X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=3c25a7fa2712627578380bda0c7d48ef5c3c81a2;hp=090db01ca69fa36155d25d93cb5a1438dc3694a6;hb=138b885a335734039daf7debb0a7dfc3dc947c00;hpb=3e0b6b2542d8464bfba365b97a6e4b95c3885f10 diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs index 090db01..3c25a7f 100644 --- a/compiler/typecheck/TcTyClsDecls.lhs +++ b/compiler/typecheck/TcTyClsDecls.lhs @@ -5,17 +5,19 @@ \begin{code} module TcTyClsDecls ( - tcTyAndClassDecls + tcTyAndClassDecls, tcIdxTyInstDecl ) where #include "HsVersions.h" import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..), ConDecl(..), Sig(..), NewOrData(..), ResType(..), - tyClDeclTyVars, isSynDecl, isClassDecl, hsConArgs, - LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr + tyClDeclTyVars, isSynDecl, isClassDecl, isIdxTyDecl, + isKindSigDecl, hsConArgs, LTyClDecl, tcdName, + hsTyVarName, LHsTyVarBndr, LHsType, HsType(..), + mkHsAppTy ) -import HsTypes ( HsBang(..), getBangStrictness ) +import HsTypes ( HsBang(..), getBangStrictness, hsLTyVarNames ) import BasicTypes ( RecFlag(..), StrictnessMark(..) ) import HscTypes ( implicitTyThings, ModDetails ) import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon, @@ -23,46 +25,54 @@ import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon, import TcRnMonad import TcEnv ( TyThing(..), tcLookupLocated, tcLookupLocatedGlobal, - tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs, - tcExtendRecEnv, tcLookupTyVar, InstInfo ) + tcExtendGlobalEnv, tcExtendKindEnv, + tcExtendKindEnvTvs, newFamInstTyConName, + tcExtendRecEnv, tcLookupTyVar, tcLookupLocatedTyCon ) import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles ) import TcClassDcl ( tcClassSigs, tcAddDeclCtxt ) import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType, kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext, - kcHsSigType, tcHsBangType, tcLHsConResTy, tcDataKindSig ) + kcHsSigType, tcHsBangType, tcLHsConResTy, + tcDataKindSig, kcCheckHsType ) import TcMType ( newKindVar, checkValidTheta, checkValidType, -- checkFreeness, UserTypeCtxt(..), SourceTyCtxt(..) ) -import TcType ( TcKind, TcType, tyVarsOfType, mkPhiTy, +import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy, mkArrowKind, liftedTypeKind, mkTyVarTys, tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe ) -import Type ( splitTyConApp_maybe, +import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy, + newTyConInstRhs, isLiftedTypeKind, Kind -- pprParendType, pprThetaArrow ) -import Kind ( mkArrowKinds, splitKindFunTys ) import Generics ( validGenericMethodType, canDoGenerics ) import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars ) -import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon ), - tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon, - tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName ) -import DataCon ( DataCon, dataConWrapId, dataConName, - dataConFieldLabels, dataConTyCon, - dataConTyVars, dataConFieldType, dataConResTys ) +import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon, + OpenNewTyCon ), + SynTyConRhs( OpenSynTyCon, SynonymTyCon ), + tyConDataCons, mkForeignTyCon, isProductTyCon, + isRecursiveTyCon, isOpenTyCon, + tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName, + isNewTyCon, isDataTyCon, tyConKind, + setTyConArgPoss ) +import DataCon ( DataCon, dataConUserType, dataConName, + dataConFieldLabels, dataConTyCon, dataConAllTyVars, + dataConFieldType, dataConResTys ) import Var ( TyVar, idType, idName ) import VarSet ( elemVarSet, mkVarSet ) import Name ( Name, getSrcLoc ) import Outputable -import Maybe ( isJust ) +import Maybe ( isJust, fromJust, isNothing, catMaybes ) import Maybes ( expectJust ) +import Monad ( unless ) import Unify ( tcMatchTys, tcMatchTyX ) import Util ( zipLazy, isSingleton, notNull, sortLe ) -import List ( partition ) -import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan ) -import ListSetOps ( equivClasses ) -import List ( delete ) +import List ( partition, elemIndex ) +import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan, + srcSpanStart ) +import ListSetOps ( equivClasses, minusList ) import Digraph ( SCC(..) ) import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics, - Opt_UnboxStrictFields ) ) + Opt_UnboxStrictFields, Opt_IndexedTypes ) ) \end{code} @@ -149,29 +159,41 @@ indeed type families). I think. tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name] -> TcM TcGblEnv -- Input env extended by types and classes -- and their implicit Ids,DataCons -tcTyAndClassDecls boot_details decls - = do { -- First check for cyclic type synonysm or classes +tcTyAndClassDecls boot_details allDecls + = do { -- Omit instances of indexed types; they are handled together + -- with the *heads* of class instances + ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls + + -- First check for cyclic type synonysm or classes -- See notes with checkCycleErrs - checkCycleErrs decls + ; checkCycleErrs decls ; mod <- getModule ; traceTc (text "tcTyAndCl" <+> ppr mod) ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) -> - do { let { -- Calculate variances and rec-flag + do { let { -- Seperate ordinary synonyms from all other type and + -- class declarations and add all associated type + -- declarations from type classes. The latter is + -- required so that the temporary environment for the + -- knot includes all associated family declarations. ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc) - decls } + decls + ; alg_at_decls = concatMap addATs alg_decls + } -- Extend the global env with the knot-tied results -- for data types and classes -- - -- We must populate the environment with the loop-tied T's right - -- away, because the kind checker may "fault in" some type - -- constructors that recursively mention T - ; let { gbl_things = mkGlobalThings alg_decls rec_alg_tyclss } + -- We must populate the environment with the loop-tied + -- T's right away, because the kind checker may "fault + -- in" some type constructors that recursively + -- mention T + ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss ; tcExtendRecEnv gbl_things $ do -- Kind-check the declarations { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls - ; let { calc_rec = calcRecFlags boot_details rec_alg_tyclss + ; let { -- Calculate rec-flag + ; calc_rec = calcRecFlags boot_details rec_alg_tyclss ; tc_decl = addLocM (tcTyClDecl calc_rec) } -- Type-check the type synonyms, and extend the envt ; syn_tycons <- tcSynDecls kc_syn_decls @@ -179,7 +201,7 @@ tcTyAndClassDecls boot_details decls -- Type-check the data types and classes { alg_tyclss <- mappM tc_decl kc_alg_decls - ; return (syn_tycons, alg_tyclss) + ; return (syn_tycons, concat alg_tyclss) }}}) -- Finished with knot-tying now -- Extend the environment with the finished things @@ -193,10 +215,22 @@ tcTyAndClassDecls boot_details decls -- Add the implicit things; -- we want them in the environment because -- they may be mentioned in interface files + -- NB: All associated types and their implicit things will be added a + -- second time here. This doesn't matter as the definitions are + -- the same. ; let { implicit_things = concatMap implicitTyThings alg_tyclss } - ; traceTc ((text "Adding" <+> ppr alg_tyclss) $$ (text "and" <+> ppr implicit_things)) + ; traceTc ((text "Adding" <+> ppr alg_tyclss) + $$ (text "and" <+> ppr implicit_things)) ; tcExtendGlobalEnv implicit_things getGblEnv }} + where + -- Pull associated types out of class declarations, to tie them into the + -- knot above. + -- NB: We put them in the same place in the list as `tcTyClDecl' will + -- eventually put the matching `TyThing's. That's crucial; otherwise, + -- the two argument lists of `mkGlobalThings' don't match up. + addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats + addATs decl = [decl] mkGlobalThings :: [LTyClDecl Name] -- The decls -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls @@ -215,6 +249,144 @@ mkGlobalThings decls things %************************************************************************ %* * +\subsection{Type checking instances of indexed types} +%* * +%************************************************************************ + +Instances of indexed types 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} +tcIdxTyInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error +tcIdxTyInstDecl (L loc decl) + = -- Prime error recovery, set source location + recoverM (returnM Nothing) $ + setSrcSpan loc $ + tcAddDeclCtxt decl $ + do { -- indexed data types require -findexed-types and can't be in an + -- hs-boot file + ; gla_exts <- doptM Opt_IndexedTypes + ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file? + ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl) + ; checkTc (not is_boot) $ badBootTyIdxDeclErr + + -- perform kind and type checking + ; tcIdxTyInstDecl1 decl + } + +tcIdxTyInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error + +tcIdxTyInstDecl1 (decl@TySynonym {}) + = kcIdxTyPats decl $ \k_tvs k_typats resKind family -> + do { -- check that the family declaration is for a synonym + unless (isSynTyCon family) $ + addErr (wrongKindOfFamily family) + + ; -- (1) kind check the right hand side of the type equation + ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind + + -- (2) type check type equation + ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars + ; t_typats <- mappM tcHsKindedType k_typats + ; t_rhs <- tcHsKindedType k_rhs + + -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs + ; return Nothing -- !!!TODO: need TyThing for indexed synonym + }} + +tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name, + tcdCons = cons}) + = kcIdxTyPats decl $ \k_tvs k_typats resKind family -> + do { -- check that the family declaration is for the right kind + unless (new_or_data == NewType && isNewTyCon family || + new_or_data == DataType && isDataTyCon family) $ + addErr (wrongKindOfFamily family) + + ; -- (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 tc_name + + -- (2) type check indexed data type declaration + ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars + ; unbox_strict <- doptM Opt_UnboxStrictFields + + -- Check that we don't use GADT syntax for indexed types + ; checkTc h98_syntax (badGadtIdxTyDecl tc_name) + + -- Check that a newtype has exactly one constructor + ; checkTc (new_or_data == DataType || isSingleton k_cons) $ + newtypeConError tc_name (length k_cons) + + ; t_typats <- mappM tcHsKindedType k_typats + ; stupid_theta <- tcHsKindedContext k_ctxt + + ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc) + ; tycon <- fixM (\ tycon -> do + { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data + tycon t_tvs)) + k_cons + ; tc_rhs <- + case new_or_data of + DataType -> return (mkDataTyConRhs data_cons) + NewType -> ASSERT( isSingleton data_cons ) + mkNewTyConRhs tc_name tycon (head data_cons) + ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive + False h98_syntax (Just (family, 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. + }) + + -- construct result + ; return $ Just (ATyCon tycon) + }} + where + h98_syntax = case cons of -- All constructors have same shape + L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False + other -> True + +-- 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 functions. +-- +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 { family <- tcLookupLocatedTyCon (tcdLName decl) + ; let { (kinds, resKind) = splitKindFunTys (tyConKind family) + ; 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 kcCheckHsType hs_typats kinds + ; thing_inside tvs typats resultKind family + } + where +\end{code} + + +%************************************************************************ +%* * Kind checking %* * %************************************************************************ @@ -241,11 +413,24 @@ So we must infer their kinds from their right-hand sides *first* and then use them, whereas for the mutually recursive data types D we bring into scope kind bindings D -> k, where k is a kind variable, and do inference. +Indexed Types +~~~~~~~~~~~~~ +This treatment of type synonyms only applies to Haskell 98-style synonyms. +General type functions can be recursive, and hence, appear in `alg_decls'. + +The kind of an indexed type is solely determinded by its kind signature; +hence, only kind signatures participate in the construction of the initial +kind environment (as constructed by `getInitialKind'). In fact, we ignore +instances of indexed types altogether in the following. However, we need to +include the kind signatures of associated types into the construction of the +initial kind environment. (This is handled by `allDecls'). + \begin{code} kcTyClDecls syn_decls alg_decls - = do { -- First extend the kind env with each data - -- type and class, mapping them to a type variable - alg_kinds <- mappM getInitialKind alg_decls + = do { -- First extend the kind env with each data type, class, and + -- indexed type, mapping them to a type variable + let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls] + ; alg_kinds <- mappM getInitialKind initialKindDecls ; tcExtendKindEnv alg_kinds $ do -- Now kind-check the type synonyms, in dependency order @@ -257,18 +442,29 @@ kcTyClDecls syn_decls alg_decls { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls) ; tcExtendKindEnv syn_kinds $ do - -- Now kind-check the data type and class declarations, - -- returning kind-annotated decls - { kc_alg_decls <- mappM (wrapLocM kcTyClDecl) alg_decls + -- Now kind-check the data type, class, and kind signatures, + -- returning kind-annotated decls; we don't kind-check + -- instances of indexed types yet, but leave this to + -- `tcInstDecls1' + { kc_alg_decls <- mappM (wrapLocM kcTyClDecl) + (filter (not . isIdxTyDecl . unLoc) alg_decls) ; return (kc_syn_decls, kc_alg_decls) }}} + where + -- get all declarations relevant for determining the initial kind + -- environment + allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at + | L _ at <- ats + , isKindSigDecl at] + allDecls decl | isIdxTyDecl decl = [] + | otherwise = [decl] ------------------------------------------------------------------------ -getInitialKind :: LTyClDecl Name -> TcM (Name, TcKind) --- Only for data type and class declarations --- Get as much info as possible from the data or class decl, +getInitialKind :: TyClDecl Name -> TcM (Name, TcKind) +-- Only for data type, class, and indexed type declarations +-- Get as much info as possible from the data, class, or indexed type decl, -- so as to maximise usefulness of error messages -getInitialKind (L _ decl) +getInitialKind decl = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl) ; res_kind <- mk_res_kind decl ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) } @@ -276,8 +472,10 @@ getInitialKind (L _ decl) mk_arg_kind (UserTyVar _) = newKindVar mk_arg_kind (KindedTyVar _ kind) = return kind - mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind - -- On GADT-style declarations we allow a kind signature + mk_res_kind (TyFunction { tcdKind = kind }) = return kind + mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind + -- On GADT-style and data signature declarations we allow a kind + -- signature -- data T :: *->* where { ... } mk_res_kind other = return liftedTypeKind @@ -318,44 +516,23 @@ kindedTyVarKind (L _ (KindedTyVar _ k)) = k kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name) -- Not used for type synonyms (see kcSynDecl) -kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons}) - = kcTyClDeclBody decl $ \ tvs' -> - do { ctxt' <- kcHsContext ctxt - ; cons' <- mappM (wrapLocM kc_con_decl) cons - ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) } - where - kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do - kcHsTyVars ex_tvs $ \ex_tvs' -> do - ex_ctxt' <- kcHsContext ex_ctxt - details' <- kc_con_details details - res' <- case res of - ResTyH98 -> return ResTyH98 - ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') } - return (ConDecl name expl ex_tvs' ex_ctxt' details' res') - - kc_con_details (PrefixCon btys) - = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') } - kc_con_details (InfixCon bty1 bty2) - = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') } - kc_con_details (RecCon fields) - = do { fields' <- mappM kc_field fields; return (RecCon fields') } +kcTyClDecl decl@(TyData {}) + = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty + kcTyClDeclBody decl $ + kcDataDecl decl - kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') } +kcTyClDecl decl@(TyFunction {}) + = kcTyClDeclBody decl $ \ tvs' -> + return (decl {tcdTyVars = tvs'}) - kc_larg_ty bty = case new_or_data of - DataType -> kcHsSigType bty - NewType -> kcHsLiftedSigType bty - -- Can't allow an unlifted type for newtypes, because we're effectively - -- going to remove the constructor while coercing it to a lifted type. - -- And newtypes can't be bang'd - --- !!!TODO -=chak -kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs}) +kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats}) = kcTyClDeclBody decl $ \ tvs' -> do { is_boot <- tcIsHsBoot ; ctxt' <- kcHsContext ctxt - ; sigs' <- mappM (wrapLocM kc_sig) sigs - ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) } + ; ats' <- mappM (wrapLocM kcTyClDecl) ats + ; sigs' <- mappM (wrapLocM kc_sig ) sigs + ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs', + tcdATs = ats'}) } where kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty ; return (TypeSig nm op_ty') } @@ -371,7 +548,7 @@ kcTyClDeclBody :: TyClDecl Name -- Unpack it, and attribute those kinds to the type variables -- Extend the env with bindings for the tyvars, taken from -- the kind of the tycon/class. Give it to the thing inside, and - -- check the result kind matches +-- check the result kind matches kcTyClDeclBody decl thing_inside = tcAddDeclCtxt decl $ do { tc_ty_thing <- tcLookupLocated (tcdLName decl) @@ -382,6 +559,42 @@ kcTyClDeclBody decl thing_inside [ L loc (KindedTyVar (hsTyVarName tv) k) | (L loc tv, k) <- zip hs_tvs kinds] ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) } + +-- Kind check a data declaration, assuming that we already extended the +-- kind environment with the type variables of the left-hand side (these +-- kinded type variables are also passed as the second parameter). +-- +kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name) +kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons}) + tvs + = do { ctxt' <- kcHsContext ctxt + ; cons' <- mappM (wrapLocM kc_con_decl) cons + ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) } + where + kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do + kcHsTyVars ex_tvs $ \ex_tvs' -> do + ex_ctxt' <- kcHsContext ex_ctxt + details' <- kc_con_details details + res' <- case res of + ResTyH98 -> return ResTyH98 + ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') } + return (ConDecl name expl ex_tvs' ex_ctxt' details' res') + + kc_con_details (PrefixCon btys) + = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') } + kc_con_details (InfixCon bty1 bty2) + = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') } + kc_con_details (RecCon fields) + = do { fields' <- mappM kc_field fields; return (RecCon fields') } + + kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') } + + kc_larg_ty bty = case new_or_data of + DataType -> kcHsSigType bty + NewType -> kcHsLiftedSigType bty + -- Can't allow an unlifted type for newtypes, because we're effectively + -- going to remove the constructor while coercing it to a lifted type. + -- And newtypes can't be bang'd \end{code} @@ -404,15 +617,51 @@ tcSynDecl = tcTyVarBndrs tvs $ \ tvs' -> do { traceTc (text "tcd1" <+> ppr tc_name) ; rhs_ty' <- tcHsKindedType rhs_ty - ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty')) } + ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) } -------------------- -tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM TyThing +tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing] tcTyClDecl calc_isrec decl = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl) -tcTyClDecl1 calc_isrec + -- kind signature for a type function +tcTyClDecl1 _calc_isrec + (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { traceTc (text "type family: " <+> ppr tc_name) + ; gla_exts <- doptM Opt_IndexedTypes + + -- Check that we don't use kind signatures without Glasgow extensions + ; checkTc gla_exts $ badSigTyDecl tc_name + + ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)] + } + + -- kind signature for an indexed data type +tcTyClDecl1 _calc_isrec + (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs, + tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { traceTc (text "data/newtype family: " <+> ppr tc_name) + ; extra_tvs <- tcDataKindSig (Just ksig) + ; let final_tvs = tvs' ++ extra_tvs -- we may not need these + + ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name + ; gla_exts <- doptM Opt_IndexedTypes + + -- Check that we don't use kind signatures without Glasgow extensions + ; checkTc gla_exts $ badSigTyDecl tc_name + + ; tycon <- buildAlgTyCon tc_name final_tvs [] + (case new_or_data of + DataType -> OpenDataTyCon + NewType -> OpenNewTyCon) + Recursive False True Nothing + ; return [ATyCon tycon] + } + +tcTyClDecl1 calc_isrec (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs, tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons}) = tcTyVarBndrs tvs $ \ tvs' -> do @@ -427,8 +676,14 @@ tcTyClDecl1 calc_isrec -- Check that we don't use GADT syntax in H98 world ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name) + -- Check that we don't use kind signatures without Glasgow extensions + ; checkTc (gla_exts || 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) + -- Check that there's at least one condecl, - -- or else we're reading an interface file, or -fglasgow-exts + -- or else we're reading an hs-boot file, or -fglasgow-exts ; checkTc (not (null cons) || gla_exts || is_boot) (emptyConDeclsErr tc_name) @@ -440,18 +695,18 @@ tcTyClDecl1 calc_isrec { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data tycon final_tvs)) cons - ; let tc_rhs - | null cons && is_boot -- In a hs-boot file, empty cons means - = AbstractTyCon -- "don't know"; hence Abstract - | otherwise - = case new_or_data of - DataType -> mkDataTyConRhs data_cons - NewType -> ASSERT( isSingleton data_cons ) - mkNewTyConRhs tycon (head data_cons) + ; tc_rhs <- + if null cons && is_boot -- In a hs-boot file, empty cons means + then return AbstractTyCon -- "don't know"; hence Abstract + else case new_or_data of + DataType -> return (mkDataTyConRhs data_cons) + NewType -> + ASSERT( isSingleton data_cons ) + mkNewTyConRhs tc_name tycon (head data_cons) ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec - (want_generic && canDoGenerics data_cons) + (want_generic && canDoGenerics data_cons) h98_syntax Nothing }) - ; return (ATyCon tycon) + ; return [ATyCon tycon] } where is_rec = calc_isrec tc_name @@ -466,50 +721,72 @@ tcTyClDecl1 calc_isrec = tcTyVarBndrs tvs $ \ tvs' -> do { ctxt' <- tcHsKindedContext ctxt ; fds' <- mappM (addLocM tc_fundep) fundeps - -- !!!TODO: process `ats`; what do we want to store in the `Class'? -=chak + ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats + ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats) ; sig_stuff <- tcClassSigs class_name sigs meths ; clas <- fixM (\ clas -> let -- This little knot is just so we can get -- hold of the name of the class TyCon, which we - -- need to look up its recursiveness and variance + -- need to look up its recursiveness tycon_name = tyConName (classTyCon clas) tc_isrec = calc_isrec tycon_name in - buildClass class_name tvs' ctxt' fds' + buildClass class_name tvs' ctxt' fds' ats' sig_stuff tc_isrec) - ; return (AClass clas) } + ; return (AClass clas : ats') + -- NB: Order is important due to the call to `mkGlobalThings' when + -- tying the the type and class declaration type checking knot. + } where tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ; ; tvs2' <- mappM tcLookupTyVar tvs2 ; ; return (tvs1', tvs2') } + -- For each AT argument compute the position of the corresponding class + -- parameter in the class head. This will later serve as a permutation + -- vector when checking the validity of instance declarations. + setTyThingPoss [ATyCon tycon] atTyVars = + let classTyVars = hsLTyVarNames tvs + poss = catMaybes + . map (`elemIndex` classTyVars) + . hsLTyVarNames + $ atTyVars + -- There will be no Nothing, as we already passed renaming + in + ATyCon (setTyConArgPoss tycon poss) + setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss" tcTyClDecl1 calc_isrec (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name}) - = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)) + = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)] ----------------------------------- tcConDecl :: Bool -- True <=> -funbox-strict_fields - -> NewOrData -> TyCon -> [TyVar] - -> ConDecl Name -> TcM DataCon + -> NewOrData + -> TyCon -> [TyVar] + -> ConDecl Name + -> TcM DataCon tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes (ConDecl name _ ex_tvs ex_ctxt details ResTyH98) = do { let tc_datacon field_lbls arg_ty = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype ; buildDataCon (unLoc name) False {- Prefix -} - True {- Vanilla -} [NotMarkedStrict] + [NotMarkedStrict] (map unLoc field_lbls) - tc_tvs [] [arg_ty'] - tycon (mkTyVarTys tc_tvs) } + tc_tvs [] -- No existentials + [] [] -- No equalities, predicates + [arg_ty'] + tycon } -- Check that a newtype has no existential stuff ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name) ; case details of - PrefixCon [arg_ty] -> tc_datacon [] arg_ty + PrefixCon [arg_ty] -> tc_datacon [] arg_ty RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty - other -> failWithTc (newtypeFieldErr name (length (hsConArgs details))) + other -> + failWithTc (newtypeFieldErr name (length (hsConArgs details))) -- Check that the constructor has exactly one field } @@ -517,30 +794,19 @@ tcConDecl unbox_strict DataType tycon tc_tvs -- Data types (ConDecl name _ tvs ctxt details res_ty) = tcTyVarBndrs tvs $ \ tvs' -> do { ctxt' <- tcHsKindedContext ctxt - ; (data_tc, res_ty_args) <- tcResultType tycon tc_tvs res_ty + ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty ; let - con_tvs = case res_ty of - ResTyH98 -> tc_tvs ++ tvs' - ResTyGADT _ -> tryVanilla tvs' res_ty_args - - -- Vanilla iff result type matches the quantified vars exactly, - -- and there is no existential context - -- Must check the context too because of implicit params; e.g. - -- data T = (?x::Int) => MkT Int - is_vanilla = res_ty_args `tcEqTypes` mkTyVarTys con_tvs - && null (unLoc ctxt) - tc_datacon is_infix field_lbls btys = do { let bangs = map getBangStrictness btys ; arg_tys <- mappM tcHsBangType btys - ; buildDataCon (unLoc name) is_infix is_vanilla + ; buildDataCon (unLoc name) is_infix (argStrictness unbox_strict tycon bangs arg_tys) (map unLoc field_lbls) - con_tvs ctxt' arg_tys - data_tc res_ty_args } - -- NB: we put data_tc, the type constructor gotten from the constructor - -- type signature into the data constructor; that way - -- checkValidDataCon can complain if it's wrong. + univ_tvs ex_tvs eq_preds ctxt' arg_tys + data_tc } + -- NB: we put data_tc, the type constructor gotten from the + -- constructor type signature into the data constructor; + -- that way checkValidDataCon can complain if it's wrong. ; case details of PrefixCon btys -> tc_datacon False [] btys @@ -551,19 +817,48 @@ tcConDecl unbox_strict DataType tycon tc_tvs -- Data types } -tcResultType :: TyCon -> [TyVar] -> ResType Name -> TcM (TyCon, [TcType]) -tcResultType tycon tvs ResTyH98 = return (tycon, mkTyVarTys tvs) -tcResultType _ _ (ResTyGADT res_ty) = tcLHsConResTy res_ty - -tryVanilla :: [TyVar] -> [TcType] -> [TyVar] --- (tryVanilla tvs tys) returns a permutation of tvs. --- It tries to re-order the tvs so that it exactly --- matches the [Type], if that is possible -tryVanilla tvs (ty:tys) | Just tv <- tcGetTyVar_maybe ty -- The type is a tyvar - , tv `elem` tvs -- That tyvar is in the list - = tv : tryVanilla (delete tv tvs) tys -tryVanilla tvs tys = tvs -- Fall through case - +tcResultType :: TyCon + -> [TyVar] -- data T a b c = ... + -> [TyVar] -- where MkT :: forall a b c. ... + -> ResType Name + -> TcM ([TyVar], -- Universal + [TyVar], -- Existential + [(TyVar,Type)], -- Equality predicates + TyCon) -- TyCon given in the ResTy + -- We don't check that the TyCon given in the ResTy is + -- the same as the parent tycon, becuase we are in the middle + -- of a recursive knot; so it's postponed until checkValidDataCon + +tcResultType decl_tycon tc_tvs dc_tvs ResTyH98 + = return (tc_tvs, dc_tvs, [], decl_tycon) + -- In H98 syntax the dc_tvs are the existential ones + -- data T a b c = forall d e. MkT ... + -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs + +tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty) + -- E.g. data T a b c where + -- MkT :: forall x y z. T (x,y) z z + -- Then we generate + -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T) + + = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty + -- NB: tc_tvs and dc_tvs are distinct + ; let univ_tvs = choose_univs [] tc_tvs res_tys + -- Each univ_tv is either a dc_tv or a tc_tv + ex_tvs = dc_tvs `minusList` univ_tvs + eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys, + tv `elem` tc_tvs] + ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) } + where + -- choose_univs uses the res_ty itself if it's a type variable + -- and hasn't already been used; otherwise it uses one of the tc_tvs + choose_univs used tc_tvs [] + = ASSERT( null tc_tvs ) [] + choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys) + | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used) + = tv : choose_univs (tv:used) tc_tvs res_tys + | otherwise + = tc_tv : choose_univs used tc_tvs res_tys ------------------- argStrictness :: Bool -- True <=> -funbox-strict_fields @@ -576,19 +871,28 @@ argStrictness unbox_strict tycon bangs arg_tys -- We attempt to unbox/unpack a strict field when either: -- (i) The field is marked '!!', or -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on. - +-- +-- We have turned off unboxing of newtypes because coercions make unboxing +-- and reboxing more complicated chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang = case bang of HsNoBang -> NotMarkedStrict - HsStrict | unbox_strict_fields && can_unbox -> MarkedUnboxed - HsUnbox | can_unbox -> MarkedUnboxed + HsStrict | unbox_strict_fields + && can_unbox arg_ty -> MarkedUnboxed + HsUnbox | can_unbox arg_ty -> MarkedUnboxed other -> MarkedStrict where - can_unbox = case splitTyConApp_maybe arg_ty of - Nothing -> False - Just (arg_tycon, _) -> not (isRecursiveTyCon tycon) && - isProductTyCon arg_tycon + -- we can unbox if the type is a chain of newtypes with a product tycon + -- at the end + can_unbox arg_ty = case splitTyConApp_maybe arg_ty of + Nothing -> False + Just (arg_tycon, tycon_args) -> + not (isRecursiveTyCon tycon) && + isProductTyCon arg_tycon && + (if isNewTyCon arg_tycon then + can_unbox (newTyConInstRhs arg_tycon tycon_args) + else True) \end{code} %************************************************************************ @@ -634,9 +938,11 @@ checkValidTyCl decl -- of the constructor. checkValidTyCon :: TyCon -> TcM () -checkValidTyCon tc +checkValidTyCon tc | isSynTyCon tc - = checkValidType syn_ctxt syn_rhs + = case synTyConRhs tc of + OpenSynTyCon _ -> return () + SynonymTyCon ty -> checkValidType syn_ctxt ty | otherwise = -- Check the context on the data decl checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_` @@ -650,7 +956,6 @@ checkValidTyCon tc where syn_ctxt = TySynCtxt name name = tyConName tc - syn_rhs = synTyConRhs tc data_cons = tyConDataCons tc groups = equivClasses cmp_fld (concatMap get_fields data_cons) @@ -658,14 +963,20 @@ checkValidTyCon tc get_fields con = dataConFieldLabels con `zip` repeat con -- dataConFieldLabels may return the empty list, which is fine - -- Note: The complicated checkOne logic below is there to accomodate - -- for different return types. Add res_ty to the mix, - -- comparing them in two steps, all for good error messages. - -- Plan: Use Unify.tcMatchTys to compare the first candidate's - -- result type against other candidates' types (check bothways). - -- If they magically agrees, take the substitution and - -- apply them to the latter ones, and see if they match perfectly. - -- check_fields fields@((first_field_label, field_ty) : other_fields) + -- See Note [GADT record selectors] in MkId.lhs + -- We must check (a) that the named field has the same + -- type in each constructor + -- (b) that those constructors have the same result type + -- + -- However, the constructors may have differently named type variable + -- and (worse) we don't know how the correspond to each other. E.g. + -- C1 :: forall a b. { f :: a, g :: b } -> T a b + -- C2 :: forall d c. { f :: c, g :: c } -> T c d + -- + -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's + -- result type against other candidates' types BOTH WAYS ROUND. + -- If they magically agrees, take the substitution and + -- apply them to the latter ones, and see if they match perfectly. check_fields fields@((label, con1) : other_fields) -- These fields all have the same name, but are from -- different constructors in the data type @@ -674,7 +985,7 @@ checkValidTyCon tc -- NB: this check assumes that all the constructors of a given -- data type use the same type variables where - tvs1 = mkVarSet (dataConTyVars con1) + tvs1 = mkVarSet (dataConAllTyVars con1) res1 = dataConResTys con1 fty1 = dataConFieldType con1 label @@ -682,7 +993,7 @@ checkValidTyCon tc = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 } where - tvs2 = mkVarSet (dataConTyVars con2) + tvs2 = mkVarSet (dataConAllTyVars con2) res2 = dataConResTys con2 fty2 = dataConFieldType con2 label @@ -699,18 +1010,9 @@ checkValidDataCon tc con = setSrcSpan (srcLocSpan (getSrcLoc con)) $ addErrCtxt (dataConCtxt con) $ do { checkTc (dataConTyCon con == tc) (badDataConTyCon con) - ; checkValidType ctxt (idType (dataConWrapId con)) } - - -- This checks the argument types and - -- ambiguity of the existential context (if any) - -- - -- Note [Sept 04] Now that tvs is all the tvs, this - -- test doesn't actually check anything --- ; checkFreeness tvs ex_theta } + ; checkValidType ctxt (dataConUserType con) } where ctxt = ConArgCtxt (dataConName con) --- (tvs, ex_theta, _, _, _) = dataConSig con - ------------------------------- checkValidClass :: Class -> TcM () @@ -732,15 +1034,11 @@ checkValidClass cls -- class has only one parameter. We can't do generic -- multi-parameter type classes! ; checkTc (unary || no_generics) (genericMultiParamErr cls) - - -- Check that the class has no associated types, unless GlaExs - ; checkTc (gla_exts || no_ats) (badATDecl cls) } where (tyvars, theta, _, op_stuff) = classBigSig cls unary = isSingleton tyvars no_generics = null [() | (_, GenDefMeth) <- op_stuff] - no_ats = True -- !!!TODO: determine whether the class has ATs -=chak check_op gla_exts (sel_id, dm) = addErrCtxt (classOpCtxt sel_id tau) $ do @@ -840,6 +1138,9 @@ badGadtDecl tc_name = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name) , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ] +badStupidTheta tc_name + = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name) + newtypeConError tycon n = sep [ptext SLIT("A newtype must have exactly one constructor,"), nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ] @@ -852,9 +1153,44 @@ newtypeFieldErr con_name n_flds = sep [ptext SLIT("The constructor of a newtype must have exactly one field"), nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds] -badATDecl cl_name - = vcat [ ptext SLIT("Illegal associated type declaration in") <+> quotes (ppr cl_name) - , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow ATs")) ] +badSigTyDecl tc_name + = vcat [ ptext SLIT("Illegal kind signature") <+> + quotes (ppr tc_name) + , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ] + +badKindSigCtxt tc_name + = vcat [ ptext SLIT("Illegal context in kind signature") <+> + quotes (ppr tc_name) + , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ] + +badIdxTyDecl tc_name + = vcat [ ptext SLIT("Illegal indexed type instance for") <+> + quotes (ppr tc_name) + , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ] + +badGadtIdxTyDecl tc_name + = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> + quotes (ppr tc_name) + , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ] + +tooManyParmsErr tc_name + = ptext SLIT("Indexed type instance has too many parameters:") <+> + quotes (ppr tc_name) + +tooFewParmsErr tc_name + = ptext SLIT("Indexed type instance has too few parameters:") <+> + quotes (ppr tc_name) + +badBootTyIdxDeclErr = + ptext SLIT("Illegal indexed type instance in hs-boot file") + +wrongKindOfFamily family = + ptext SLIT("Wrong category of type instance; declaration was for a") <+> + kindOfFamily + where + kindOfFamily | isSynTyCon family = ptext SLIT("type synonym") + | isDataTyCon family = ptext SLIT("data type") + | isNewTyCon family = ptext SLIT("newtype") emptyConDeclsErr tycon = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),