X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=e4dbf5c0c082281cbdcf2fcd860418a14d45f662;hb=fbff1b7b9c89f6369c4394a0b10fa7c06e011698;hp=8db89b9c07abffd1168f8a3aa43bfc1e390ab4ea;hpb=27310213397bb89555bb03585e057ba1b017e895;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index 8db89b9..e4dbf5c 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -16,11 +16,10 @@ module TcClassDcl ( tcClassSigs, tcClassDecl2, import HsSyn import RnHsSyn -import RnExpr import Inst import InstEnv -import TcPat( addInlinePrags ) import TcEnv +import TcPat( addInlinePrags ) import TcBinds import TcUnify import TcHsType @@ -35,7 +34,6 @@ import MkId import Id import Name import Var -import NameEnv import NameSet import Outputable import PrelNames @@ -97,48 +95,36 @@ Death to "ExpandingDicts". tcClassSigs :: Name -- Name of the class -> [LSig Name] -> LHsBinds Name - -> TcM [TcMethInfo] + -> TcM [TcMethInfo] -- One for each method tcClassSigs clas sigs def_methods - = do { dm_env <- mapM (addLocM (checkDefaultBind clas op_names)) - (bagToList def_methods) - ; mapM (tcClassSig (mkNameEnv dm_env)) op_sigs } - where - op_sigs = [sig | sig@(L _ (TypeSig _ _)) <- sigs] - op_names = [n | (L _ (TypeSig (L _ n) _)) <- op_sigs] - -checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, DefMethSpec) - -- Check default bindings - -- a) must be for a class op for this class - -- b) must be all generic or all non-generic -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 - ; case (none_generic, all_generic) of - (True, _) -> return (op, VanillaDM) - (_, True) -> return (op, GenericDM) - _ -> failWith (mixedGenericErr op) - } - where - n_generic = count (isJust . maybeGenericMatch) matches - none_generic = n_generic == 0 - all_generic = matches `lengthIs` n_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 ] -checkDefaultBind _ _ b = pprPanic "checkDefaultBind" (ppr b) + ; 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 -tcClassSig :: NameEnv DefMethSpec -- 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 = lookupNameEnv dm_env op_name `orElse` NoDM - ; return (op_name, dm, op_ty) } -tcClassSig _ s = pprPanic "tcClassSig" (ppr s) + ; return op_info } + where + 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} @@ -174,62 +160,88 @@ tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, pred = mkClassPred clas (mkTyVarTys clas_tyvars) ; this_dict <- newEvVar pred + ; traceTc "TIM2" (ppr sigs) ; let tc_dm = tcDefMeth clas clas_tyvars - this_dict default_binds + this_dict default_binds sigs sig_fn prag_fn ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ mapM tc_dm op_items - ; return (listToBag (catMaybes dm_binds)) } + ; return (unionManyBags dm_binds) } tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) -tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name +tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name -> [LSig Name] -> SigFun -> PragFun -> ClassOpItem - -> TcM (Maybe (LHsBind Id)) + -> 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 clas tyvars this_dict binds_in sig_fn prag_fn (sel_id, dm_info) +tcDefMeth clas tyvars this_dict binds_in sigs sig_fn prag_fn (sel_id, dm_info) = case dm_info of - NoDefMeth -> return Nothing - GenDefMeth -> return Nothing - DefMeth dm_name -> do - { let sel_name = idName sel_id - ; local_dm_name <- newLocalName sel_name - -- Base the local_dm_name on the selector name, because - -- type errors from tcInstanceMethodBody come from here - - -- See Note [Silly default-method bind] - -- (possibly out of date) - - ; let meth_bind = findMethodBind sel_name binds_in - `orElse` pprPanic "tcDefMeth" (ppr sel_id) - -- dm_info = DefMeth dm_name only if there is a binding in binds_in - - dm_sig_fn _ = sig_fn sel_name - dm_id = mkDefaultMethodId sel_id dm_name - local_dm_type = instantiateMethod clas sel_id (mkTyVarTys tyvars) - local_dm_id = mkLocalId local_dm_name local_dm_type - prags = prag_fn sel_name - - ; dm_id_w_inline <- addInlinePrags dm_id prags - ; spec_prags <- tcSpecPrags dm_id prags - - ; warnTc (not (null spec_prags)) - (ptext (sLit "Ignoring SPECIALISE pragmas on default method") - <+> quotes (ppr sel_name)) - - ; liftM Just $ - tcInstanceMethodBody (ClsSkol clas) - tyvars - [this_dict] - dm_id_w_inline local_dm_id - dm_sig_fn IsDefaultMethod meth_bind } + NoDefMeth -> do { mapM_ (addLocM (badDmPrag sel_id)) prags + ; return emptyBag } + DefMeth dm_name -> tc_dm dm_name (instantiateMethod clas sel_id (mkTyVarTys tyvars)) + GenDefMeth dm_name -> do { tau <- tc_genop_ty (findGenericSig sigs sel_name) + ; tc_dm dm_name tau } + -- In the case of a generic default, we have to get the type from the signature + -- Otherwise we can get it by instantiating the method selector + where + sel_name = idName sel_id + prags = prag_fn sel_name + dm_sig_fn _ = sig_fn sel_name + dm_bind = findMethodBind sel_name binds_in + `orElse` pprPanic "tcDefMeth" (ppr sel_id) + + -- Eg. class C a where + -- op :: forall b. Eq b => a -> [b] -> a + -- gen_op :: a -> a + -- generic gen_op :: D a => a -> a + -- The "local_dm_ty" is precisely the type in the above + -- type signatures, ie with no "forall a. C a =>" prefix + + tc_dm dm_name local_dm_ty + = do { local_dm_name <- newLocalName sel_name + -- Base the local_dm_name on the selector name, because + -- type errors from tcInstanceMethodBody come from here + + ; let dm_ty = mkSigmaTy tyvars [mkClassPred clas (mkTyVarTys tyvars)] local_dm_ty + dm_id = mkExportedLocalId dm_name dm_ty + local_dm_id = mkLocalId local_dm_name local_dm_ty + + ; dm_id_w_inline <- addInlinePrags dm_id prags + ; spec_prags <- tcSpecPrags dm_id prags + + ; warnTc (not (null spec_prags)) + (ptext (sLit "Ignoring SPECIALISE pragmas on default method") + <+> quotes (ppr sel_name)) + + ; tc_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict] + dm_id_w_inline local_dm_id dm_sig_fn + IsDefaultMethod dm_bind + + ; return (unitBag tc_bind) } + + tc_genop_ty :: LHsType Name -> TcM Type + tc_genop_ty hs_ty + = setSrcSpan (getLoc hs_ty) $ + do { tau <- tcHsKindedType hs_ty + ; checkValidType (FunSigCtxt sel_name) tau + ; return tau } + +findGenericSig :: [LSig Name] -> Name -> LHsType Name +-- Find the 'generic op :: ty' signature among the sigs +-- If dm_info is GenDefMeth, the corresponding signature +-- should jolly well exist! Hence the panic +findGenericSig sigs sel_name + = case [lty | L _ (GenericSig (L _ n) lty) <- sigs + , n == sel_name ] of + [lty] -> lty + _ -> pprPanic "tcDefMeth" (ppr sel_name $$ ppr sigs) --------------- tcInstanceMethodBody :: SkolemInfo -> [TcTyVar] -> [EvVar] @@ -246,7 +258,7 @@ tcInstanceMethodBody skol_info tyvars dfun_ev_vars let lm_bind = L loc (bind { fun_id = L loc (idName local_meth_id) }) -- Substitute the local_meth_name for the binder -- NB: the binding is always a FunBind - + ; traceTc "TIM" (ppr local_meth_id $$ ppr (meth_sig_fn (idName local_meth_id))) ; (ev_binds, (tc_bind, _)) <- checkConstraints skol_info tyvars dfun_ev_vars $ tcExtendIdEnv [local_meth_id] $ @@ -359,42 +371,20 @@ gives rise to the instance declarations op Unit = ... \begin{code} -mkGenericDefMethBind :: Class -> [Type] -> Id -> TcM (LHsBind Name) -mkGenericDefMethBind clas inst_tys sel_id +mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind 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 (idName sel_id)) - [mkSimpleMatch [] rn_rhs]) } + [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] @@ -562,6 +552,11 @@ 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), @@ -571,22 +566,6 @@ 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"), @@ -605,7 +584,9 @@ dupGenericInsts tc_inst_infos 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) +badDmPrag :: Id -> Sig Name -> TcM () +badDmPrag sel_id prag + = addErrTc (ptext (sLit "The") <+> hsSigDoc prag <+> ptext (sLit "for default method") + <+> quotes (ppr sel_id) + <+> ptext (sLit "lacks an accompanying binding")) \end{code}