X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=97e5d5b99e29bb7b43e36bb07a5f392f88072ae2;hb=17985eb4007ae2415a97335b26fabc82fc38521f;hp=3994e93952ab2bc9a97d14967ea00554e34bdd2d;hpb=788faebb40b51d37e73ed94dfc99460d39a1a811;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 3994e93..97e5d5b 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -4,23 +4,22 @@ \section[TcClassDcl]{Typechecking class declarations} \begin{code} -module TcClassDcl ( tcClassDecl1, tcClassDecls2, +module TcClassDcl ( tcClassDecl1, checkValidClass, tcClassDecls2, tcMethodBind, badMethodErr ) where #include "HsVersions.h" import HsSyn ( TyClDecl(..), Sig(..), MonoBinds(..), - HsExpr(..), HsLit(..), HsType(..), HsPred(..), + HsExpr(..), HsLit(..), mkSimpleMatch, andMonoBinds, andMonoBindList, isClassOpSig, isPragSig, - getClassDeclSysNames, + getClassDeclSysNames, placeHolderType ) -import BasicTypes ( TopLevelFlag(..), RecFlag(..) ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..), StrictnessMark(..) ) import RnHsSyn ( RenamedTyClDecl, RenamedClassOpSig, RenamedMonoBinds, - RenamedContext, RenamedSig, - maybeGenericMatch + RenamedSig, maybeGenericMatch ) import TcHsSyn ( TcMonoBinds ) @@ -31,25 +30,25 @@ import TcEnv ( RecTcEnv, TyThingDetails(..), tcAddImportedIdInfo, tcExtendLocalValEnv, tcExtendTyVarEnv ) import TcBinds ( tcBindWithSigs, tcSpecSigs ) -import TcMonoType ( tcHsRecType, tcRecTheta, checkSigTyVars, checkAmbiguity, sigCtxt, mkTcSig ) +import TcMonoType ( tcHsType, tcHsTheta, checkSigTyVars, sigCtxt, mkTcSig ) import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns ) -import TcType ( TcType, TcTyVar, tcInstTyVars ) +import TcMType ( tcInstTyVars, checkValidTheta, checkValidType, SourceTyCtxt(..), UserTypeCtxt(..) ) +import TcType ( Type, mkSigmaTy, mkTyVarTys, mkPredTys, mkClassPred, + tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitSigmaTy + ) import TcMonad import Generics ( mkGenericRhs, validGenericMethodType ) import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) -import Class ( classTyVars, classBigSig, classTyCon, +import Class ( classTyVars, classBigSig, classTyCon, className, Class, ClassOpItem, DefMeth (..) ) import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) -import DataCon ( mkDataCon, notMarkedStrict ) -import Id ( Id, idType, idName ) +import DataCon ( mkDataCon ) +import Id ( idType, idName ) import Module ( Module ) import Name ( Name, NamedThing(..) ) -import NameEnv ( NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv, nameEnvElts ) +import NameEnv ( NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv ) import NameSet ( emptyNameSet ) import Outputable -import Type ( Type, ThetaType, mkTyVarTys, mkPredTys, mkClassPred, - splitTyConApp_maybe, isTyVarTy - ) import Var ( TyVar ) import VarSet ( mkVarSet, emptyVarSet ) import CmdLineOpts @@ -101,21 +100,13 @@ Death to "ExpandingDicts". \begin{code} -tcClassDecl1 :: RecFlag -> RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails) -tcClassDecl1 is_rec rec_env +tcClassDecl1 :: RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails) +tcClassDecl1 rec_env (ClassDecl {tcdCtxt = context, tcdName = class_name, tcdTyVars = tyvar_names, tcdFDs = fundeps, tcdSigs = class_sigs, tcdMeths = def_methods, tcdSysNames = sys_names, tcdLoc = src_loc}) - = -- CHECK ARITY 1 FOR HASKELL 1.4 - doptsTc Opt_GlasgowExts `thenTc` \ gla_ext_opt -> - let - gla_exts = gla_ext_opt || not (maybeToBool def_methods) - -- Accept extensions if gla_exts is on, - -- or if we're looking at an interface file decl - in -- (in which case def_methods = Nothing - - -- LOOK THINGS UP IN THE ENVIRONMENT + = -- LOOK THINGS UP IN THE ENVIRONMENT tcLookupClass class_name `thenTc` \ clas -> let tyvars = classTyVars clas @@ -125,34 +116,27 @@ tcClassDecl1 is_rec rec_env in tcExtendTyVarEnv tyvars $ - -- SOURCE-CODE CONSISTENCY CHECKS - (case def_methods of - Nothing -> -- Not source - returnTc Nothing - - Just dms -> -- Source so do error checks - checkTc (gla_exts || length tyvar_names == 1) - (classArityErr class_name) `thenTc_` - - checkDefaultBinds clas op_names dms `thenTc` \ dm_env -> - checkGenericClassIsUnary clas dm_env `thenTc_` - returnTc (Just dm_env) - ) `thenTc` \ mb_dm_env -> + checkDefaultBinds clas op_names def_methods `thenTc` \ mb_dm_env -> -- CHECK THE CONTEXT - tcSuperClasses is_rec gla_exts clas context sc_sel_names `thenTc` \ (sc_theta, sc_sel_ids) -> + -- The renamer has already checked that the context mentions + -- only the type variable of the class decl. + -- Context is already kind-checked + ASSERT( length context == length sc_sel_names ) + tcHsTheta context `thenTc` \ sc_theta -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig is_rec rec_env clas tyvars mb_dm_env) op_sigs `thenTc` \ sig_stuff -> + mapTc (tcClassSig rec_env clas tyvars mb_dm_env) op_sigs `thenTc` \ sig_stuff -> -- MAKE THE CLASS DETAILS let (op_tys, op_items) = unzip sig_stuff sc_tys = mkPredTys sc_theta dict_component_tys = sc_tys ++ op_tys + sc_sel_ids = [mkDictSelId sc_name clas | sc_name <- sc_sel_names] dict_con = mkDataCon datacon_name - [notMarkedStrict | _ <- dict_component_tys] + [NotMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] tyvars [{-No context-}] @@ -168,8 +152,8 @@ tcClassDecl1 is_rec rec_env \end{code} \begin{code} -checkDefaultBinds :: Class -> [Name] -> RenamedMonoBinds - -> TcM (NameEnv Bool) +checkDefaultBinds :: Class -> [Name] -> Maybe RenamedMonoBinds + -> TcM (Maybe (NameEnv Bool)) -- The returned environment says -- x not in env => no default method -- x -> True => generic default method @@ -182,74 +166,39 @@ checkDefaultBinds :: Class -> [Name] -> RenamedMonoBinds -- But do all this only for source binds -checkDefaultBinds clas ops EmptyMonoBinds = returnTc emptyNameEnv +checkDefaultBinds clas ops Nothing + = returnTc Nothing -checkDefaultBinds clas ops (AndMonoBinds b1 b2) - = checkDefaultBinds clas ops b1 `thenTc` \ dm_info1 -> - checkDefaultBinds clas ops b2 `thenTc` \ dm_info2 -> - returnTc (dm_info1 `plusNameEnv` dm_info2) +checkDefaultBinds clas ops (Just mbs) + = go mbs `thenTc` \ dm_env -> + returnTc (Just dm_env) + where + go EmptyMonoBinds = returnTc emptyNameEnv -checkDefaultBinds clas ops (FunMonoBind op _ matches loc) - = tcAddSrcLoc loc $ + go (AndMonoBinds b1 b2) + = go b1 `thenTc` \ dm_info1 -> + go b2 `thenTc` \ dm_info2 -> + returnTc (dm_info1 `plusNameEnv` dm_info2) + + go (FunMonoBind op _ matches loc) + = tcAddSrcLoc loc $ -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` + checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` -- Check that all the defns ar generic, or none are - checkTc (all_generic || none_generic) (mixedGenericErr op) `thenTc_` + checkTc (all_generic || none_generic) (mixedGenericErr op) `thenTc_` - returnTc (unitNameEnv op all_generic) - where - n_generic = count (maybeToBool . maybeGenericMatch) matches - none_generic = n_generic == 0 - all_generic = n_generic == length matches - -checkGenericClassIsUnary clas dm_env - = -- Check that if the class has generic methods, then the - -- class has only one parameter. We can't do generic - -- multi-parameter type classes! - checkTc (unary || no_generics) (genericMultiParamErr clas) - where - unary = length (classTyVars clas) == 1 - no_generics = not (or (nameEnvElts dm_env)) + returnTc (unitNameEnv op all_generic) + where + n_generic = count (maybeToBool . maybeGenericMatch) matches + none_generic = n_generic == 0 + all_generic = n_generic == length matches \end{code} \begin{code} -tcSuperClasses :: RecFlag -> Bool -> Class - -> RenamedContext -- class context - -> [Name] -- Names for superclass selectors - -> TcM (ThetaType, -- the superclass context - [Id]) -- superclass selector Ids - -tcSuperClasses is_rec gla_exts clas context sc_sel_names - = ASSERT( length context == length sc_sel_names ) - -- 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 - mapTc_ check_constraint context `thenTc_` - - -- Context is already kind-checked - tcRecTheta is_rec context `thenTc` \ sc_theta -> - let - sc_sel_ids = [mkDictSelId sc_name clas | sc_name <- sc_sel_names] - in - -- Done - returnTc (sc_theta, sc_sel_ids) - - where - check_constraint sc = checkTc (ok sc) (superClassErr clas sc) - ok (HsClassP c tys) | gla_exts = True - | otherwise = all is_tyvar tys - ok (HsIParam _ _) = False -- Never legal - - is_tyvar (HsTyVar _) = True - is_tyvar other = False - - -tcClassSig :: RecFlag -> RecTcEnv -- Knot tying only! +tcClassSig :: RecTcEnv -- Knot tying only! -> Class -- ...ditto... -> [TyVar] -- The class type variable, used for error check only -> Maybe (NameEnv Bool) -- Info about default methods @@ -262,20 +211,17 @@ tcClassSig :: RecFlag -> RecTcEnv -- Knot tying only! -- so we distinguish them in checkDefaultBinds, and pass this knowledge in the -- Class.DefMeth data structure. -tcClassSig is_rec unf_env clas clas_tyvars maybe_dm_env +tcClassSig unf_env clas clas_tyvars maybe_dm_env (ClassOpSig op_name sig_dm 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. + tcHsType op_ty `thenTc` \ local_ty -> - tcHsRecType is_rec op_ty `thenTc` \ local_ty -> - - -- Check for ambiguous class op types let theta = [mkClassPred clas (mkTyVarTys clas_tyvars)] - in - checkAmbiguity is_rec True clas_tyvars theta local_ty `thenTc` \ global_ty -> + global_ty = mkSigmaTy clas_tyvars theta local_ty -- The default method's type should really come from the -- iface file, since it could be usage-generalised, but this -- requires altering the mess of knots in TcModule and I'm @@ -283,7 +229,6 @@ tcClassSig is_rec unf_env clas clas_tyvars maybe_dm_env -- of types of default methods (and dict funs) by annotating them -- TyGenNever (in MkId). Ugh! KSW 1999-09. - let -- Build the selector id and default method id sel_id = mkDictSelId op_name clas dm_id = mkDefaultMethodId dm_name global_ty @@ -303,14 +248,56 @@ tcClassSig is_rec unf_env clas clas_tyvars maybe_dm_env Just True -> GenDefMeth Just False -> DefMeth dm_id in - -- Check that for a generic method, the type of - -- the method is sufficiently simple - checkTc (dm_info /= GenDefMeth || validGenericMethodType local_ty) - (badGenericMethodType op_name op_ty) `thenTc_` - returnTc (local_ty, (sel_id, dm_info)) \end{code} +checkValidClass is called once the mutually-recursive knot has been +tied, so we can look at things freely. + +\begin{code} +checkValidClass :: Class -> TcM () +checkValidClass cls + = -- CHECK ARITY 1 FOR HASKELL 1.4 + doptsTc Opt_GlasgowExts `thenTc` \ gla_exts -> + + -- Check that the class is unary, unless GlaExs + checkTc (arity > 0) (nullaryClassErr cls) `thenTc_` + checkTc (gla_exts || unary) (classArityErr cls) `thenTc_` + + -- Check the super-classes + checkValidTheta (ClassSCCtxt (className cls)) theta `thenTc_` + + -- Check the class operations + mapTc_ check_op op_stuff `thenTc_` + + -- Check that if the class has generic methods, then the + -- class has only one parameter. We can't do generic + -- multi-parameter type classes! + checkTc (unary || no_generics) (genericMultiParamErr cls) + + where + (tyvars, theta, sel_ids, op_stuff) = classBigSig cls + arity = length tyvars + unary = arity == 1 + no_generics = null [() | (_, GenDefMeth) <- op_stuff] + + check_op (sel_id, dm) + = checkValidTheta SigmaCtxt (tail theta) `thenTc_` + -- The 'tail' removes the initial (C a) from the + -- class itself, leaving just the method type + + checkValidType (FunSigCtxt op_name) tau `thenTc_` + + -- Check that for a generic method, the type of + -- the method is sufficiently simple + checkTc (dm /= GenDefMeth || validGenericMethodType op_ty) + (badGenericMethodType op_name op_ty) + where + op_name = idName sel_id + op_ty = idType sel_id + (_,theta,tau) = tcSplitSigmaTy op_ty +\end{code} + %************************************************************************ %* * @@ -518,7 +505,7 @@ tcMethodBind clas origin inst_tyvars inst_tys inst_theta Just user_bind -> returnTc user_bind Nothing -> mkDefMethRhs is_inst_decl clas inst_tys sel_id loc dm_info `thenTc` \ rhs -> returnTc (FunMonoBind meth_name False -- Not infix decl - [mkSimpleMatch [] rhs Nothing loc] loc) + [mkSimpleMatch [] rhs placeHolderType loc] loc) ) `thenTc` \ meth_bind -> -- Check the bindings; first add inst_tyvars to the envt -- so that we don't quantify over them in nested places @@ -526,7 +513,7 @@ tcMethodBind clas origin inst_tyvars inst_tys inst_theta tcExtendGlobalTyVars (mkVarSet inst_tyvars) (tcAddErrCtxt (methodCtxt sel_id) $ tcBindWithSigs NotTopLevel meth_bind - [sig_info] meth_prags NonRecursive + [sig_info] meth_prags NonRecursive ) `thenTc` \ (binds, insts, _) -> tcExtendLocalValEnv [(meth_name, meth_id)] @@ -561,9 +548,9 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc (DefMeth dm_id) mkDefMethRhs is_inst_decl clas inst_tys sel_id loc NoDefMeth = -- No default method -- Warn only if -fwarn-missing-methods - doptsTc Opt_WarnMissingMethods `thenNF_Tc` \ warn -> + doptsTc Opt_WarnMissingMethods `thenNF_Tc` \ warn -> warnTc (is_inst_decl && warn) - (omittedMethodWarn sel_id clas) `thenNF_Tc_` + (omittedMethodWarn sel_id) `thenNF_Tc_` returnTc error_rhs where error_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) @@ -578,7 +565,7 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth -- a type constructor applied to type arguments in the instance decl -- (checkTc, so False provokes the error) checkTc (not is_inst_decl || simple_inst) - (badGenericInstance sel_id clas) `thenTc_` + (badGenericInstance sel_id) `thenTc_` ioToTc (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenNF_Tc_` returnTc rhs @@ -596,9 +583,9 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth clas_tyvar = head (classTyVars clas) Just tycon = maybe_tycon maybe_tycon = case inst_tys of - [ty] -> case splitTyConApp_maybe ty of - Just (tycon, arg_tys) | all isTyVarTy arg_tys -> Just tycon - other -> Nothing + [ty] -> case tcSplitTyConApp_maybe ty of + Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon + other -> Nothing other -> Nothing \end{code} @@ -628,12 +615,12 @@ find_prags sel_name meth_name (prag:prags) = find_prags sel_name meth_name prags Contexts and errors ~~~~~~~~~~~~~~~~~~~ \begin{code} -classArityErr class_name - = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) +nullaryClassErr cls + = ptext SLIT("No parameters for class") <+> quotes (ppr cls) -superClassErr clas sc - = ptext SLIT("Illegal superclass constraint") <+> quotes (ppr sc) - <+> ptext SLIT("in declaration for class") <+> quotes (ppr clas) +classArityErr cls + = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls), + parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))] defltMethCtxt clas = ptext SLIT("When checking the default methods for class") <+> quotes (ppr clas) @@ -645,20 +632,18 @@ badMethodErr clas op = hsep [ptext SLIT("Class"), quotes (ppr clas), ptext SLIT("does not have a method"), quotes (ppr op)] -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)] +omittedMethodWarn sel_id + = ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id) badGenericMethodType op op_ty = hang (ptext SLIT("Generic method type is too complex")) 4 (vcat [ppr op <+> dcolon <+> ppr op_ty, ptext SLIT("You can only use type variables, arrows, and tuples")]) -badGenericInstance sel_id clas +badGenericInstance sel_id = sep [ptext SLIT("Can't derive generic code for") <+> quotes (ppr sel_id), ptext SLIT("because the instance declaration is not for a simple type (T a b c)"), - ptext SLIT("(where T is a derivable type constructor)"), - ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)] + ptext SLIT("(where T is a derivable type constructor)")] mixedGenericErr op = ptext SLIT("Can't mix generic and non-generic equations for class method") <+> quotes (ppr op)