X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcDeriv.lhs;h=fab7c61ff07cd2e388a1bf4a0d7141255c112e18;hp=3466cbfab1e9df61aa0bfe28f4af51fe0e9ecc4d;hb=74e1e73af872e63fbbec2bc9442494c3657053c3;hpb=895eccb09f195beefeba9d3c59d7dfa557c6f7d1 diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs index 3466cbf..fab7c61 100644 --- a/compiler/typecheck/TcDeriv.lhs +++ b/compiler/typecheck/TcDeriv.lhs @@ -40,10 +40,13 @@ import Name import NameSet import TyCon import TcType +import BuildTyCl +import BasicTypes import Var import VarSet import PrelNames import SrcLoc +import UniqSupply import Util import ListSetOps import Outputable @@ -68,10 +71,11 @@ Overall plan 3. Add the derived bindings, generating InstInfos + \begin{code} -- DerivSpec is purely local to this module data DerivSpec = DS { ds_loc :: SrcSpan - , ds_orig :: InstOrigin + , ds_orig :: CtOrigin , ds_name :: Name , ds_tvs :: [TyVar] , ds_theta :: ThetaType @@ -84,14 +88,27 @@ data DerivSpec = DS { ds_loc :: SrcSpan -- df :: forall tvs. theta => C tys -- The Name is the name for the DFun we'll build -- The tyvars bind all the variables in the theta - -- For family indexes, the tycon in + -- For type families, the tycon in -- in ds_tys is the *family* tycon -- in ds_tc, ds_tc_args is the *representation* tycon -- For non-family tycons, both are the same -- ds_newtype = True <=> Newtype deriving -- False <=> Vanilla deriving +\end{code} + +Example: + + newtype instance T [a] = MkT (Tree a) deriving( C s ) +==> + axiom T [a] = :RTList a + axiom :RTList a = Tree a + + DS { ds_tvs = [a,s], ds_cls = C, ds_tys = [s, T [a]] + , ds_tc = :RTList, ds_tc_args = [a] + , ds_newtype = True } +\begin{code} type DerivContext = Maybe ThetaType -- Nothing <=> Vanilla deriving; infer the context of the instance decl -- Just theta <=> Standalone deriving: context supplied by programmer @@ -111,6 +128,9 @@ pprDerivSpec (DS { ds_loc = l, ds_name = n, ds_tvs = tvs, ds_cls = c, ds_tys = tys, ds_theta = rhs }) = parens (hsep [ppr l, ppr n, ppr tvs, ppr c, ppr tys] <+> equals <+> ppr rhs) + +instance Outputable DerivSpec where + ppr = pprDerivSpec \end{code} @@ -278,17 +298,21 @@ both of them. So we gather defs/uses from deriving just like anything else. tcDeriving :: [LTyClDecl Name] -- All type constructors -> [LInstDecl Name] -- All instance declarations -> [LDerivDecl Name] -- All stand-alone deriving declarations - -> TcM ([InstInfo Name], -- The generated "instance decls" - HsValBinds Name, -- Extra generated top-level bindings - DefUses) + -> TcM ([InstInfo Name] -- The generated "instance decls" + ,HsValBinds Name -- Extra generated top-level bindings + ,DefUses + ,[TyCon] -- Extra generated top-level types + ,[TyCon]) -- Extra generated type family instances tcDeriving tycl_decls inst_decls deriv_decls - = recoverM (return ([], emptyValBindsOut, emptyDUs)) $ + = recoverM (return ([], emptyValBindsOut, emptyDUs, [], [])) $ do { -- Fish the "deriving"-related information out of the TcEnv -- And make the necessary "equations". is_boot <- tcIsHsBoot - ; traceTc (text "tcDeriving" <+> ppr is_boot) - ; early_specs <- makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls + ; traceTc "tcDeriving" (ppr is_boot) + ; (early_specs, genericsExtras) + <- makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls + ; let (repMetaTys, repTyCons, metaInsts) = unzip3 genericsExtras ; overlap_flag <- getOverlapFlag ; let (infer_specs, given_specs) = splitEithers early_specs @@ -299,19 +323,44 @@ tcDeriving tycl_decls inst_decls deriv_decls ; insts2 <- mapM (genInst False overlap_flag) final_specs - -- Generate the generic to/from functions from each type declaration - ; gen_binds <- mkGenericBinds is_boot tycl_decls - ; (inst_info, rn_binds, rn_dus) <- renameDeriv is_boot gen_binds (insts1 ++ insts2) + -- We no longer generate the old generic to/from functions + -- from each type declaration, so this is emptyBag + ; gen_binds <- return emptyBag -- mkGenericBinds is_boot tycl_decls + + ; (inst_info, rn_binds, rn_dus) + <- renameDeriv is_boot gen_binds (insts1 ++ insts2 ++ concat metaInsts) ; dflags <- getDOpts ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances" - (ddump_deriving inst_info rn_binds)) - - ; return (inst_info, rn_binds, rn_dus) } + (ddump_deriving inst_info rn_binds repMetaTys repTyCons metaInsts)) +{- + ; when (not (null inst_info)) $ + dumpDerivingInfo (ddump_deriving inst_info rn_binds) +-} + ; return ( inst_info, rn_binds, rn_dus + , concat (map metaTyCons2TyCons repMetaTys), repTyCons) } where - ddump_deriving :: [InstInfo Name] -> HsValBinds Name -> SDoc - ddump_deriving inst_infos extra_binds - = vcat (map pprInstInfoDetails inst_infos) $$ ppr extra_binds + ddump_deriving :: [InstInfo Name] -> HsValBinds Name + -> [MetaTyCons] -- ^ Empty data constructors + -> [TyCon] -- ^ Rep type family instances + -> [[(InstInfo RdrName, DerivAuxBinds)]] + -- ^ Instances for the repMetaTys + -> SDoc + ddump_deriving inst_infos extra_binds repMetaTys repTyCons metaInsts + = hang (ptext (sLit "Derived instances")) + 2 (vcat (map (\i -> pprInstInfoDetails i $$ text "") inst_infos) + $$ ppr extra_binds) + $$ hangP "Generic representation" ( + hangP "Generated datatypes for meta-information" + (vcat (map ppr repMetaTys)) + -- The Outputable instance for TyCon unfortunately only prints the name... + $$ hangP "Representation types" + (vcat (map ppr repTyCons)) + $$ hangP "Meta-information instances" + (vcat (map (pprInstInfoDetails . fst) (concat metaInsts)))) + + hangP s x = text "" $$ hang (ptext (sLit s)) 2 x + renameDeriv :: Bool -> LHsBinds RdrName -> [(InstInfo RdrName, DerivAuxBinds)] @@ -334,13 +383,12 @@ renameDeriv is_boot gen_binds insts -- notably "con2tag" and/or "tag2con" functions. -- Bring those names into scope before renaming the instances themselves ; loc <- getSrcSpanM -- Generic loc for shared bindings - ; let aux_binds = listToBag $ map (genAuxBind loc) $ - rm_dups [] $ concat deriv_aux_binds - ; rn_aux_lhs <- rnTopBindsLHS emptyFsEnv (ValBindsIn aux_binds []) - ; let aux_names = map unLoc (collectHsValBinders rn_aux_lhs) - - ; bindLocalNames aux_names $ - do { (rn_aux, dus_aux) <- rnTopBindsRHS (mkNameSet aux_names) rn_aux_lhs + ; let (aux_binds, aux_sigs) = unzip $ map (genAuxBind loc) $ + rm_dups [] $ concat deriv_aux_binds + aux_val_binds = ValBindsIn (listToBag aux_binds) aux_sigs + ; rn_aux_lhs <- rnTopBindsLHS emptyFsEnv aux_val_binds + ; bindLocalNames (collectHsValBinders rn_aux_lhs) $ + do { (rn_aux, dus_aux) <- rnTopBindsRHS rn_aux_lhs ; (rn_inst_infos, fvs_insts) <- mapAndUnzipM rn_inst_info inst_infos ; return (rn_inst_infos, rn_aux `plusHsValBinds` rn_gen, dus_gen `plusDU` dus_aux `plusDU` usesOnly (plusFVs fvs_insts)) } } @@ -354,36 +402,44 @@ renameDeriv is_boot gen_binds insts | otherwise = rm_dups (b:acc) bs - rn_inst_info (InstInfo { iSpec = inst, iBinds = NewTypeDerived co }) - = return (InstInfo { iSpec = inst, iBinds = NewTypeDerived co }, emptyFVs) + rn_inst_info :: InstInfo RdrName -> TcM (InstInfo Name, FreeVars) + rn_inst_info info@(InstInfo { iBinds = NewTypeDerived coi tc }) + = return ( info { iBinds = NewTypeDerived coi tc } + , mkFVs (map dataConName (tyConDataCons tc))) + -- See Note [Newtype deriving and unused constructors] - rn_inst_info (InstInfo { iSpec = inst, iBinds = VanillaInst binds sigs standalone_deriv }) + rn_inst_info inst_info@(InstInfo { iSpec = inst, iBinds = VanillaInst binds sigs standalone_deriv }) = -- Bring the right type variables into -- scope (yuk), and rename the method binds ASSERT( null sigs ) bindLocalNames (map Var.varName tyvars) $ - do { (rn_binds, fvs) <- rnMethodBinds clas_nm (\_ -> []) [] binds + do { (rn_binds, fvs) <- rnMethodBinds clas_nm (\_ -> []) binds ; let binds' = VanillaInst rn_binds [] standalone_deriv - ; return (InstInfo { iSpec = inst, iBinds = binds' }, fvs) } + ; return (inst_info { iBinds = binds' }, fvs) } where (tyvars,_, clas,_) = instanceHead inst clas_nm = className clas - ------------------------------------------ -mkGenericBinds :: Bool -> [LTyClDecl Name] -> TcM (LHsBinds RdrName) -mkGenericBinds is_boot tycl_decls - | is_boot - = return emptyBag - | otherwise - = do { tcs <- mapM tcLookupTyCon [ tcdName d - | L _ d <- tycl_decls, isDataDecl d ] - ; return (unionManyBags [ mkTyConGenericBinds tc - | tc <- tcs, tyConHasGenerics tc ]) } - -- We are only interested in the data type declarations, - -- and then only in the ones whose 'has-generics' flag is on - -- The predicate tyConHasGenerics finds both of these \end{code} +Note [Newtype deriving and unused constructors] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider this (see Trac #1954): + + module Bug(P) where + newtype P a = MkP (IO a) deriving Monad + +If you compile with -fwarn-unused-binds you do not expect the warning +"Defined but not used: data consructor MkP". Yet the newtype deriving +code does not explicitly mention MkP, but it should behave as if you +had written + instance Monad P where + return x = MkP (return x) + ...etc... + +So we want to signal a user of the data constructor 'MkP'. That's +what we do in rn_inst_info, and it's the only reason we have the TyCon +stored in NewTypeDerived. + %************************************************************************ %* * @@ -394,37 +450,93 @@ mkGenericBinds is_boot tycl_decls @makeDerivSpecs@ fishes around to find the info about needed derived instances. \begin{code} +-- Make the "extras" for the generic representation +mkGenDerivExtras :: TyCon + -> TcRn (MetaTyCons, TyCon, [(InstInfo RdrName, DerivAuxBinds)]) +mkGenDerivExtras tc = do + { (metaTyCons, rep0TyInst) <- genGenericRepExtras tc + ; metaInsts <- genDtMeta (tc, metaTyCons) + ; return (metaTyCons, rep0TyInst, metaInsts) } + makeDerivSpecs :: Bool -> [LTyClDecl Name] - -> [LInstDecl Name] + -> [LInstDecl Name] -> [LDerivDecl Name] - -> TcM [EarlyDerivSpec] - + -> TcM ( [EarlyDerivSpec] + , [(MetaTyCons, TyCon, [(InstInfo RdrName, DerivAuxBinds)])]) makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls - | is_boot -- No 'deriving' at all in hs-boot files - = do { mapM_ add_deriv_err deriv_locs - ; return [] } + | is_boot -- No 'deriving' at all in hs-boot files + = do { mapM_ add_deriv_err deriv_locs + ; return ([],[]) } | otherwise - = do { eqns1 <- mapAndRecoverM deriveTyData all_tydata - ; eqns2 <- mapAndRecoverM deriveStandalone deriv_decls - ; return (eqns1 ++ eqns2) } + = do { eqns1 <- mapAndRecoverM deriveTyData all_tydata + ; eqns2 <- mapAndRecoverM deriveStandalone deriv_decls + + -- Generic representation stuff: we might need to add some "extras" + -- to the instances + ; xDerRep <- getDOpts >>= return . xopt Opt_DeriveGeneric + ; generic_extras_deriv <- if not xDerRep + -- No extras if the flag is off + then (return []) + else do { + let allTyNames = [ tcdName d | L _ d <- tycl_decls, isDataDecl d ] + -- Select only those types that derive Generic + ; let sel_tydata = [ tcdName t | (L _ c, L _ t) <- all_tydata + , getClassName c == Just genClassName ] + ; let sel_deriv_decls = catMaybes [ getTypeName t + | L _ (DerivDecl (L _ t)) <- deriv_decls + , getClassName t == Just genClassName ] + ; derTyDecls <- mapM tcLookupTyCon $ + filter (needsExtras xDerRep + (sel_tydata ++ sel_deriv_decls)) allTyNames + -- We need to generate the extras to add to what has + -- already been derived + ; {- pprTrace "sel_tydata" (ppr sel_tydata) $ + pprTrace "sel_deriv_decls" (ppr sel_deriv_decls) $ + pprTrace "derTyDecls" (ppr derTyDecls) $ + pprTrace "deriv_decls" (ppr deriv_decls) $ -} + mapM mkGenDerivExtras derTyDecls } + + -- Merge and return + ; return ( eqns1 ++ eqns2, generic_extras_deriv) } where + -- We need extras if the flag DeriveGeneric is on and this type is + -- deriving Generic + needsExtras xDerRep tydata tc_name = xDerRep && tc_name `elem` tydata + + -- Extracts the name of the class in the deriving + getClassName :: HsType Name -> Maybe Name + getClassName (HsForAllTy _ _ _ (L _ n)) = getClassName n + getClassName (HsPredTy (HsClassP n _)) = Just n + getClassName _ = Nothing + + -- Extracts the name of the type in the deriving + -- This function (and also getClassName above) is not really nice, and I + -- might not have covered all possible cases. I wonder if there is no easier + -- way to extract class and type name from a LDerivDecl... + getTypeName :: HsType Name -> Maybe Name + getTypeName (HsForAllTy _ _ _ (L _ n)) = getTypeName n + getTypeName (HsTyVar n) = Just n + getTypeName (HsOpTy _ (L _ n) _) = Just n + getTypeName (HsPredTy (HsClassP _ [L _ n])) = getTypeName n + getTypeName (HsAppTy (L _ n) _) = getTypeName n + getTypeName (HsParTy (L _ n)) = getTypeName n + getTypeName (HsKindSig (L _ n) _) = getTypeName n + getTypeName _ = Nothing + extractTyDataPreds decls = [(p, d) | d@(L _ (TyData {tcdDerivs = Just preds})) <- decls, p <- preds] all_tydata :: [(LHsType Name, LTyClDecl Name)] - -- Derived predicate paired with its data type declaration - all_tydata = extractTyDataPreds tycl_decls ++ - [ pd -- Traverse assoc data families - | L _ (InstDecl _ _ _ ats) <- inst_decls - , pd <- extractTyDataPreds ats ] + -- Derived predicate paired with its data type declaration + all_tydata = extractTyDataPreds (instDeclATs inst_decls ++ tycl_decls) deriv_locs = map (getLoc . snd) all_tydata - ++ map getLoc deriv_decls + ++ map getLoc deriv_decls add_deriv_err loc = setSrcSpan loc $ - addErr (hang (ptext (sLit "Deriving not permitted in hs-boot file")) - 2 (ptext (sLit "Use an instance declaration instead"))) + addErr (hang (ptext (sLit "Deriving not permitted in hs-boot file")) + 2 (ptext (sLit "Use an instance declaration instead"))) ------------------------------------------------------------------ deriveStandalone :: LDerivDecl Name -> TcM EarlyDerivSpec @@ -434,22 +546,22 @@ deriveStandalone :: LDerivDecl Name -> TcM EarlyDerivSpec deriveStandalone (L loc (DerivDecl deriv_ty)) = setSrcSpan loc $ addErrCtxt (standaloneCtxt deriv_ty) $ - do { traceTc (text "standalone deriving decl for" <+> ppr deriv_ty) - ; (tvs, theta, tau) <- tcHsInstHead deriv_ty - ; traceTc (text "standalone deriving;" - <+> text "tvs:" <+> ppr tvs - <+> text "theta:" <+> ppr theta - <+> text "tau:" <+> ppr tau) - ; (cls, inst_tys) <- checkValidInstHead tau - ; checkValidInstance tvs theta cls inst_tys + do { traceTc "Standalone deriving decl for" (ppr deriv_ty) + ; (tvs, theta, cls, inst_tys) <- tcHsInstHead deriv_ty + ; traceTc "Standalone deriving;" $ vcat + [ text "tvs:" <+> ppr tvs + , text "theta:" <+> ppr theta + , text "cls:" <+> ppr cls + , text "tys:" <+> ppr inst_tys ] + ; checkValidInstance deriv_ty tvs theta cls inst_tys -- C.f. TcInstDcls.tcLocalInstDecl1 ; let cls_tys = take (length inst_tys - 1) inst_tys inst_ty = last inst_tys - ; traceTc (text "standalone deriving;" - <+> text "class:" <+> ppr cls - <+> text "class types:" <+> ppr cls_tys - <+> text "type:" <+> ppr inst_ty) + ; traceTc "Standalone deriving:" $ vcat + [ text "class:" <+> ppr cls + , text "class types:" <+> ppr cls_tys + , text "type:" <+> ppr inst_ty ] ; mkEqnHelp StandAloneDerivOrigin tvs cls cls_tys inst_ty (Just theta) } @@ -499,7 +611,7 @@ deriveTyData (L loc deriv_pred, L _ decl@(TyData { tcdLName = L _ tycon_name, -- Type families can't be partially applied -- e.g. newtype instance T Int a = MkT [a] deriving( Monad ) -- Note [Deriving, type families, and partial applications] - ; checkTc (not (isOpenTyCon tc) || n_args_to_drop == 0) + ; checkTc (not (isFamilyTyCon tc) || n_args_to_drop == 0) (typeFamilyPapErr tc cls cls_tys inst_ty) ; mkEqnHelp DerivOrigin (varSetElems univ_tvs) cls cls_tys inst_ty Nothing } } @@ -530,8 +642,8 @@ When there are no type families, it's quite easy: newtype S a = MkS [a] -- :CoS :: S ~ [] -- Eta-reduced - instance Eq [a] => Eq (S a) -- by coercion sym (Eq (coMkS a)) : Eq [a] ~ Eq (S a) - instance Monad [] => Monad S -- by coercion sym (Monad coMkS) : Monad [] ~ Monad S + instance Eq [a] => Eq (S a) -- by coercion sym (Eq (:CoS a)) : Eq [a] ~ Eq (S a) + instance Monad [] => Monad S -- by coercion sym (Monad :CoS) : Monad [] ~ Monad S When type familes are involved it's trickier: @@ -552,7 +664,7 @@ After all, we can write it out ... etc ... \begin{code} -mkEqnHelp :: InstOrigin -> [TyVar] -> Class -> [Type] -> Type +mkEqnHelp :: CtOrigin -> [TyVar] -> Class -> [Type] -> Type -> DerivContext -- Just => context supplied (standalone deriving) -- Nothing => context inferred (deriving on data decl) -> TcRn EarlyDerivSpec @@ -564,74 +676,46 @@ mkEqnHelp :: InstOrigin -> [TyVar] -> Class -> [Type] -> Type mkEqnHelp orig tvs cls cls_tys tc_app mtheta | Just (tycon, tc_args) <- tcSplitTyConApp_maybe tc_app , isAlgTyCon tycon -- Check for functions, primitive types etc - = do { (rep_tc, rep_tc_args) <- tcLookupFamInstExact tycon tc_args - -- Be careful to test rep_tc here: in the case of families, - -- we want to check the instance tycon, not the family tycon - - -- For standalone deriving (mtheta /= Nothing), - -- check that all the data constructors are in scope. - -- No need for this when deriving Typeable, becuase we don't need - -- the constructors for that. - ; rdr_env <- getGlobalRdrEnv - ; let hidden_data_cons = isAbstractTyCon rep_tc || any not_in_scope (tyConDataCons rep_tc) - not_in_scope dc = null (lookupGRE_Name rdr_env (dataConName dc)) - ; checkTc (isNothing mtheta || - not hidden_data_cons || - className cls `elem` typeableClassNames) - (derivingHiddenErr tycon) - - ; dflags <- getDOpts - ; if isDataTyCon rep_tc then - mkDataTypeEqn orig dflags tvs cls cls_tys - tycon tc_args rep_tc rep_tc_args mtheta - else - mkNewTypeEqn orig dflags tvs cls cls_tys - tycon tc_args rep_tc rep_tc_args mtheta } + = mk_alg_eqn tycon tc_args | otherwise = failWithTc (derivingThingErr False cls cls_tys tc_app (ptext (sLit "The last argument of the instance must be a data or newtype application"))) -\end{code} -Note [Looking up family instances for deriving] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -tcLookupFamInstExact is an auxiliary lookup wrapper which requires -that looked-up family instances exist. If called with a vanilla -tycon, the old type application is simply returned. - -If we have - data instance F () = ... deriving Eq - data instance F () = ... deriving Eq -then tcLookupFamInstExact will be confused by the two matches; -but that can't happen because tcInstDecls1 doesn't call tcDeriving -if there are any overlaps. - -There are two other things that might go wrong with the lookup. -First, we might see a standalone deriving clause - deriving Eq (F ()) -when there is no data instance F () in scope. - -Note that it's OK to have - data instance F [a] = ... - deriving Eq (F [(a,b)]) -where the match is not exact; the same holds for ordinary data types -with standalone deriving declrations. + where + bale_out msg = failWithTc (derivingThingErr False cls cls_tys tc_app msg) -\begin{code} -tcLookupFamInstExact :: TyCon -> [Type] -> TcM (TyCon, [Type]) -tcLookupFamInstExact tycon tys - | not (isOpenTyCon tycon) - = return (tycon, tys) - | otherwise - = do { maybeFamInst <- tcLookupFamInst tycon tys - ; case maybeFamInst of - Nothing -> famInstNotFound tycon tys - Just famInst -> return famInst - } - -famInstNotFound :: TyCon -> [Type] -> TcM a -famInstNotFound tycon tys - = failWithTc (ptext (sLit "No family instance for") - <+> quotes (pprTypeApp tycon tys)) + mk_alg_eqn tycon tc_args + | className cls `elem` typeableClassNames + = do { dflags <- getDOpts + ; case checkTypeableConditions (dflags, tycon) of + Just err -> bale_out err + Nothing -> mk_typeable_eqn orig tvs cls tycon tc_args mtheta } + + | isDataFamilyTyCon tycon + , length tc_args /= tyConArity tycon + = bale_out (ptext (sLit "Unsaturated data family application")) + + | otherwise + = do { (rep_tc, rep_tc_args) <- tcLookupDataFamInst tycon tc_args + -- Be careful to test rep_tc here: in the case of families, + -- we want to check the instance tycon, not the family tycon + + -- For standalone deriving (mtheta /= Nothing), + -- check that all the data constructors are in scope. + ; rdr_env <- getGlobalRdrEnv + ; let hidden_data_cons = isAbstractTyCon rep_tc || + any not_in_scope (tyConDataCons rep_tc) + not_in_scope dc = null (lookupGRE_Name rdr_env (dataConName dc)) + ; unless (isNothing mtheta || not hidden_data_cons) + (bale_out (derivingHiddenErr tycon)) + + ; dflags <- getDOpts + ; if isDataTyCon rep_tc then + mkDataTypeEqn orig dflags tvs cls cls_tys + tycon tc_args rep_tc rep_tc_args mtheta + else + mkNewTypeEqn orig dflags tvs cls cls_tys + tycon tc_args rep_tc rep_tc_args mtheta } \end{code} @@ -642,7 +726,7 @@ famInstNotFound tycon tys %************************************************************************ \begin{code} -mkDataTypeEqn :: InstOrigin +mkDataTypeEqn :: CtOrigin -> DynFlags -> [Var] -- Universally quantified type variables in the instance -> Class -- Class for which we need to derive an instance @@ -666,15 +750,10 @@ mkDataTypeEqn orig dflags tvs cls cls_tys go_for_it = mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta bale_out msg = failWithTc (derivingThingErr False cls cls_tys (mkTyConApp tycon tc_args) msg) -mk_data_eqn, mk_typeable_eqn - :: InstOrigin -> [TyVar] -> Class - -> TyCon -> [TcType] -> TyCon -> [TcType] -> DerivContext - -> TcM EarlyDerivSpec +mk_data_eqn :: CtOrigin -> [TyVar] -> Class + -> TyCon -> [TcType] -> TyCon -> [TcType] -> DerivContext + -> TcM EarlyDerivSpec mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta - | getName cls `elem` typeableClassNames - = mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta - - | otherwise = do { dfun_name <- new_dfun_name cls tycon ; loc <- getSrcSpanM ; let inst_tys = [mkTyConApp tycon tc_args] @@ -689,7 +768,11 @@ mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta ; return (if isJust mtheta then Right spec -- Specified context else Left spec) } -- Infer context -mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta +---------------------- +mk_typeable_eqn :: CtOrigin -> [TyVar] -> Class + -> TyCon -> [TcType] -> DerivContext + -> TcM EarlyDerivSpec +mk_typeable_eqn orig tvs cls tycon tc_args mtheta -- The Typeable class is special in several ways -- data T a b = ... deriving( Typeable ) -- gives @@ -703,7 +786,7 @@ mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta = do { checkTc (cls `hasKey` typeableClassKey) (ptext (sLit "Use deriving( Typeable ) on a data type declaration")) ; real_cls <- tcLookupClass (typeableClassNames !! tyConArity tycon) - ; mk_typeable_eqn orig tvs real_cls tycon [] rep_tc [] (Just []) } + ; mk_typeable_eqn orig tvs real_cls tycon [] (Just []) } | otherwise -- standaone deriving = do { checkTc (null tc_args) @@ -714,15 +797,20 @@ mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta ; return (Right $ DS { ds_loc = loc, ds_orig = orig, ds_name = dfun_name, ds_tvs = [] , ds_cls = cls, ds_tys = [mkTyConApp tycon []] - , ds_tc = rep_tc, ds_tc_args = rep_tc_args + , ds_tc = tycon, ds_tc_args = [] , ds_theta = mtheta `orElse` [], ds_newtype = False }) } - +---------------------- inferConstraints :: [TyVar] -> Class -> [TcType] -> TyCon -> [TcType] -> ThetaType -- Generate a sufficiently large set of constraints that typechecking the -- generated method definitions should succeed. This set will be simplified -- before being used in the instance declaration -inferConstraints tvs cls inst_tys rep_tc rep_tc_args +inferConstraints _ cls inst_tys rep_tc rep_tc_args + -- Generic constraints are easy + | cls `hasKey` genClassKey + = [] + -- The others are a bit more complicated + | otherwise = ASSERT2( equalLength rep_tc_tvs all_rep_tc_args, ppr cls <+> ppr rep_tc ) stupid_constraints ++ extra_constraints ++ sc_constraints ++ con_arg_constraints @@ -746,7 +834,7 @@ inferConstraints tvs cls inst_tys rep_tc rep_tc_args get_constrained_tys :: [Type] -> [Type] get_constrained_tys tys - | is_functor_like = concatMap (deepSubtypesContaining last_tv) tys + | is_functor_like = concatMap (deepSubtypesContaining last_tv) tys | otherwise = tys rep_tc_tvs = tyConTyVars rep_tc @@ -763,15 +851,20 @@ inferConstraints tvs cls inst_tys rep_tc rep_tc_args stupid_constraints = substTheta subst (tyConStupidTheta rep_tc) subst = zipTopTvSubst rep_tc_tvs all_rep_tc_args - -- Extra constraints + -- Extra Data constraints -- The Data class (only) requires that for - -- instance (...) => Data (T a b) - -- then (Data a, Data b) are among the (...) constraints - -- Reason: that's what you need to typecheck the method - -- dataCast1 f = gcast1 f + -- instance (...) => Data (T t1 t2) + -- IF t1:*, t2:* + -- THEN (Data t1, Data t2) are among the (...) constraints + -- Reason: when the IF holds, we generate a method + -- dataCast2 f = gcast2 f + -- and we need the Data constraints to typecheck the method extra_constraints - | cls `hasKey` dataClassKey = [mkClassPred cls [mkTyVarTy tv] | tv <- tvs] - | otherwise = [] + | cls `hasKey` dataClassKey + , all (isLiftedTypeKind . typeKind) rep_tc_args + = [mkClassPred cls [ty] | ty <- rep_tc_args] + | otherwise + = [] ------------------------------------------------------------------ -- Check side conditions that dis-allow derivability for particular classes @@ -798,6 +891,9 @@ checkSideConditions dflags mtheta cls cls_tys rep_tc where ty_args_why = quotes (ppr (mkClassPred cls cls_tys)) <+> ptext (sLit "is not a class") +checkTypeableConditions :: Condition +checkTypeableConditions = checkFlag Opt_DeriveDataTypeable `andCond` cond_typeableOK + nonStdErr :: Class -> SDoc nonStdErr cls = quotes (ppr cls) <+> ptext (sLit "is not a derivable class") @@ -818,7 +914,8 @@ sideConditions mtheta cls cond_functorOK False) -- Functor/Fold/Trav works ok for rank-n types | cls_key == traversableClassKey = Just (checkFlag Opt_DeriveTraversable `andCond` cond_functorOK False) - | getName cls `elem` typeableClassNames = Just (checkFlag Opt_DeriveDataTypeable `andCond` cond_typeableOK) + | cls_key == genClassKey = Just (cond_RepresentableOk `andCond` + checkFlag Opt_DeriveGeneric) | otherwise = Nothing where cls_key = getUnique cls @@ -834,11 +931,11 @@ type Condition = (DynFlags, TyCon) -> Maybe SDoc orCond :: Condition -> Condition -> Condition orCond c1 c2 tc = case c1 tc of - Nothing -> Nothing -- c1 succeeds - Just x -> case c2 tc of -- c1 fails + Nothing -> Nothing -- c1 succeeds + Just x -> case c2 tc of -- c1 fails Nothing -> Nothing - Just y -> Just (x $$ ptext (sLit " and") $$ y) - -- Both fail + Just y -> Just (x $$ ptext (sLit " or") $$ y) + -- Both fail andCond :: Condition -> Condition -> Condition andCond c1 c2 tc = case c1 tc of @@ -849,24 +946,29 @@ cond_stdOK :: DerivContext -> Condition cond_stdOK (Just _) _ = Nothing -- Don't check these conservative conditions for -- standalone deriving; just generate the code + -- and let the typechecker handle the result cond_stdOK Nothing (_, rep_tc) - | null data_cons = Just (no_cons_why $$ suggestion) + | null data_cons = Just (no_cons_why rep_tc $$ suggestion) | not (null con_whys) = Just (vcat con_whys $$ suggestion) | otherwise = Nothing where suggestion = ptext (sLit "Possible fix: use a standalone deriving declaration instead") data_cons = tyConDataCons rep_tc - no_cons_why = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "has no data constructors") - con_whys = mapCatMaybes check_con data_cons check_con :: DataCon -> Maybe SDoc check_con con | isVanillaDataCon con , all isTauTy (dataConOrigArgTys con) = Nothing - | otherwise = Just (badCon con (ptext (sLit "does not have a Haskell-98 type"))) + | otherwise = Just (badCon con (ptext (sLit "must have a Haskell-98 type"))) +no_cons_why :: TyCon -> SDoc +no_cons_why rep_tc = quotes (pprSourceTyCon rep_tc) <+> + ptext (sLit "must have at least one data constructor") + +cond_RepresentableOk :: Condition +cond_RepresentableOk (_,t) = canDoGenerics t + cond_enumOrProduct :: Condition cond_enumOrProduct = cond_isEnumeration `orCond` (cond_isProduct `andCond` cond_noUnliftedArgs) @@ -880,15 +982,17 @@ cond_noUnliftedArgs (_, tc) where bad_cons = [ con | con <- tyConDataCons tc , any isUnLiftedType (dataConOrigArgTys con) ] - why = badCon (head bad_cons) (ptext (sLit "has arguments of unlifted type")) + why = badCon (head bad_cons) (ptext (sLit "must have only arguments of lifted type")) cond_isEnumeration :: Condition cond_isEnumeration (_, rep_tc) - | isEnumerationTyCon rep_tc = Nothing - | otherwise = Just why + | isEnumerationTyCon rep_tc = Nothing + | otherwise = Just why where - why = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "has non-nullary constructors") + why = sep [ quotes (pprSourceTyCon rep_tc) <+> + ptext (sLit "must be an enumeration type") + , ptext (sLit "(an enumeration consists of one or more nullary, non-GADT constructors)") ] + -- See Note [Enumeration types] in TyCon cond_isProduct :: Condition cond_isProduct (_, rep_tc) @@ -896,42 +1000,50 @@ cond_isProduct (_, rep_tc) | otherwise = Just why where why = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "has more than one constructor") + ptext (sLit "must have precisely one constructor") cond_typeableOK :: Condition -- OK for Typeable class -- Currently: (a) args all of kind * -- (b) 7 or fewer args -cond_typeableOK (_, rep_tc) - | tyConArity rep_tc > 7 = Just too_many - | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars rep_tc)) - = Just bad_kind - | isFamInstTyCon rep_tc = Just fam_inst -- no Typable for family insts - | otherwise = Nothing +cond_typeableOK (_, tc) + | tyConArity tc > 7 = Just too_many + | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars tc)) + = Just bad_kind + | otherwise = Nothing where - too_many = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "has too many arguments") - bad_kind = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "has arguments of kind other than `*'") - fam_inst = quotes (pprSourceTyCon rep_tc) <+> - ptext (sLit "is a type family") - + too_many = quotes (pprSourceTyCon tc) <+> + ptext (sLit "must have 7 or fewer arguments") + bad_kind = quotes (pprSourceTyCon tc) <+> + ptext (sLit "must only have arguments of kind `*'") functorLikeClassKeys :: [Unique] functorLikeClassKeys = [functorClassKey, foldableClassKey, traversableClassKey] cond_functorOK :: Bool -> Condition --- OK for Functor class +-- OK for Functor/Foldable/Traversable class -- Currently: (a) at least one argument -- (b) don't use argument contravariantly -- (c) don't use argument in the wrong place, e.g. data T a = T (X a a) -- (d) optionally: don't use function types -cond_functorOK allowFunctions (dflags, rep_tc) - | not (dopt Opt_DeriveFunctor dflags) - = Just (ptext (sLit "You need -XDeriveFunctor to derive an instance for this class")) +-- (e) no "stupid context" on data type +cond_functorOK allowFunctions (_, rep_tc) + | null tc_tvs + = Just (ptext (sLit "Data type") <+> quotes (ppr rep_tc) + <+> ptext (sLit "must have some type parameters")) + + | not (null bad_stupid_theta) + = Just (ptext (sLit "Data type") <+> quotes (ppr rep_tc) + <+> ptext (sLit "must not have a class context") <+> pprTheta bad_stupid_theta) + | otherwise = msum (map check_con data_cons) -- msum picks the first 'Just', if any where + tc_tvs = tyConTyVars rep_tc + Just (_, last_tv) = snocView tc_tvs + bad_stupid_theta = filter is_bad (tyConStupidTheta rep_tc) + is_bad pred = last_tv `elemVarSet` tyVarsOfPred pred + data_cons = tyConDataCons rep_tc check_con con = msum (check_vanilla con : foldDataConArgs (ft_check con) con) @@ -949,14 +1061,14 @@ cond_functorOK allowFunctions (dflags, rep_tc) , ft_bad_app = Just (badCon con wrong_arg) , ft_forall = \_ x -> x } - existential = ptext (sLit "has existential arguments") - covariant = ptext (sLit "uses the type variable in a function argument") - functions = ptext (sLit "contains function types") - wrong_arg = ptext (sLit "uses the type variable in an argument other than the last") + existential = ptext (sLit "must not have existential arguments") + covariant = ptext (sLit "must not use the type variable in a function argument") + functions = ptext (sLit "must not contain function types") + wrong_arg = ptext (sLit "must not use the type variable in an argument other than the last") -checkFlag :: DynFlag -> Condition +checkFlag :: ExtensionFlag -> Condition checkFlag flag (dflags, _) - | dopt flag dflags = Nothing + | xopt flag dflags = Nothing | otherwise = Just why where why = ptext (sLit "You need -X") <> text flag_str @@ -966,13 +1078,25 @@ checkFlag flag (dflags, _) other -> pprPanic "checkFlag" (ppr other) std_class_via_iso :: Class -> Bool -std_class_via_iso clas -- These standard classes can be derived for a newtype - -- using the isomorphism trick *even if no -fglasgow-exts* +-- These standard classes can be derived for a newtype +-- using the isomorphism trick *even if no -XGeneralizedNewtypeDeriving +-- because giving so gives the same results as generating the boilerplate +std_class_via_iso clas = classKey clas `elem` [eqClassKey, ordClassKey, ixClassKey, boundedClassKey] -- Not Read/Show because they respect the type -- Not Enum, because newtypes are never in Enum +non_iso_class :: Class -> Bool +-- *Never* derive Read, Show, Typeable, Data, Generic by isomorphism, +-- even with -XGeneralizedNewtypeDeriving +non_iso_class cls + = classKey cls `elem` ([ readClassKey, showClassKey, dataClassKey + , genClassKey] ++ typeableClassKeys) + +typeableClassKeys :: [Unique] +typeableClassKeys = map getUnique typeableClassNames + new_dfun_name :: Class -> TyCon -> TcM Name new_dfun_name clas tycon -- Just a simple wrapper = do { loc <- getSrcSpanM -- The location of the instance decl, not of the tycon @@ -1016,7 +1140,7 @@ a context for the Data instances: %************************************************************************ \begin{code} -mkNewTypeEqn :: InstOrigin -> DynFlags -> [Var] -> Class +mkNewTypeEqn :: CtOrigin -> DynFlags -> [Var] -> Class -> [Type] -> TyCon -> [Type] -> TyCon -> [Type] -> DerivContext -> TcRn EarlyDerivSpec @@ -1024,7 +1148,7 @@ mkNewTypeEqn orig dflags tvs cls cls_tys tycon tc_args rep_tycon rep_tc_args mtheta -- Want: instance (...) => cls (cls_tys ++ [tycon tc_args]) where ... | can_derive_via_isomorphism && (newtype_deriving || std_class_via_iso cls) - = do { traceTc (text "newtype deriving:" <+> ppr tycon <+> ppr rep_tys) + = do { traceTc "newtype deriving:" (ppr tycon <+> ppr rep_tys <+> ppr all_preds) ; dfun_name <- new_dfun_name cls tycon ; loc <- getSrcSpanM ; let spec = DS { ds_loc = loc, ds_orig = orig @@ -1038,18 +1162,21 @@ mkNewTypeEqn orig dflags tvs | otherwise = case checkSideConditions dflags mtheta cls cls_tys rep_tycon of - CanDerive -> go_for_it -- Use the standard H98 method - DerivableClassError msg -> bale_out msg -- Error with standard class + CanDerive -> go_for_it -- Use the standard H98 method + DerivableClassError msg -- Error with standard class + | can_derive_via_isomorphism -> bale_out (msg $$ suggest_nd) + | otherwise -> bale_out msg NonDerivableClass -- Must use newtype deriving - | newtype_deriving -> bale_out cant_derive_err -- Too hard, even with newtype deriving - | otherwise -> bale_out non_std_err -- Try newtype deriving! + | newtype_deriving -> bale_out cant_derive_err -- Too hard, even with newtype deriving + | can_derive_via_isomorphism -> bale_out (non_std $$ suggest_nd) -- Try newtype deriving! + | otherwise -> bale_out non_std where - newtype_deriving = dopt Opt_GeneralizedNewtypeDeriving dflags + newtype_deriving = xopt Opt_GeneralizedNewtypeDeriving dflags go_for_it = mk_data_eqn orig tvs cls tycon tc_args rep_tycon rep_tc_args mtheta bale_out msg = failWithTc (derivingThingErr newtype_deriving cls cls_tys inst_ty msg) - non_std_err = nonStdErr cls $$ - ptext (sLit "Try -XGeneralizedNewtypeDeriving for GHC's newtype-deriving extension") + non_std = nonStdErr cls + suggest_nd = ptext (sLit "Try -XGeneralizedNewtypeDeriving for GHC's newtype-deriving extension") -- Here is the plan for newtype derivings. We see -- newtype T a1...an = MkT (t ak+1...an) deriving (.., C s1 .. sm, ...) @@ -1133,10 +1260,6 @@ mkNewTypeEqn orig dflags tvs && ats_ok -- && not (isRecursiveTyCon tycon) -- Note [Recursive newtypes] - -- Never derive Read,Show,Typeable,Data by isomorphism - non_iso_class cls = className cls `elem` ([readClassName, showClassName, dataClassName] ++ - typeableClassNames) - arity_ok = length cls_tys + 1 == classArity cls -- Well kinded; eg not: newtype T ... deriving( ST ) -- because ST needs *2* type params @@ -1206,7 +1329,7 @@ inferInstanceContexts :: OverlapFlag -> [DerivSpec] -> TcM [DerivSpec] inferInstanceContexts _ [] = return [] inferInstanceContexts oflag infer_specs - = do { traceTc (text "inferInstanceContexts" <+> vcat (map pprDerivSpec infer_specs)) + = do { traceTc "inferInstanceContexts" $ vcat (map pprDerivSpec infer_specs) ; iterate_deriv 1 initial_solutions } where ------------------------------------------------------------------ @@ -1248,25 +1371,33 @@ inferInstanceContexts oflag infer_specs gen_soln (DS { ds_loc = loc, ds_orig = orig, ds_tvs = tyvars , ds_cls = clas, ds_tys = inst_tys, ds_theta = deriv_rhs }) = setSrcSpan loc $ - addErrCtxt (derivInstCtxt clas inst_tys) $ - do { theta <- tcSimplifyDeriv orig tyvars deriv_rhs - -- checkValidInstance tyvars theta clas inst_tys - -- Not necessary; see Note [Exotic derived instance contexts] - -- in TcSimplify - - -- Check for a bizarre corner case, when the derived instance decl should + addErrCtxt (derivInstCtxt the_pred) $ + do { -- Check for a bizarre corner case, when the derived instance decl should -- have form instance C a b => D (T a) where ... -- Note that 'b' isn't a parameter of T. This gives rise to all sorts -- of problems; in particular, it's hard to compare solutions for - -- equality when finding the fixpoint. So I just rule it out for now. + -- equality when finding the fixpoint. Moreover, simplifyDeriv + -- has an assert failure because it finds a TyVar when it expects + -- only TcTyVars. So I just rule it out for now. I'm not + -- even sure how it can arise. + ; let tv_set = mkVarSet tyvars - weird_preds = [pred | pred <- theta, not (tyVarsOfPred pred `subVarSet` tv_set)] + weird_preds = [pred | pred <- deriv_rhs + , not (tyVarsOfPred pred `subVarSet` tv_set)] ; mapM_ (addErrTc . badDerivedPred) weird_preds + ; theta <- simplifyDeriv orig the_pred tyvars deriv_rhs + -- checkValidInstance tyvars theta clas inst_tys + -- Not necessary; see Note [Exotic derived instance contexts] + -- in TcSimplify + + ; traceTc "TcDeriv" (ppr deriv_rhs $$ ppr theta) -- Claim: the result instance declaration is guaranteed valid -- Hence no need to call: -- checkValidInstance tyvars theta clas inst_tys ; return (sortLe (<=) theta) } -- Canonicalise before returning the solution + where + the_pred = mkClassPred clas inst_tys ------------------------------------------------------------------ mkInstance :: OverlapFlag -> ThetaType -> DerivSpec -> Instance @@ -1362,33 +1493,33 @@ the renamer. What a great hack! genInst :: Bool -- True <=> standalone deriving -> OverlapFlag -> DerivSpec -> TcM (InstInfo RdrName, DerivAuxBinds) -genInst standalone_deriv oflag spec - | ds_newtype spec - = return (InstInfo { iSpec = mkInstance oflag (ds_theta spec) spec - , iBinds = NewTypeDerived co }, []) +genInst standalone_deriv oflag + spec@(DS { ds_tc = rep_tycon, ds_tc_args = rep_tc_args + , ds_theta = theta, ds_newtype = is_newtype + , ds_name = name, ds_cls = clas }) + | is_newtype + = return (InstInfo { iSpec = inst_spec + , iBinds = NewTypeDerived co rep_tycon }, []) | otherwise - = do { let loc = getSrcSpan (ds_name spec) - inst = mkInstance oflag (ds_theta spec) spec - clas = ds_cls spec - - -- In case of a family instance, we need to use the representation - -- tycon (after all, it has the data constructors) - ; fix_env <- getFixityEnv - ; let (meth_binds, aux_binds) = genDerivBinds loc fix_env clas rep_tycon - binds = VanillaInst meth_binds [] standalone_deriv - ; return (InstInfo { iSpec = inst, iBinds = binds }, aux_binds) - } + = do { fix_env <- getFixityEnv + ; let loc = getSrcSpan name + (meth_binds, aux_binds) = genDerivBinds loc fix_env clas rep_tycon + -- In case of a family instance, we need to use the representation + -- tycon (after all, it has the data constructors) + + ; return (InstInfo { iSpec = inst_spec + , iBinds = VanillaInst meth_binds [] standalone_deriv } + , aux_binds) } where - rep_tycon = ds_tc spec - rep_tc_args = ds_tc_args spec + inst_spec = mkInstance oflag theta spec co1 = case tyConFamilyCoercion_maybe rep_tycon of - Nothing -> IdCo - Just co_con -> ACo (mkTyConApp co_con rep_tc_args) - co2 = case newTyConCo_maybe rep_tycon of - Nothing -> IdCo -- The newtype is transparent; no need for a cast - Just co_con -> ACo (mkTyConApp co_con rep_tc_args) - co = co1 `mkTransCoI` co2 + Just co_con -> mkAxInstCo co_con rep_tc_args + Nothing -> id_co + -- Not a family => rep_tycon = main tycon + co2 = mkAxInstCo (newTyConCo rep_tycon) rep_tc_args + co = co1 `mkTransCo` co2 + id_co = mkReflCo (mkTyConApp rep_tycon rep_tc_args) -- Example: newtype instance N [a] = N1 (Tree a) -- deriving instance Eq b => Eq (N [(b,b)]) @@ -1409,20 +1540,159 @@ genDerivBinds loc fix_env clas tycon Nothing -> pprPanic "genDerivBinds: bad derived class" (ppr clas) where gen_list :: [(Unique, SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds))] - gen_list = [(eqClassKey, gen_Eq_binds) - ,(ordClassKey, gen_Ord_binds) - ,(enumClassKey, gen_Enum_binds) - ,(boundedClassKey, gen_Bounded_binds) - ,(ixClassKey, gen_Ix_binds) - ,(showClassKey, gen_Show_binds fix_env) - ,(readClassKey, gen_Read_binds fix_env) - ,(dataClassKey, gen_Data_binds) - ,(functorClassKey, gen_Functor_binds) - ,(foldableClassKey, gen_Foldable_binds) - ,(traversableClassKey, gen_Traversable_binds) + gen_list = [(eqClassKey, gen_Eq_binds) + ,(ordClassKey, gen_Ord_binds) + ,(enumClassKey, gen_Enum_binds) + ,(boundedClassKey, gen_Bounded_binds) + ,(ixClassKey, gen_Ix_binds) + ,(showClassKey, gen_Show_binds fix_env) + ,(readClassKey, gen_Read_binds fix_env) + ,(dataClassKey, gen_Data_binds) + ,(functorClassKey, gen_Functor_binds) + ,(foldableClassKey, gen_Foldable_binds) + ,(traversableClassKey, gen_Traversable_binds) + ,(genClassKey, genGenericBinds) ] \end{code} +%************************************************************************ +%* * +\subsection[TcDeriv-generic-binds]{Bindings for the new generic deriving mechanism} +%* * +%************************************************************************ + +For the generic representation we need to generate: +\begin{itemize} +\item A Generic instance +\item A Rep type instance +\item Many auxiliary datatypes and instances for them (for the meta-information) +\end{itemize} + +@genGenericBinds@ does (1) +@genGenericRepExtras@ does (2) and (3) +@genGenericAll@ does all of them + +\begin{code} +genGenericBinds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds) +genGenericBinds _ tc = (mkBindsRep tc, [ {- No DerivAuxBinds -} ]) + +genGenericRepExtras :: TyCon -> TcM (MetaTyCons, TyCon) +genGenericRepExtras tc = + do uniqS <- newUniqueSupply + let + -- Uniques for everyone + (uniqD:uniqs) = uniqsFromSupply uniqS + (uniqsC,us) = splitAt (length tc_cons) uniqs + uniqsS :: [[Unique]] -- Unique supply for the S datatypes + uniqsS = mkUniqsS tc_arits us + mkUniqsS [] _ = [] + mkUniqsS (n:t) us = case splitAt n us of + (us1,us2) -> us1 : mkUniqsS t us2 + + tc_name = tyConName tc + tc_cons = tyConDataCons tc + tc_arits = map dataConSourceArity tc_cons + + tc_occ = nameOccName tc_name + d_occ = mkGenD tc_occ + c_occ m = mkGenC tc_occ m + s_occ m n = mkGenS tc_occ m n + mod_name = nameModule (tyConName tc) + d_name = mkExternalName uniqD mod_name d_occ wiredInSrcSpan + c_names = [ mkExternalName u mod_name (c_occ m) wiredInSrcSpan + | (u,m) <- zip uniqsC [0..] ] + s_names = [ [ mkExternalName u mod_name (s_occ m n) wiredInSrcSpan + | (u,n) <- zip us [0..] ] | (us,m) <- zip uniqsS [0..] ] + + mkTyCon name = ASSERT( isExternalName name ) + buildAlgTyCon name [] [] mkAbstractTyConRhs + NonRecursive False NoParentTyCon Nothing + + metaDTyCon <- mkTyCon d_name + metaCTyCons <- sequence [ mkTyCon c_name | c_name <- c_names ] + metaSTyCons <- mapM sequence + [ [ mkTyCon s_name + | s_name <- s_namesC ] | s_namesC <- s_names ] + + let metaDts = MetaTyCons metaDTyCon metaCTyCons metaSTyCons + + rep0_tycon <- tc_mkRepTyCon tc metaDts + + -- pprTrace "rep0" (ppr rep0_tycon) $ + return (metaDts, rep0_tycon) +{- +genGenericAll :: TyCon + -> TcM ((InstInfo RdrName, DerivAuxBinds), MetaTyCons, TyCon) +genGenericAll tc = + do (metaDts, rep0_tycon) <- genGenericRepExtras tc + clas <- tcLookupClass genClassName + dfun_name <- new_dfun_name clas tc + let + mkInstRep = (InstInfo { iSpec = inst, iBinds = binds } + , [ {- No DerivAuxBinds -} ]) + inst = mkLocalInstance dfun NoOverlap + binds = VanillaInst (mkBindsRep tc) [] False + + tvs = tyConTyVars tc + tc_ty = mkTyConApp tc (mkTyVarTys tvs) + + dfun = mkDictFunId dfun_name (tyConTyVars tc) [] clas [tc_ty] + return (mkInstRep, metaDts, rep0_tycon) +-} +genDtMeta :: (TyCon, MetaTyCons) -> TcM [(InstInfo RdrName, DerivAuxBinds)] +genDtMeta (tc,metaDts) = + do dClas <- tcLookupClass datatypeClassName + d_dfun_name <- new_dfun_name dClas tc + cClas <- tcLookupClass constructorClassName + c_dfun_names <- sequence [ new_dfun_name cClas tc | _ <- metaC metaDts ] + sClas <- tcLookupClass selectorClassName + s_dfun_names <- sequence (map sequence [ [ new_dfun_name sClas tc + | _ <- x ] + | x <- metaS metaDts ]) + fix_env <- getFixityEnv + + let + (dBinds,cBinds,sBinds) = mkBindsMetaD fix_env tc + + -- Datatype + d_metaTycon = metaD metaDts + d_inst = mkLocalInstance d_dfun NoOverlap + d_binds = VanillaInst dBinds [] False + d_dfun = mkDictFunId d_dfun_name (tyConTyVars tc) [] dClas + [ mkTyConTy d_metaTycon ] + d_mkInst = (InstInfo { iSpec = d_inst, iBinds = d_binds }, []) + + -- Constructor + c_metaTycons = metaC metaDts + c_insts = [ mkLocalInstance (c_dfun c ds) NoOverlap + | (c, ds) <- myZip1 c_metaTycons c_dfun_names ] + c_binds = [ VanillaInst c [] False | c <- cBinds ] + c_dfun c dfun_name = mkDictFunId dfun_name (tyConTyVars tc) [] cClas + [ mkTyConTy c ] + c_mkInst = [ (InstInfo { iSpec = is, iBinds = bs }, []) + | (is,bs) <- myZip1 c_insts c_binds ] + + -- Selector + s_metaTycons = metaS metaDts + s_insts = map (map (\(s,ds) -> mkLocalInstance (s_dfun s ds) NoOverlap)) + (myZip2 s_metaTycons s_dfun_names) + s_binds = [ [ VanillaInst s [] False | s <- ss ] | ss <- sBinds ] + s_dfun s dfun_name = mkDictFunId dfun_name (tyConTyVars tc) [] sClas + [ mkTyConTy s ] + s_mkInst = map (map (\(is,bs) -> (InstInfo {iSpec=is, iBinds=bs}, []))) + (myZip2 s_insts s_binds) + + myZip1 :: [a] -> [b] -> [(a,b)] + myZip1 l1 l2 = ASSERT (length l1 == length l2) zip l1 l2 + + myZip2 :: [[a]] -> [[b]] -> [[(a,b)]] + myZip2 l1 l2 = + ASSERT (and (zipWith (>=) (map length l1) (map length l2))) + [ zip x1 x2 | (x1,x2) <- zip l1 l2 ] + + return (d_mkInst : c_mkInst ++ concat s_mkInst) +\end{code} + %************************************************************************ %* * @@ -1469,9 +1739,9 @@ standaloneCtxt :: LHsType Name -> SDoc standaloneCtxt ty = hang (ptext (sLit "In the stand-alone deriving instance for")) 2 (quotes (ppr ty)) -derivInstCtxt :: Class -> [Type] -> Message -derivInstCtxt clas inst_tys - = ptext (sLit "When deriving the instance for") <+> parens (pprClassPred clas inst_tys) +derivInstCtxt :: PredType -> Message +derivInstCtxt pred + = ptext (sLit "When deriving the instance for") <+> parens (ppr pred) badDerivedPred :: PredType -> Message badDerivedPred pred