X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=de26ef9bb3fcdabbe5cc2b656c94cd49e98fe0cc;hb=ebf2c80221ccf11aeb7a0a2be27bfc72529855a5;hp=d4d3c25c4777b8faeff9842a3b668d0a538d0928;hpb=12899612693163154531da3285ec99c1c8ca2226;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index d4d3c25..de26ef9 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -1,323 +1,447 @@ % -% (c) The AQUA Project, Glasgow University, 1996 +% (c) The AQUA Project, Glasgow University, 1996-1998 % \section[TcTyClsDecls]{Typecheck type and class declarations} \begin{code} -#include "HsVersions.h" - module TcTyClsDecls ( - tcTyAndClassDecls1 + tcTyAndClassDecls ) where -IMP_Ubiq(){-uitous-} +#include "HsVersions.h" -import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), - ClassDecl(..), MonoType(..), PolyType(..), - Sig(..), MonoBinds, Fake, InPat, HsBinds(..), Bind, HsExpr ) -import RnHsSyn ( isRnTyCon, RenamedTyDecl(..), RenamedClassDecl(..), - RnName(..){-instance Uniquable-} +import CmdLineOpts ( DynFlags, DynFlag(..), dopt ) +import HsSyn ( TyClDecl(..), + ConDecl(..), Sig(..), HsPred(..), + tyClDeclName, hsTyVarNames, + isIfaceSigDecl, isClassDecl, isSynDecl, isClassOpSig ) -import TcHsSyn ( SYN_IE(TcHsBinds), TcIdOcc(..) ) - -import TcMonad hiding ( rnMtoTcM ) -import Inst ( SYN_IE(InstanceMapper) ) +import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs ) +import BasicTypes ( RecFlag(..), NewOrData(..), isRec ) +import HscTypes ( implicitTyThingIds ) + +import TcMonad +import TcEnv ( TcEnv, RecTcEnv, TcTyThing(..), TyThing(..), TyThingDetails(..), + tcExtendKindEnv, tcLookup, tcExtendGlobalEnv, tcExtendGlobalValEnv ) +import TcTyDecls ( tcTyDecl1, kcConDetails, mkNewTyConRep ) import TcClassDcl ( tcClassDecl1 ) -import TcEnv ( tcExtendTyConEnv, tcExtendClassEnv, - tcTyVarScope ) -import SpecEnv ( SpecEnv ) -import TcKind ( TcKind, newKindVars ) -import TcTyDecls ( tcTyDecl, mkDataBinds ) - -import Bag -import Class ( SYN_IE(Class), classSelIds ) -import Digraph ( findSCCs, SCC(..) ) -import Name ( getSrcLoc ) -import PprStyle -import Pretty -import UniqSet ( SYN_IE(UniqSet), emptyUniqSet, - unitUniqSet, unionUniqSets, - unionManyUniqSets, uniqSetToList ) -import SrcLoc ( SrcLoc ) -import TyCon ( TyCon ) -import Unique ( Unique ) -import Util ( panic{-, pprTrace-} ) - +import TcMonoType ( kcHsTyVars, kcHsType, kcHsLiftedSigType, kcHsContext, mkTyClTyVars ) +import TcType ( TcKind, newKindVar, zonkKindEnv ) + +import TcUnify ( unifyKind ) +import TcInstDcls ( tcAddDeclCtxt ) +import Type ( Kind, mkArrowKind, zipFunTys ) +import Variance ( calcTyConArgVrcs ) +import Class ( Class, mkClass, classTyCon ) +import TyCon ( TyCon, tyConKind, ArgVrcs, AlgTyConFlavour(..), + mkSynTyCon, mkAlgTyCon, mkClassTyCon ) +import DataCon ( isNullaryDataCon ) +import Var ( varName ) +import FiniteMap +import Digraph ( stronglyConnComp, SCC(..) ) +import Name ( Name, getSrcLoc, isTyVarName ) +import NameEnv ( NameEnv, mkNameEnv, lookupNameEnv_NF ) +import NameSet +import Outputable +import Maybes ( mapMaybe ) +import ErrUtils ( Message ) +import HsDecls ( getClassDeclSysNames ) +import Generics ( mkTyConGenInfo ) \end{code} + +%************************************************************************ +%* * +\subsection{Type checking for type and class declarations} +%* * +%************************************************************************ + The main function ~~~~~~~~~~~~~~~~~ \begin{code} -data Decl = TyD RenamedTyDecl | ClD RenamedClassDecl - -tcTyAndClassDecls1 :: InstanceMapper - -> Bag RenamedTyDecl -> Bag RenamedClassDecl - -> TcM s (TcEnv s) - -tcTyAndClassDecls1 inst_mapper rnty_decls rncls_decls - = sortByDependency syn_decls cls_decls decls `thenTc` \ groups -> - tcGroups inst_mapper groups - where - cls_decls = mapBag ClD rncls_decls - ty_decls = mapBag TyD rnty_decls - syn_decls = filterBag is_syn_decl ty_decls - decls = ty_decls `unionBags` cls_decls +tcTyAndClassDecls :: RecTcEnv -- Knot tying stuff + -> [RenamedTyClDecl] + -> TcM TcEnv - is_syn_decl (TyD (TySynonym _ _ _ _)) = True - is_syn_decl _ = False +tcTyAndClassDecls unf_env decls + = sortByDependency decls `thenTc` \ groups -> + tcGroups unf_env groups -tcGroups inst_mapper [] +tcGroups unf_env [] = tcGetEnv `thenNF_Tc` \ env -> returnTc env -tcGroups inst_mapper (group:groups) - = tcGroup inst_mapper group `thenTc` \ new_env -> - - -- Extend the environment using the new tycons and classes - tcSetEnv new_env $ - - -- Do the remaining groups - tcGroups inst_mapper groups +tcGroups unf_env (group:groups) + = tcGroup unf_env group `thenTc` \ env -> + tcSetEnv env $ + tcGroups unf_env groups \end{code} Dealing with a group ~~~~~~~~~~~~~~~~~~~~ +Consider a mutually-recursive group, binding +a type constructor T and a class C. + +Step 1: getInitialKind + Construct a KindEnv by binding T and C to a kind variable + +Step 2: kcTyClDecl + In that environment, do a kind check + +Step 3: Zonk the kinds + +Step 4: buildTyConOrClass + Construct an environment binding T to a TyCon and C to a Class. + a) Their kinds comes from zonking the relevant kind variable + b) Their arity (for synonyms) comes direct from the decl + c) The funcional dependencies come from the decl + d) The rest comes a knot-tied binding of T and C, returned from Step 4 + e) The variances of the tycons in the group is calculated from + the knot-tied stuff + +Step 5: tcTyClDecl1 + In this environment, walk over the decls, constructing the TyCons and Classes. + This uses in a strict way items (a)-(c) above, which is why they must + be constructed in Step 4. Feed the results back to Step 4. + For this step, pass the is-recursive flag as the wimp-out flag + to tcTyClDecl1. + + +Step 6: tcTyClDecl1 again + For a recursive group only, check all the decls again, just + but this time with the wimp flag off. Now we can check things + like whether a function argument is an unlifted tuple, looking + through type synonyms properly. We can't do that in Step 5. + +Step 7: Extend environment + We extend the type environment with bindings not only for the TyCons and Classes, + but also for their "implicit Ids" like data constructors and class selectors + +The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to +@TyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s. + \begin{code} -tcGroup :: InstanceMapper -> Bag Decl -> TcM s (TcEnv s) -tcGroup inst_mapper decls - = -- pprTrace "tcGroup: " (ppCat (map (fst.fmt_decl) (bagToList decls))) $ +tcGroup :: RecTcEnv -> SCC RenamedTyClDecl -> TcM TcEnv +tcGroup unf_env scc + = getDOptsTc `thenTc` \ dflags -> + -- Step 1 + mapNF_Tc getInitialKind decls `thenNF_Tc` \ initial_kinds -> + + -- Step 2 + tcExtendKindEnv initial_kinds (mapTc kcTyClDecl decls) `thenTc_` + + -- Step 3 + zonkKindEnv initial_kinds `thenNF_Tc` \ final_kinds -> + + -- Tie the knot + fixTc ( \ ~(rec_details_list, _, _) -> + -- Step 4 + let + kind_env = mkNameEnv final_kinds + rec_details = mkNameEnv rec_details_list + + tyclss, all_tyclss :: [TyThing] + tyclss = map (buildTyConOrClass dflags is_rec kind_env + rec_vrcs rec_details) decls + + -- Add the tycons that come from the classes + -- We want them in the environment because + -- they are mentioned in interface files + all_tyclss = [ ATyCon (classTyCon clas) | AClass clas <- tyclss] + ++ tyclss + + -- Calculate variances, and (yes!) feed back into buildTyConOrClass. + rec_vrcs = calcTyConArgVrcs [tc | ATyCon tc <- all_tyclss] + in + -- Step 5 + tcExtendGlobalEnv all_tyclss $ + mapTc (tcTyClDecl1 is_rec unf_env) decls `thenTc` \ tycls_details -> + + -- Return results + tcGetEnv `thenNF_Tc` \ env -> + returnTc (tycls_details, all_tyclss, env) + ) `thenTc` \ (_, all_tyclss, env) -> + + tcSetEnv env $ + + -- Step 6 + -- For a recursive group, check all the types again, + -- this time with the wimp flag off + (if isRec is_rec then + mapTc_ (tcTyClDecl1 NonRecursive unf_env) decls + else + returnTc () + ) `thenTc_` + + -- Step 7 + -- Extend the environment with the final TyCons/Classes + -- and their implicit Ids + tcExtendGlobalValEnv (implicitTyThingIds all_tyclss) tcGetEnv - -- TIE THE KNOT - fixTc ( \ ~(tycons,classes,_) -> + where + is_rec = case scc of + AcyclicSCC _ -> NonRecursive + CyclicSCC _ -> Recursive - -- EXTEND TYPE AND CLASS ENVIRONMENTS - -- NB: it's important that the tycons and classes come back in just - -- the same order from this fix as from get_binders, so that these - -- extend-env things work properly. A bit UGH-ish. - tcExtendTyConEnv tycon_names_w_arities tycons $ - tcExtendClassEnv class_names classes $ + decls = case scc of + AcyclicSCC decl -> [decl] + CyclicSCC decls -> decls - -- DEAL WITH TYPE VARIABLES - tcTyVarScope tyvar_names ( \ tyvars -> +tcTyClDecl1 is_rec unf_env decl + | isClassDecl decl = tcAddDeclCtxt decl (tcClassDecl1 is_rec unf_env decl) + | otherwise = tcAddDeclCtxt decl (tcTyDecl1 is_rec unf_env decl) +\end{code} - -- DEAL WITH THE DEFINITIONS THEMSELVES - foldBag combine (tcDecl inst_mapper) - (returnTc (emptyBag, emptyBag)) - decls - ) `thenTc` \ (tycon_bag,class_bag) -> - let - tycons = bagToList tycon_bag - classes = bagToList class_bag - in - -- SNAFFLE ENV TO RETURN - tcGetEnv `thenNF_Tc` \ final_env -> +%************************************************************************ +%* * +\subsection{Step 1: Initial environment} +%* * +%************************************************************************ - returnTc (tycons, classes, final_env) - ) `thenTc` \ (_, _, final_env) -> +\begin{code} +getInitialKind :: RenamedTyClDecl -> NF_TcM (Name, TcKind) +getInitialKind decl + = kcHsTyVars (tcdTyVars decl) `thenNF_Tc` \ arg_kinds -> + newKindVar `thenNF_Tc` \ result_kind -> + returnNF_Tc (tcdName decl, mk_kind arg_kinds result_kind) + +mk_kind tvs_w_kinds res_kind = foldr (mkArrowKind . snd) res_kind tvs_w_kinds +\end{code} - returnTc final_env - where - (tyvar_rn_names, tycon_names_w_arities, class_names) = get_binders decls +%************************************************************************ +%* * +\subsection{Step 2: Kind checking} +%* * +%************************************************************************ - tyvar_names = map de_rn tyvar_rn_names - de_rn (RnName n) = n +We need to kind check all types in the mutually recursive group +before we know the kind of the type variables. For example: - combine do_a do_b - = do_a `thenTc` \ (a1,a2) -> - do_b `thenTc` \ (b1,b2) -> - returnTc (a1 `unionBags` b1, a2 `unionBags` b2) +class C a where + op :: D b => a -> b -> b + +class D c where + bop :: (Monad c) => ... + +Here, the kind of the locally-polymorphic type variable "b" +depends on *all the uses of class D*. For example, the use of +Monad c in bop's type signature means that D must have kind Type->Type. + +\begin{code} +kcTyClDecl :: RenamedTyClDecl -> TcM () + +kcTyClDecl decl@(TySynonym {tcdSynRhs = rhs}) + = kcTyClDeclBody decl $ \ result_kind -> + kcHsType rhs `thenTc` \ rhs_kind -> + unifyKind result_kind rhs_kind + +kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = context, tcdCons = con_decls}) + = kcTyClDeclBody decl $ \ result_kind -> + kcHsContext context `thenTc_` + mapTc_ kc_con_decl con_decls + where + kc_con_decl (ConDecl _ _ ex_tvs ex_ctxt details loc) + = kcHsTyVars ex_tvs `thenNF_Tc` \ kind_env -> + tcExtendKindEnv kind_env $ + kcConDetails new_or_data ex_ctxt details + +kcTyClDecl decl@(ClassDecl {tcdCtxt = context, tcdSigs = class_sigs}) + = kcTyClDeclBody decl $ \ result_kind -> + kcHsContext context `thenTc_` + mapTc_ kc_sig (filter isClassOpSig class_sigs) + where + kc_sig (ClassOpSig _ _ op_ty loc) = kcHsLiftedSigType op_ty + +kcTyClDeclBody :: RenamedTyClDecl -> (Kind -> TcM a) -> TcM a +-- 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 +kcTyClDeclBody decl thing_inside + = tcAddDeclCtxt decl $ + tcLookup (tcdName decl) `thenNF_Tc` \ thing -> + let + kind = case thing of + AGlobal (ATyCon tc) -> tyConKind tc + AGlobal (AClass cl) -> tyConKind (classTyCon cl) + AThing kind -> kind + -- For some odd reason, a class doesn't include its kind + + (tyvars_w_kinds, result_kind) = zipFunTys (hsTyVarNames (tcdTyVars decl)) kind + in + tcExtendKindEnv tyvars_w_kinds (thing_inside result_kind) \end{code} -Dealing with one decl -~~~~~~~~~~~~~~~~~~~~~ + +%************************************************************************ +%* * +\subsection{Step 4: Building the tycon/class} +%* * +%************************************************************************ + \begin{code} -tcDecl :: InstanceMapper - -> Decl - -> TcM s (Bag TyCon, Bag Class) +buildTyConOrClass + :: DynFlags + -> RecFlag -> NameEnv Kind + -> FiniteMap TyCon ArgVrcs -> NameEnv TyThingDetails + -> RenamedTyClDecl -> TyThing + +buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details + (TySynonym {tcdName = tycon_name, tcdTyVars = tyvar_names}) + = ATyCon tycon + where + tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty argvrcs + tycon_kind = lookupNameEnv_NF kenv tycon_name + arity = length tyvar_names + tyvars = mkTyClTyVars tycon_kind tyvar_names + SynTyDetails rhs_ty = lookupNameEnv_NF rec_details tycon_name + argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon + +buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details + (TyData {tcdND = data_or_new, tcdName = tycon_name, tcdTyVars = tyvar_names, + tcdNCons = nconstrs, tcdSysNames = sys_names}) + = ATyCon tycon + where + tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt argvrcs + data_cons nconstrs sel_ids + flavour is_rec gen_info + + gen_info | not (dopt Opt_Generics dflags) = Nothing + | otherwise = mkTyConGenInfo tycon sys_names -tcDecl inst_mapper (TyD decl) - = tcTyDecl decl `thenTc` \ tycon -> - returnTc (unitBag tycon, emptyBag) + DataTyDetails ctxt data_cons sel_ids = lookupNameEnv_NF rec_details tycon_name -tcDecl inst_mapper (ClD decl) - = tcClassDecl1 inst_mapper decl `thenTc` \ clas -> - returnTc (emptyBag, unitBag clas) + tycon_kind = lookupNameEnv_NF kenv tycon_name + tyvars = mkTyClTyVars tycon_kind tyvar_names + argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon + + flavour = case data_or_new of + NewType -> NewTyCon (mkNewTyConRep tycon) + DataType | all isNullaryDataCon data_cons -> EnumTyCon + | otherwise -> DataTyCon + +buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details + (ClassDecl {tcdName = class_name, tcdTyVars = tyvar_names, + tcdFDs = fundeps, tcdSysNames = name_list} ) + = AClass clas + where + (tycon_name, _, _, _) = getClassDeclSysNames name_list + clas = mkClass class_name tyvars fds + sc_theta sc_sel_ids op_items + tycon + + tycon = mkClassTyCon tycon_name class_kind tyvars + argvrcs dict_con + clas -- Yes! It's a dictionary + flavour + + ClassDetails sc_theta sc_sel_ids op_items dict_con = lookupNameEnv_NF rec_details class_name + + class_kind = lookupNameEnv_NF kenv class_name + tyvars = mkTyClTyVars class_kind tyvar_names + argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon + n_fields = length sc_sel_ids + length op_items + + flavour | n_fields == 1 = NewTyCon (mkNewTyConRep tycon) + | otherwise = DataTyCon + + -- We can find the functional dependencies right away, + -- and it is vital to do so. Why? Because in the next pass + -- we check for ambiguity in all the type signatures, and we + -- need the functional dependcies to be done by then + fds = [(map lookup xs, map lookup ys) | (xs,ys) <- fundeps] + tyvar_env = mkNameEnv [(varName tv, tv) | tv <- tyvars] + lookup = lookupNameEnv_NF tyvar_env + +bogusVrcs = panic "Bogus tycon arg variances" \end{code} + +%************************************************************************ +%* * +\subsection{Dependency analysis} +%* * +%************************************************************************ + Dependency analysis ~~~~~~~~~~~~~~~~~~~ \begin{code} -sortByDependency :: Bag Decl -> Bag Decl -> Bag Decl -> TcM s [Bag Decl] -sortByDependency syn_decls cls_decls decls - = let -- CHECK FOR SYNONYM CYCLES - syn_sccs = findSCCs mk_edges syn_decls - syn_cycles = [map fmt_decl (bagToList decls) - | CyclicSCC decls <- syn_sccs] - +sortByDependency :: [RenamedTyClDecl] -> TcM [SCC RenamedTyClDecl] +sortByDependency decls + = let -- CHECK FOR CLASS CYCLES + cls_sccs = stronglyConnComp (mapMaybe mkClassEdges tycl_decls) + cls_cycles = [ decls | CyclicSCC decls <- cls_sccs] in - checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_` + checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_` - let -- CHECK FOR CLASS CYCLES - cls_sccs = findSCCs mk_edges cls_decls - cls_cycles = [map fmt_decl (bagToList decls) - | CyclicSCC decls <- cls_sccs] + let -- CHECK FOR SYNONYM CYCLES + syn_sccs = stronglyConnComp (filter is_syn_decl edges) + syn_cycles = [ decls | CyclicSCC decls <- syn_sccs] in - checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_` + checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_` - -- DO THE MAIN DEPENDENCY ANALYSIS + -- DO THE MAIN DEPENDENCY ANALYSIS let - decl_sccs = findSCCs mk_edges decls - scc_bags = map bag_acyclic decl_sccs + decl_sccs = stronglyConnComp edges in - returnTc (scc_bags) - - where - bag_acyclic (AcyclicSCC scc) = unitBag scc - bag_acyclic (CyclicSCC sccs) = sccs - -fmt_decl decl - = (ppr PprForUser name, getSrcLoc name) + returnTc decl_sccs where - name = get_name decl - get_name (TyD (TyData _ name _ _ _ _ _)) = name - get_name (TyD (TyNew _ name _ _ _ _ _)) = name - get_name (TyD (TySynonym name _ _ _)) = name - get_name (ClD (ClassDecl _ name _ _ _ _ _)) = name + tycl_decls = filter (not . isIfaceSigDecl) decls + edges = map mkEdges tycl_decls + + is_syn_decl (d, _, _) = isSynDecl d \end{code} Edges in Type/Class decls ~~~~~~~~~~~~~~~~~~~~~~~~~ + \begin{code} -mk_edges (TyD (TyData ctxt name _ condecls derivs _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecls `unionUniqSets` get_deriv derivs)) -mk_edges (TyD (TyNew ctxt name _ condecl derivs _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecl `unionUniqSets` get_deriv derivs)) -mk_edges (TyD (TySynonym name _ rhs _)) - = (uniqueOf name, set_to_bag (get_ty rhs)) -mk_edges (ClD (ClassDecl ctxt name _ sigs _ _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_sigs sigs)) - -get_ctxt ctxt - = unionManyUniqSets (map (set_name.fst) ctxt) - -get_deriv Nothing = emptyUniqSet -get_deriv (Just clss) = unionManyUniqSets (map set_name clss) - -get_cons cons - = unionManyUniqSets (map get_con cons) - where - get_con (ConDecl _ btys _) - = unionManyUniqSets (map get_bty btys) - get_con (ConOpDecl bty1 _ bty2 _) - = unionUniqSets (get_bty bty1) (get_bty bty2) - get_con (NewConDecl _ ty _) - = get_ty ty - get_con (RecConDecl _ nbtys _) - = unionManyUniqSets (map (get_bty.snd) nbtys) - - get_bty (Banged ty) = get_pty ty - get_bty (Unbanged ty) = get_pty ty - -get_ty (MonoTyVar tv) - = emptyUniqSet -get_ty (MonoTyApp name tys) - = (if isRnTyCon name then set_name name else emptyUniqSet) - `unionUniqSets` get_tys tys -get_ty (MonoFunTy ty1 ty2) - = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (MonoListTy ty) - = get_ty ty -- careful when defining [] (,,) etc as -get_ty (MonoTupleTy tys) -- [ty] (ty,ty,ty) will not give edges! - = get_tys tys -get_ty other = panic "TcTyClsDecls:get_ty" - -get_pty (HsForAllTy _ ctxt mty) - = get_ctxt ctxt `unionUniqSets` get_ty mty -get_pty other = panic "TcTyClsDecls:get_pty" - -get_tys tys - = unionManyUniqSets (map get_ty tys) - -get_sigs sigs - = unionManyUniqSets (map get_sig sigs) - where - get_sig (ClassOpSig _ ty _ _) = get_pty ty - get_sig other = panic "TcTyClsDecls:get_sig" - -set_name name = unitUniqSet (uniqueOf name) - -set_to_bag set = listToBag (uniqSetToList set) -\end{code} +tyClDeclFTVs :: RenamedTyClDecl -> [Name] + -- Find the free non-tyvar vars +tyClDeclFTVs d = foldNameSet add [] (tyClDeclFVs d) + where + add n fvs | isTyVarName n = fvs + | otherwise = n : fvs +---------------------------------------------------- +-- mk_cls_edges looks only at the context of class decls +-- Its used when we are figuring out if there's a cycle in the +-- superclass hierarchy -get_binders -~~~~~~~~~~~ -Extract *binding* names from type and class decls. Type variables are -bound in type, data, newtype and class declarations and the polytypes -in the class op sigs. +mkClassEdges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Name, [Name]) -Why do we need to grab all these type variables at once, including -those locally-quantified type variables in class op signatures? -Because we can only commit to the final kind of a type variable when -we've completed the mutually recursive group. For example: +mkClassEdges decl@(ClassDecl {tcdCtxt = ctxt, tcdName = name}) = Just (decl, name, [c | HsClassP c _ <- ctxt]) +mkClassEdges other_decl = Nothing -class C a where - op :: D b => a -> b -> b - -class D c where - bop :: (Monad c) => ... +mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name]) +mkEdges decl = (decl, tyClDeclName decl, tyClDeclFTVs decl) +\end{code} -Here, the kind of the locally-polymorphic type variable "b" -depends on *all the uses of class D*. For example, the use of -Monad c in bop's type signature means that D must have kind Type->Type. +%************************************************************************ +%* * +\subsection{Error management +%* * +%************************************************************************ \begin{code} -get_binders :: Bag Decl - -> ([RnName], -- TyVars; no dups - [(RnName, Maybe Arity)],-- Tycons; no dups; arities for synonyms - [RnName]) -- Classes; no dups +typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message -get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes) - where - (tyvars, tycons, classes) = foldBag union3 get_binders1 - (emptyBag,emptyBag,emptyBag) - decls - - union3 (a1,a2,a3) (b1,b2,b3) - = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3) - -get_binders1 (TyD (TyData _ name tyvars _ _ _ _)) - = (listToBag tyvars, unitBag (name,Nothing), emptyBag) -get_binders1 (TyD (TyNew _ name tyvars _ _ _ _)) - = (listToBag tyvars, unitBag (name,Nothing), emptyBag) -get_binders1 (TyD (TySynonym name tyvars _ _)) - = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag) -get_binders1 (ClD (ClassDecl _ name tyvar sigs _ _ _)) - = (unitBag tyvar `unionBags` sigs_tvs sigs, - emptyBag, unitBag name) - -sigs_tvs sigs = unionManyBags (map sig_tvs sigs) - where - sig_tvs (ClassOpSig _ ty _ _) = pty_tvs ty - pty_tvs (HsForAllTy tvs _ _) = listToBag tvs -- tvs doesn't include the class tyvar -\end{code} +typeCycleErr syn_cycles + = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles) +classCycleErr cls_cycles + = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles) -\begin{code} -typeCycleErr syn_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles) - -classCycleErr cls_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles) - -pp_cycle sty str things - = ppHang (ppStr str) - 4 (ppAboves (map pp_thing things)) +pp_cycle str decls + = hang (text str) + 4 (vcat (map pp_decl decls)) where - pp_thing (pp_name, loc) - = ppCat [pp_name, ppr sty loc] + pp_decl decl + = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)] + where + name = tyClDeclName decl + \end{code}