X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcDeriv.lhs;h=5d7741970847922b51280f901e3bbe123d80978d;hb=0a7b8d872ebf93a1bfc8f87a8a60cce0097ecfc2;hp=08d28dc95cc66b9c0cb0ad753de8259430913668;hpb=88f315a135bd00d2efa00d991bb9487929562d91;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs index 08d28dc..5d77419 100644 --- a/ghc/compiler/typecheck/TcDeriv.lhs +++ b/ghc/compiler/typecheck/TcDeriv.lhs @@ -10,44 +10,53 @@ module TcDeriv ( tcDeriving ) where #include "HsVersions.h" -import HsSyn ( HsBinds(..), MonoBinds(..), collectLocatedMonoBinders ) +import HsSyn ( HsBinds(..), MonoBinds(..), TyClDecl(..), + collectLocatedMonoBinders ) import RdrHsSyn ( RdrNameMonoBinds ) -import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds ) +import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl, RenamedHsPred ) import CmdLineOpts ( DynFlag(..), DynFlags ) import TcMonad -import TcEnv ( TcEnv, tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo ) +import TcEnv ( tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo, + tcLookupClass, tcLookupTyCon, tcExtendTyVarEnv + ) import TcGenDeriv -- Deriv stuff import InstEnv ( InstEnv, simpleDFunClassTyCon, extendInstEnv ) +import TcMonoType ( tcHsPred ) import TcSimplify ( tcSimplifyThetas ) import RnBinds ( rnMethodBinds, rnTopMonoBinds ) import RnEnv ( bindLocatedLocalsRn ) -import RnMonad ( --RnNameSupply, - renameSourceCode, thenRn, mapRn, returnRn ) +import RnMonad ( renameDerivedCode, thenRn, mapRn, returnRn ) import HscTypes ( DFunId, PersistentRenamerState ) -import BasicTypes ( Fixity ) -import Class ( 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, isFrom, getSrcLoc ) +import Name ( Name, getSrcLoc, nameUnique ) import RdrName ( RdrName ) -import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings, +import TyCon ( tyConTyVars, tyConDataCons, tyConArity, newTyConRep, tyConTheta, maybeTyConSingleCon, isDataTyCon, isEnumerationTyCon, TyCon ) -import Type ( TauType, PredType(..), mkTyVarTys, mkTyConApp, isUnboxedType ) -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, thenCmp ) +import Util ( zipWithEqual, sortLt ) import ListSetOps ( removeDups, assoc ) import Outputable +import Maybe ( isJust ) +import List ( nub ) +import FastString ( FastString ) \end{code} %************************************************************************ @@ -139,9 +148,7 @@ type DerivEqn = (Name, Class, TyCon, [TyVar], DerivRhs) -- The Name is the name for the DFun we'll build -- The tyvars bind all the variables in the RHS -type DerivRhs = [(Class, [TauType])] -- Same as a ThetaType! - --[PredType] -- ... | Class Class [Type==TauType] - +type DerivRhs = ThetaType type DerivSoln = DerivRhs \end{code} @@ -181,21 +188,41 @@ tcDeriving :: PersistentRenamerState -> Module -- name of module under scrutiny -> InstEnv -- What we already know about instances -> (Name -> Maybe Fixity) -- used in deriving Show and Read - -> [TyCon] -- All type constructors + -> [RenamedTyClDecl] -- All type constructors -> TcM ([InstInfo], -- The generated "instance decls". RenamedHsBinds) -- Extra generated bindings -tcDeriving prs mod inst_env_in get_fixity tycons +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 mod tycons `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 - -- Take the equation list and solve it, to deliver a list of + 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) $$ ppr extra_binds + + +----------------------------------------- +deriveOrdinaryStuff mod prs inst_env_in get_fixity [] -- Short cut + = returnTc ([], EmptyBinds) + +deriveOrdinaryStuff mod prs inst_env_in get_fixity eqns + = -- Take the equation list and solve it, to deliver a list of -- solutions, a.k.a. the contexts for the instance decls -- required for the corresponding equations. solveDerivEqns inst_env_in eqns `thenTc` \ new_dfuns -> @@ -205,11 +232,10 @@ tcDeriving prs mod inst_env_in get_fixity tycons -- generate extra not-one-inst-decl-specific binds, notably -- "con2tag" and/or "tag2con" functions. We do these -- separately. - gen_taggery_Names new_dfuns `thenTc` \ nm_alist_etc -> tcGetEnv `thenNF_Tc` \ env -> - getDOptsTc `thenTc` \ dflags -> + getDOptsTc `thenNF_Tc` \ dflags -> let extra_mbind_list = map gen_tag_n_con_monobind nm_alist_etc extra_mbinds = foldr AndMonoBinds EmptyMonoBinds extra_mbind_list @@ -220,34 +246,24 @@ tcDeriving prs mod inst_env_in get_fixity tycons -- The only tricky bit is that the extra_binds must scope over the -- method bindings for the instances. (rn_method_binds_s, rn_extra_binds) - = renameSourceCode dflags mod prs ( + = renameDerivedCode dflags mod prs ( bindLocatedLocalsRn (ptext (SLIT("deriving"))) mbinders $ \ _ -> rnTopMonoBinds extra_mbinds [] `thenRn` \ (rn_extra_binds, _) -> mapRn rn_meths method_binds_s `thenRn` \ rn_method_binds_s -> returnRn (rn_method_binds_s, rn_extra_binds) ) - new_inst_infos = zipWith gen_inst_info new_dfuns rn_method_binds_s in - - ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances" - (ddump_deriving new_inst_infos rn_extra_binds)) `thenTc_` - returnTc (new_inst_infos, rn_extra_binds) - where - ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc - ddump_deriving inst_infos extra_binds - = vcat (map pprInstInfo inst_infos) $$ 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 - = InstInfo { iLocal = True, iDFunId = dfun, - iBinds = binds, iPrags = [] } + = InstInfo { iDFunId = dfun, iBinds = binds, iPrags = [] } - rn_meths meths = rnMethodBinds [] meths `thenRn` \ (meths', _) -> returnRn meths' - -- Ignore the free vars returned + rn_meths (cls, meths) = rnMethodBinds cls [] meths `thenRn` \ (meths', _) -> + returnRn meths' -- Ignore the free vars returned \end{code} @@ -273,85 +289,169 @@ or} has just one data constructor (e.g., tuples). all those. \begin{code} -makeDerivEqns :: Module -> [TyCon] -> TcM [DerivEqn] +makeDerivEqns :: [RenamedTyClDecl] + -> TcM ([DerivEqn], -- Ordinary derivings + [InstInfo]) -- Special newtype derivings -makeDerivEqns this_mod tycons - = let - think_about_deriving = need_deriving tycons - (derive_these, _) = removeDups cmp_deriv think_about_deriving - in - if null think_about_deriving then - returnTc [] -- Bale out now - else - mapTc mk_eqn derive_these `thenTc` \ maybe_eqns -> - returnTc (catMaybes maybe_eqns) +makeDerivEqns tycl_decls + = mapAndUnzipTc mk_eqn derive_these `thenTc` \ (maybe_ordinaries, maybe_newtypes) -> + returnTc (catMaybes maybe_ordinaries, catMaybes maybe_newtypes) where ------------------------------------------------------------------ - need_deriving :: [TyCon] -> [(Class, TyCon)] - -- find the tycons that have `deriving' clauses; - - need_deriving tycons_to_consider - = [ (clas,tycon) | tycon <- tycons_to_consider, - isFrom this_mod tycon, - clas <- tyConDerivings tycon ] + 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 = [ (nd, tycon, pred) + | TyData {tcdND = nd, tcdName = tycon, tcdDerivs = Just preds} <- tycl_decls, + pred <- preds ] ------------------------------------------------------------------ - cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> Ordering - cmp_deriv (c1, t1) (c2, t2) - = (c1 `compare` c2) `thenCmp` (t1 `compare` t2) - - ------------------------------------------------------------------ - mk_eqn :: (Class, TyCon) -> 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, tycon) - = case chk_out clas tycon of - Just err -> addErrTc err `thenNF_Tc_` - returnNF_Tc Nothing - Nothing -> newDFunName this_mod clas tyvar_tys locn `thenNF_Tc` \ dfun_name -> - returnNF_Tc (Just (dfun_name, clas, tycon, tyvars, constraints)) + 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 + + ------------------------------------------------------------------ + 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 - clas_key = classKey clas - tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ??? - tyvar_tys = mkTyVarTys tyvars + tyvars = tyConTyVars tycon data_cons = tyConDataCons tycon - locn = getSrcLoc 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? + ] - constraints = extra_constraints ++ concat (map mk_constraints data_cons) + + -- "extra_constraints": see notes above about contexts on data decls + extra_constraints | offensive_class = tyConTheta tycon + | otherwise = [] + + offensive_class = classKey clas `elem` needsDataDeclCtxtClassKeys - -- "extra_constraints": see notes above about contexts on data decls - extra_constraints - | offensive_class = tyConTheta tycon - | otherwise = [] - where - offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys - mk_constraints data_con - = [ (clas, [arg_ty]) - | arg_ty <- instd_arg_tys, - not (isUnboxedType arg_ty) -- No constraints for unboxed types? - ] - where - instd_arg_tys = dataConArgTys data_con tyvar_tys + 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 - | any isExistentialDataCon (tyConDataCons tycon) = 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") + 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} %************************************************************************ @@ -407,13 +507,14 @@ 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 -- Simplify each RHS tcSetInstEnv inst_env ( - listTc [ tcAddErrCtxt (derivCtxt tc) $ + listTc [ tcAddSrcLoc (getSrcLoc tc) $ + tcAddErrCtxt (derivCtxt tc) $ tcSimplifyThetas deriv_rhs | (_, _,tc,_,deriv_rhs) <- orig_eqns ] ) `thenTc` \ next_solns -> @@ -442,10 +543,9 @@ add_solns dflags inst_env_in eqns solns -- They'll appear later, when we do the top-level extendInstEnvs mk_deriv_dfun (dfun_name, clas, tycon, tyvars, _) theta - = mkDictFunId dfun_name clas tyvars [mkTyConApp tycon (mkTyVarTys tyvars)] - (map pair2PredType theta) - - pair2PredType (clas, tautypes) = Class clas tautypes + = mkDictFunId dfun_name clas tyvars + [mkTyConApp tycon (mkTyVarTys tyvars)] + theta \end{code} %************************************************************************ @@ -512,24 +612,26 @@ the renamer. What a great hack! \begin{code} -- Generate the method bindings for the required instance --- (paired with class name, as we need that when generating dict --- names.) -gen_bind :: (Name -> Maybe Fixity) -> DFunId -> RdrNameMonoBinds +-- (paired with class name, as we need that when renaming +-- the method binds) +gen_bind :: (Name -> Maybe Fixity) -> DFunId -> (Name, RdrNameMonoBinds) gen_bind get_fixity dfun - | clas `hasKey` showClassKey = gen_Show_binds get_fixity tycon - | clas `hasKey` readClassKey = gen_Read_binds get_fixity tycon - | otherwise - = assoc "gen_bind:bad derived class" - [(eqClassKey, gen_Eq_binds) - ,(ordClassKey, gen_Ord_binds) - ,(enumClassKey, gen_Enum_binds) - ,(boundedClassKey, gen_Bounded_binds) - ,(ixClassKey, gen_Ix_binds) - ] - (classKey clas) - tycon + = (cls_nm, binds) where + cls_nm = className clas (clas, tycon) = simpleDFunClassTyCon dfun + + binds = assoc "gen_bind:bad derived class" gen_list + (nameUnique cls_nm) tycon + + gen_list = [(eqClassKey, gen_Eq_binds) + ,(ordClassKey, gen_Ord_binds) + ,(enumClassKey, gen_Enum_binds) + ,(boundedClassKey, gen_Bounded_binds) + ,(ixClassKey, gen_Ix_binds) + ,(showClassKey, gen_Show_binds get_fixity) + ,(readClassKey, gen_Read_binds get_fixity) + ] \end{code} @@ -544,7 +646,7 @@ data Foo ... = ... con2tag_Foo :: Foo ... -> Int# tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int# -maxtag_Foo :: Int -- ditto (NB: not unboxed) +maxtag_Foo :: Int -- ditto (NB: not unlifted) We have a @con2tag@ function for a tycon if: @@ -614,17 +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} +