X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=a5ce2eaf62f48841f2d19bda10953dccb61c6214;hp=3814f239b68f23086018dc3df42e3cf6e8b521a4;hb=ce2ea8274f72199ac32d5219fcadb0aaeb968707;hpb=aaed05e88978688e37dc74177dd4eba51a6ab4d0 diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index 3814f23..a5ce2ea 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -7,8 +7,8 @@ Typechecking class declarations \begin{code} module TcClassDcl ( tcClassSigs, tcClassDecl2, - findMethodBind, tcInstanceMethodBody, - mkGenericDefMethBind, getGenericInstances, mkDefMethRdrName, + findMethodBind, instantiateMethod, tcInstanceMethodBody, + mkGenericDefMethBind, getGenericInstances, tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn ) where @@ -16,44 +16,38 @@ module TcClassDcl ( tcClassSigs, tcClassDecl2, import HsSyn import RnHsSyn -import RnExpr -import RnEnv import Inst import InstEnv import TcEnv import TcBinds -import TcSimplify +import TcUnify import TcHsType import TcMType import TcType import TcRnMonad +import BuildTyCl( TcMethInfo ) import Generics import Class import TyCon -import Type import MkId import Id import Name import Var -import NameEnv import NameSet -import OccName -import RdrName import Outputable import PrelNames import DynFlags import ErrUtils import Util -import Unique import ListSetOps import SrcLoc import Maybes -import List import BasicTypes import Bag import FastString import Control.Monad +import Data.List \end{code} @@ -100,58 +94,36 @@ Death to "ExpandingDicts". tcClassSigs :: Name -- Name of the class -> [LSig Name] -> LHsBinds Name - -> TcM [TcMethInfo] + -> TcM [TcMethInfo] -- One for each method -type TcMethInfo = (Name, DefMeth, Type) -- A temporary intermediate, to communicate - -- between tcClassSigs and buildClass tcClassSigs clas sigs def_methods - = do { dm_env <- checkDefaultBinds clas op_names def_methods - ; mapM (tcClassSig dm_env) op_sigs } - where - op_sigs = [sig | sig@(L _ (TypeSig _ _)) <- sigs] - op_names = [n | (L _ (TypeSig (L _ n) _)) <- op_sigs] - - -checkDefaultBinds :: Name -> [Name] -> LHsBinds Name -> TcM (NameEnv Bool) - -- Check default bindings - -- a) must be for a class op for this class - -- b) must be all generic or all non-generic - -- and return a mapping from class-op to Bool - -- where True <=> it's a generic default method -checkDefaultBinds clas ops binds - = do dm_infos <- mapM (addLocM (checkDefaultBind clas ops)) (bagToList binds) - return (mkNameEnv dm_infos) - -checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, Bool) -checkDefaultBind clas ops (FunBind {fun_id = L _ op, fun_matches = MatchGroup matches _ }) - = do { -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) - - -- Check that all the defns ar generic, or none are - ; checkTc (all_generic || none_generic) (mixedGenericErr op) - - ; return (op, all_generic) - } + = do { -- Check that all def_methods are in the class + ; op_info <- mapM (addLocM tc_sig) [sig | sig@(L _ (TypeSig _ _)) <- sigs] + ; let op_names = [ n | (n,_,_) <- op_info ] + + ; sequence_ [ failWithTc (badMethodErr clas n) + | n <- dm_bind_names, not (n `elem` op_names) ] + -- Value binding for non class-method (ie no TypeSig) + + ; sequence_ [ failWithTc (badGenericMethod clas n) + | n <- genop_names, not (n `elem` dm_bind_names) ] + -- Generic signature without value binding + + ; return op_info } where - n_generic = count (isJust . maybeGenericMatch) matches - none_generic = n_generic == 0 - all_generic = matches `lengthIs` n_generic -checkDefaultBind _ _ b = pprPanic "checkDefaultBind" (ppr b) - - -tcClassSig :: NameEnv Bool -- Info about default methods; - -> LSig Name - -> TcM TcMethInfo - -tcClassSig dm_env (L loc (TypeSig (L _ op_name) op_hs_ty)) - = setSrcSpan loc $ do - { op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope - ; let dm = case lookupNameEnv dm_env op_name of - Nothing -> NoDefMeth - Just False -> DefMeth - Just True -> GenDefMeth - ; return (op_name, dm, op_ty) } -tcClassSig _ s = pprPanic "tcClassSig" (ppr s) + dm_bind_names :: [Name] -- These ones have a value binding in the class decl + dm_bind_names = [op | L _ (FunBind {fun_id = L _ op}) <- bagToList def_methods] + + genop_names :: [Name] -- These ones have a generic signature + genop_names = [n | L _ (GenericSig (L _ n) _) <- sigs] + + tc_sig (TypeSig (L _ op_name) op_hs_ty) + = do { op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope + ; let dm | op_name `elem` genop_names = GenericDM + | op_name `elem` dm_bind_names = VanillaDM + | otherwise = NoDM + ; return (op_name, dm, op_ty) } + tc_sig sig = pprPanic "tc_cls_sig" (ppr sig) \end{code} @@ -163,12 +135,12 @@ tcClassSig _ s = pprPanic "tcClassSig" (ppr s) \begin{code} tcClassDecl2 :: LTyClDecl Name -- The class declaration - -> TcM (LHsBinds Id, [Id]) + -> TcM (LHsBinds Id) tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, tcdMeths = default_binds})) - = recoverM (return (emptyLHsBinds, [])) $ - setSrcSpan loc $ + = recoverM (return emptyLHsBinds) $ + setSrcSpan loc $ do { clas <- tcLookupLocatedClass class_name -- We make a separate binding for each default method. @@ -181,133 +153,152 @@ tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, -- default methods. Better to make separate AbsBinds for each ; let (tyvars, _, _, op_items) = classBigSig clas - rigid_info = ClsSkol clas - prag_fn = mkPragFun sigs - sig_fn = mkTcSigFun sigs - clas_tyvars = tcSkolSigTyVars rigid_info tyvars + prag_fn = mkPragFun sigs default_binds + sig_fn = mkSigFun sigs + clas_tyvars = tcSuperSkolTyVars tyvars pred = mkClassPred clas (mkTyVarTys clas_tyvars) - ; inst_loc <- getInstLoc (SigOrigin rigid_info) - ; this_dict <- newDictBndr inst_loc pred + ; this_dict <- newEvVar pred - ; let tc_dm = tcDefMeth rigid_info clas clas_tyvars [pred] - this_dict default_binds + ; traceTc "TIM2" (ppr sigs) + ; let tc_dm = tcDefMeth clas clas_tyvars + this_dict default_binds sigs sig_fn prag_fn - -- tc_dm is called only for a sel_id - -- that has a binding in default_binds - dm_sel_ids = [sel_id | (sel_id, DefMeth) <- op_items] - -- Generate code for polymorphic default methods only (hence DefMeth) - -- (Generic default methods have turned into instance decls by now.) - -- This is incompatible with Hugs, which expects a polymorphic - -- default method for every class op, regardless of whether or not - -- the programmer supplied an explicit default decl for the class. - -- (If necessary we can fix that, but we don't have a convenient Id to hand.) + ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ + mapM tc_dm op_items - ; (defm_binds, dm_ids) <- tcExtendTyVarEnv clas_tyvars $ - mapAndUnzipM tc_dm dm_sel_ids - - ; return (unionManyBags defm_binds, dm_ids) } + ; return (unionManyBags dm_binds) } tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) -tcDefMeth :: SkolemInfo -> Class -> [TyVar] -> ThetaType -> Inst -> LHsBinds Name - -> TcSigFun -> TcPragFun -> Id - -> TcM (LHsBinds Id, Id) -tcDefMeth rigid_info clas tyvars theta this_dict binds_in sig_fn prag_fn sel_id - = do { let sel_name = idName sel_id - ; local_dm_name <- newLocalName sel_name - ; let meth_bind = findMethodBind sel_name local_dm_name binds_in - `orElse` pprPanic "tcDefMeth" (ppr sel_id) - -- We only call tcDefMeth on selectors for which - -- there is a binding in binds_in - - meth_sig_fn _ = sig_fn sel_name - meth_prag_fn _ = prag_fn sel_name - - ; (top_dm_id, bind) <- tcInstanceMethodBody rigid_info - clas tyvars [this_dict] theta (mkTyVarTys tyvars) - Nothing sel_id - local_dm_name - meth_sig_fn meth_prag_fn - meth_bind - - ; return (bind, top_dm_id) } - -mkDefMethRdrName :: Name -> RdrName -mkDefMethRdrName sel_name = mkDerivedRdrName sel_name mkDefaultMethodOcc +tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name -> [LSig Name] + -> SigFun -> PragFun -> ClassOpItem + -> TcM (LHsBinds TcId) +-- Generate code for polymorphic default methods only (hence DefMeth) +-- (Generic default methods have turned into instance decls by now.) +-- This is incompatible with Hugs, which expects a polymorphic +-- default method for every class op, regardless of whether or not +-- the programmer supplied an explicit default decl for the class. +-- (If necessary we can fix that, but we don't have a convenient Id to hand.) +tcDefMeth _ tyvars _ binds_in sigs sig_fn prag_fn (sel_id, dm_info) + | NoDefMeth <- dm_info = return emptyBag + | otherwise + = do { (dm_id, tvs, sig_loc) <- tc_dm_id dm_info + ; let L loc meth_bind = findMethodBind sel_name binds_in + `orElse` pprPanic "tcDefMeth" (ppr sel_id) + dm_bind = L loc (meth_bind { fun_id = L loc (idName dm_id) }) + -- Substitute the meth_name for the binder + -- NB: the binding is always a FunBind + + dm_sig_fn _ = Just (clas_tv_names ++ tvs, sig_loc) + dm_prag_fn _ = prag_fn sel_name + + ; (binds,_) <- tcExtendIdEnv [dm_id] $ + tcPolyBinds TopLevel dm_sig_fn dm_prag_fn + NonRecursive NonRecursive + [dm_bind] + ; return binds } + where + sel_name = idName sel_id + clas_tv_names = map getName tyvars + + -- Find the 'generic op :: ty' signature among the sigs + -- If dm_info is GenDefMeth, the corresponding signature + -- should jolly well exist! Hence the panic + genop_lhs_ty = case [lty | L _ (GenericSig (L _ n) lty) <- sigs + , n == sel_name ] of + [lty] -> lty + _ -> pprPanic "tcDefMeth" (ppr sel_name $$ ppr sigs) + + tc_dm_id :: DefMeth -> TcM (Id, [Name], SrcSpan) + -- Make a default-method Id of the appropriate type + -- That may entail getting the generic-default signature + -- from the type signatures. + -- Also return the in-scope tyvars for the default method, and their binding site + tc_dm_id NoDefMeth = panic "tc_dm_id" + tc_dm_id (DefMeth dm_name) + | Just (tvs, loc) <- sig_fn sel_name + = return (mkDefaultMethodId sel_id dm_name, tvs, loc) + | otherwise + = pprPanic "No sig for" (ppr sel_name) + tc_dm_id (GenDefMeth dm_name) + = setSrcSpan loc $ + do { tau <- tcHsKindedType genop_lhs_ty + ; checkValidType (FunSigCtxt sel_name) tau + ; return ( mkExportedLocalId dm_name (mkForAllTys tyvars tau) + , hsExplicitTvs genop_lhs_ty, loc ) } + where + loc = getLoc genop_lhs_ty + +--------------- +tcInstanceMethodBody :: SkolemInfo -> [TcTyVar] -> [EvVar] + -> Id -> Id + -> SigFun -> TcSpecPrags -> LHsBind Name + -> TcM (LHsBind Id) +tcInstanceMethodBody skol_info tyvars dfun_ev_vars + meth_id local_meth_id + meth_sig_fn specs + (L loc bind) + = do { -- Typecheck the binding, first extending the envt + -- so that when tcInstSig looks up the local_meth_id to find + -- its signature, we'll find it in the environment + let lm_bind = L loc (bind { fun_id = L loc (idName local_meth_id) }) + -- Substitute the local_meth_name for the binder + -- NB: the binding is always a FunBind + ; traceTc "TIM" (ppr local_meth_id $$ ppr (meth_sig_fn (idName local_meth_id))) + ; (ev_binds, (tc_bind, _)) + <- checkConstraints skol_info tyvars dfun_ev_vars $ + tcExtendIdEnv [local_meth_id] $ + tcPolyBinds TopLevel meth_sig_fn no_prag_fn + NonRecursive NonRecursive + [lm_bind] + + ; let full_bind = AbsBinds { abs_tvs = tyvars, abs_ev_vars = dfun_ev_vars + , abs_exports = [(tyvars, meth_id, local_meth_id, specs)] + , abs_ev_binds = ev_binds + , abs_binds = tc_bind } + + ; return (L loc full_bind) } + where + no_prag_fn _ = [] -- No pragmas for local_meth_id; + -- they are all for meth_id +\end{code} + +\begin{code} +instantiateMethod :: Class -> Id -> [TcType] -> TcType +-- Take a class operation, say +-- op :: forall ab. C a => forall c. Ix c => (b,c) -> a +-- Instantiate it at [ty1,ty2] +-- Return the "local method type": +-- forall c. Ix x => (ty2,c) -> ty1 +instantiateMethod clas sel_id inst_tys + = ASSERT( ok_first_pred ) local_meth_ty + where + (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id) + rho_ty = ASSERT( length sel_tyvars == length inst_tys ) + substTyWith sel_tyvars inst_tys sel_rho + + (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty + `orElse` pprPanic "tcInstanceMethod" (ppr sel_id) + + ok_first_pred = case getClassPredTys_maybe first_pred of + Just (clas1, _tys) -> clas == clas1 + Nothing -> False + -- The first predicate should be of form (C a b) + -- where C is the class in question + --------------------------- --- The renamer just puts the selector ID as the binder in the method binding --- but we must use the method name; so we substitute it here. Crude but simple. -findMethodBind :: Name -> Name -- Selector and method name +findMethodBind :: Name -- Selector name -> LHsBinds Name -- A group of bindings - -> Maybe (LHsBind Name) -- The binding, with meth_name replacing sel_name -findMethodBind sel_name meth_name binds + -> Maybe (LHsBind Name) -- The binding +findMethodBind sel_name binds = foldlBag mplus Nothing (mapBag f binds) where - f (L loc1 bind@(FunBind { fun_id = L loc2 op_name })) - | op_name == sel_name - = Just (L loc1 (bind { fun_id = L loc2 meth_name })) - f _other = Nothing - ---------------- -tcInstanceMethodBody :: SkolemInfo -> Class -> [TcTyVar] -> [Inst] - -> TcThetaType -> [TcType] - -> Maybe (Inst, LHsBind Id) -> Id - -> Name -- The local method name - -> TcSigFun -> TcPragFun -> LHsBind Name - -> TcM (Id, LHsBinds Id) -tcInstanceMethodBody rigid_info clas tyvars dfun_dicts theta inst_tys - mb_this_bind sel_id local_meth_name - sig_fn prag_fn bind@(L loc _) - = do { let (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id) - rho_ty = ASSERT( length sel_tyvars == length inst_tys ) - substTyWith sel_tyvars inst_tys sel_rho - - (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty - `orElse` pprPanic "tcInstanceMethod" (ppr sel_id) - - local_meth_id = mkLocalId local_meth_name local_meth_ty - meth_ty = mkSigmaTy tyvars theta local_meth_ty - sel_name = idName sel_id - - -- The first predicate should be of form (C a b) - -- where C is the class in question - ; MASSERT( case getClassPredTys_maybe first_pred of - { Just (clas1, _tys) -> clas == clas1 ; Nothing -> False } ) - - -- Typecheck the binding, first extending the envt - -- so that when tcInstSig looks up the local_meth_id to find - -- its signature, we'll find it in the environment - ; ((tc_bind, _), lie) <- getLIE $ - tcExtendIdEnv [local_meth_id] $ - tcPolyBinds TopLevel sig_fn prag_fn - NonRecursive NonRecursive - (unitBag bind) - - ; meth_id <- case rigid_info of - ClsSkol _ -> do { dm_name <- lookupTopBndrRn (mkDefMethRdrName sel_name) - ; return (mkDefaultMethodId dm_name meth_ty) } - _other -> do { meth_name <- newLocalName sel_name - ; return (mkLocalId meth_name meth_ty) } - - ; let (avails, this_dict_bind) - = case mb_this_bind of - Nothing -> (dfun_dicts, emptyBag) - Just (this, bind) -> (this : dfun_dicts, unitBag bind) - - ; inst_loc <- getInstLoc (SigOrigin rigid_info) - ; lie_binds <- tcSimplifyCheck inst_loc tyvars avails lie - - ; let full_bind = L loc $ - AbsBinds tyvars dfun_lam_vars - [(tyvars, meth_id, local_meth_id, [])] - (this_dict_bind `unionBags` lie_binds - `unionBags` tc_bind) - - dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities - - ; return (meth_id, unitBag full_bind) } + f bind@(L _ (FunBind { fun_id = L _ op_name })) + | op_name == sel_name + = Just bind + f _other = Nothing \end{code} Note [Polymorphic methods] @@ -366,43 +357,21 @@ gives rise to the instance declarations instance C 1 where op Unit = ... - \begin{code} mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind Name) -mkGenericDefMethBind clas inst_tys sel_id meth_name +mkGenericDefMethBind clas inst_tys sel_id dm_name = -- A generic default method - -- If the method is defined generically, we can only do the job if the - -- instance declaration is for a single-parameter type class with - -- a type constructor applied to type arguments in the instance decl - -- (checkTc, so False provokes the error) - do { checkTc (isJust maybe_tycon) - (badGenericInstance sel_id (notSimple inst_tys)) - ; checkTc (tyConHasGenerics tycon) - (badGenericInstance sel_id (notGeneric tycon)) - - ; dflags <- getDOpts + -- If the method is defined generically, we only have to call the + -- dm_name. + do { dflags <- getDOpts ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Filling in method body" (vcat [ppr clas <+> ppr inst_tys, nest 2 (ppr sel_id <+> equals <+> ppr rhs)])) - -- Rename it before returning it - ; (rn_rhs, _) <- rnLExpr rhs - ; return (noLoc $ mkFunBind (noLoc meth_name) [mkSimpleMatch [] rn_rhs]) } + ; return (noLoc $ mkFunBind (noLoc (idName sel_id)) + [mkSimpleMatch [] rhs]) } where - rhs = mkGenericRhs sel_id clas_tyvar tycon - - -- The tycon is only used in the generic case, and in that - -- case we require that the instance decl is for a single-parameter - -- type class with type variable arguments: - -- instance (...) => C (T a b) - clas_tyvar = ASSERT (not (null (classTyVars clas))) head (classTyVars clas) - Just tycon = maybe_tycon - maybe_tycon = case inst_tys of - [ty] -> case tcSplitTyConApp_maybe ty of - Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon - _ -> Nothing - _ -> Nothing - + rhs = nlHsVar dm_name --------------------------- getGenericInstances :: [LTyClDecl Name] -> TcM [InstInfo Name] @@ -415,9 +384,8 @@ getGenericInstances class_decls else do -- Otherwise print it out - { dflags <- getDOpts - ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances" - (vcat (map pprInstInfoDetails gen_inst_info))) + { dumpDerivingInfo $ hang (ptext (sLit "Generic instances")) + 2 (vcat (map pprInstInfoDetails gen_inst_info)) ; return gen_inst_info }} get_generics :: TyClDecl Name -> TcM [InstInfo Name] @@ -452,7 +420,7 @@ get_generics decl@(ClassDecl {tcdLName = class_name, tcdMeths = def_methods}) group `lengthExceeds` 1] get_uniq (tc,_) = getUnique tc - mapM (addErrTc . dupGenericInsts) bad_groups + mapM_ (addErrTc . dupGenericInsts) bad_groups -- Check that there is an InstInfo for each generic type constructor let @@ -516,7 +484,8 @@ mkGenericInstance clas (hs_ty, binds) = do -- and wrap them as forall'd tyvars, so that kind inference -- works in the standard way let - sig_tvs = map (noLoc.UserTyVar) (nameSetToList (extractHsTyVars (noLoc hs_ty))) + sig_tvs = userHsTyVarBndrs $ map noLoc $ nameSetToList $ + extractHsTyVars (noLoc hs_ty) hs_forall_ty = noLoc $ mkExplicitHsForAllTy sig_tvs (noLoc []) (noLoc hs_ty) -- Type-check the instance type, and check its form @@ -534,9 +503,9 @@ mkGenericInstance clas (hs_ty, binds) = do let inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars] dfun_id = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty] - ispec = mkLocalInstance dfun_id overlap_flag + ispec = mkLocalInstance dfun_id overlap_flag - return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] }) + return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] False }) \end{code} @@ -570,6 +539,11 @@ badMethodErr clas op = hsep [ptext (sLit "Class"), quotes (ppr clas), ptext (sLit "does not have a method"), quotes (ppr op)] +badGenericMethod :: Outputable a => a -> Name -> SDoc +badGenericMethod clas op + = hsep [ptext (sLit "Class"), quotes (ppr clas), + ptext (sLit "has a generic-default signature without a binding"), quotes (ppr op)] + badATErr :: Class -> Name -> SDoc badATErr clas at = hsep [ptext (sLit "Class"), quotes (ppr clas), @@ -579,26 +553,10 @@ omittedATWarn :: Name -> SDoc omittedATWarn at = ptext (sLit "No explicit AT declaration for") <+> quotes (ppr at) -badGenericInstance :: Var -> SDoc -> SDoc -badGenericInstance sel_id because - = sep [ptext (sLit "Can't derive generic code for") <+> quotes (ppr sel_id), - because] - -notSimple :: [Type] -> SDoc -notSimple inst_tys - = vcat [ptext (sLit "because the instance type(s)"), - nest 2 (ppr inst_tys), - ptext (sLit "is not a simple type of form (T a1 ... an)")] - -notGeneric :: TyCon -> SDoc -notGeneric tycon - = vcat [ptext (sLit "because the instance type constructor") <+> quotes (ppr tycon) <+> - ptext (sLit "was not compiled with -XGenerics")] - badGenericInstanceType :: LHsBinds Name -> SDoc badGenericInstanceType binds = vcat [ptext (sLit "Illegal type pattern in the generic bindings"), - nest 4 (ppr binds)] + nest 2 (ppr binds)] missingGenericInstances :: [Name] -> SDoc missingGenericInstances missing @@ -607,13 +565,9 @@ missingGenericInstances missing dupGenericInsts :: [(TyCon, InstInfo a)] -> SDoc dupGenericInsts tc_inst_infos = vcat [ptext (sLit "More than one type pattern for a single generic type constructor:"), - nest 4 (vcat (map ppr_inst_ty tc_inst_infos)), + nest 2 (vcat (map ppr_inst_ty tc_inst_infos)), ptext (sLit "All the type patterns for a generic type constructor must be identical") ] where ppr_inst_ty (_,inst) = ppr (simpleInstInfoTy inst) - -mixedGenericErr :: Name -> SDoc -mixedGenericErr op - = ptext (sLit "Can't mix generic and non-generic equations for class method") <+> quotes (ppr op) \end{code}