X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=00c1087e27f47f37aba2be2c651390322f32fd21;hb=d0f325ce37d6ee322168e44392f10e0ed52f8294;hp=fea81a43da4da9e2e61f3dcfdb07f611be4ae345;hpb=f7ecf7234c224489be8a5e63fced903b655d92ee;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index fea81a4..00c1087e 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -4,60 +4,63 @@ \section[TcClassDcl]{Typechecking class declarations} \begin{code} -#include "HsVersions.h" - -module TcClassDcl ( tcClassDecl1, tcClassDecls2 ) where +module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) 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(..), ClassDecl(..), Sig(..), MonoBinds(..), + InPat(..), andMonoBinds, getTyVarName + ) import HsPragmas ( ClassPragmas(..) ) +import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) ) import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), SYN_IE(RenamedMonoBinds), - RenamedGenPragmas(..), RenamedContext(..), - RnName{-instance Uniquable-} + RenamedClassOpSig(..), RenamedMonoBinds, + RenamedContext(..), RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), SYN_IE(TcExpr), - mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType ) - -import Inst ( Inst, InstOrigin(..), SYN_IE(LIE), emptyLIE, plusLIE, newDicts, newMethod ) -import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds, tcExtendGlobalTyVars ) -import TcInstDcls ( processInstBinds ) -import TcKind ( unifyKind, TcKind ) -import TcMonad hiding ( rnMtoTcM ) -import TcMonoType ( tcPolyType, tcMonoType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), tcInstType, tcInstSigTyVars, tcInstSigType ) +import TcHsSyn ( TcMonoBinds ) -import Bag ( foldBag, unionManyBags ) -import Class ( GenClass, mkClass, mkClassOp, classBigSig, - classOps, classOpString, classOpLocalType, - classOpTagByString, SYN_IE(ClassOp) +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod ) +import TcEnv ( TcIdOcc(..), tcAddImportedIdInfo, + tcLookupClass, tcLookupTyVar, + tcExtendGlobalTyVars, tcExtendLocalValEnv ) -import Id ( mkSuperDictSelId, mkMethodSelId, mkDefaultMethodId, - idType ) +import TcBinds ( tcBindWithSigs, checkSigTyVars, sigCtxt, tcPragmaSigs, TcSigInfo(..) ) +import TcKind ( unifyKinds, TcKind ) +import TcMonad +import TcMonoType ( tcHsType, tcContext ) +import TcSimplify ( tcSimplifyAndCheck ) +import TcType ( TcType, TcTyVar, TcTyVarSet, tcInstSigTyVars, + zonkSigTyVar, tcInstSigTcType + ) +import FieldLabel ( firstFieldLabelTag ) +import Bag ( unionManyBags ) +import Class ( mkClass, classBigSig, Class ) +import CmdLineOpts ( opt_GlasgowExts ) +import MkId ( mkDataCon, mkSuperDictSelId, + mkMethodSelId, mkDefaultMethodId + ) +import Id ( Id, StrictnessMark(..), + getIdUnfolding, idType, idName + ) +import CoreUnfold ( getUnfoldingTemplate ) import IdInfo -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 ( unitTyVarSet, GenTyVar ) -import Unique ( Unique ) +import Name ( Name, isLocallyDefined, OccName, nameOccName, + NamedThing(..) ) +import Outputable +import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, splitRhoTy, + mkSigmaTy, mkForAllTys, Type, ThetaType + ) +import TyVar ( mkTyVarSet, tyVarKind, TyVar ) +import TyCon ( mkDataTyCon ) +import Kind ( mkBoxedTypeKind, mkArrowKind ) +import Unique ( Unique, Uniquable(..) ) import Util +import Maybes ( assocMaybe, maybeToBool ) -- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo `addInfo` spec, +tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo, noIdInfo) \end{code} @@ -97,169 +100,149 @@ Death to "ExpandingDicts". \begin{code} -tcClassDecl1 rec_inst_mapper +tcClassDecl1 rec_env rec_inst_mapper (ClassDecl context class_name - tyvar_name class_sigs def_methods pragmas src_loc) + tyvar_names class_sigs def_methods pragmas + tycon_name datacon_name src_loc) = tcAddSrcLoc src_loc $ tcAddErrCtxt (classDeclCtxt class_name) $ + -- CHECK ARITY 1 FOR HASKELL 1.4 + checkTc (opt_GlasgowExts || length tyvar_names == 1) + (classArityErr class_name) `thenTc_` + -- 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 + tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) -> + mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names + `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) -> -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKind class_kind tyvar_kind `thenTc_` + unifyKinds class_kinds tyvar_kinds `thenTc_` -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvar context pragmas - `thenTc` \ (scs, sc_sel_ids) -> + tcClassContext rec_class rec_tyvars context pragmas + `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> -- 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 rec_tyvars) 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_sel_ids, defm_ids) = unzip3 sig_stuff + rec_class_inst_env = rec_inst_mapper rec_class + clas = mkClass (getName class_name) rec_tyvars + sc_theta sc_sel_ids op_sel_ids defm_ids + 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 - dict_con_id = mkDataCon class_name - [NotMarkedStrict] + dict_con_id = mkDataCon datacon_name + [NotMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] - [clas_tyvar] + rec_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 -}] + tycon = mkDataTyCon tycon_name + (foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars) + rec_tyvars + [] -- No context + [dict_con_id] -- Constructors + [] -- No derivings + (Just clas) -- Yes! It's a dictionary new_or_data + NonRecursive in + returnTc clas +\end{code} \begin{code} -tcClassContext :: Class -> TyVar +tcClassContext :: Class -> [TyVar] -> RenamedContext -- class context -> RenamedClassPragmas -- pragmas for superclasses - -> TcM s ([Class], -- the superclasses - [Id]) -- superclass selector Ids + -> TcM s (ThetaType, -- the superclass context + [Type], -- types of the superclass dictionaries + [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvar context pragmas +tcClassContext rec_class rec_tyvars context pragmas = -- Check the context. -- The renamer has already checked that the context mentions -- only the type variable of the class decl. - tcContext context `thenTc` \ theta -> + tcContext context `thenTc` \ sc_theta -> let - super_classes = [ supers | (supers, _) <- theta ] + sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_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 + -- We number them off, 1, 2, 3 etc so that we can construct + -- names for the selectors. Thus + -- class (C a, C b) => D a b where ... + -- gives superclass selectors + -- D_sc1, D_sc2 + -- (We used to call them D_C, but now we can have two different + -- superclasses both called C!) + mapTc mk_super_id (sc_theta `zip` [firstFieldLabelTag..]) `thenTc` \ sc_sel_ids -> -- 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 + rec_tyvar_tys = mkTyVarTys rec_tyvars + + mk_super_id ((super_class, tys), index) + = tcGetUnique `thenNF_Tc` \ uniq -> + let + ty = mkForAllTys rec_tyvars $ + mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys) + in + returnTc (mkSuperDictSelId uniq rec_class index ty) + + +tcClassSig :: TcEnv s -- Knot tying only! + -> Class -- ...ditto... + -> [TyVar] -- The class type variable, used for error check only -> RenamedClassOpSig - -> TcM s (ClassOp, -- class op + -> TcM s (Type, -- Type of the method Id, -- selector id - Id) -- default-method ids + Maybe Id) -- default-method ids -tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn - (ClassOpSig op_name +tcClassSig rec_env rec_clas rec_clas_tyvars + (ClassOpSig op_name maybe_dm_name op_ty - pragmas src_loc) + 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 -> + tcHsType op_ty `thenTc` \ local_ty -> let - global_ty = mkSigmaTy [rec_clas_tyvar] - [(rec_clas, mkTyVarTy rec_clas_tyvar)] + global_ty = mkSigmaTy rec_clas_tyvars + [(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 = mkMethodSelId op_name rec_clas global_ty + maybe_dm_id = case maybe_dm_name of + Nothing -> Nothing + Just dm_name -> let + dm_id = mkDefaultMethodId dm_name rec_clas global_ty + in + Just (tcAddImportedIdInfo rec_env dm_id) in - returnTc (class_op, sel_id, defm_id) - ) + returnTc (local_ty, sel_id, maybe_dm_id) \end{code} @@ -286,183 +269,56 @@ 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 s, TcMonoBinds s) tcClassDecls2 decls - = foldBag combine - tcClassDecl2 - (returnNF_Tc (emptyLIE, EmptyBinds)) - decls + = foldr combine + (returnNF_Tc (emptyLIE, EmptyMonoBinds)) + [tcClassDecl2 cls_decl | ClD cls_decl <- decls] 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) + -> NF_TcM s (LIE s, TcMonoBinds s) 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 $ + = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc src_loc $ -- Get the relevant class - tcLookupClass class_name `thenNF_Tc` \ (_, clas) -> + tcLookupClass class_name `thenTc` \ (_, clas) -> let - (tyvar, scs, sc_sel_ids, ops, op_sel_ids, defm_ids) - = classBigSig clas - in - tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], _, _) -> + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas - -- 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) -> + -- The selector binds are already in the selector Id's unfoldings + sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id)) + | sel_id <- sc_sel_ids ++ op_sel_ids, + isLocallyDefined sel_id + ] - returnTc (const_insts, sel_binds `ThenBinds` meth_binds) -\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 + final_sel_binds = andMonoBinds sel_binds 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. - + -- Generate bindings for the default methods + tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) -> - -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! - -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. - -\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 - )))) + returnTc (const_insts, + final_sel_binds `AndMonoBinds` meth_binds) \end{code} - %************************************************************************ %* * \subsection[Default methods]{Default methods} @@ -537,98 +393,151 @@ dfun.Foo.List \end{verbatim} \begin{code} -buildDefaultMethodBinds +tcDefaultMethodBinds :: Class - -> TcTyVar s - -> [Id] -> RenamedMonoBinds - -> TcM s (LIE s, TcHsBinds s) + -> TcM s (LIE s, TcMonoBinds s) -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) -> +tcDefaultMethodBinds clas default_binds + = -- Construct suitable signatures + tcInstSigTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) -> + + -- Typecheck the default bindings let - avail_insts = this_dict `plusLIE` unionManyBags insts_s -- Insts available - clas_tyvar_set = unitTyVarSet clas_tyvar - in - tcExtendGlobalTyVars clas_tyvar_set ( - processInstBinds - clas - (makeClassDeclDefaultMethodRhs clas local_defm_ids) - avail_insts - local_defm_ids - default_binds - ) `thenTc` \ (insts_needed, default_binds') -> + tc_dm meth_bind + = case [pair | pair@(sel_id,_) <- sel_ids_w_dms, + idName sel_id == bndr_name] of + [] -> -- Binding for something that isn't in the class signature + failWithTc (badMethodErr bndr_name clas) + + ((sel_id, Just dm_id):_) -> + -- We're looking at a default-method binding, so the dm_id + -- is sure to be there! Hence the inner "Just". + -- Normal case + + tcMethodBind clas origin inst_tys clas_tyvars + sel_id meth_bind [{- No prags -}] + `thenTc` \ (bind, insts, (_, local_dm_id)) -> + returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id)) + where + bndr_name = case meth_bind of + FunMonoBind name _ _ _ -> name + PatMonoBind (VarPatIn name) _ _ -> name + + in + mapAndUnzip3Tc tc_dm + (flatten default_binds []) `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) -> + + -- Check the context + newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + let + avail_insts = this_dict + in + tcAddErrCtxt (classDeclCtxt clas) $ + mapNF_Tc zonkSigTyVar clas_tyvars `thenNF_Tc` \ clas_tyvars' -> tcSimplifyAndCheck - clas_tyvar_set + (ptext SLIT("class") <+> ppr clas) + (mkTyVarSet clas_tyvars') avail_insts - insts_needed `thenTc` \ (const_lie, dict_binds) -> - + (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) -> let - defm_binds = AbsBinds - [clas_tyvar] + full_binds = AbsBinds + clas_tyvars' [this_dict_id] - (local_defm_ids `zip` map RealId default_method_ids) - dict_binds - (RecBind default_binds') + abs_bind_stuff + (dict_binds `AndMonoBinds` andMonoBinds defm_binds) in - returnTc (const_lie, defm_binds) + returnTc (const_lie, full_binds) + where - inst_ty = mkTyVarTy clas_tyvar - mk_method defm_id = newMethod origin (RealId defm_id) [inst_ty] + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas + sel_ids_w_dms = op_sel_ids `zip` defm_ids origin = ClassDeclOrigin + + flatten EmptyMonoBinds rest = rest + flatten (AndMonoBinds b1 b2) rest = flatten b1 (flatten b2 rest) + flatten a_bind rest = a_bind : rest \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 s + -> [TcType s] -- Instance types + -> [TcTyVar s] -- Free variables of those instance types + -- they'll be signature tyvars, and we + -- want to check that they don't bound + -> Id -- The method selector + -> RenamedMonoBinds -- Method binding (just one) + -> [RenamedSig] -- Pramgas (just for this one) + -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) + +tcMethodBind clas origin inst_tys inst_tyvars sel_id meth_bind prags + = tcAddSrcLoc src_loc $ + newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId meth_id) -> + tcInstSigTcType (idType meth_id) `thenNF_Tc` \ (tyvars', rho_ty') -> + let + (theta', tau') = splitRhoTy rho_ty' + sig_info = TySigInfo meth_name meth_id tyvars' theta' tau' src_loc + meth_name = idName meth_id + meth_bind' = case meth_bind of + FunMonoBind _ fix matches loc -> FunMonoBind meth_name fix matches loc + PatMonoBind (VarPatIn _) rhs loc -> PatMonoBind (VarPatIn meth_name) rhs loc + -- 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. + in + tcExtendLocalValEnv [meth_name] [meth_id] ( + tcPragmaSigs prags + ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> + + tcExtendGlobalTyVars inst_tyvars ( + tcAddErrCtxt (methodCtxt sel_id) $ + tcBindWithSigs NotTopLevel [meth_name] meth_bind' [sig_info] + NonRecursive prag_info_fn + ) `thenTc` \ (binds, insts, _) -> + + -- 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 + tcAddErrCtxt (monoCtxt sel_id) ( + tcAddErrCtxt (sigCtxt sel_id) $ + checkSigTyVars inst_tyvars (idType meth_id) + ) `thenTc_` + + returnTc (binds `AndMonoBinds` prag_binds, + insts `plusLIE` prag_lie, + meth) + where + src_loc = case meth_bind of + FunMonoBind name _ _ loc -> loc + PatMonoBind (VarPatIn name) _ loc -> loc +\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) +classDeclCtxt class_name + = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name) - error_msg = _UNPK_ clas_mod ++ "." ++ _UNPK_ clas_name ++ "." - ++ (ppShow 80 (ppr PprForUser class_op)) - ++ "\"" -\end{code} +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) +monoCtxt sel_id + = sep [ptext SLIT("Probable cause: the right hand side of") <+> quotes (ppr sel_id), + nest 4 (ptext SLIT("mentions a top-level variable subject to the dreaded monomorphism restriction")) + ] -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)] \end{code}