X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcTyClsDecls.lhs;fp=compiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=43a0da7b359607ed0b18c67b74a457b2b71875ff;hp=cb16097ef0e18e0d9c5a2b80e3292c7462439d1e;hb=1b381af863d64aaa0a4dd9c816170c58e6131a9e;hpb=c25b934ef544fa3eba0a9f9da41b363c470156cb diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs index cb16097..43a0da7 100644 --- a/compiler/typecheck/TcTyClsDecls.lhs +++ b/compiler/typecheck/TcTyClsDecls.lhs @@ -7,7 +7,8 @@ TcTyClsDecls: Typecheck type and class declarations \begin{code} module TcTyClsDecls ( - tcTyAndClassDecls, tcFamInstDecl, mkRecSelBinds + tcTyAndClassDecls, kcDataDecl, tcConDecls, mkRecSelBinds, + checkValidTyCon, dataDeclChecks, badFamInstDecl ) where #include "HsVersions.h" @@ -140,188 +141,6 @@ zipRecTyClss decls_s rec_things %************************************************************************ %* * - Type checking family instances -%* * -%************************************************************************ - -Family instances are somewhat of a hybrid. They are processed together with -class instance heads, but can contain data constructors and hence they share a -lot of kinding and type checking code with ordinary algebraic data types (and -GADTs). - -\begin{code} -tcFamInstDecl :: TopLevelFlag -> LTyClDecl Name -> TcM TyThing -tcFamInstDecl top_lvl (L loc decl) - = -- Prime error recovery, set source location - setSrcSpan loc $ - tcAddDeclCtxt decl $ - do { -- type family instances require -XTypeFamilies - -- and can't (currently) be in an hs-boot file - ; type_families <- xoptM Opt_TypeFamilies - ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file? - ; checkTc type_families $ badFamInstDecl (tcdLName decl) - ; checkTc (not is_boot) $ badBootFamInstDeclErr - - -- Perform kind and type checking - ; tc <- tcFamInstDecl1 decl - ; checkValidTyCon tc -- Remember to check validity; - -- no recursion to worry about here - - -- Check that toplevel type instances are not for associated types. - ; when (isTopLevel top_lvl && isAssocFamily tc) - (addErr $ assocInClassErr (tcdName decl)) - - ; return (ATyCon tc) } - -isAssocFamily :: TyCon -> Bool -- Is an assocaited type -isAssocFamily tycon - = case tyConFamInst_maybe tycon of - Nothing -> panic "isAssocFamily: no family?!?" - Just (fam, _) -> isTyConAssoc fam - -assocInClassErr :: Name -> SDoc -assocInClassErr name - = ptext (sLit "Associated type") <+> quotes (ppr name) <+> - ptext (sLit "must be inside a class instance") - - - -tcFamInstDecl1 :: TyClDecl Name -> TcM TyCon - - -- "type instance" -tcFamInstDecl1 (decl@TySynonym {tcdLName = L loc tc_name}) - = kcIdxTyPats decl $ \k_tvs k_typats resKind family -> - do { -- check that the family declaration is for a synonym - checkTc (isFamilyTyCon family) (notFamily family) - ; checkTc (isSynTyCon family) (wrongKindOfFamily family) - - ; -- (1) kind check the right-hand side of the type equation - ; k_rhs <- kcCheckLHsType (tcdSynRhs decl) (EK resKind EkUnk) - -- ToDo: the ExpKind could be better - - -- we need the exact same number of type parameters as the family - -- declaration - ; let famArity = tyConArity family - ; checkTc (length k_typats == famArity) $ - wrongNumberOfParmsErr famArity - - -- (2) type check type equation - ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars - ; t_typats <- mapM tcHsKindedType k_typats - ; t_rhs <- tcHsKindedType k_rhs - - -- (3) check the well-formedness of the instance - ; checkValidTypeInst t_typats t_rhs - - -- (4) construct representation tycon - ; rep_tc_name <- newFamInstTyConName tc_name t_typats loc - ; buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs) - (typeKind t_rhs) - NoParentTyCon (Just (family, t_typats)) - }} - - -- "newtype instance" and "data instance" -tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name, - tcdCons = cons}) - = kcIdxTyPats decl $ \k_tvs k_typats resKind fam_tycon -> - do { -- check that the family declaration is for the right kind - checkTc (isFamilyTyCon fam_tycon) (notFamily fam_tycon) - ; checkTc (isAlgTyCon fam_tycon) (wrongKindOfFamily fam_tycon) - - ; -- (1) kind check the data declaration as usual - ; k_decl <- kcDataDecl decl k_tvs - ; let k_ctxt = tcdCtxt k_decl - k_cons = tcdCons k_decl - - -- result kind must be '*' (otherwise, we have too few patterns) - ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr (tyConArity fam_tycon) - - -- (2) type check indexed data type declaration - ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars - ; unbox_strict <- doptM Opt_UnboxStrictFields - - -- kind check the type indexes and the context - ; t_typats <- mapM tcHsKindedType k_typats - ; stupid_theta <- tcHsKindedContext k_ctxt - - -- (3) Check that - -- (a) left-hand side contains no type family applications - -- (vanilla synonyms are fine, though, and we checked for - -- foralls earlier) - ; mapM_ checkTyFamFreeness t_typats - - -- Check that we don't use GADT syntax in H98 world - ; gadt_ok <- xoptM Opt_GADTs - ; checkTc (gadt_ok || consUseH98Syntax cons) (badGadtDecl tc_name) - - -- (b) a newtype has exactly one constructor - ; checkTc (new_or_data == DataType || isSingleton k_cons) $ - newtypeConError tc_name (length k_cons) - - -- (4) construct representation tycon - ; rep_tc_name <- newFamInstTyConName tc_name t_typats loc - ; let ex_ok = True -- Existentials ok for type families! - ; fixM (\ rep_tycon -> do - { let orig_res_ty = mkTyConApp fam_tycon t_typats - ; data_cons <- tcConDecls unbox_strict ex_ok rep_tycon - (t_tvs, orig_res_ty) k_cons - ; tc_rhs <- - case new_or_data of - DataType -> return (mkDataTyConRhs data_cons) - NewType -> ASSERT( not (null data_cons) ) - mkNewTyConRhs rep_tc_name rep_tycon (head data_cons) - ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive - h98_syntax NoParentTyCon (Just (fam_tycon, t_typats)) - -- We always assume that indexed types are recursive. Why? - -- (1) Due to their open nature, we can never be sure that a - -- further instance might not introduce a new recursive - -- dependency. (2) They are always valid loop breakers as - -- they involve a coercion. - }) - }} - where - h98_syntax = case cons of -- All constructors have same shape - L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False - _ -> True - -tcFamInstDecl1 d = pprPanic "tcFamInstDecl1" (ppr d) - --- Kind checking of indexed types --- - - --- Kind check type patterns and kind annotate the embedded type variables. --- --- * Here we check that a type instance matches its kind signature, but we do --- not check whether there is a pattern for each type index; the latter --- check is only required for type synonym instances. - -kcIdxTyPats :: TyClDecl Name - -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a) - -- ^^kinded tvs ^^kinded ty pats ^^res kind - -> TcM a -kcIdxTyPats decl thing_inside - = kcHsTyVars (tcdTyVars decl) $ \tvs -> - do { let tc_name = tcdLName decl - ; fam_tycon <- tcLookupLocatedTyCon tc_name - ; let { (kinds, resKind) = splitKindFunTys (tyConKind fam_tycon) - ; hs_typats = fromJust $ tcdTyPats decl } - - -- we may not have more parameters than the kind indicates - ; checkTc (length kinds >= length hs_typats) $ - tooManyParmsErr (tcdLName decl) - - -- type functions can have a higher-kinded result - ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind - ; typats <- zipWithM kcCheckLHsType hs_typats - [ EK kind (EkArg (ppr tc_name) n) - | (kind,n) <- kinds `zip` [1..]] - ; thing_inside tvs typats resultKind fam_tycon - } -\end{code} - - -%************************************************************************ -%* * Kind checking %* * %************************************************************************ @@ -666,34 +485,17 @@ tcTyClDecl1 _parent calc_isrec ; let final_tvs = tvs' ++ extra_tvs ; stupid_theta <- tcHsKindedContext ctxt ; unbox_strict <- doptM Opt_UnboxStrictFields - ; empty_data_decls <- xoptM Opt_EmptyDataDecls ; kind_signatures <- xoptM Opt_KindSignatures ; existential_ok <- xoptM Opt_ExistentialQuantification ; gadt_ok <- xoptM Opt_GADTs - ; gadtSyntax_ok <- xoptM Opt_GADTSyntax ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file? ; let ex_ok = existential_ok || gadt_ok -- Data cons can have existential context - -- Check that we don't use GADT syntax in H98 world - ; checkTc (gadtSyntax_ok || h98_syntax) (badGadtDecl tc_name) - -- Check that we don't use kind signatures without Glasgow extensions ; checkTc (kind_signatures || isNothing mb_ksig) (badSigTyDecl tc_name) - -- Check that the stupid theta is empty for a GADT-style declaration - ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name) + ; dataDeclChecks tc_name new_or_data stupid_theta cons - -- Check that a newtype has exactly one constructor - -- Do this before checking for empty data decls, so that - -- we don't suggest -XEmptyDataDecls for newtypes - ; checkTc (new_or_data == DataType || isSingleton cons) - (newtypeConError tc_name (length cons)) - - -- Check that there's at least one condecl, - -- or else we're reading an hs-boot file, or -XEmptyDataDecls - ; checkTc (not (null cons) || empty_data_decls || is_boot) - (emptyConDeclsErr tc_name) - ; tycon <- fixM (\ tycon -> do { let res_ty = mkTyConApp tycon (mkTyVarTys final_tvs) ; data_cons <- tcConDecls unbox_strict ex_ok @@ -750,6 +552,29 @@ tcTyClDecl1 _ _ tcTyClDecl1 _ _ d = pprPanic "tcTyClDecl1" (ppr d) +dataDeclChecks :: Name -> NewOrData -> ThetaType -> [LConDecl Name] -> TcM () +dataDeclChecks tc_name new_or_data stupid_theta cons + = do { -- Check that we don't use GADT syntax in H98 world + gadtSyntax_ok <- xoptM Opt_GADTSyntax + ; let h98_syntax = consUseH98Syntax cons + ; checkTc (gadtSyntax_ok || h98_syntax) (badGadtDecl tc_name) + + -- Check that the stupid theta is empty for a GADT-style declaration + ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name) + + -- Check that a newtype has exactly one constructor + -- Do this before checking for empty data decls, so that + -- we don't suggest -XEmptyDataDecls for newtypes + ; checkTc (new_or_data == DataType || isSingleton cons) + (newtypeConError tc_name (length cons)) + + -- Check that there's at least one condecl, + -- or else we're reading an hs-boot file, or -XEmptyDataDecls + ; empty_data_decls <- xoptM Opt_EmptyDataDecls + ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file? + ; checkTc (not (null cons) || empty_data_decls || is_boot) + (emptyConDeclsErr tc_name) } + ----------------------------------- tcConDecls :: Bool -> Bool -> TyCon -> ([TyVar], Type) -> [LConDecl Name] -> TcM [DataCon] @@ -1102,14 +927,14 @@ checkNewDataCon con -- One argument ; checkTc (null eq_spec) (newtypePredError con) -- Return type is (T a b c) - ; checkTc (null ex_tvs && null eq_theta && null dict_theta) (newtypeExError con) + ; checkTc (null ex_tvs && null theta) (newtypeExError con) -- No existentials ; checkTc (not (any isBanged (dataConStrictMarks con))) (newtypeStrictError con) -- No strictness } where - (_univ_tvs, ex_tvs, eq_spec, eq_theta, dict_theta, arg_tys, _res_ty) = dataConFullSig con + (_univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _res_ty) = dataConFullSig con ------------------------------- checkValidClass :: Class -> TcM () @@ -1503,39 +1328,6 @@ badFamInstDecl tc_name quotes (ppr tc_name) , nest 2 (parens $ ptext (sLit "Use -XTypeFamilies to allow indexed type families")) ] -tooManyParmsErr :: Located Name -> SDoc -tooManyParmsErr tc_name - = ptext (sLit "Family instance has too many parameters:") <+> - quotes (ppr tc_name) - -tooFewParmsErr :: Arity -> SDoc -tooFewParmsErr arity - = ptext (sLit "Family instance has too few parameters; expected") <+> - ppr arity - -wrongNumberOfParmsErr :: Arity -> SDoc -wrongNumberOfParmsErr exp_arity - = ptext (sLit "Number of parameters must match family declaration; expected") - <+> ppr exp_arity - -badBootFamInstDeclErr :: SDoc -badBootFamInstDeclErr - = ptext (sLit "Illegal family instance in hs-boot file") - -notFamily :: TyCon -> SDoc -notFamily tycon - = vcat [ ptext (sLit "Illegal family instance for") <+> quotes (ppr tycon) - , nest 2 $ parens (ppr tycon <+> ptext (sLit "is not an indexed type family"))] - -wrongKindOfFamily :: TyCon -> SDoc -wrongKindOfFamily family - = ptext (sLit "Wrong category of family instance; declaration was for a") - <+> kindOfFamily - where - kindOfFamily | isSynTyCon family = ptext (sLit "type synonym") - | isAlgTyCon family = ptext (sLit "data type") - | otherwise = pprPanic "wrongKindOfFamily" (ppr family) - emptyConDeclsErr :: Name -> SDoc emptyConDeclsErr tycon = sep [quotes (ppr tycon) <+> ptext (sLit "has no constructors"),