X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcDeriv.lhs;h=5d7741970847922b51280f901e3bbe123d80978d;hb=0a7b8d872ebf93a1bfc8f87a8a60cce0097ecfc2;hp=ee364ac23783e88280334e6918b51582d94ce092;hpb=61fae1d3fb61c5f53c3fbcb94afe7c548ad31591;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs index ee364ac..5d77419 100644 --- a/ghc/compiler/typecheck/TcDeriv.lhs +++ b/ghc/compiler/typecheck/TcDeriv.lhs @@ -13,15 +13,16 @@ module TcDeriv ( tcDeriving ) where import HsSyn ( HsBinds(..), MonoBinds(..), TyClDecl(..), collectLocatedMonoBinders ) import RdrHsSyn ( RdrNameMonoBinds ) -import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl ) +import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl, RenamedHsPred ) import CmdLineOpts ( DynFlag(..), DynFlags ) import TcMonad import TcEnv ( tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo, - tcLookupClass, tcLookupTyCon + tcLookupClass, tcLookupTyCon, tcExtendTyVarEnv ) import TcGenDeriv -- Deriv stuff import InstEnv ( InstEnv, simpleDFunClassTyCon, extendInstEnv ) +import TcMonoType ( tcHsPred ) import TcSimplify ( tcSimplifyThetas ) import RnBinds ( rnMethodBinds, rnTopMonoBinds ) @@ -29,29 +30,33 @@ import RnEnv ( bindLocatedLocalsRn ) import RnMonad ( renameDerivedCode, thenRn, mapRn, returnRn ) import HscTypes ( DFunId, PersistentRenamerState ) -import BasicTypes ( Fixity ) -import Class ( className, classKey, Class ) +import BasicTypes ( Fixity, NewOrData(..) ) +import Class ( className, classKey, classTyVars, Class ) import ErrUtils ( dumpIfSet_dyn, Message ) import MkId ( mkDictFunId ) -import DataCon ( dataConArgTys, isNullaryDataCon, isExistentialDataCon ) +import DataCon ( dataConRepArgTys, isNullaryDataCon, isExistentialDataCon ) import PrelInfo ( needsDataDeclCtxtClassKeys ) import Maybes ( maybeToBool, catMaybes ) import Module ( Module ) import Name ( Name, getSrcLoc, nameUnique ) import RdrName ( RdrName ) -import TyCon ( tyConTyVars, tyConDataCons, +import TyCon ( tyConTyVars, tyConDataCons, tyConArity, newTyConRep, tyConTheta, maybeTyConSingleCon, isDataTyCon, isEnumerationTyCon, TyCon ) -import TcType ( ThetaType, mkTyVarTys, mkTyConApp, - isUnLiftedType, mkClassPred ) -import Var ( TyVar ) +import TcType ( TcType, ThetaType, mkTyVarTys, mkTyConApp, getClassPredTys_maybe, + isUnLiftedType, mkClassPred, tyVarsOfTypes, tcSplitFunTys, + tcSplitTyConApp_maybe, tcEqTypes ) +import Var ( TyVar, tyVarKind ) +import VarSet ( mkVarSet, subVarSet ) import PrelNames import Util ( zipWithEqual, sortLt ) import ListSetOps ( removeDups, assoc ) import Outputable +import Maybe ( isJust ) import List ( nub ) +import FastString ( FastString ) \end{code} %************************************************************************ @@ -187,17 +192,37 @@ tcDeriving :: PersistentRenamerState -> TcM ([InstInfo], -- The generated "instance decls". RenamedHsBinds) -- Extra generated bindings -tcDeriving prs mod inst_env_in get_fixity tycl_decls +tcDeriving prs mod inst_env get_fixity tycl_decls = recoverTc (returnTc ([], EmptyBinds)) $ -- Fish the "deriving"-related information out of the TcEnv -- and make the necessary "equations". - makeDerivEqns tycl_decls `thenTc` \ eqns -> - if null eqns then - returnTc ([], EmptyBinds) - else + makeDerivEqns tycl_decls `thenTc` \ (ordinary_eqns, inst_info2) -> + + deriveOrdinaryStuff mod prs inst_env get_fixity + ordinary_eqns `thenTc` \ (inst_info1, binds) -> + let + inst_info = inst_info2 ++ inst_info1 -- info2 usually empty + in + + getDOptsTc `thenNF_Tc` \ dflags -> + ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances" + (ddump_deriving inst_info binds)) `thenTc_` + + returnTc (inst_info, binds) + + where + ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc + ddump_deriving inst_infos extra_binds + = vcat (map pprInstInfo inst_infos) $$ ppr extra_binds + - -- Take the equation list and solve it, to deliver a list of +----------------------------------------- +deriveOrdinaryStuff mod prs inst_env_in get_fixity [] -- Short cut + = returnTc ([], EmptyBinds) + +deriveOrdinaryStuff mod prs inst_env_in get_fixity eqns + = -- Take the equation list and solve it, to deliver a list of -- solutions, a.k.a. the contexts for the instance decls -- required for the corresponding equations. solveDerivEqns inst_env_in eqns `thenTc` \ new_dfuns -> @@ -207,11 +232,10 @@ tcDeriving prs mod inst_env_in get_fixity tycl_decls -- generate extra not-one-inst-decl-specific binds, notably -- "con2tag" and/or "tag2con" functions. We do these -- separately. - gen_taggery_Names new_dfuns `thenTc` \ nm_alist_etc -> tcGetEnv `thenNF_Tc` \ env -> - getDOptsTc `thenTc` \ dflags -> + getDOptsTc `thenNF_Tc` \ dflags -> let extra_mbind_list = map gen_tag_n_con_monobind nm_alist_etc extra_mbinds = foldr AndMonoBinds EmptyMonoBinds extra_mbind_list @@ -228,20 +252,11 @@ tcDeriving prs mod inst_env_in get_fixity tycl_decls mapRn rn_meths method_binds_s `thenRn` \ rn_method_binds_s -> returnRn (rn_method_binds_s, rn_extra_binds) ) - new_inst_infos = zipWith gen_inst_info new_dfuns rn_method_binds_s in - - ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances" - (ddump_deriving new_inst_infos rn_extra_binds)) `thenTc_` - returnTc (new_inst_infos, rn_extra_binds) - where - ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc - ddump_deriving inst_infos extra_binds - = vcat (map pprInstInfo inst_infos) $$ ppr extra_binds - where + where -- Make a Real dfun instead of the dummy one we have so far gen_inst_info :: DFunId -> RenamedMonoBinds -> InstInfo gen_inst_info dfun binds @@ -274,79 +289,169 @@ or} has just one data constructor (e.g., tuples). all those. \begin{code} -makeDerivEqns :: [RenamedTyClDecl] -> TcM [DerivEqn] +makeDerivEqns :: [RenamedTyClDecl] + -> TcM ([DerivEqn], -- Ordinary derivings + [InstInfo]) -- Special newtype derivings makeDerivEqns tycl_decls - = mapTc mk_eqn derive_these `thenTc` \ maybe_eqns -> - returnTc (catMaybes maybe_eqns) + = mapAndUnzipTc mk_eqn derive_these `thenTc` \ (maybe_ordinaries, maybe_newtypes) -> + returnTc (catMaybes maybe_ordinaries, catMaybes maybe_newtypes) where ------------------------------------------------------------------ - derive_these :: [(Name, Name)] - -- Find the (Class,TyCon) pairs that must be `derived' + derive_these :: [(NewOrData, Name, RenamedHsPred)] + -- Find the (nd, TyCon, Pred) pairs that must be `derived' -- NB: only source-language decls have deriving, no imported ones do - derive_these = [ (clas,tycon) - | TyData {tcdName = tycon, tcdDerivs = Just classes} <- tycl_decls, - clas <- nub classes ] + derive_these = [ (nd, tycon, pred) + | TyData {tcdND = nd, tcdName = tycon, tcdDerivs = Just preds} <- tycl_decls, + pred <- preds ] ------------------------------------------------------------------ - mk_eqn :: (Name, Name) -> NF_TcM (Maybe DerivEqn) - -- we swizzle the tyvars and datacons out of the tycon + mk_eqn :: (NewOrData, Name, RenamedHsPred) -> NF_TcM (Maybe DerivEqn, Maybe InstInfo) + -- We swizzle the tyvars and datacons out of the tycon -- to make the rest of the equation - mk_eqn (clas_name, tycon_name) - = tcLookupClass clas_name `thenNF_Tc` \ clas -> - tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> - let - clas_key = classKey clas - tyvars = tyConTyVars tycon - tyvar_tys = mkTyVarTys tyvars - ty = mkTyConApp tycon tyvar_tys - data_cons = tyConDataCons tycon - locn = getSrcLoc tycon - constraints = extra_constraints ++ concat (map mk_constraints data_cons) + mk_eqn (new_or_data, tycon_name, pred) + = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> + tcAddSrcLoc (getSrcLoc tycon) $ + tcAddErrCtxt (derivCtxt tycon) $ + tcExtendTyVarEnv (tyConTyVars tycon) $ -- Deriving preds may (now) mention + -- the type variables for the type constructor + tcHsPred pred `thenTc` \ pred' -> + case getClassPredTys_maybe pred' of + Nothing -> bale_out (malformedPredErr tycon pred) + Just (clas, tys) -> mk_eqn_help new_or_data tycon clas tys - -- "extra_constraints": see notes above about contexts on data decls - extra_constraints - | offensive_class = tyConTheta tycon - | otherwise = [] + ------------------------------------------------------------------ + mk_eqn_help DataType tycon clas tys + | Just err <- chk_out clas tycon tys + = bale_out (derivingThingErr clas tys tycon tyvars err) + | otherwise + = new_dfun_name clas tycon `thenNF_Tc` \ dfun_name -> + returnNF_Tc (Just (dfun_name, clas, tycon, tyvars, constraints), Nothing) + where + tyvars = tyConTyVars tycon + data_cons = tyConDataCons tycon + constraints = extra_constraints ++ + [ mkClassPred clas [arg_ty] + | data_con <- tyConDataCons tycon, + arg_ty <- dataConRepArgTys data_con, + -- Use the same type variables + -- as the type constructor, + -- hence no need to instantiate + not (isUnLiftedType arg_ty) -- No constraints for unlifted types? + ] - offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys - - mk_constraints data_con - = [ mkClassPred clas [arg_ty] - | arg_ty <- dataConArgTys data_con tyvar_tys, - not (isUnLiftedType arg_ty) -- No constraints for unlifted types? - ] - in - case chk_out clas tycon of - Just err -> tcAddSrcLoc (getSrcLoc tycon) $ - addErrTc err `thenNF_Tc_` - returnNF_Tc Nothing - Nothing -> newDFunName clas [ty] locn `thenNF_Tc` \ dfun_name -> - returnNF_Tc (Just (dfun_name, clas, tycon, tyvars, constraints)) + + -- "extra_constraints": see notes above about contexts on data decls + extra_constraints | offensive_class = tyConTheta tycon + | otherwise = [] + + offensive_class = classKey clas `elem` needsDataDeclCtxtClassKeys + mk_eqn_help NewType tycon clas tys + = doptsTc Opt_GlasgowExts `thenTc` \ gla_exts -> + if can_derive_via_isomorphism && (gla_exts || standard_instance) then + -- Go ahead and use the isomorphism + new_dfun_name clas tycon `thenNF_Tc` \ dfun_name -> + returnTc (Nothing, Just (NewTypeDerived (mk_dfun dfun_name))) + else + if standard_instance then + mk_eqn_help DataType tycon clas [] -- Go via bale-out route + else + bale_out cant_derive_err + where + -- Here is the plan for newtype derivings. We see + -- newtype T a1...an = T (t ak...an) deriving (C1...Cm) + -- where aj...an do not occur free in t, and the Ci are *partial applications* of + -- classes with the last parameter missing + -- + -- We generate the instances + -- instance Ci (t ak...aj) => Ci (T a1...aj) + -- where T a1...aj is the partial application of the LHS of the correct kind + -- + -- Running example: newtype T s a = MkT (ST s a) deriving( Monad ) + + kind = tyVarKind (last (classTyVars clas)) + -- Kind of the thing we want to instance + -- e.g. argument kind of Monad, *->* + + (arg_kinds, _) = tcSplitFunTys kind + n_args_to_drop = length arg_kinds + -- Want to drop 1 arg from (T s a) and (ST s a) + -- to get instance Monad (ST s) => Monad (T s) + + (tyvars, rep_ty) = newTyConRep tycon + maybe_rep_app = tcSplitTyConApp_maybe rep_ty + Just (rep_tc, rep_ty_args) = maybe_rep_app + + n_tyvars_to_keep = tyConArity tycon - n_args_to_drop + tyvars_to_drop = drop n_tyvars_to_keep tyvars + tyvars_to_keep = take n_tyvars_to_keep tyvars + + n_args_to_keep = tyConArity rep_tc - n_args_to_drop + args_to_drop = drop n_args_to_keep rep_ty_args + args_to_keep = take n_args_to_keep rep_ty_args + + ctxt_pred = mkClassPred clas (tys ++ [mkTyConApp rep_tc args_to_keep]) + + mk_dfun dfun_name = mkDictFunId dfun_name clas tyvars + (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars_to_keep)] ) + [ctxt_pred] + + -- We can only do this newtype deriving thing if: + standard_instance = null tys && classKey clas `elem` derivableClassKeys + + can_derive_via_isomorphism + = not (clas `hasKey` readClassKey) -- Never derive Read,Show this way + && not (clas `hasKey` showClassKey) + && n_tyvars_to_keep >= 0 -- Well kinded; + -- eg not: newtype T = T Int deriving( Monad ) + && isJust maybe_rep_app -- The rep type is a type constructor app + && n_args_to_keep >= 0 -- Well kinded: + -- eg not: newtype T a = T Int deriving( Monad ) + && eta_ok -- Eta reduction works + + -- Check that eta reduction is OK + -- (a) the dropped-off args are identical + -- (b) the remaining type args mention + -- only the remaining type variables + eta_ok = (args_to_drop `tcEqTypes` mkTyVarTys tyvars_to_drop) + && (tyVarsOfTypes args_to_keep `subVarSet` mkVarSet tyvars_to_keep) + + cant_derive_err = derivingThingErr clas tys tycon tyvars_to_keep + SLIT("too hard for cunning newtype deriving") + + + bale_out err = addErrTc err `thenNF_Tc_` returnNF_Tc (Nothing, Nothing) ------------------------------------------------------------------ - chk_out :: Class -> TyCon -> Maybe Message - chk_out clas tycon - | clas `hasKey` enumClassKey && not is_enumeration = bog_out nullary_why - | clas `hasKey` boundedClassKey && not is_enumeration_or_single = bog_out single_nullary_why - | clas `hasKey` ixClassKey && not is_enumeration_or_single = bog_out single_nullary_why - | null data_cons = bog_out no_cons_why - | any isExistentialDataCon data_cons = Just (existentialErr clas tycon) - | otherwise = Nothing + chk_out :: Class -> TyCon -> [TcType] -> Maybe FastString + chk_out clas tycon tys + | not (null tys) = Just non_std_why + | not (getUnique clas `elem` derivableClassKeys) = Just non_std_why + | clas `hasKey` enumClassKey && not is_enumeration = Just nullary_why + | clas `hasKey` boundedClassKey && not is_enumeration_or_single = Just single_nullary_why + | clas `hasKey` ixClassKey && not is_enumeration_or_single = Just single_nullary_why + | null data_cons = Just no_cons_why + | any isExistentialDataCon data_cons = Just existential_why + | otherwise = Nothing where data_cons = tyConDataCons tycon is_enumeration = isEnumerationTyCon tycon is_single_con = maybeToBool (maybeTyConSingleCon tycon) is_enumeration_or_single = is_enumeration || is_single_con - single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected") - nullary_why = SLIT("data type with all nullary constructors expected") - no_cons_why = SLIT("type has no data constructors") + single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected") + nullary_why = SLIT("data type with all nullary constructors expected") + no_cons_why = SLIT("type has no data constructors") + non_std_why = SLIT("not a derivable class") + existential_why = SLIT("it has existentially-quantified constructor(s)") - bog_out why = Just (derivingThingErr clas tycon why) +new_dfun_name clas tycon -- Just a simple wrapper + = newDFunName clas [mkTyConApp tycon []] (getSrcLoc tycon) + -- The type passed to newDFunName is only used to generate + -- a suitable string; hence the empty type arg list \end{code} %************************************************************************ @@ -402,7 +507,7 @@ solveDerivEqns inst_env_in orig_eqns iterateOnce current_solns = -- Extend the inst info from the explicit instance decls -- with the current set of solutions, giving a - getDOptsTc `thenTc` \ dflags -> + getDOptsTc `thenNF_Tc` \ dflags -> let (new_dfuns, inst_env) = add_solns dflags inst_env_in orig_eqns current_solns in @@ -611,17 +716,15 @@ gen_taggery_Names dfuns \end{code} \begin{code} -derivingThingErr :: Class -> TyCon -> FAST_STRING -> Message - -derivingThingErr clas tycon why - = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr clas)], - hsep [ptext SLIT("for the type"), quotes (ppr tycon)], +derivingThingErr clas tys tycon tyvars why + = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr pred)], parens (ptext why)] + where + pred = mkClassPred clas (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars)]) -existentialErr clas tycon - = sep [ptext SLIT("Can't derive any instances for type") <+> quotes (ppr tycon), - ptext SLIT("because it has existentially-quantified constructor(s)")] +malformedPredErr tycon pred = ptext SLIT("Illegal deriving item") <+> ppr pred derivCtxt tycon = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon) \end{code} +