyvar_names con_decls derivings pragmas src_loc - -tcTyDecl (TyNew context tycon_name tyvar_names con_decl derivings pragmas src_loc) - = tcTyDataOrNew NewType context tycon_name tyvar_names con_decl derivings pragmas src_loc - - -tcTyDataOrNew data_or_new context tycon_name tyvar_names con_decls derivings pragmas src_loc - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (tyDataCtxt tycon_name) $ - - -- Lookup the pieces - tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) -> - mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) -> - tc_derivs derivings `thenNF_Tc` \ derived_classes -> - - -- Typecheck the context - tcContext context `thenTc` \ ctxt -> - - -- Unify tycon kind with (k1->...->kn->Type) - unifyKind tycon_kind - (foldr mkTcArrowKind mkTcTypeKind tyvar_kinds) - `thenTc_` - - -- Walk the condecls - mapTc (tcConDecl rec_tycon rec_tyvars ctxt) con_decls - `thenTc` \ con_ids -> +tcTyDecl1 :: RecFlag -> RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails) +tcTyDecl1 is_rec unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs}) + = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> + tcExtendTyVarEnv (tyConTyVars tycon) $ + tcHsRecType is_rec rhs `thenTc` \ rhs_ty -> + -- Note tcHsRecType not tcHsRecSigType; we allow type synonyms + -- that aren't types; e.g. type List = [] + -- + -- If the RHS mentions tyvars that aren't in scope, we'll + -- quantify over them: + -- e.g. type T = a->a + -- will become type T = forall a. a->a + -- + -- With gla-exts that's right, but for H98 we should complain. + -- We can now do that here without falling into + -- a black hole, we still do it in rnDecl (TySynonym case) + + returnTc (tycon_name, SynTyDetails rhs_ty) + +tcTyDecl1 is_rec unf_env (TyData {tcdND = new_or_data, tcdCtxt = context, + tcdName = tycon_name, tcdCons = con_decls}) + = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> let - -- Construct the tycon - final_tycon_kind :: Kind -- NB not TcKind! - final_tycon_kind = foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars - - tycon = mkDataTyCon (getName tycon_name) - final_tycon_kind - rec_tyvars - ctxt - con_ids - derived_classes - data_or_new + tyvars = tyConTyVars tycon in - returnTc tycon - -tc_derivs Nothing = returnNF_Tc [] -tc_derivs (Just ds) = mapNF_Tc tc_deriv ds - -tc_deriv name - = tcLookupClass name `thenNF_Tc` \ (_, clas) -> - returnNF_Tc clas -\end{code} - -Generating constructor/selector bindings for data declarations -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -\begin{code} -mkDataBinds :: [TyCon] -> TcM s ([Id], TcHsBinds s) -mkDataBinds [] = returnTc ([], EmptyBinds) -mkDataBinds (tycon : tycons) - | isSynTyCon tycon = mkDataBinds tycons - | otherwise = mkDataBinds_one tycon `thenTc` \ (ids1, b1) -> - mkDataBinds tycons `thenTc` \ (ids2, b2) -> - returnTc (ids1++ids2, b1 `ThenBinds` b2) - -mkDataBinds_one tycon - = ASSERT( isDataTyCon tycon || isNewTyCon tycon ) - mapAndUnzipTc mkConstructor data_cons `thenTc` \ (con_ids, con_binds) -> - mapAndUnzipTc (mkRecordSelector tycon) groups `thenTc` \ (sel_ids, sel_binds) -> - returnTc (con_ids ++ sel_ids, - SingleBind $ NonRecBind $ - foldr AndMonoBinds - (foldr AndMonoBinds EmptyMonoBinds sel_binds) - con_binds - ) - where - data_cons = tyConDataCons tycon - fields = [ (con, field) | con <- data_cons, - field <- dataConFieldLabels con - ] + tcExtendTyVarEnv tyvars $ - -- groups is list of fields that share a common name - groups = equivClasses cmp_name fields - cmp_name (_, field1) (_, field2) - = fieldLabelName field1 `cmp` fieldLabelName field2 + -- Typecheck the pieces + tcRecTheta is_rec context `thenTc` \ ctxt -> + mapTc (tcConDecl is_rec new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons -> + tcRecordSelectors is_rec unf_env tycon data_cons `thenTc` \ sel_ids -> + returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids) \end{code} -We're going to build a constructor that looks like: - - data (Data a, C b) => T a b = T1 !a !Int b - - T1 = /\ a b -> - \d1::Data a, d2::C b -> - \p q r -> case p of { p -> - case q of { q -> - HsCon T1 [a,b] [p,q,r]}} - -Notice that - -* d2 is thrown away --- a context in a data decl is used to make sure - one *could* construct dictionaries at the site the constructor - is used, but the dictionary isn't actually used. - -* We have to check that we can construct Data dictionaries for - the types a and Int. Once we've done that we can throw d1 away too. - -* We use (case p of ...) to evaluate p, rather than "seq" because - all that matters is that the arguments are evaluated. "seq" is - very careful to preserve evaluation order, which we don't need - to be here. - \begin{code} -mkConstructor con_id - | not (isLocallyDefinedName (getName con_id)) - = returnTc (con_id, EmptyMonoBinds) +mkNewTyConRep :: TyCon -> Type +-- Find the representation type for this newtype TyCon +-- The trick is to to deal correctly with recursive newtypes +-- such as newtype T = MkT T - | otherwise -- It is locally defined - = tcInstId con_id `thenNF_Tc` \ (tc_tyvars, tc_theta, tc_tau) -> - newDicts DataDeclOrigin tc_theta `thenNF_Tc` \ (_, dicts) -> - let - (tc_arg_tys, tc_result_ty) = splitFunTy tc_tau - n_args = length tc_arg_tys - in - newLocalIds (nOfThem n_args SLIT("con")) tc_arg_tys `thenNF_Tc` \ args -> - - -- Check that all the types of all the strict arguments are in Eval - tcLookupClassByKey evalClassKey `thenNF_Tc` \ eval_clas -> - let - (_,theta,tau) = splitSigmaTy (idType con_id) - (arg_tys, _) = splitFunTy tau - strict_marks = dataConStrictMarks con_id - eval_theta = [ (eval_clas,arg_ty) - | (arg_ty, MarkedStrict) <- zipEqual "strict_args" - arg_tys strict_marks - ] - in - tcSimplifyThetas classInstEnv theta eval_theta `thenTc` \ eval_theta' -> - checkTc (null eval_theta') - (missingEvalErr con_id eval_theta') `thenTc_` - - -- Build the data constructor - let - con_rhs = mkHsTyLam tc_tyvars $ - mkHsDictLam dicts $ - mk_pat_match args $ - mk_case (zipEqual "strict_args" args strict_marks) $ - HsCon con_id (mkTyVarTys tc_tyvars) (map HsVar args) - - mk_pat_match [] body = body - mk_pat_match (arg:args) body = HsLam $ - PatMatch (VarPat arg) $ - SimpleMatch (mk_pat_match args body) - - mk_case [] body = body - mk_case ((arg,MarkedStrict):args) body = HsCase (HsVar arg) - [PatMatch (VarPat arg) $ - SimpleMatch (mk_case args body)] - src_loc - mk_case (_:args) body = mk_case args body - - src_loc = nameSrcLoc (getName con_id) - in - - returnTc (con_id, VarMonoBind (RealId con_id) con_rhs) +mkNewTyConRep tc + = mkForAllTys tvs (loop [] (mkTyConApp tc (mkTyVarTys tvs))) + where + tvs = tyConTyVars tc + loop tcs ty = case splitAlgTyConApp_maybe ty of { + Nothing -> ty ; + Just (tc, tys, data_cons) | not (isNewTyCon tc) -> ty + | tc `elem` tcs -> unitTy + | otherwise -> + + case splitFunTy (applyTys (dataConRepType (head data_cons)) tys) of + (rep_ty, _) -> loop (tc:tcs) rep_ty + } \end{code} -We're going to build a record selector that looks like this: - - data T a b c = T1 { op :: a, ...} - | T2 { op :: a, ...} - | T3 - - sel :: forall a b c. T a b c -> a - sel = /\ a b c -> \ T1 { sel = x } -> x - T2 { sel = 2 } -> x - -Note that the selector Id itself is used as the field -label; it has to be an Id, you see! -\begin{code} -mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields) - = let - field_ty = fieldLabelType first_field_label - field_name = fieldLabelName first_field_label - other_tys = [fieldLabelType fl | (_, fl) <- other_fields] - (tyvars, _, _, _) = dataConSig first_con - data_ty = applyTyCon tycon (mkTyVarTys tyvars) - -- tyvars of first_con may be free in field_ty - in - - -- Check that all the fields in the group have the same type - -- This check assumes that all the constructors of a given - -- data type use the same type variables - checkTc (all (eqTy field_ty) other_tys) - (fieldTypeMisMatch field_name) `thenTc_` - - -- Create an Id for the field itself - tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', tyvar_tys, tenv) -> - tcInstType tenv field_ty `thenNF_Tc` \ field_ty' -> - let - data_ty' = applyTyCon tycon tyvar_tys - in - newLocalId SLIT("x") field_ty' `thenNF_Tc` \ field_id -> - newLocalId SLIT("r") data_ty' `thenNF_Tc` \ record_id -> +%************************************************************************ +%* * +\subsection{Kind and type check constructors} +%* * +%************************************************************************ - -- Now build the selector - let - selector_ty :: Type - selector_ty = mkForAllTys tyvars $ - mkFunTy data_ty $ - field_ty - - selector_id :: Id - selector_id = mkRecordSelId first_field_label selector_ty - - -- HsSyn is dreadfully verbose for defining the selector! - selector_rhs = mkHsTyLam tyvars' $ - HsLam $ - PatMatch (VarPat record_id) $ - SimpleMatch $ - selector_body - - selector_body = HsCase (HsVar record_id) (map mk_match fields) (getSrcLoc tycon) - - mk_match (con_id, field_label) - = PatMatch (RecPat con_id data_ty' [(selector_id, VarPat field_id, False)]) $ - SimpleMatch $ - HsVar field_id - in - returnTc (selector_id, if isLocallyDefinedName (getName tycon) - then VarMonoBind (RealId selector_id) selector_rhs - else EmptyMonoBinds) -\end{code} - -Constructors -~~~~~~~~~~~~ \begin{code} -tcConDecl :: TyCon -> [TyVar] -> [(Class,Type)] -> RenamedConDecl -> TcM s Id - -tcConDecl tycon tyvars ctxt (ConDecl name btys src_loc) - = tcDataCon tycon tyvars ctxt name btys src_loc - -tcConDecl tycon tyvars ctxt (ConOpDecl bty1 op bty2 src_loc) - = tcDataCon tycon tyvars ctxt op [bty1,bty2] src_loc - -tcConDecl tycon tyvars ctxt (NewConDecl name ty src_loc) - = tcAddSrcLoc src_loc $ - tcMonoType ty `thenTc` \ arg_ty -> - let - data_con = mkDataCon (getName name) - [NotMarkedStrict] - [{- No labelled fields -}] - tyvars - ctxt - [arg_ty] - tycon - -- nullSpecEnv - in - returnTc data_con - -tcConDecl tycon tyvars ctxt (RecConDecl name fields src_loc) - = tcAddSrcLoc src_loc $ - mapTc tcField fields `thenTc` \ field_label_infos_s -> - let - field_label_infos = concat field_label_infos_s - stricts = [strict | (_, _, strict) <- field_label_infos] - arg_tys = [ty | (_, ty, _) <- field_label_infos] - - field_labels = [ mkFieldLabel (getName name) ty tag - | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags ] - - data_con = mkDataCon (getName name) - stricts - field_labels - tyvars - (thinContext arg_tys ctxt) +kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM () +kcConDetails new_or_data ex_ctxt details + = kcHsContext ex_ctxt `thenTc_` + mapTc_ kc_sig_type (conDetailsTys details) + where + kc_sig_type = case new_or_data of + DataType -> kcHsSigType + NewType -> kcHsLiftedSigType + -- Can't allow an unlifted type here, because we're effectively + -- going to remove the constructor while coercing it to a lifted type. + + +tcConDecl :: RecFlag -> NewOrData -> TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM DataCon + +tcConDecl is_rec new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc) + = tcAddSrcLoc src_loc $ + tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars -> + tcRecTheta is_rec ex_ctxt `thenTc` \ ex_theta -> + case details of + VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys + InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2] + RecCon fields -> tc_rec_con ex_tyvars ex_theta fields + where + tc_datacon ex_tyvars ex_theta btys + = let + arg_stricts = map getBangStrictness btys + tys = map getBangType btys + in + mapTc (tcHsRecType is_rec) tys `thenTc` \ arg_tys -> + mk_data_con ex_tyvars ex_theta arg_stricts arg_tys [] + + tc_rec_con ex_tyvars ex_theta fields + = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_` + mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s -> + let + field_labels = concat field_labels_s + arg_stricts = [str | (ns, bty) <- fields, + let str = getBangStrictness bty, + n <- ns -- One for each. E.g x,y,z :: !Int + ] + in + mk_data_con ex_tyvars ex_theta arg_stricts + (map fieldLabelType field_labels) field_labels + + tc_field ((field_label_names, bty), tag) + = tcHsRecType is_rec (getBangType bty) `thenTc` \ field_ty -> + returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names] + + mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields + = let + data_con = mkDataCon name arg_stricts fields + tyvars (thinContext arg_tys ctxt) + ex_tyvars ex_theta arg_tys - tycon - -- nullSpecEnv - in - returnTc data_con + tycon data_con_id data_con_wrap_id -tcField (field_label_names, bty) - = tcPolyType (get_pty bty) `thenTc` \ field_ty -> - returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names] - -tcDataCon tycon tyvars ctxt name btys src_loc - = tcAddSrcLoc src_loc $ - let - stricts = map get_strictness btys - tys = map get_pty btys - in - mapTc tcPolyType tys `thenTc` \ arg_tys -> - let - data_con = mkDataCon (getName name) - stricts - [{- No field labels -}] - tyvars - (thinContext arg_tys ctxt) - arg_tys - tycon - -- nullSpecEnv - in - returnTc data_con + data_con_id = mkDataConId wkr_name data_con + data_con_wrap_id = mkDataConWrapId data_con + in + returnNF_Tc data_con -- The context for a data constructor should be limited to -- the type variables mentioned in the arg_tys @@ -421,34 +179,67 @@ thinContext arg_tys ctxt = filter in_arg_tys ctxt where arg_tyvars = tyVarsOfTypes arg_tys - in_arg_tys (clas,ty) = getTyVar "tcDataCon" ty `elementOfTyVarSet` arg_tyvars - -get_strictness (Banged _) = MarkedStrict -get_strictness (Unbanged _) = NotMarkedStrict - -get_pty (Banged ty) = ty -get_pty (Unbanged ty) = ty + in_arg_tys pred = not $ isEmptyVarSet $ + tyVarsOfPred pred `intersectVarSet` arg_tyvars \end{code} +%************************************************************************ +%* * +\subsection{Record selectors} +%* * +%************************************************************************ -Errors and contexts -~~~~~~~~~~~~~~~~~~~ \begin{code} -tySynCtxt tycon_name sty - = ppCat [ppStr "In the type declaration for", ppr sty tycon_name] +tcRecordSelectors is_rec unf_env tycon data_cons + -- Omit the check that the fields have consistent types if + -- the group is recursive; TcTyClsDecls.tcGroup will repeat + -- with NonRecursive once we have tied the knot + | isRec is_rec = returnTc sel_ids + | otherwise = mapTc check groups `thenTc_` + returnTc sel_ids + where + fields = [ field | con <- data_cons + , field <- dataConFieldLabels con ] + + -- groups is list of fields that share a common name + groups = equivClasses cmp_name fields + cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2 + + sel_ids = [ mkRecordSelId tycon field unpack_id unpackUtf8_id + | (field : _) <- groups ] + + check fields@(first_field_label : other_fields) + -- These fields all have the same name, but are from + -- different constructors in the data type + = -- Check that all the fields in the group have the same type + -- NB: this check assumes that all the constructors of a given + -- data type use the same type variables + checkTc (all (== field_ty) other_tys) (fieldTypeMisMatch field_name) + where + field_ty = fieldLabelType first_field_label + field_name = fieldLabelName first_field_label + other_tys = map fieldLabelType other_fields + + unpack_id = tcLookupRecId unf_env unpackCStringName + unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name +\end{code} + -tyDataCtxt tycon_name sty - = ppCat [ppStr "In the data declaration for", ppr sty tycon_name] -tyNewCtxt tycon_name sty - = ppCat [ppStr "In the newtype declaration for", ppr sty tycon_name] +%************************************************************************ +%* * +\subsection{Errors and contexts} +%* * +%************************************************************************ -fieldTypeMisMatch field_name sty - = ppSep [ppStr "Declared types differ for field", ppr sty field_name] -missingEvalErr con eval_theta sty - = ppCat [ppStr "Missing Eval context for constructor", - ppQuote (ppr sty con), - ppStr ":", ppr sty eval_theta] +\begin{code} +fieldTypeMisMatch field_name + = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)] + +exRecConErr name + = ptext SLIT("Can't combine named fields with locally-quantified type variables") + $$ + (ptext SLIT("In the declaration of data constructor") <+> ppr name) \end{code}