X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=a04654541686ec33312e9188a35025c091e980c3;hb=bb91427f27c940e4dd0fc6c7360e7ef61264b240;hp=90a5af4337c4a0117f9d95e17f7cbfdc7393be9b;hpb=ae45ff0e9831a0dc862a5d68d03e355d7e323c62;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 90a5af4..a046545 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,66 +1,70 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcClassDcl]{Typechecking class declarations} \begin{code} -#include "HsVersions.h" - -module TcClassDcl ( - tcClassDecl1, tcClassDecls2 - ) where +module TcClassDcl ( kcClassDecl, tcClassDecl1, tcClassDecls2, mkImplicitClassBinds, + tcMethodBind, checkFromThisClass + ) where -IMP_Ubiq() +#include "HsVersions.h" -import HsSyn ( ClassDecl(..), HsBinds(..), Bind(..), MonoBinds(..), - Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..), - HsLit(..), OutPat(..), Sig(..), PolyType(..), MonoType, - Stmt, Qualifier, ArithSeqInfo, InPat, Fake ) +import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..), + InPat(..), HsBinds(..), GRHSs(..), + HsExpr(..), HsLit(..), HsType(..), HsPred(..), + pprHsClassAssertion, mkSimpleMatch, + andMonoBinds, andMonoBindList, getTyVarName, + isClassDecl, isClassOpSig, isPragSig, collectMonoBinders + ) import HsPragmas ( ClassPragmas(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), RenamedMonoBinds(..), - RenamedGenPragmas(..), RenamedContext(..), - RnName{-instance Uniquable-} +import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) ) +import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcIdOcc(..), TcHsBinds(..), TcMonoBinds(..), TcExpr(..), - mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType ) - -import Inst ( Inst, InstOrigin(..), LIE(..), emptyLIE, plusLIE, newDicts ) -import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds) -import TcInstDcls ( processInstBinds, newMethodId ) -import TcKind ( TcKind ) -import TcKind ( unifyKind ) -import TcMonad hiding ( rnMtoTcM ) -import TcMonoType ( tcPolyType, tcMonoType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcType(..), TcTyVar(..), tcInstType, tcInstSigTyVars, tcInstSigType ) - -import Bag ( foldBag, unionManyBags ) -import Class ( GenClass, mkClass, mkClassOp, classBigSig, - classOps, classOpString, classOpLocalType, - classOpTagByString +import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) + +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) +import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo, + tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, + tcExtendLocalValEnv + ) +import TcBinds ( tcBindWithSigs, tcSpecSigs ) +import TcTyDecls ( mkNewTyConRep ) +import TcUnify ( unifyKinds ) +import TcMonad +import TcMonoType ( kcHsType, tcHsTopType, tcExtendTopTyVarScope, + tcContext, checkSigTyVars, sigCtxt, mkTcSig ) -import Id ( mkSuperDictSelId, mkMethodSelId, mkDefaultMethodId, - idType ) -import IdInfo ( noIdInfo ) -import Name ( isLocallyDefined, origName, getLocalName ) -import PrelVals ( nO_DEFAULT_METHOD_ERROR_ID ) -import PprStyle -import Pretty -import PprType ( GenType, GenTyVar, GenClassOp ) -import SpecEnv ( SpecEnv(..) ) -import SrcLoc ( mkGeneratedSrcLoc ) -import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, - mkForAllTy, mkSigmaTy, splitSigmaTy) -import TysWiredIn ( stringTy ) -import TyVar ( mkTyVarSet, GenTyVar ) -import Unique ( Unique ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar ) +import TcInstUtil ( classDataCon ) +import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) +import FieldLabel ( firstFieldLabelTag ) +import Bag ( unionManyBags, bagToList ) +import Class ( mkClass, classBigSig, classSelIds, Class, ClassOpItem ) +import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) +import DataCon ( mkDataCon, dataConId, dataConWrapId, notMarkedStrict ) +import Id ( Id, setInlinePragma, idUnfolding, idType, idName ) +import CoreUnfold ( unfoldingTemplate ) +import IdInfo +import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..) ) +import NameSet ( emptyNameSet ) +import Outputable +import Type ( Type, ThetaType, ClassContext, + mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, mkDictTys, + mkSigmaTy, mkForAllTys, mkClassPred, classesOfPreds, + boxedTypeKind, mkArrowKind + ) +import Var ( tyVarKind, TyVar ) +import VarSet ( mkVarSet, emptyVarSet ) +import TyCon ( AlgTyConFlavour(..), mkClassTyCon ) +import Unique ( Unique, Uniquable(..) ) import Util - - --- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) -tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo, noIdInfo) +import Maybes ( seqMaybe ) +import FiniteMap ( lookupWithDefaultFM ) \end{code} @@ -98,170 +102,191 @@ Now DictTy in Type is just a form of type synomym: Death to "ExpandingDicts". +%************************************************************************ +%* * +\subsection{Kind checking} +%* * +%************************************************************************ + \begin{code} -tcClassDecl1 rec_inst_mapper - (ClassDecl context class_name - tyvar_name class_sigs def_methods pragmas src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (classDeclCtxt class_name) $ +kcClassDecl (ClassDecl context class_name + tyvar_names fundeps class_sigs def_methods pragmas + _ _ _ _ src_loc) + = -- CHECK ARITY 1 FOR HASKELL 1.4 + checkTc (opt_GlasgowExts || length tyvar_names == 1) + (classArityErr class_name) `thenTc_` + + -- Get the (mutable) class kind + tcLookupTy class_name `thenNF_Tc` \ (kind, _, _) -> + + -- Make suitable tyvars and do kind checking + -- The net effect is to mutate the class kind + tcExtendTopTyVarScope kind tyvar_names $ \ _ _ -> + tcContext context `thenTc_` + mapTc kc_sig the_class_sigs `thenTc_` + + returnTc () + where + the_class_sigs = filter isClassOpSig class_sigs + + kc_sig (ClassOpSig _ _ _ op_ty loc) = tcAddSrcLoc loc (kcHsType op_ty) +\end{code} - -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenNF_Tc` \ (class_kind, rec_class) -> - tcLookupTyVar tyvar_name `thenNF_Tc` \ (tyvar_kind, rec_tyvar) -> - let - (rec_class_inst_env, rec_class_op_inst_fn) = rec_inst_mapper rec_class - in - -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKind class_kind tyvar_kind `thenTc_` +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ +\begin{code} +tcClassDecl1 rec_env rec_inst_mapper rec_vrcs + (ClassDecl context class_name + tyvar_names fundeps class_sigs def_methods pragmas + tycon_name datacon_name datacon_wkr_name sc_sel_names src_loc) + = -- LOOK THINGS UP IN THE ENVIRONMENT + tcLookupTy class_name `thenTc` \ (class_kind, _, AClass rec_class) -> + tcExtendTopTyVarScope class_kind tyvar_names $ \ tyvars _ -> + -- The class kind is by now immutable + -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvar context pragmas - `thenTc` \ (scs, sc_sel_ids) -> +-- traceTc (text "tcClassCtxt" <+> ppr class_name) `thenTc_` + tcClassContext class_name rec_class tyvars context sc_sel_names + `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> +-- traceTc (text "tcClassCtxt done" <+> ppr class_name) `thenTc_` + + -- CHECK THE FUNCTIONAL DEPENDENCIES, + tcFundeps fundeps `thenTc` \ fds -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_class rec_tyvar rec_class_op_inst_fn) class_sigs - `thenTc` \ sig_stuff -> + mapTc (tcClassSig rec_env rec_class tyvars) + (filter isClassOpSig class_sigs) + `thenTc` \ sig_stuff -> -- MAKE THE CLASS OBJECT ITSELF let - (ops, op_sel_ids, defm_ids) = unzip3 sig_stuff - clas = mkClass (uniqueOf class_name) (getName class_name) rec_tyvar - scs sc_sel_ids ops op_sel_ids defm_ids + (op_tys, op_items) = unzip sig_stuff + rec_class_inst_env = rec_inst_mapper rec_class + clas = mkClass class_name tyvars fds + sc_theta sc_sel_ids op_items + tycon rec_class_inst_env - in - returnTc clas -\end{code} - - let - clas_ty = mkTyVarTy clas_tyvar - dict_component_tys = [mkDictTy sc clas_ty | sc <- scs] ++ - [classOpLocalType op | op <- ops]) + dict_component_tys = sc_tys ++ op_tys new_or_data = case dict_component_tys of - [_] -> NewType - other -> DataType + [_] -> NewTyCon (mkNewTyConRep tycon) + other -> DataTyCon - dict_con_id = mkDataCon class_name - [NotMarkedStrict] + dict_con = mkDataCon datacon_name + [notMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] - [clas_tyvar] + tyvars [{-No context-}] + [{-No existential tyvars-}] [{-Or context-}] dict_component_tys - tycon - - tycon = mkDataTyCon class_name - (tyVarKind rec_tyvar `mkArrowKind` mkBoxedTypeKind) - [rec_tyvar] - [{- Empty context -}] - [dict_con_id] - [{- No derived classes -}] - new_or_data + tycon dict_con_id dict_wrap_id + + dict_con_id = mkDataConId datacon_wkr_name dict_con + dict_wrap_id = mkDataConWrapId dict_con + + argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcClassDecl1: argvrcs:" $ + ppr tycon_name) + tycon_name + + tycon = mkClassTyCon tycon_name + class_kind + tyvars + argvrcs + dict_con -- Constructors + clas -- Yes! It's a dictionary + new_or_data in + returnTc clas +\end{code} +\begin{code} +tcFundeps = mapTc tc_fundep +tc_fundep (us, vs) = + mapTc tc_fd_tyvar us `thenTc` \ us' -> + mapTc tc_fd_tyvar vs `thenTc` \ vs' -> + returnTc (us', vs') +tc_fd_tyvar v = + tcLookupTy v `thenTc` \(_, _, thing) -> + case thing of + ATyVar tv -> returnTc tv + -- ZZ else should fail more gracefully +\end{code} \begin{code} -tcClassContext :: Class -> TyVar +tcClassContext :: Name -> Class -> [TyVar] -> RenamedContext -- class context - -> RenamedClassPragmas -- pragmas for superclasses - -> TcM s ([Class], -- the superclasses - [Id]) -- superclass selector Ids + -> [Name] -- Names for superclass selectors + -> TcM s (ClassContext, -- the superclass context + [Type], -- types of the superclass dictionaries + [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvar context pragmas +tcClassContext class_name rec_class rec_tyvars context sc_sel_names = -- Check the context. -- The renamer has already checked that the context mentions -- only the type variable of the class decl. - tcContext context `thenTc` \ theta -> - let - super_classes = [ supers | (supers, _) <- theta ] - in - -- Make super-class selector ids - mapTc (mk_super_id rec_class) - (super_classes `zip` maybe_pragmas) `thenTc` \ sc_sel_ids -> - -- NB: we worry about matching list lengths below + -- For std Haskell check that the context constrains only tyvars + (if opt_GlasgowExts then + returnTc [] + else + mapTc check_constraint context + ) `thenTc_` + + tcContext context `thenTc` \ sc_theta -> + let + sc_theta' = classesOfPreds sc_theta + sc_tys = mkDictTys sc_theta' + sc_sel_ids = [mkDictSelId sc_name rec_class | sc_name <- sc_sel_names] + in -- Done - returnTc (super_classes, sc_sel_ids) + returnTc (sc_theta', sc_tys, sc_sel_ids) where - mk_super_id rec_class (super_class, maybe_pragma) - = fixTc ( \ rec_super_id -> - tcGetUnique `thenNF_Tc` \ uniq -> - - -- GET THE PRAGMA INFO FOR THE SUPERCLASS - (case maybe_pragma of - Nothing -> returnNF_Tc noIdInfo - Just prag -> tcGenPragmas Nothing{-ty unknown-} rec_super_id prag - ) `thenNF_Tc` \ id_info -> - let - rec_tyvar_ty = mkTyVarTy rec_tyvar - ty = mkForAllTy rec_tyvar $ - mkFunTy (mkDictTy rec_class rec_tyvar_ty) - (mkDictTy super_class rec_tyvar_ty) - in - -- BUILD THE SUPERCLASS ID - returnTc (mkSuperDictSelId uniq rec_class super_class ty id_info) - ) - - maybe_pragmas :: [Maybe RenamedGenPragmas] - maybe_pragmas = case pragmas of - NoClassPragmas -> repeat Nothing - SuperDictPragmas prags -> ASSERT(length prags == length context) - map Just prags - -- If there are any pragmas there should - -- be one for each superclass - - - -tcClassSig :: Class -- Knot tying only! - -> TyVar -- The class type variable, used for error check only - -> (ClassOp -> SpecEnv) -- Ditto; the spec info for the class ops + check_constraint (HsPClass c tys) = checkTc (all is_tyvar tys) + (superClassErr class_name (c, tys)) + + is_tyvar (MonoTyVar _) = True + is_tyvar other = False + + +tcClassSig :: ValueEnv -- Knot tying only! + -> Class -- ...ditto... + -> [TyVar] -- The class type variable, used for error check only -> RenamedClassOpSig - -> TcM s (ClassOp, -- class op - Id, -- selector id - Id) -- default-method ids - -tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn - (ClassOpSig op_name - op_ty - pragmas src_loc) + -> TcM s (Type, -- Type of the method + ClassOpItem) -- Selector Id, default-method Id, True if explicit default binding + + +tcClassSig rec_env rec_clas rec_clas_tyvars + (ClassOpSig op_name dm_name explicit_dm + op_ty src_loc) = tcAddSrcLoc src_loc $ - fixTc ( \ ~(_, rec_sel_id, rec_defm_id) -> -- Knot for pragmas -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. -- NB: Renamer checks that the class type variable is mentioned in local_ty, -- and that it is not constrained by theta - tcPolyType op_ty `thenTc` \ local_ty -> +-- traceTc (text "tcClassSig" <+> ppr op_name) `thenTc_` + tcHsTopType op_ty `thenTc` \ local_ty -> let - global_ty = mkSigmaTy [rec_clas_tyvar] - [(rec_clas, mkTyVarTy rec_clas_tyvar)] + global_ty = mkSigmaTy rec_clas_tyvars + [mkClassPred rec_clas (mkTyVarTys rec_clas_tyvars)] local_ty - class_op_nm = getLocalName op_name - class_op = mkClassOp class_op_nm - (classOpTagByString rec_clas{-yeeps!-} class_op_nm) - local_ty - in - - -- Munch the pragmas - tcClassOpPragmas - global_ty - rec_sel_id rec_defm_id - (rec_classop_spec_fn class_op) - pragmas `thenNF_Tc` \ (op_info, defm_info) -> -- Build the selector id and default method id - tcGetUnique `thenNF_Tc` \ d_uniq -> - let - op_uniq = uniqueOf op_name - sel_id = mkMethodSelId op_uniq rec_clas class_op global_ty op_info - defm_id = mkDefaultMethodId d_uniq rec_clas class_op False global_ty defm_info - -- ToDo: improve the "False" + sel_id = mkDictSelId op_name rec_clas + dm_id = mkDefaultMethodId dm_name rec_clas global_ty + final_dm_id = tcAddImportedIdInfo rec_env dm_id in - returnTc (class_op, sel_id, defm_id) - ) +-- traceTc (text "tcClassSig done" <+> ppr op_name) `thenTc_` + returnTc (local_ty, (sel_id, final_dm_id, explicit_dm)) \end{code} @@ -288,183 +313,58 @@ The function @tcClassDecls2@ just arranges to apply @tcClassDecl2@ to each local class decl. \begin{code} -tcClassDecls2 :: Bag RenamedClassDecl - -> NF_TcM s (LIE s, TcHsBinds s) +tcClassDecls2 :: [RenamedHsDecl] + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecls2 decls - = foldBag combine - tcClassDecl2 - (returnNF_Tc (emptyLIE, EmptyBinds)) - decls + = foldr combine + (returnNF_Tc (emptyLIE, EmptyMonoBinds)) + [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, isClassDecl cls_decl] where combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> tc2 `thenNF_Tc` \ (lie2, binds2) -> returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `ThenBinds` binds2) + binds1 `AndMonoBinds` binds2) \end{code} @tcClassDecl2@ is the business end of things. \begin{code} -tcClassDecl2 :: RenamedClassDecl -- The class declaration - -> NF_TcM s (LIE s, TcHsBinds s) +tcClassDecl2 :: RenamedTyClDecl -- The class declaration + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecl2 (ClassDecl context class_name - tyvar_name class_sigs default_binds pragmas src_loc) + tyvar_names _ class_sigs default_binds pragmas _ _ _ _ src_loc) | not (isLocallyDefined class_name) - = returnNF_Tc (emptyLIE, EmptyBinds) + = returnNF_Tc (emptyLIE, EmptyMonoBinds) | otherwise -- It is locally defined - = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $ - tcAddSrcLoc src_loc $ - - -- Get the relevant class - tcLookupClass class_name `thenNF_Tc` \ (_, clas) -> - let - (tyvar, scs, sc_sel_ids, ops, op_sel_ids, defm_ids) - = classBigSig clas - in - tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], _, _) -> - - -- Generate bindings for the selector functions - buildSelectors clas tyvar clas_tyvar scs sc_sel_ids ops op_sel_ids - `thenNF_Tc` \ sel_binds -> - -- Ditto for the methods - buildDefaultMethodBinds clas clas_tyvar defm_ids default_binds - `thenTc` \ (const_insts, meth_binds) -> - - returnTc (const_insts, sel_binds `ThenBinds` meth_binds) + = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc src_loc $ + tcLookupClass class_name `thenNF_Tc` \ clas -> + tcDefaultMethodBinds clas default_binds class_sigs \end{code} -%************************************************************************ -%* * -\subsection[ClassDcl-bld-sels]{Building the selector functions for methods and superclasses} -%* * -%************************************************************************ - \begin{code} -buildSelectors :: Class -- The class object - -> TyVar -- Class type variable - -> TcTyVar s -- Instantiated class type variable (TyVarTy) - -> [Class] -> [Id] -- Superclasses and selectors - -> [ClassOp] -> [Id] -- Class ops and selectors - -> NF_TcM s (TcHsBinds s) - -buildSelectors clas clas_tyvar clas_tc_tyvar scs sc_sel_ids ops op_sel_ids - = - -- Make new Ids for the components of the dictionary - let - clas_tyvar_ty = mkTyVarTy clas_tc_tyvar - mk_op_ty = tcInstType [(clas_tyvar, clas_tyvar_ty)] . classOpLocalType - in - mapNF_Tc mk_op_ty ops `thenNF_Tc` \ op_tys -> - newLocalIds (map classOpString ops) op_tys `thenNF_Tc` \ method_ids -> - - newDicts ClassDeclOrigin - [ (super_clas, clas_tyvar_ty) - | super_clas <- scs ] `thenNF_Tc` \ (_,dict_ids) -> - - newDicts ClassDeclOrigin - [ (clas, clas_tyvar_ty) ] `thenNF_Tc` \ (_,[clas_dict]) -> - - -- Make suitable bindings for the selectors - let - mk_sel sel_id method_or_dict - = mkSelBind sel_id clas_tc_tyvar clas_dict dict_ids method_ids method_or_dict - in - listNF_Tc (zipWithEqual "mk_sel1" mk_sel op_sel_ids method_ids) `thenNF_Tc` \ op_sel_binds -> - listNF_Tc (zipWithEqual "mk_sel2" mk_sel sc_sel_ids dict_ids) `thenNF_Tc` \ sc_sel_binds -> - - returnNF_Tc (SingleBind ( - NonRecBind ( - foldr AndMonoBinds - (foldr AndMonoBinds EmptyMonoBinds op_sel_binds) - sc_sel_binds - ))) -\end{code} - -%************************************************************************ -%* * -\subsection[ClassDcl-misc]{Miscellaneous} -%* * -%************************************************************************ - -Make a selector expression for @sel_id@ from a dictionary @clas_dict@ -consisting of @dicts@ and @methods@. - -====================== OLD ============================ -We have to do a bit of jiggery pokery to get the type variables right. -Suppose we have the class decl: -\begin{verbatim} - class Foo a where - op1 :: Ord b => a -> b -> a - op2 :: ... -\end{verbatim} -Then the method selector for \tr{op1} is like this: -\begin{verbatim} - op1_sel = /\a b -> \dFoo dOrd -> case dFoo of - (op1_method,op2_method) -> op1_method b dOrd -\end{verbatim} -Note that the type variable for \tr{b} and the (Ord b) dictionary -are lifted to the top lambda, and -\tr{op1_method} is applied to them. This is preferable to the alternative: -\begin{verbatim} - op1_sel' = /\a -> \dFoo -> case dFoo of - (op1_method,op2_method) -> op1_method -\end{verbatim} -because \tr{op1_sel'} then has the rather strange type -\begin{verbatim} - op1_sel' :: forall a. Foo a -> forall b. Ord b -> a -> b -> a -\end{verbatim} -whereas \tr{op1_sel} (the one we use) has the decent type -\begin{verbatim} - op1_sel :: forall a b. Foo a -> Ord b -> a -> b -> a -\end{verbatim} -========================= END OF OLD =========================== - -NEW COMMENT: instead we now go for op1_sel' above. Seems tidier and -the rest of the compiler darn well ought to cope. - - - -NOTE that we return a TcMonoBinds (which is later zonked) even though -there's no real back-substitution to do. It's just simpler this way! +mkImplicitClassBinds :: [Class] -> NF_TcM s ([Id], TcMonoBinds) +mkImplicitClassBinds classes + = returnNF_Tc (concat cls_ids_s, andMonoBindList binds_s) + -- The selector binds are already in the selector Id's unfoldings + where + (cls_ids_s, binds_s) = unzip (map mk_implicit classes) -NOTE ALSO that the selector has no free type variables, so we -don't bother to instantiate the class-op's local type; instead -we just use the variables inside it. + mk_implicit clas = (all_cls_ids, binds) + where + dict_con = classDataCon clas + all_cls_ids = dataConId dict_con : cls_ids + cls_ids = dataConWrapId dict_con : classSelIds clas -\begin{code} -mkSelBind :: Id -- the selector id - -> TcTyVar s -> TcIdOcc s -- class tyvar and dict - -> [TcIdOcc s] -> [TcIdOcc s] -- superclasses and methods in class dict - -> TcIdOcc s -- the superclass/method being slected - -> NF_TcM s (TcMonoBinds s) - -mkSelBind sel_id clas_tyvar clas_dict dicts methods method_or_dict@(TcId op) - = - -- sel_id = /\ clas_tyvar -> \ clas_dict -> - -- case clas_dict of - -- -> method_or_dict - - returnNF_Tc (VarMonoBind (RealId sel_id) ( - TyLam [clas_tyvar] ( - DictLam [clas_dict] ( - HsCase - (HsVar clas_dict) - ([PatMatch (DictPat dicts methods) ( - GRHSMatch (GRHSsAndBindsOut - [OtherwiseGRHS - (HsVar method_or_dict) - mkGeneratedSrcLoc] - EmptyBinds - (idType op)))]) - mkGeneratedSrcLoc - )))) + -- The wrapper and selectors get bindings, the worker does not + binds | isLocallyDefined clas = idsToMonoBinds cls_ids + | otherwise = EmptyMonoBinds \end{code} - %************************************************************************ %* * \subsection[Default methods]{Default methods} @@ -487,23 +387,11 @@ we get the default methods: defm.Foo.op1 :: forall a. Foo a => a -> Bool defm.Foo.op1 = /\a -> \dfoo -> \x -> True -====================== OLD ================== -\begin{verbatim} -defm.Foo.op2 :: forall a, b. (Foo a, Ord b) => a -> b -> b -> b -defm.Foo.op2 = /\ a b -> \ dfoo dord -> \x y z -> - if (op1 a dfoo x) && (< b dord y z) then y else z -\end{verbatim} -Notice that, like all ids, the foralls of defm.Foo.op2 are at the top. -====================== END OF OLD =================== - -NEW: -\begin{verbatim} defm.Foo.op2 :: forall a. Foo a => forall b. Ord b => a -> b -> b -> b defm.Foo.op2 = /\ a -> \ dfoo -> /\ b -> \ dord -> \x y z -> if (op1 a dfoo x) && (< b dord y z) then y else z \end{verbatim} - When we come across an instance decl, we may need to use the default methods: \begin{verbatim} @@ -539,96 +427,235 @@ dfun.Foo.List \end{verbatim} \begin{code} -buildDefaultMethodBinds +tcDefaultMethodBinds :: Class - -> TcTyVar s - -> [Id] -> RenamedMonoBinds - -> TcM s (LIE s, TcHsBinds s) + -> [RenamedSig] + -> TcM s (LIE, TcMonoBinds) + +tcDefaultMethodBinds clas default_binds sigs + = -- Check that the default bindings come from this class + checkFromThisClass clas op_items default_binds `thenNF_Tc_` + + -- Do each default method separately + -- For Hugs compatibility we make a default-method for every + -- class op, regardless of whether or not the programmer supplied an + -- explicit default decl for the class. GHC will actually never + -- call the default method for such operations, because it'll whip up + -- a more-informative default method at each instance decl. + mapAndUnzipTc tc_dm op_items `thenTc` \ (defm_binds, const_lies) -> + + returnTc (plusLIEs const_lies, andMonoBindList defm_binds) + where + prags = filter isPragSig sigs -buildDefaultMethodBinds clas clas_tyvar - default_method_ids default_binds - = newDicts origin [(clas,inst_ty)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> - mapAndUnzipNF_Tc mk_method default_method_ids `thenNF_Tc` \ (insts_s, local_defm_ids) -> - let - avail_insts = this_dict `plusLIE` unionManyBags insts_s -- Insts available - in - processInstBinds - clas - (makeClassDeclDefaultMethodRhs clas local_defm_ids) - [clas_tyvar] -- Tyvars in scope - avail_insts - local_defm_ids - default_binds `thenTc` \ (insts_needed, default_binds') -> - - tcSimplifyAndCheck - (mkTyVarSet [clas_tyvar]) - avail_insts - insts_needed `thenTc` \ (const_lie, dict_binds) -> - + (tyvars, _, _, op_items) = classBigSig clas - let - defm_binds = AbsBinds - [clas_tyvar] - [this_dict_id] - (local_defm_ids `zip` map RealId default_method_ids) - dict_binds - (RecBind default_binds') - in - returnTc (const_lie, defm_binds) - where - inst_ty = mkTyVarTy clas_tyvar - mk_method defm_id = newMethodId defm_id inst_ty origin origin = ClassDeclOrigin + + -- We make a separate binding for each default method. + -- At one time I used a single AbsBinds for all of them, thus + -- AbsBind [d] [dm1, dm2, dm3] { dm1 = ...; dm2 = ...; dm3 = ... } + -- But that desugars into + -- ds = \d -> (..., ..., ...) + -- dm1 = \d -> case ds d of (a,b,c) -> a + -- And since ds is big, it doesn't get inlined, so we don't get good + -- default methods. Better to make separate AbsBinds for each + + tc_dm op_item@(_, dm_id, _) + = tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) -> + let + theta = [(mkClassPred clas inst_tys)] + in + newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + let + avail_insts = this_dict + in + tcExtendTyVarEnvForMeths tyvars clas_tyvars ( + tcMethodBind clas origin clas_tyvars inst_tys theta + default_binds prags False + op_item + ) `thenTc` \ (defm_bind, insts_needed, (_, local_dm_id)) -> + + tcAddErrCtxt (defltMethCtxt clas) $ + + -- tcMethodBind has checked that the class_tyvars havn't + -- been unified with each other or another type, but we must + -- still zonk them before passing them to tcSimplifyAndCheck + mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' -> + + -- Check the context + tcSimplifyAndCheck + (ptext SLIT("class") <+> ppr clas) + (mkVarSet clas_tyvars') + avail_insts + insts_needed `thenTc` \ (const_lie, dict_binds) -> + + let + full_bind = AbsBinds + clas_tyvars' + [this_dict_id] + [(clas_tyvars', dm_id, local_dm_id)] + emptyNameSet -- No inlines (yet) + (dict_binds `andMonoBinds` defm_bind) + in + returnTc (full_bind, const_lie) +\end{code} + +\begin{code} +checkFromThisClass :: Class -> [ClassOpItem] -> RenamedMonoBinds -> NF_TcM s () +checkFromThisClass clas op_items mono_binds + = mapNF_Tc check_from_this_class bndrs `thenNF_Tc_` + returnNF_Tc () + where + check_from_this_class (bndr, loc) + | nameOccName bndr `elem` sel_names = returnNF_Tc () + | otherwise = tcAddSrcLoc loc $ + addErrTc (badMethodErr bndr clas) + sel_names = [getOccName sel_id | (sel_id,_,_) <- op_items] + bndrs = bagToList (collectMonoBinders mono_binds) \end{code} + -@makeClassDeclDefaultMethodRhs@ builds the default method for a -class declaration when no explicit default method is given. +@tcMethodBind@ is used to type-check both default-method and +instance-decl method declarations. We must type-check methods one at a +time, because their signatures may have different contexts and +tyvar sets. \begin{code} -makeClassDeclDefaultMethodRhs +tcMethodBind :: Class - -> [TcIdOcc s] - -> Int - -> NF_TcM s (TcExpr s) - -makeClassDeclDefaultMethodRhs clas method_ids tag - = -- Return the expression - -- error ty "No default method for ..." - -- The interesting thing is that method_ty is a for-all type; - -- this is fun, although unusual in a type application! - - returnNF_Tc (HsApp (mkHsTyApp (HsVar (RealId nO_DEFAULT_METHOD_ERROR_ID)) [tcIdType method_id]) - (HsLitOut (HsString (_PK_ error_msg)) stringTy)) - -{- OLD AND COMPLICATED - tcInstSigType () `thenNF_Tc` \ method_ty -> - let - (tyvars, theta, tau) = splitSigmaTy method_ty - in - newDicts ClassDeclOrigin theta `thenNF_Tc` \ (lie, dict_ids) -> - - returnNF_Tc (mkHsTyLam tyvars ( - mkHsDictLam dict_ids ( - HsApp (mkHsTyApp (HsVar (RealId nO_DEFAULT_METHOD_ERROR_ID)) [tau]) - (HsLitOut (HsString (_PK_ error_msg)) stringTy)))) --} + -> InstOrigin + -> [TcTyVar] -- Instantiated type variables for the + -- enclosing class/instance decl. + -- They'll be signature tyvars, and we + -- want to check that they don't get bound + -> [TcType] -- Instance types + -> TcThetaType -- Available theta; this could be used to check + -- the method signature, but actually that's done by + -- the caller; here, it's just used for the error message + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> [RenamedSig] -- Pramgas (just for this one) + -> Bool -- True <=> This method is from an instance declaration + -> ClassOpItem -- The method selector and default-method Id + -> TcM s (TcMonoBinds, LIE, (LIE, TcId)) + +tcMethodBind clas origin inst_tyvars inst_tys inst_theta + meth_binds prags is_inst_decl + (sel_id, dm_id, explicit_dm) + = tcGetSrcLoc `thenNF_Tc` \ loc -> + + newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) -> + mkTcSig meth_id loc `thenNF_Tc` \ sig_info -> + + let + meth_name = idName meth_id + maybe_user_bind = find_bind meth_name meth_binds + + no_user_bind = case maybe_user_bind of {Nothing -> True; other -> False} + + meth_bind = case maybe_user_bind of + Just bind -> bind + Nothing -> mk_default_bind meth_name loc + + meth_prags = find_prags meth_name prags + in + + -- Warn if no method binding, only if -fwarn-missing-methods + warnTc (is_inst_decl && opt_WarnMissingMethods && no_user_bind && not explicit_dm) + (omittedMethodWarn sel_id clas) `thenNF_Tc_` + + -- Check the bindings; first add inst_tyvars to the envt + -- so that we don't quantify over them in nested places + -- The *caller* put the class/inst decl tyvars into the envt + tcExtendGlobalTyVars (mkVarSet inst_tyvars) ( + tcAddErrCtxt (methodCtxt sel_id) $ + tcBindWithSigs NotTopLevel meth_bind + [sig_info] meth_prags NonRecursive + ) `thenTc` \ (binds, insts, _) -> + + + tcExtendLocalValEnv [(meth_name, meth_id)] ( + tcSpecSigs meth_prags + ) `thenTc` \ (prag_binds1, prag_lie) -> + + -- The prag_lie for a SPECIALISE pragma will mention the function + -- itself, so we have to simplify them away right now lest they float + -- outwards! + bindInstsOfLocalFuns prag_lie [meth_id] `thenTc` \ (prag_lie', prag_binds2) -> + + + -- Now check that the instance type variables + -- (or, in the case of a class decl, the class tyvars) + -- have not been unified with anything in the environment + tcAddErrCtxtM (sigCtxt sig_msg inst_tyvars inst_theta (idType meth_id)) $ + checkSigTyVars inst_tyvars emptyVarSet `thenTc_` + + returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2, + insts `plusLIE` prag_lie', + meth) + where + sig_msg = ptext SLIT("When checking the expected type for class method") <+> ppr sel_name + + sel_name = idName sel_id + + -- 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. + find_bind meth_name (FunMonoBind op_name fix matches loc) + | op_name == sel_name = Just (FunMonoBind meth_name fix matches loc) + find_bind meth_name (AndMonoBinds b1 b2) + = find_bind meth_name b1 `seqMaybe` find_bind meth_name b2 + find_bind meth_name other = Nothing -- Default case + + + -- Find the prags for this method, and replace the + -- selector name with the method name + find_prags meth_name [] = [] + find_prags meth_name (SpecSig name ty loc : prags) + | name == sel_name = SpecSig meth_name ty loc : find_prags meth_name prags + find_prags meth_name (InlineSig name phase loc : prags) + | name == sel_name = InlineSig meth_name phase loc : find_prags meth_name prags + find_prags meth_name (NoInlineSig name phase loc : prags) + | name == sel_name = NoInlineSig meth_name phase loc : find_prags meth_name prags + find_prags meth_name (prag:prags) = find_prags meth_name prags + + mk_default_bind local_meth_name loc + = FunMonoBind local_meth_name + False -- Not infix decl + [mkSimpleMatch [] (default_expr loc) Nothing loc] + loc + + default_expr loc + | explicit_dm = HsVar (getName dm_id) -- There's a default method + | otherwise = error_expr loc -- No default method + + error_expr loc = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) + (HsLit (HsString (_PK_ (error_msg loc)))) + + error_msg loc = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) +\end{code} - where - (OrigName clas_mod clas_name) = origName "makeClassDeclDefaultMethodRhs" clas +Contexts and errors +~~~~~~~~~~~~~~~~~~~ +\begin{code} +classArityErr class_name + = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) - method_id = method_ids !! (tag-1) - class_op = (classOps clas) !! (tag-1) +superClassErr class_name sc + = ptext SLIT("Illegal superclass constraint") <+> quotes (pprHsClassAssertion sc) + <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name) - error_msg = _UNPK_ clas_mod ++ "." ++ _UNPK_ clas_name ++ "." - ++ (ppShow 80 (ppr PprForUser class_op)) - ++ "\"" -\end{code} +defltMethCtxt class_name + = ptext SLIT("When checking the default methods for class") <+> quotes (ppr class_name) +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) -Contexts -~~~~~~~~ -\begin{code} -classDeclCtxt class_name sty - = ppCat [ppStr "In the class declaration for", ppr sty class_name] +badMethodErr bndr clas + = hsep [ptext SLIT("Class"), quotes (ppr clas), + ptext SLIT("does not have a method"), quotes (ppr bndr)] + +omittedMethodWarn sel_id clas + = sep [ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id), + ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)] \end{code}