X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyDecls.lhs;h=0ed2fef7421f5bf540b62757d5643918b01fb143;hb=711e4d7a4d65472a3a1fb35bcad8e1c9a109c728;hp=b117f2fa94c6f025fa26e28803fa08723dcdc69d;hpb=ca5a4a480d10d61e5b7a52eb4d556e8b8c33e69d;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyDecls.lhs b/ghc/compiler/typecheck/TcTyDecls.lhs index b117f2f..0ed2fef 100644 --- a/ghc/compiler/typecheck/TcTyDecls.lhs +++ b/ghc/compiler/typecheck/TcTyDecls.lhs @@ -1,408 +1,216 @@ % -% (c) The AQUA Project, Glasgow University, 1996 +% (c) The AQUA Project, Glasgow University, 1996-1998 % \section[TcTyDecls]{Typecheck type declarations} \begin{code} +module TcTyDecls ( tcTyDecl, checkValidTyCon, kcConDetails ) where + #include "HsVersions.h" -module TcTyDecls ( - tcTyDecl, - tcConDecl, - mkDataBinds - ) where - -import Ubiq{-uitous-} - -import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..), - Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..), - HsBinds(..), HsLit, Stmt, Qual, ArithSeqInfo, - PolyType, Fake, InPat, - Bind(..), MonoBinds(..), Sig, - MonoType ) -import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..), - RnName{-instance Outputable-} - ) -import TcHsSyn ( mkHsTyLam, mkHsDictLam, tcIdType, zonkId, - TcHsBinds(..), TcIdOcc(..) - ) -import Inst ( newDicts, InstOrigin(..), Inst ) -import TcMonoType ( tcMonoTypeKind, tcMonoType, tcPolyType, tcContext ) -import TcType ( tcInstTyVars, tcInstType, tcInstId ) -import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass, - newLocalId, newLocalIds - ) -import TcMonad hiding ( rnMtoTcM ) -import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind ) - -import Class ( GenClass{-instance Eq-} ) -import Id ( mkDataCon, dataConSig, mkRecordSelId, - dataConFieldLabels, dataConStrictMarks, - StrictnessMark(..), - GenId{-instance NamedThing-} - ) -import FieldLabel -import Kind ( Kind, mkArrowKind, mkBoxedTypeKind ) -import SpecEnv ( SpecEnv(..), nullSpecEnv ) -import Name ( nameSrcLoc, isLocallyDefinedName, getSrcLoc, - Name{-instance Ord3-} +import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..), + getBangType, getBangStrictness, conDetailsTys ) -import Pretty -import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, isDataTyCon, - isNewTyCon, tyConDataCons +import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext ) +import BasicTypes ( NewOrData(..) ) + +import TcMonoType ( tcHsTyVars, tcHsTheta, tcHsType, + kcHsContext, kcHsSigType, kcHsLiftedSigType ) -import Type ( typeKind, getTyVar, tyVarsOfTypes, eqTy, - applyTyCon, mkTyVarTys, mkForAllTys, mkFunTy, - splitFunTy, mkTyVarTy, getTyVar_maybe +import TcEnv ( tcExtendTyVarEnv, + tcLookupTyCon, tcLookupRecId, + TyThingDetails(..), RecTcEnv ) -import TyVar ( tyVarKind, elementOfTyVarSet, GenTyVar{-instance Eq-} ) -import Unique ( Unique {- instance Eq -}, evalClassKey ) -import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, UniqSet(..) ) -import Util ( equivClasses, zipEqual, panic, assertPanic ) -\end{code} +import TcType ( tcEqType, tyVarsOfTypes, tyVarsOfPred, ThetaType ) +import TcMType ( checkValidType, UserTypeCtxt(..), checkValidTheta, SourceTyCtxt(..) ) +import TcMonad -\begin{code} -tcTyDecl :: RenamedTyDecl -> TcM s TyCon +import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConWrapId, dataConName ) +import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId ) +import FieldLabel +import Var ( TyVar, idType ) +import Name ( Name, NamedThing(..) ) +import Outputable +import TyCon ( TyCon, DataConDetails(..), visibleDataCons, + tyConName, tyConTheta, getSynTyConDefn, + tyConTyVars, tyConDataCons, isSynTyCon ) +import VarSet ( intersectVarSet, isEmptyVarSet ) +import PrelNames ( unpackCStringName, unpackCStringUtf8Name ) +import ListSetOps ( equivClasses ) +import List ( nubBy ) \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_` +tcTyDecl :: RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails) +tcTyDecl unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs}) + = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> + tcExtendTyVarEnv (tyConTyVars tycon) $ + tcHsType rhs `thenTc` \ rhs_ty -> + returnTc (tycon_name, SynTyDetails rhs_ty) + +tcTyDecl unf_env (TyData {tcdND = new_or_data, tcdCtxt = context, + tcdName = tycon_name, tcdCons = con_decls}) + = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> 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 + tyvars = tyConTyVars tycon 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 -> + tcExtendTyVarEnv tyvars $ + tcHsTheta context `thenTc` \ ctxt -> + tcConDecls new_or_data tycon tyvars ctxt con_decls `thenTc` \ data_cons -> 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 + sel_ids = mkRecordSelectors unf_env tycon data_cons in - returnTc tycon + returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids) -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} +tcTyDecl unf_env (ForeignType {tcdName = tycon_name}) + = returnTc (tycon_name, ForeignTyDetails) -Generating constructor/selector bindings for data declarations -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -mkDataBinds :: TyCon -> TcM s ([Id], TcHsBinds s) -mkDataBinds 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 - ) +mkRecordSelectors unf_env tycon data_cons + = -- We'll check later that fields with the same name + -- from different constructors have the same type. + [ mkRecordSelId tycon field unpack_id unpackUtf8_id + | field <- nubBy eq_name fields ] where - data_cons = tyConDataCons tycon - fields = [ (con, field) | con <- data_cons, - field <- dataConFieldLabels con - ] + fields = [ field | con <- visibleDataCons data_cons, + field <- dataConFieldLabels con ] + eq_name field1 field2 = fieldLabelName field1 == fieldLabelName field2 - -- groups is list of fields that share a common name - groups = equivClasses cmp_name fields - cmp_name (_, field1) (_, field2) - = fieldLabelName field1 `cmp` fieldLabelName field2 + unpack_id = tcLookupRecId unf_env unpackCStringName + unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name \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. +%************************************************************************ +%* * +\subsection{Validity check} +%* * +%************************************************************************ -* 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. +checkValidTyCon is called once the mutually-recursive knot has been +tied, so we can look at things freely. \begin{code} -mkConstructor con_id - | not (isLocallyDefinedName (getName con_id)) - = returnTc (con_id, EmptyMonoBinds) - - | otherwise -- It is locally defined - = tcInstId con_id `thenNF_Tc` \ (tyvars, theta, tau) -> - newDicts DataDeclOrigin theta `thenNF_Tc` \ (_, dicts) -> - let - (arg_tys, result_ty) = splitFunTy tau - n_args = length arg_tys - in - newLocalIds (take n_args (repeat SLIT("con"))) arg_tys - `thenNF_Tc` \ args -> - - -- Check that all the types of all the strict arguments are in Data. - -- This is trivially true of everything except type variables, for - -- which we must check the context. - let - strict_marks = dataConStrictMarks con_id - strict_args = [arg | (arg, MarkedStrict) <- args `zipEqual` strict_marks] - - data_tyvars = -- The tyvars in the constructor's context that are arguments - -- to the Data class - [getTyVar "mkConstructor" ty - | (clas,ty) <- theta, uniqueOf clas == evalClassKey] +checkValidTyCon :: TyCon -> TcM () +checkValidTyCon tc + | isSynTyCon tc = checkValidType (TySynCtxt name) syn_rhs + | otherwise + = -- Check the context on the data decl + checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenTc_` + + -- Check arg types of data constructors + mapTc_ check_data_con data_cons `thenTc_` + + -- Check that fields with the same name share a type + mapTc_ check_fields groups - check_data arg = case getTyVar_maybe (tcIdType arg) of - Nothing -> returnTc () -- Not a tyvar, so OK - Just tyvar -> checkTc (tyvar `elem` data_tyvars) (missingDataErr tyvar) - in - mapTc check_data strict_args `thenTc_` - - -- Build the data constructor - let - con_rhs = mkHsTyLam tyvars $ - mkHsDictLam dicts $ - mk_pat_match args $ - mk_case strict_args $ - HsCon con_id (mkTyVarTys 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:args) body = HsCase (HsVar arg) - [PatMatch (VarPat arg) (SimpleMatch (mk_case args body))] - src_loc - - src_loc = nameSrcLoc (getName con_id) - in + where + name = tyConName tc + (_, syn_rhs) = getSynTyConDefn tc + data_cons = tyConDataCons tc - returnTc (con_id, VarMonoBind (RealId con_id) con_rhs) + fields = [field | con <- data_cons, field <- dataConFieldLabels con] + groups = equivClasses cmp_name fields + cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2 + + check_data_con con = checkValidType (ConArgCtxt (dataConName con)) + (idType (dataConWrapId con)) + -- This checks the argument types and + -- the existential context (if any) + + check_fields 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 (tcEqType 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 \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! +%************************************************************************ +%* * +\subsection{Kind and type check constructors} +%* * +%************************************************************************ \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_` +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. + + +tcConDecls :: NewOrData -> TyCon -> [TyVar] -> ThetaType + -> DataConDetails RenamedConDecl -> TcM (DataConDetails DataCon) + +tcConDecls new_or_data tycon tyvars ctxt con_decls + = case con_decls of + Unknown -> returnTc Unknown + HasCons n -> returnTc (HasCons n) + DataCons cs -> mapTc tc_con_decl cs `thenTc` \ data_cons -> + returnTc (DataCons data_cons) + where + tc_con_decl (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 -> + tcHsTheta 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 + = mapTc tcHsType (map getBangType btys) `thenTc` \ arg_tys -> + mk_data_con ex_tyvars ex_theta (map getBangStrictness btys) arg_tys [] - -- 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 -> - - -- 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) - arg_tys - tycon - -- nullSpecEnv - in - returnTc data_con - -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 + 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) + = tcHsType (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 data_con_id data_con_wrap_id + + 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 @@ -410,32 +218,24 @@ 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{Errors and contexts} +%* * +%************************************************************************ -Errors and contexts -~~~~~~~~~~~~~~~~~~~ -\begin{code} -tySynCtxt tycon_name sty - = ppCat [ppStr "In the type declaration for", ppr sty tycon_name] - -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] - -fieldTypeMisMatch field_name sty - = ppSep [ppStr "Declared types differ for field", ppr sty field_name] +\begin{code} +fieldTypeMisMatch field_name + = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)] -missingDataErr tyvar sty - = ppStr "Missing `data' (???)" -- ToDo: improve +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}