X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=be9a07384505d5351da0f11091abc5d64d4df7ae;hb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;hp=a890255ed1b71dc1c4235d338837ba13ac642036;hpb=68a1f0233996ed79824d11d946e9801473f6946c;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index a890255..be9a073 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,192 +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 ( - tcClassDecls1, tcClassDecls2, - ClassInfo -- abstract - ) where +module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where -IMPORT_Trace -- ToDo: rm (debugging) -import Pretty -- add proper one below +#include "HsVersions.h" -import TcMonad -- typechecking monad machinery -import TcMonadFns ( newDicts, newClassOpLocals, copyTyVars ) -import AbsSyn -- the stuff being typechecked +import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..), + InPat(..), HsBinds(..), GRHSsAndBinds(..), + HsExpr(..), HsLit(..), HsType(..), pprClassAssertion, + unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName + ) +import HsPragmas ( ClassPragmas(..) ) +import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) ) +import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig + ) +import TcHsSyn ( TcMonoBinds ) -import AbsPrel ( pAT_ERROR_ID ) -import AbsUniType ( mkClass, getClassKey, getClassBigSig, - getClassOpString, getClassOps, splitType, - mkSuperDictSelType, InstTyEnv(..), - instantiateTy, instantiateThetaTy, UniType +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 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 BackSubst ( applyTcSubstToBinds ) -import CE -- ( nullCE, unitCE, plusCE, CE(..), UniqFM ) -import E ( mkE, getE_TCE, getE_CE, tvOfE, nullGVE, plusGVE, E, TCE(..), UniqFM, GVE(..) ) -import Errors ( confusedNameErr, Error(..) ) -import HsPragmas -- ****** NEED TO SEE CONSTRUCTORS ****** -import Id ( mkSuperDictSelId, mkInstId, getIdUniType, - Id, DictFun(..) +import DataCon ( mkDataCon ) +import Id ( Id, + getIdUnfolding, idType, idName ) +import CoreUnfold ( getUnfoldingTemplate ) import IdInfo -import Inst ( InstOrigin(..), Inst ) -import InstEnv -import LIE ( nullLIE, mkLIE, plusLIE, LIE ) -import Maybes ( Maybe(..) ) -import Name ( Name(..) ) -import PlainCore ( escErrorMsg ) -import Spec ( specTy ) -import TVE ( mkTVE, TVE(..) - IF_ATTACK_PRAGMAS(COMMA u2i) +import Name ( Name, isLocallyDefined, NamedThing(..) ) +import Outputable +import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, + mkSigmaTy, mkForAllTys, Type, ThetaType, + boxedTypeKind, mkArrowKind ) -import TcClassSig ( tcClassSigs ) -import TcContext ( tcContext ) -import TcInstDcls ( processInstBinds ) -import TcPragmas ( tcGenPragmas ) +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 (spec `setSpecInfo` noIdInfo, + noIdInfo) \end{code} -@ClassInfo@ communicates the essential information about -locally-defined classes between passes 1 and 2. + + +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} -data ClassInfo - = ClassInfo Class - RenamedMonoBinds +tcClassDecl1 rec_env rec_inst_mapper + (ClassDecl context class_name + 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 `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 + unifyKinds class_kinds tyvar_kinds `thenTc_` + + -- CHECK THE CONTEXT + tcClassContext class_name rec_class rec_tyvars context pragmas + `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> + + -- CHECK THE CLASS SIGNATURES, + mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs + `thenTc` \ sig_stuff -> + + -- MAKE THE CLASS OBJECT ITSELF + let + (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} -%************************************************************************ -%* * -\subsection[TcClassDcl]{Does the real work (apart from default methods)} -%* * -%************************************************************************ - \begin{code} -tcClassDecls1 - :: E -- Consult the CE/TCE args only to build knots - -> InstanceMapper -- Maps class name to its instances, - -- ...and its ops to their instances, - -> [RenamedClassDecl] - -> TcM ([ClassInfo], -- boiled-down info related to classes - CE, -- env so we can look up classes elsewhere - GVE) -- env so we can look up class ops elsewhere - -tcClassDecls1 e rec_inst_mapper [] - = returnTc ([], nullCE, nullGVE) - -tcClassDecls1 e rec_inst_mapper (cd:cds) - = tc_clas1 cd `thenTc` \ (cinfo1_maybe, ce1, gve1) -> - tcClassDecls1 e rec_inst_mapper cds `thenTc` \ (cinfo2, ce2, gve2) -> +tcClassContext :: Name -> Class -> [TyVar] + -> RenamedContext -- class context + -> RenamedClassPragmas -- pragmas for superclasses + -> TcM s (ThetaType, -- the superclass context + [Type], -- types of the superclass dictionaries + [Id]) -- superclass selector Ids + +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. + + -- 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 - glued_cinfos - = case cinfo1_maybe of - Nothing -> cinfo2 - Just xx -> xx : cinfo2 + sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta] in - returnTc (glued_cinfos, ce1 `plusCE` ce2, gve1 `plusGVE` gve2) - where - rec_ce = getE_CE e - rec_tce = getE_TCE e - tc_clas1 (ClassDecl context class_name - tyvar_name class_sigs def_methods pragmas src_loc) + -- Make super-class selector 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 -> - = addSrcLocTc src_loc ( + -- Done + returnTc (sc_theta, sc_tys, sc_sel_ids) - -- The knot is needed so that the signatures etc can point - -- back to the class itself - fixTc (\ ~(rec_clas, _) -> - let - (rec_clas_inst_env, rec_class_op_inst_fn) = rec_inst_mapper rec_clas - in - -- Get new (template) type variables for the class - let (tve, [clas_tyvar], [alpha]) = mkTVE [tyvar_name] in - - -- Typecheck the class context; since there is only one type - -- variable in scope, we are assured that the it will be of - -- the form (C1 a, C2 a...) - babyTcMtoTcM (tcContext rec_ce rec_tce tve context) `thenTc` \ theta -> - - -- Make the superclass selector ids; the "class" pragmas - -- may have info about the superclass dict selectors; - -- so it is only tcClassPragmas that gives back the - -- final Ids. - getUniquesTc (length theta) `thenNF_Tc` \ uniqs -> - let - super_classes = [ supers | (supers, _) <- theta ] - super_tys - = [ mkSuperDictSelType rec_clas super | super <- super_classes ] - super_info = zip3 super_classes uniqs super_tys - in - (case pragmas of - NoClassPragmas -> - returnNF_Tc [ mk_super_id rec_clas info noIdInfo | info <- super_info ] - - SuperDictPragmas prags -> --- pprTrace "SuperDictPragmas:" (ppAboves (ppr PprDebug prags : map pp super_info)) ( - mapNF_Tc (mk_super_id_w_info rec_clas) (super_info `zipEqual` prags) --- ) --- where --- pp (sc, u, ty) = ppCat [ppr PprDebug sc, ppr PprDebug ty] - - ) `thenNF_Tc` \ super_class_sel_ids -> - - -- Typecheck the class signatures, checking that each mentions - -- the class type variable somewhere, and manufacturing - -- suitable Ids for selectors and default methods. - babyTcMtoTcM - (tcClassSigs e tve rec_clas rec_class_op_inst_fn - clas_tyvar defm_names class_sigs) - `thenTc` \ (ops, ops_gve, op_sel_ids, defm_ids) -> - - -- Make the class object itself, producing clas::Class + where + rec_tyvar_tys = mkTyVarTys rec_tyvars + + mk_super_id ((super_class, tys), index) + = tcGetUnique `thenNF_Tc` \ uniq -> let - clas - = mkClass class_name clas_tyvar - super_classes super_class_sel_ids - ops op_sel_ids defm_ids - rec_clas_inst_env + ty = mkForAllTys rec_tyvars $ + mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys) in - returnTc (clas, ops_gve) - ) `thenTc` \ (clas, ops_gve) -> - - -- Return the class decl for further work if it is - -- local, otherwise just return the CE - returnTc (if (isLocallyDefined class_name) then - Just (ClassInfo clas def_methods) - else - Nothing, - unitCE (getClassKey clas) clas, - ops_gve - )) - where - defm_names = collectMonoBinders def_methods - - ----------- - mk_super_id clas (super_clas, uniq, ty) id_info - = mkSuperDictSelId uniq clas super_clas ty id_info - - ----------- - mk_super_id_w_info clas ((super_clas, uniq, ty), gen_prags) - = fixNF_Tc ( \ rec_super_id -> - babyTcMtoNF_TcM - (tcGenPragmas e{-fake_E-} Nothing{-ty unknown-} rec_super_id gen_prags) - `thenNF_Tc` \ id_info -> - - returnNF_Tc(mkSuperDictSelId uniq clas super_clas ty id_info) - ) - -{- SOMETHING LIKE THIS NEEDED? ToDo [WDP] - tc_clas1 (ClassDecl _ bad_name _ _ _ _ src_loc) - = failTc (confusedNameErr - "Bad name for a class (a type constructor, or Prelude name?)" - bad_name src_loc) --} + 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 (Type, -- Type of the method + Id, -- selector id + Maybe Id) -- default-method ids + +tcClassSig rec_env rec_clas rec_clas_tyvars + (ClassOpSig op_name maybe_dm_name + op_ty + src_loc) + = tcAddSrcLoc src_loc $ + + -- 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 + tcHsType op_ty `thenTc` \ local_ty -> + let + global_ty = mkSigmaTy rec_clas_tyvars + [(rec_clas, mkTyVarTys rec_clas_tyvars)] + local_ty + in + + -- Build the selector id and default method id + let + 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 (local_ty, sel_id, maybe_dm_id) \end{code} @@ -204,192 +278,65 @@ using them to produce a complete set of default-method decls. (Omitted ones elicit an error message.) \item to produce a definition for the selector function for each method +and superclass dictionary. \end{enumerate} Pass~2 only applies to locally-defined class declarations. -The function @tcClassDecls2@ just arranges to apply -@tcClassDecls2_help@ to each local class decl. +The function @tcClassDecls2@ just arranges to apply @tcClassDecl2@ to +each local class decl. \begin{code} -tcClassDecls2 e class_info - = let - -- Get type variables free in environment. Sadly, there may be - -- some, because of the dreaded monomorphism restriction - free_tyvars = tvOfE e - in - tcClassDecls2_help e free_tyvars class_info +tcClassDecls2 :: [RenamedHsDecl] + -> NF_TcM s (LIE s, TcMonoBinds s) -tcClassDecls2_help - :: E - -> [TyVar] - -> [ClassInfo] - -> NF_TcM (LIE, TypecheckedBinds) - -tcClassDecls2_help e free_tyvars [] = returnNF_Tc (nullLIE, EmptyBinds) - -tcClassDecls2_help e free_tyvars ((ClassInfo clas default_binds) : rest) - = tcClassDecl2 e free_tyvars clas default_binds `thenNF_Tc` \ (lie1, binds1) -> - tcClassDecls2_help e free_tyvars rest `thenNF_Tc` \ (lie2, binds2) -> - returnNF_Tc (lie1 `plusLIE` lie2, binds1 `ThenBinds` binds2) +tcClassDecls2 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 `AndMonoBinds` binds2) \end{code} @tcClassDecl2@ is the business end of things. \begin{code} -tcClassDecl2 :: E - -> [TyVar] -- Free in the envt - -> Class - -> RenamedMonoBinds -- The default decls - -> NF_TcM (LIE, TypecheckedBinds) - -tcClassDecl2 e free_tyvars clas default_binds - = let - src_loc = getSrcLoc clas - origin = ClassDeclOrigin src_loc - (clas_tyvar_tmpl, scs, sc_sel_ids, ops, op_sel_ids, defm_ids) - = getClassBigSig clas - in - -- Prune the substitution when we are finished, and arrange error recovery - recoverTc (nullLIE, EmptyBinds) ( - addSrcLocTc src_loc ( - pruneSubstTc free_tyvars ( - - -- Generate bindings for the selector functions - buildSelectors origin clas clas_tyvar_tmpl scs sc_sel_ids ops op_sel_ids - `thenNF_Tc` \ sel_binds -> - -- Ditto for the methods - buildDefaultMethodBinds e free_tyvars origin clas clas_tyvar_tmpl - defm_ids default_binds `thenTc` \ (const_insts, meth_binds) -> - - -- Back-substitute through the definitions - applyTcSubstToInsts const_insts `thenNF_Tc` \ final_const_insts -> - applyTcSubstToBinds (sel_binds `ThenBinds` meth_binds) `thenNF_Tc` \ final_binds -> - returnTc (mkLIE final_const_insts, final_binds) - ))) -\end{code} +tcClassDecl2 :: RenamedClassDecl -- The class declaration + -> NF_TcM s (LIE s, TcMonoBinds s) -%************************************************************************ -%* * -\subsection[ClassDcl-bld-sels]{Building the selector functions for methods and superclasses} -%* * -%************************************************************************ +tcClassDecl2 (ClassDecl context class_name + tyvar_names class_sigs default_binds pragmas _ _ src_loc) -\begin{code} -buildSelectors :: InstOrigin - -> Class -- The class object - -> TyVarTemplate -- Class type variable - -> [Class] -> [Id] -- Superclasses and selectors - -> [ClassOp] -> [Id] -- Class ops and selectors - -> NF_TcM TypecheckedBinds - -buildSelectors origin clas clas_tyvar_tmpl - scs sc_sel_ids - ops op_sel_ids - = - -- Instantiate the class variable - copyTyVars [clas_tyvar_tmpl] `thenNF_Tc` \ (inst_env, [clas_tyvar], [clas_tyvar_ty]) -> - -- Make an Inst for each class op, and - -- dicts for the superclasses. These are used to - -- construct the selector functions - newClassOpLocals inst_env ops `thenNF_Tc` \ method_ids -> - newDicts origin [ (super_clas, clas_tyvar_ty) - | super_clas <- scs - ] `thenNF_Tc` \ dicts -> - let dict_ids = map mkInstId dicts in - - -- Make suitable bindings for the selectors - let mk_op_sel op sel_id method_id - = mkSelExpr origin clas_tyvar dict_ids method_ids method_id `thenNF_Tc` \ rhs -> - returnNF_Tc (VarMonoBind sel_id rhs) - mk_sc_sel sc sel_id dict_id - = mkSelExpr origin clas_tyvar dict_ids method_ids dict_id `thenNF_Tc` \ rhs -> - returnNF_Tc (VarMonoBind sel_id rhs) - in - listNF_Tc (zipWith3 mk_op_sel ops op_sel_ids method_ids) `thenNF_Tc` \ op_sel_binds -> - listNF_Tc (zipWith3 mk_sc_sel scs sc_sel_ids dict_ids) `thenNF_Tc` \ sc_sel_binds -> + | not (isLocallyDefined class_name) + = returnNF_Tc (emptyLIE, EmptyMonoBinds) - returnNF_Tc (SingleBind ( - NonRecBind ( - foldr AndMonoBinds EmptyMonoBinds ( - op_sel_binds ++ sc_sel_binds)))) -\end{code} - -%************************************************************************ -%* * -\subsection[ClassDcl-misc]{Miscellaneous} -%* * -%************************************************************************ - -Make a selector expression for @local@ from a dictionary consisting of -@dicts@ and @op_locals@. - -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 = /\ab -> \dFoo -> case dFoo of - (op1_method,op2_method) -> op1_method b -\end{verbatim} -Note that the type variable for \tr{b} is lifted to the top big lambda, and -\tr{op1_method} is applied to it. 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} - -{\em NOTE:} -We could do the same thing for the dictionaries, giving -\begin{verbatim} - op1_sel = /\ab -> \dFoo -> \dOrd -> case dFoo of - (m1,m2) -> m1 b dOrd -\end{verbatim} -but WE ASSUME THAT DICTIONARY APPLICATION IS CURRIED, so the two are -precisely equivalent, and have the same type, namely -\begin{verbatim} - op1_sel :: forall a b. Foo a -> Ord b -> a -> b -> a -\end{verbatim} + | otherwise -- It is locally defined + = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc src_loc $ -WDP 95/03: Quite false (``DICTIONARY APPLICATION IS CURRIED''). -Specialisation now wants to see all type- and dictionary-applications -absolutely explicitly. - -\begin{code} -mkSelExpr :: InstOrigin -> TyVar -> [Id] -> [Id] -> Id -> NF_TcM TypecheckedExpr - -mkSelExpr origin clas_tyvar dicts op_locals local - = let - (op_tyvar_tmpls,local_theta,_) = splitType (getIdUniType local) - in - copyTyVars op_tyvar_tmpls `thenNF_Tc` \ (inst_env, op_tyvars, tys) -> + -- Get the relevant class + tcLookupClass class_name `thenTc` \ (_, clas) -> let - inst_theta = instantiateThetaTy inst_env local_theta + (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 - newDicts origin inst_theta `thenNF_Tc` \ local_dict_insts -> - let - local_dicts = map mkInstId local_dict_insts - in - returnNF_Tc (TyLam (clas_tyvar:op_tyvars) - (ClassDictLam - dicts - op_locals - (mkDictLam local_dicts - (mkDictApp (mkTyApp (Var local) tys) local_dicts)))) -\end{code} + -- Generate bindings for the default methods + tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_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} %************************************************************************ %* * @@ -413,11 +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: @@ -430,14 +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 {} @@ -446,66 +405,210 @@ dfun.Foo.List = /\ a -> \ dfoo_a -> let rec op1 = defm.Foo.op1 [a] dfoo_list - op2 = /\b -> defm.Foo.op2 [a] b dfoo_list + op2 = defm.Foo.op2 [a] dfoo_list dfoo_list = (op1, op2) in dfoo_list \end{verbatim} \begin{code} -buildDefaultMethodBinds - :: E - -> [TyVar] - -> InstOrigin - -> Class - -> TyVarTemplate - -> [Id] +tcDefaultMethodBinds + :: Class -> RenamedMonoBinds - -> TcM ([Inst], TypecheckedBinds) - -buildDefaultMethodBinds e free_tyvars origin clas clas_tyvar_tmpl - default_method_ids default_binds - = -- Deal with the method declarations themselves - processInstBinds e - free_tyvars - (makeClassDeclDefaultMethodRhs clas origin default_method_ids) - [] -- No tyvars in scope for "this inst decl" - [] -- No insts available - default_method_ids - default_binds `thenTc` \ (dicts_needed, default_binds') -> - - returnTc (dicts_needed, SingleBind (NonRecBind default_binds')) + -> TcM s (LIE s, TcMonoBinds s) + +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) + + where + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas + + 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 + + origin = ClassDeclOrigin \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 - -> InstOrigin - -> [Id] - -> Int - -> NF_TcM TypecheckedExpr - -makeClassDeclDefaultMethodRhs clas origin method_ids tag - = specTy origin (getIdUniType method_id) `thenNF_Tc` \ (tyvars, dicts, tau) -> - - returnNF_Tc (mkTyLam tyvars ( - mkDictLam (map mkInstId dicts) ( - App (mkTyApp (Var pAT_ERROR_ID) [tau]) - (Lit (StringLit (_PK_ error_msg)))))) - where - method_id = method_ids !! (tag-1) - class_op = (getClassOps clas) !! (tag-1) + -> 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) - error_msg = "%D" -- => No default method for \" - ++ unencoded_part_of_msg +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) - unencoded_part_of_msg = escErrorMsg ( - _UNPK_ clas_mod ++ "." ++ _UNPK_ clas_name ++ "." - ++ (ppShow 80 (ppr PprForUser class_op)) - ++ "\"" ) +badMethodErr bndr clas + = hsep [ptext SLIT("Class"), quotes (ppr clas), + ptext SLIT("does not have a method"), quotes (ppr bndr)] - (clas_mod, clas_name) = getOrigName clas +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}