From 8bdd26e3d2864151c4d0dccbc530c2deac362892 Mon Sep 17 00:00:00 2001 From: Richard Eisenberg Date: Fri, 21 Dec 2012 20:56:25 -0500 Subject: Implement overlapping type family instances. An ordered, overlapping type family instance is introduced by 'type instance where', followed by equations. See the new section in the user manual (7.7.2.2) for details. The canonical example is Boolean equality at the type level: type family Equals (a :: k) (b :: k) :: Bool type instance where Equals a a = True Equals a b = False A branched family instance, such as this one, checks its equations in order and applies only the first the matches. As explained in the note [Instance checking within groups] in FamInstEnv.lhs, we must be careful not to simplify, say, (Equals Int b) to False, because b might later unify with Int. This commit includes all of the commits on the overlapping-tyfams branch. SPJ requested that I combine all my commits over the past several months into one monolithic commit. The following GHC repos are affected: ghc, testsuite, utils/haddock, libraries/template-haskell, and libraries/dph. Here are some details for the interested: - The definition of CoAxiom has been moved from TyCon.lhs to a new file CoAxiom.lhs. I made this decision because of the number of definitions necessary to support BranchList. - BranchList is a GADT whose type tracks whether it is a singleton list or not-necessarily-a-singleton-list. The reason I introduced this type is to increase static checking of places where GHC code assumes that a FamInst or CoAxiom is indeed a singleton. This assumption takes place roughly 10 times throughout the code. I was worried that a future change to GHC would invalidate the assumption, and GHC might subtly fail to do the right thing. By explicitly labeling CoAxioms and FamInsts as being Unbranched (singleton) or Branched (not-necessarily-singleton), we make this assumption explicit and checkable. Furthermore, to enforce the accuracy of this label, the list of branches of a CoAxiom or FamInst is stored using a BranchList, whose constructors constrain its type index appropriately. I think that the decision to use BranchList is probably the most controversial decision I made from a code design point of view. Although I provide conversions to/from ordinary lists, it is more efficient to use the brList... functions provided in CoAxiom than always to convert. The use of these functions does not wander far from the core CoAxiom/FamInst logic. BranchLists are motivated and explained in the note [Branched axioms] in CoAxiom.lhs. - The CoAxiom type has changed significantly. You can see the new type in CoAxiom.lhs. It uses a CoAxBranch type to track branches of the CoAxiom. Correspondingly various functions producing and consuming CoAxioms had to change, including the binary layout of interface files. - To get branched axioms to work correctly, it is important to have a notion of type "apartness": two types are apart if they cannot unify, and no substitution of variables can ever get them to unify, even after type family simplification. (This is different than the normal failure to unify because of the type family bit.) This notion in encoded in tcApartTys, in Unify.lhs. Because apartness is finer-grained than unification, the tcUnifyTys now calls tcApartTys. - CoreLinting axioms has been updated, both to reflect the new form of CoAxiom and to enforce the apartness rules of branch application. The formalization of the new rules is in docs/core-spec/core-spec.pdf. - The FamInst type (in types/FamInstEnv.lhs) has changed significantly, paralleling the changes to CoAxiom. Of course, this forced minor changes in many files. - There are several new Notes in FamInstEnv.lhs, including one discussing confluent overlap and why we're not doing it. - lookupFamInstEnv, lookupFamInstEnvConflicts, and lookup_fam_inst_env' (the function that actually does the work) have all been more-or-less completely rewritten. There is a Note [lookup_fam_inst_env' implementation] describing the implementation. One of the changes that affects other files is to change the type of matches from a pair of (FamInst, [Type]) to a new datatype (which now includes the index of the matching branch). This seemed a better design. - The TySynInstD constructor in Template Haskell was updated to use the new datatype TySynEqn. I also bumped the TH version number, requiring changes to DPH cabal files. (That's why the DPH repo has an overlapping-tyfams branch.) - As SPJ requested, I refactored some of the code in HsDecls: * splitting up TyDecl into SynDecl and DataDecl, correspondingly changing HsTyDefn to HsDataDefn (with only one constructor) * splitting FamInstD into TyFamInstD and DataFamInstD and splitting FamInstDecl into DataFamInstDecl and TyFamInstDecl * making the ClsInstD take a ClsInstDecl, for parallelism with InstDecl's other constructors * changing constructor TyFamily into FamDecl * creating a FamilyDecl type that stores the details for a family declaration; this is useful because FamilyDecls can appear in classes but other decls cannot * restricting the associated types and associated type defaults for a * class to be the new, more restrictive types * splitting cid_fam_insts into cid_tyfam_insts and cid_datafam_insts, according to the new types * perhaps one or two more that I'm overlooking None of these changes has far-reaching implications. - The user manual, section 7.7.2.2, is updated to describe the new type family instances. --- src/Haddock/Interface/AttachInstances.hs | 2 +- src/Haddock/Interface/Create.hs | 25 +++++--- src/Haddock/Interface/Rename.hs | 102 ++++++++++++++++++++----------- 3 files changed, 82 insertions(+), 47 deletions(-) (limited to 'src/Haddock/Interface') diff --git a/src/Haddock/Interface/AttachInstances.hs b/src/Haddock/Interface/AttachInstances.hs index a4d4764e..86d1a7b8 100644 --- a/src/Haddock/Interface/AttachInstances.hs +++ b/src/Haddock/Interface/AttachInstances.hs @@ -53,7 +53,7 @@ attachToExportItem :: Interface -> IfaceMap -> InstIfaceMap -> ExportItem Name - attachToExportItem iface ifaceMap instIfaceMap export = case export of ExportDecl { expItemDecl = L _ (TyClD d) } -> do - mb_info <- getAllInfo (unLoc (tcdLName d)) + mb_info <- getAllInfo (tcdName d) let export' = export { expItemInstances = diff --git a/src/Haddock/Interface/Create.hs b/src/Haddock/Interface/Create.hs index 9fca453d..8f429d9c 100644 --- a/src/Haddock/Interface/Create.hs +++ b/src/Haddock/Interface/Create.hs @@ -268,7 +268,7 @@ mkMaps dflags gre instances decls = do instanceMap = M.fromList [ (getSrcSpan n, n) | i <- instances, let n = getName i ] names :: HsDecl Name -> [Name] - names (InstD (ClsInstD { cid_poly_ty = L l _ })) = maybeToList (M.lookup l instanceMap) -- See note [2]. + names (InstD (ClsInstD (ClsInstDecl { cid_poly_ty = L l _ }))) = maybeToList (M.lookup l instanceMap) -- See note [2]. names decl = getMainDeclBinder decl -- Note [2]: @@ -296,7 +296,7 @@ subordinates (TyClD decl) ] dataSubs = constrs ++ fields where - cons = map unL $ (td_cons (tcdTyDefn decl)) + cons = map unL $ (dd_cons (tcdDataDefn decl)) constrs = [ (unL $ con_name c, maybeToList $ fmap unL $ con_doc c, M.empty) | c <- cons ] fields = [ (unL n, maybeToList $ fmap unL doc, M.empty) @@ -312,7 +312,7 @@ typeDocs d = case d of SigD (TypeSig _ ty) -> docs (unLoc ty) ForD (ForeignImport _ ty _ _) -> docs (unLoc ty) - TyClD (TyDecl { tcdTyDefn = TySynonym {td_synRhs = ty}}) -> docs (unLoc ty) + TyClD (SynDecl { tcdRhs = ty }) -> docs (unLoc ty) _ -> M.empty where go n (HsForAllTy _ _ _ ty) = go n (unLoc ty) @@ -331,7 +331,7 @@ classDecls class_ = filterDecls . collectDocs . sortByLoc $ decls docs = mkDecls tcdDocs DocD class_ defs = mkDecls (bagToList . tcdMeths) ValD class_ sigs = mkDecls tcdSigs SigD class_ - ats = mkDecls tcdATs TyClD class_ + ats = mkDecls tcdATs (TyClD . FamDecl) class_ -- | The top-level declarations of a module that we care about, @@ -374,7 +374,11 @@ warnAboutFilteredDecls :: DynFlags -> Module -> [LHsDecl Name] -> ErrMsgM () warnAboutFilteredDecls dflags mdl decls = do let modStr = moduleString mdl let typeInstances = - nub [ unLoc (fid_tycon d) | L _ (InstD (FamInstD { lid_inst = d })) <- decls ] + nub (concat [[ unLoc (tfie_tycon eqn) + | L _ (InstD (TyFamInstD (TyFamInstDecl { tfid_eqns = eqns }))) <- decls + , L _ eqn <- eqns ], + [ unLoc (dfid_tycon d) + | L _ (InstD (DataFamInstD { dfid_inst = d })) <- decls ]]) unless (null typeInstances) $ tell [ @@ -383,8 +387,11 @@ warnAboutFilteredDecls dflags mdl decls = do ++ "will be filtered out:\n " ++ (intercalate ", " $ map (occNameString . nameOccName) typeInstances) ] - let instances = nub [ pretty dflags i | L _ (InstD (ClsInstD { cid_poly_ty = i, cid_fam_insts = ats })) <- decls - , not (null ats) ] + let instances = nub [ pretty dflags i | L _ (InstD (ClsInstD (ClsInstDecl + { cid_poly_ty = i + , cid_tyfam_insts = ats + , cid_datafam_insts = adts }))) <- decls + , not (null ats) || not (null adts) ] unless (null instances) $ tell [ @@ -734,11 +741,11 @@ extractDecl name mdl decl _ -> error "internal: extractDecl" TyClD d | isDataDecl d -> let (n, tyvar_names) = name_and_tyvars d - L pos sig = extractRecSel name mdl n tyvar_names (td_cons (tcdTyDefn d)) + L pos sig = extractRecSel name mdl n tyvar_names (dd_cons (tcdDataDefn d)) in L pos (SigD sig) _ -> error "internal: extractDecl" where - name_and_tyvars d = (unLoc (tcdLName d), hsLTyVarLocNames (tcdTyVars d)) + name_and_tyvars d = (tcdName d, hsLTyVarLocNames (tyClDeclTyVars d)) toTypeNoLoc :: Located Name -> LHsType Name diff --git a/src/Haddock/Interface/Rename.hs b/src/Haddock/Interface/Rename.hs index 6109c341..b384886c 100644 --- a/src/Haddock/Interface/Rename.hs +++ b/src/Haddock/Interface/Rename.hs @@ -322,10 +322,8 @@ renameDecl decl = case decl of return (InstD d') _ -> error "renameDecl" - -renameLTyClD :: LTyClDecl Name -> RnM (LTyClDecl DocName) -renameLTyClD (L loc d) = return . L loc =<< renameTyClD d - +renameLThing :: (a Name -> RnM (a DocName)) -> Located (a Name) -> RnM (Located (a DocName)) +renameLThing fn (L loc x) = return . L loc =<< fn x renameTyClD :: TyClDecl Name -> RnM (TyClDecl DocName) renameTyClD d = case d of @@ -334,19 +332,21 @@ renameTyClD d = case d of return (ForeignType lname' b) -- TyFamily flav lname ltyvars kind tckind -> do - TyFamily flav lname ltyvars tckind -> do - lname' <- renameL lname - ltyvars' <- renameLTyVarBndrs ltyvars --- kind' <- renameMaybeLKind kind - tckind' <- renameMaybeLKind tckind --- return (TyFamily flav lname' ltyvars' kind' tckind) - return (TyFamily flav lname' ltyvars' tckind') + FamDecl { tcdFam = decl } -> do + decl' <- renameFamilyDecl decl + return (FamDecl { tcdFam = decl' }) + + SynDecl { tcdLName = lname, tcdTyVars = tyvars, tcdRhs = rhs, tcdFVs = fvs } -> do + lname' <- renameL lname + tyvars' <- renameLTyVarBndrs tyvars + rhs' <- renameLType rhs + return (SynDecl { tcdLName = lname', tcdTyVars = tyvars', tcdRhs = rhs', tcdFVs = fvs }) - TyDecl { tcdLName = lname, tcdTyVars = tyvars, tcdTyDefn = defn, tcdFVs = fvs } -> do + DataDecl { tcdLName = lname, tcdTyVars = tyvars, tcdDataDefn = defn, tcdFVs = fvs } -> do lname' <- renameL lname tyvars' <- renameLTyVarBndrs tyvars - defn' <- renameTyDefn defn - return (TyDecl { tcdLName = lname', tcdTyVars = tyvars', tcdTyDefn = defn', tcdFVs = fvs }) + defn' <- renameDataDefn defn + return (DataDecl { tcdLName = lname', tcdTyVars = tyvars', tcdDataDefn = defn', tcdFVs = fvs }) ClassDecl { tcdCtxt = lcontext, tcdLName = lname, tcdTyVars = ltyvars , tcdFDs = lfundeps, tcdSigs = lsigs, tcdATs = ats, tcdATDefs = at_defs } -> do @@ -355,8 +355,8 @@ renameTyClD d = case d of ltyvars' <- renameLTyVarBndrs ltyvars lfundeps' <- mapM renameLFunDep lfundeps lsigs' <- mapM renameLSig lsigs - ats' <- mapM renameLTyClD ats - at_defs' <- mapM (mapM renameFamInstD) at_defs + ats' <- mapM (renameLThing renameFamilyDecl) ats + at_defs' <- mapM (mapM renameTyFamInstD) at_defs -- we don't need the default methods or the already collected doc entities return (ClassDecl { tcdCtxt = lcontext', tcdLName = lname', tcdTyVars = ltyvars' , tcdFDs = lfundeps', tcdSigs = lsigs', tcdMeths= emptyBag @@ -370,19 +370,24 @@ renameTyClD d = case d of renameLSig (L loc sig) = return . L loc =<< renameSig sig -renameTyDefn :: HsTyDefn Name -> RnM (HsTyDefn DocName) -renameTyDefn (TyData { td_ND = nd, td_ctxt = lcontext, td_cType = cType - , td_kindSig = k, td_cons = cons }) = do +renameFamilyDecl :: FamilyDecl Name -> RnM (FamilyDecl DocName) +renameFamilyDecl (FamilyDecl { fdFlavour = flav, fdLName = lname + , fdTyVars = ltyvars, fdKindSig = tckind }) = do + lname' <- renameL lname + ltyvars' <- renameLTyVarBndrs ltyvars + tckind' <- renameMaybeLKind tckind + return (FamilyDecl { fdFlavour = flav, fdLName = lname' + , fdTyVars = ltyvars', fdKindSig = tckind' }) + +renameDataDefn :: HsDataDefn Name -> RnM (HsDataDefn DocName) +renameDataDefn (HsDataDefn { dd_ND = nd, dd_ctxt = lcontext, dd_cType = cType + , dd_kindSig = k, dd_cons = cons }) = do lcontext' <- renameLContext lcontext k' <- renameMaybeLKind k cons' <- mapM (mapM renameCon) cons -- I don't think we need the derivings, so we return Nothing - return (TyData { td_ND = nd, td_ctxt = lcontext', td_cType = cType - , td_kindSig = k', td_cons = cons', td_derivs = Nothing }) - -renameTyDefn (TySynonym { td_synRhs = ltype }) = do - ltype' <- renameLType ltype - return (TySynonym { td_synRhs = ltype' }) + return (HsDataDefn { dd_ND = nd, dd_ctxt = lcontext', dd_cType = cType + , dd_kindSig = k', dd_cons = cons', dd_derivs = Nothing }) renameCon :: ConDecl Name -> RnM (ConDecl DocName) renameCon decl@(ConDecl { con_name = lname, con_qvars = ltyvars @@ -435,24 +440,47 @@ renameForD (ForeignExport lname ltype co x) = do renameInstD :: InstDecl Name -> RnM (InstDecl DocName) -renameInstD (ClsInstD { cid_poly_ty =ltype, cid_fam_insts = lATs }) = do +renameInstD (ClsInstD { cid_inst = d }) = do + d' <- renameClsInstD d + return (ClsInstD { cid_inst = d' }) +renameInstD (TyFamInstD { tfid_inst = d }) = do + d' <- renameTyFamInstD d + return (TyFamInstD { tfid_inst = d' }) +renameInstD (DataFamInstD { dfid_inst = d }) = do + d' <- renameDataFamInstD d + return (DataFamInstD { dfid_inst = d' }) + +renameClsInstD :: ClsInstDecl Name -> RnM (ClsInstDecl DocName) +renameClsInstD (ClsInstDecl { cid_poly_ty =ltype, cid_tyfam_insts = lATs, cid_datafam_insts = lADTs }) = do ltype' <- renameLType ltype - lATs' <- mapM (mapM renameFamInstD) lATs - return (ClsInstD { cid_poly_ty = ltype', cid_binds = emptyBag, cid_sigs = [] - , cid_fam_insts = lATs' }) + lATs' <- mapM (mapM renameTyFamInstD) lATs + lADTs' <- mapM (mapM renameDataFamInstD) lADTs + return (ClsInstDecl { cid_poly_ty = ltype', cid_binds = emptyBag, cid_sigs = [] + , cid_tyfam_insts = lATs', cid_datafam_insts = lADTs' }) -renameInstD (FamInstD { lid_inst = d }) = do - d' <- renameFamInstD d - return (FamInstD { lid_inst = d' }) -renameFamInstD :: FamInstDecl Name -> RnM (FamInstDecl DocName) -renameFamInstD (FamInstDecl { fid_tycon = tc, fid_pats = pats_w_bndrs, fid_defn = defn }) +renameTyFamInstD :: TyFamInstDecl Name -> RnM (TyFamInstDecl DocName) +renameTyFamInstD (TyFamInstDecl { tfid_eqns = eqns , tfid_group = eqn_group }) + = do { eqns' <- mapM (renameLThing renameTyFamInstEqn) eqns + ; return (TyFamInstDecl { tfid_eqns = eqns' + , tfid_group = eqn_group + , tfid_fvs = placeHolderNames }) } + +renameTyFamInstEqn :: TyFamInstEqn Name -> RnM (TyFamInstEqn DocName) +renameTyFamInstEqn (TyFamInstEqn { tfie_tycon = tc, tfie_pats = pats_w_bndrs, tfie_rhs = rhs }) = do { tc' <- renameL tc ; pats' <- mapM renameLType (hswb_cts pats_w_bndrs) - ; defn' <- renameTyDefn defn - ; return (FamInstDecl { fid_tycon = tc', fid_pats = pats_w_bndrs { hswb_cts = pats' } - , fid_defn = defn', fid_fvs = placeHolderNames }) } + ; rhs' <- renameLType rhs + ; return (TyFamInstEqn { tfie_tycon = tc', tfie_pats = pats_w_bndrs { hswb_cts = pats' } + , tfie_rhs = rhs' }) } +renameDataFamInstD :: DataFamInstDecl Name -> RnM (DataFamInstDecl DocName) +renameDataFamInstD (DataFamInstDecl { dfid_tycon = tc, dfid_pats = pats_w_bndrs, dfid_defn = defn }) + = do { tc' <- renameL tc + ; pats' <- mapM renameLType (hswb_cts pats_w_bndrs) + ; defn' <- renameDataDefn defn + ; return (DataFamInstDecl { dfid_tycon = tc', dfid_pats = pats_w_bndrs { hswb_cts = pats' } + , dfid_defn = defn', dfid_fvs = placeHolderNames }) } renameExportItem :: ExportItem Name -> RnM (ExportItem DocName) renameExportItem item = case item of -- cgit v1.2.3