X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=be9a07384505d5351da0f11091abc5d64d4df7ae;hb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;hp=df5924d5fee7edef4e517557c0c80ee3072b0737;hpb=a77abe6a30ea2763cfa1c0ca83cdce9b7200ced2;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index df5924d..be9a073 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,206 +1,266 @@ % -% (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 ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where -import Ubiq +#include "HsVersions.h" -import HsSyn ( ClassDecl(..), HsBinds(..), Bind(..), MonoBinds(..), - Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..), - HsLit(..), OutPat(..), Sig(..), PolyType(..), MonoType, - Stmt, Qual, ArithSeqInfo, InPat, Fake ) +import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..), + InPat(..), HsBinds(..), GRHSsAndBinds(..), + HsExpr(..), HsLit(..), HsType(..), pprClassAssertion, + unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName + ) import HsPragmas ( ClassPragmas(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), RenamedMonoBinds(..), - RenamedGenPragmas(..), RenamedContext(..), - RnName{-instance Uniquable-} +import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) ) +import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcIdOcc(..), TcHsBinds(..), TcMonoBinds(..), TcExpr(..), - mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, unZonkId ) +import TcHsSyn ( TcMonoBinds ) +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod ) +import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcAddImportedIdInfo, + tcLookupClass, tcLookupTyVar, + tcExtendGlobalTyVars, tcExtendLocalValEnv + ) +import TcBinds ( tcBindWithSigs, tcPragmaSigs ) +import TcUnify ( unifyKinds ) import TcMonad -import Inst ( Inst, InstOrigin(..), LIE(..), emptyLIE, plusLIE, newDicts ) -import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds) -import TcInstDcls ( processInstBinds ) -import TcKind ( unifyKind ) -import TcMonoType ( tcMonoType, tcContext ) -import TcType ( TcType(..), TcTyVar(..), tcInstType, tcInstSigTyVars ) -import TcKind ( TcKind ) - -import Bag ( foldBag ) -import Class ( GenClass, mkClass, mkClassOp, classBigSig, - classOps, classOpString, classOpLocalType, - classOpTagByString +import TcMonoType ( tcHsType, tcContext, checkSigTyVars, sigCtxt, mkTcSig ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr ) +import PrelVals ( nO_METHOD_BINDING_ERROR_ID ) +import FieldLabel ( firstFieldLabelTag ) +import Bag ( unionManyBags ) +import Class ( mkClass, classBigSig, Class ) +import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import MkId ( mkSuperDictSelId, mkDataConId, + mkMethodSelId, mkDefaultMethodId + ) +import DataCon ( mkDataCon ) +import Id ( Id, + getIdUnfolding, idType, idName ) -import Id ( mkSuperDictSelId, mkMethodSelId, mkDefaultMethodId, - idType ) -import IdInfo ( noIdInfo ) -import Name ( isLocallyDefined, moduleNamePair, getLocalName ) -import PrelVals ( nO_DEFAULT_METHOD_ERROR_ID ) -import PprStyle -import Pretty -import PprType ( GenType, GenTyVar, GenClassOp ) -import SpecEnv ( SpecEnv(..) ) -import SrcLoc ( mkGeneratedSrcLoc ) +import CoreUnfold ( getUnfoldingTemplate ) +import IdInfo +import Name ( Name, isLocallyDefined, NamedThing(..) ) +import Outputable import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, - mkForAllTy, mkSigmaTy, splitSigmaTy) -import TysWiredIn ( stringTy ) -import TyVar ( GenTyVar ) -import Unique ( Unique ) + mkSigmaTy, mkForAllTys, Type, ThetaType, + boxedTypeKind, mkArrowKind + ) +import Var ( tyVarKind, TyVar ) +import VarSet ( mkVarSet ) +import TyCon ( mkAlgTyCon ) +import Unique ( Unique, Uniquable(..) ) import Util +import Maybes ( seqMaybe ) + -- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo, noIdInfo) - +tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo, + noIdInfo) \end{code} + + +Dictionary handling +~~~~~~~~~~~~~~~~~~~ +Every class implicitly declares a new data type, corresponding to dictionaries +of that class. So, for example: + + class (D a) => C a where + op1 :: a -> a + op2 :: forall b. Ord b => a -> b -> b + +would implicitly declare + + data CDict a = CDict (D a) + (a -> a) + (forall b. Ord b => a -> b -> b) + +(We could use a record decl, but that means changing more of the existing apparatus. +One step at at time!) + +For classes with just one superclass+method, we use a newtype decl instead: + + class C a where + op :: forallb. a -> b -> b + +generates + + newtype CDict a = CDict (forall b. a -> b -> b) + +Now DictTy in Type is just a form of type synomym: + DictTy c t = TyConTy CDict `AppTy` t + +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 class_name 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 --- BOGUS: --- tcGetUnique `thenNF_Tc` \ uniq -> 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 + + dict_component_tys = sc_tys ++ op_tys + new_or_data = case dict_component_tys of + [_] -> NewType + other -> DataType + + dict_con = mkDataCon datacon_name + [NotMarkedStrict | _ <- dict_component_tys] + [{- No labelled fields -}] + rec_tyvars + [{-No context-}] + [{-No existential tyvars-}] [{-Or context-}] + dict_component_tys + tycon dict_con_id + dict_con_id = mkDataConId dict_con + + tycon = mkAlgTyCon tycon_name + (foldr (mkArrowKind . tyVarKind) boxedTypeKind rec_tyvars) + rec_tyvars + [] -- No context + [dict_con] -- 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 :: Name -> 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 class_name 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 -> + + -- 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 - 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 -> + -- 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 - ty = mkForAllTy rec_tyvar ( - mkFunTy (mkDictTy rec_class (mkTyVarTy rec_tyvar)) - (mkDictTy super_class (mkTyVarTy rec_tyvar)) - ) - 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) + + check_constraint (c, tys) = checkTc (all is_tyvar tys) + (superClassErr class_name (c, tys)) + + is_tyvar (MonoTyVar _) = True + is_tyvar other = False + + +tcClassSig :: GlobalValueEnv -- 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 - (HsForAllTy tyvar_names context monotype) - pragmas src_loc) +tcClassSig rec_env rec_clas rec_clas_tyvars + (ClassOpSig op_name maybe_dm_name + 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. - tcContext context `thenTc` \ theta -> - tcMonoType monotype `thenTc` \ tau -> - mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (_,tyvars) -> + + -- NB: Renamer checks that the class type variable is mentioned in local_ty, + -- and that it is not constrained by theta + tcHsType op_ty `thenTc` \ local_ty -> let - full_tyvars = rec_clas_tyvar : tyvars - full_theta = (rec_clas, mkTyVarTy rec_clas_tyvar) : theta - global_ty = mkSigmaTy full_tyvars full_theta tau - local_ty = mkSigmaTy tyvars theta tau - class_op_nm = getLocalName op_name - class_op = mkClassOp class_op_nm - (classOpTagByString rec_clas{-yeeps!-} class_op_nm) - local_ty + global_ty = mkSigmaTy rec_clas_tyvars + [(rec_clas, mkTyVarTys rec_clas_tyvars)] + 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} @@ -227,183 +287,59 @@ 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) -> - 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) -\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 + tcLookupClass class_name `thenTc` \ (_, clas) -> let - clas_tyvar_ty = mkTyVarTy clas_tc_tyvar - mk_op_ty = tcInstType [(clas_tyvar, clas_tyvar_ty)] . classOpLocalType + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas + + -- 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 +-- ] +-- +-- final_sel_binds = andMonoBindList sel_binds 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) -> + -- Generate bindings for the default methods + tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) -> - 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_sel op_sel_ids method_ids) `thenNF_Tc` \ op_sel_binds -> - listNF_Tc (zipWithEqual 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 - ))) + returnTc (const_insts, meth_binds) +-- final_sel_binds `AndMonoBinds` meth_binds) +-- Leave 'em out for now. They always get inlined anyway. SLPJ June '98 \end{code} %************************************************************************ %* * -\subsection[ClassDcl-misc]{Miscellaneous} -%* * -%************************************************************************ - -Make a selector expression for @sel_id@ from a dictionary @clas_dict@ -consisting of @dicts@ and @methods@. - -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} - -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) - = let - (op_tyvars,op_theta,op_tau) = splitSigmaTy (idType op) - op_tys = mkTyVarTys op_tyvars - in - newDicts ClassDeclOrigin op_theta `thenNF_Tc` \ (_, op_dicts) -> - - -- sel_id = /\ clas_tyvar op_tyvars -> \ clas_dict op_dicts -> - -- case clas_dict of - -- -> method_or_dict op_tyvars op_dicts - - returnNF_Tc (VarMonoBind (RealId sel_id) ( - TyLam (clas_tyvar:op_tyvars) ( - DictLam (clas_dict:op_dicts) ( - HsCase - (HsVar clas_dict) - ([PatMatch (DictPat dicts methods) ( - GRHSMatch (GRHSsAndBindsOut - [OtherwiseGRHS - (mkHsDictApp (mkHsTyApp (HsVar method_or_dict) op_tys) op_dicts) - mkGeneratedSrcLoc] - EmptyBinds - op_tau))]) - mkGeneratedSrcLoc - )))) -\end{code} - - -%************************************************************************ -%* * \subsection[Default methods]{Default methods} %* * %************************************************************************ @@ -424,11 +360,22 @@ 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: @@ -441,14 +388,15 @@ const.Foo.Int.op1 :: Int -> Bool const.Foo.Int.op1 = defm.Foo.op1 Int dfun.Foo.Int const.Foo.Int.op2 :: forall b. Ord b => Int -> b -> b -> b -const.Foo.Int.op2 = /\b -> defm.Foo.op2 Int b dfun.Foo.Int +const.Foo.Int.op2 = defm.Foo.op2 Int dfun.Foo.Int dfun.Foo.Int :: Foo Int dfun.Foo.Int = (const.Foo.Int.op1, const.Foo.Int.op2) \end{verbatim} Notice that, as with method selectors above, we assume that dictionary application is curried, so there's no need to mention the Ord dictionary -in const.Foo.Int.op2 +in const.Foo.Int.op2 (or the type variable). + \begin{verbatim} instance Foo a => Foo [a] where {} @@ -457,71 +405,210 @@ dfun.Foo.List = /\ a -> \ dfoo_a -> let rec op1 = defm.Foo.op1 [a] dfoo_list - op2 = /\b -> \dord -> defm.Foo.op2 [a] b dfoo_list dord + op2 = defm.Foo.op2 [a] dfoo_list dfoo_list = (op1, op2) in dfoo_list \end{verbatim} \begin{code} -buildDefaultMethodBinds +tcDefaultMethodBinds :: Class - -> TcTyVar s - -> [Id] -> RenamedMonoBinds - -> TcM s (LIE s, TcHsBinds s) - -buildDefaultMethodBinds clas clas_tyvar - default_method_ids default_binds - = -- Deal with the method declarations themselves - mapNF_Tc unZonkId default_method_ids `thenNF_Tc` \ tc_defm_ids -> - processInstBinds - clas - (makeClassDeclDefaultMethodRhs clas default_method_ids) - [] -- No tyvars in scope for "this inst decl" - emptyLIE -- No insts available - (map TcId tc_defm_ids) - default_binds `thenTc` \ (dicts_needed, default_binds') -> - - returnTc (dicts_needed, SingleBind (NonRecBind default_binds')) -\end{code} + -> TcM s (LIE s, TcMonoBinds s) -@makeClassDeclDefaultMethodRhs@ builds the default method for a -class declaration when no explicit default method is given. +tcDefaultMethodBinds clas default_binds + = -- Construct suitable signatures + tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) -> + + -- Typecheck the default bindings + let + tc_dm sel_id_w_dm@(_, Just dm_id) + = tcMethodBind clas origin inst_tys clas_tyvars + default_binds [{-no prags-}] False + sel_id_w_dm `thenTc` \ (bind, insts, (_, local_dm_id)) -> + returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id)) + in + mapAndUnzip3Tc tc_dm sel_ids_w_dms `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) $ + + -- tcMethodBind has checked that the class_tyvars havn't + -- been unified with each other or another type, but we must + -- still zonk them + mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' -> + + tcSimplifyAndCheck + (ptext SLIT("class") <+> ppr clas) + (mkVarSet clas_tyvars') + avail_insts + (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) -> + + let + full_binds = AbsBinds + clas_tyvars' + [this_dict_id] + abs_bind_stuff + (dict_binds `andMonoBinds` andMonoBindList defm_binds) + in + returnTc (const_lie, full_binds) -\begin{code} -makeClassDeclDefaultMethodRhs - :: Class - -> [Id] - -> Int - -> NF_TcM s (TcExpr s) - -makeClassDeclDefaultMethodRhs clas method_ids tag - = tcInstType [] (idType method_id) `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)))) where - (clas_mod, clas_name) = moduleNamePair clas + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas - method_id = method_ids !! (tag-1) - class_op = (classOps clas) !! (tag-1) + sel_ids_w_dms = [pair | pair@(_, Just _) <- op_sel_ids `zip` defm_ids] + -- Just the ones for which there is an explicit + -- user default declaration - error_msg = _UNPK_ clas_mod ++ "." ++ _UNPK_ clas_name ++ "." - ++ (ppShow 80 (ppr PprForUser class_op)) - ++ "\"" + origin = ClassDeclOrigin \end{code} +@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. -Contexts -~~~~~~~~ \begin{code} -classDeclCtxt class_name sty - = ppCat [ppStr "In the class declaration for", ppr sty class_name] +tcMethodBind + :: Class + -> 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 + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> [RenamedSig] -- Pramgas (just for this one) + -> Bool -- True <=> supply default decl if no explicit decl + -- This is true for instance decls, + -- false for class decls + -> (Id, Maybe Id) -- The method selector and default-method Id + -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) + +tcMethodBind clas origin inst_tys inst_tyvars + meth_binds prags supply_default_bind + (sel_id, maybe_dm_id) + = tcGetSrcLoc `thenNF_Tc` \ loc -> + + newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId 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} + no_user_default = case maybe_dm_id 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 + if no_user_bind && not supply_default_bind then + pprPanic "tcMethodBind" (ppr clas <+> ppr inst_tys) + else + warnTc (opt_WarnMissingMethods && no_user_bind && no_user_default) + (omittedMethodWarn sel_id clas) `thenNF_Tc_` + + -- Check the pragmas + tcExtendLocalValEnv [meth_name] [meth_id] ( + tcPragmaSigs meth_prags + ) `thenTc` \ (prag_info_fn, prag_binds1, prag_lie) -> + + -- Check the bindings + tcExtendGlobalTyVars (mkVarSet inst_tyvars) ( + tcAddErrCtxt (methodCtxt sel_id) $ + tcBindWithSigs NotTopLevel meth_bind [sig_info] + NonRecursive prag_info_fn + ) `thenTc` \ (binds, insts, _) -> + + + -- 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 (quotes (ppr sel_id)) (idType meth_id)) ( + checkSigTyVars inst_tyvars `thenTc_` + + returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2, + insts `plusLIE` prag_lie', + meth)) + + where + 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 (PatMonoBind (VarPatIn op_name) rhs loc) + | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) rhs 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 spec loc : prags) + | name == sel_name = SpecSig meth_name ty spec loc : find_prags meth_name prags + find_prags meth_name (InlineSig name loc : prags) + | name == sel_name = InlineSig meth_name loc : find_prags meth_name prags + find_prags meth_name (NoInlineSig name loc : prags) + | name == sel_name = NoInlineSig meth_name loc : find_prags meth_name prags + find_prags meth_name (prag:prags) = find_prags meth_name prags + + mk_default_bind local_meth_name loc + = PatMonoBind (VarPatIn local_meth_name) + (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds) + loc + + default_expr loc + = case maybe_dm_id of + Just dm_id -> HsVar (getName dm_id) -- There's a default method + Nothing -> 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} + +Contexts and errors +~~~~~~~~~~~~~~~~~~~ +\begin{code} +classArityErr class_name + = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) + +classDeclCtxt class_name + = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name) + +superClassErr class_name sc + = ptext SLIT("Illegal superclass constraint") <+> quotes (pprClassAssertion sc) + <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name) + +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) + +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}