X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fiface%2FBuildTyCl.lhs;h=eabe8c45aa42da1eefd91253f619c9c624bffe71;hp=707de1cbf73f1be46606d1c0cfacdc59cb135779;hb=86add45dbfb6f962b65e371143dd467ae783f9e7;hpb=b1ab4b8a607addc4d097588db5761313c996a41f diff --git a/compiler/iface/BuildTyCl.lhs b/compiler/iface/BuildTyCl.lhs index 707de1c..eabe8c4 100644 --- a/compiler/iface/BuildTyCl.lhs +++ b/compiler/iface/BuildTyCl.lhs @@ -5,154 +5,150 @@ \begin{code} module BuildTyCl ( - buildSynTyCon, buildAlgTyCon, buildDataCon, - buildClass, - mkAbstractTyConRhs, mkOpenDataTyConRhs, mkOpenNewTyConRhs, - mkNewTyConRhs, mkDataTyConRhs + buildSynTyCon, + buildAlgTyCon, + buildDataCon, + TcMethInfo, buildClass, + mkAbstractTyConRhs, + mkNewTyConRhs, mkDataTyConRhs, + newImplicitBinder ) where #include "HsVersions.h" import IfaceEnv -import TcRnMonad import DataCon import Var import VarSet -import TysWiredIn import BasicTypes import Name -import OccName import MkId import Class import TyCon import Type import Coercion -import Data.List +import TcRnMonad +import Data.List ( partition ) +import Outputable \end{code} \begin{code} ------------------------------------------------------ buildSynTyCon :: Name -> [TyVar] - -> SynTyConRhs - -> Maybe (TyCon, [Type]) -- family instance if applicable + -> SynTyConRhs + -> Kind -- ^ Kind of the RHS + -> TyConParent + -> Maybe (TyCon, [Type]) -- ^ family instance if applicable -> TcRnIf m n TyCon - -buildSynTyCon tc_name tvs rhs@(OpenSynTyCon rhs_ki _) _ - = let - kind = mkArrowKinds (map tyVarKind tvs) rhs_ki - in - return $ mkSynTyCon tc_name kind tvs rhs NoParentTyCon - -buildSynTyCon tc_name tvs rhs@(SynonymTyCon rhs_ty) mb_family - = do { -- We need to tie a knot as the coercion of a data instance depends - -- on the instance representation tycon and vice versa. - ; tycon <- fixM (\ tycon_rec -> do - { parent <- mkParentInfo mb_family tc_name tvs tycon_rec - ; let { tycon = mkSynTyCon tc_name kind tvs rhs parent - ; kind = mkArrowKinds (map tyVarKind tvs) (typeKind rhs_ty) - } - ; return tycon - }) - ; return tycon - } +buildSynTyCon tc_name tvs rhs rhs_kind parent mb_family + | Just fam_inst_info <- mb_family + = ASSERT( isNoParent parent ) + fixM $ \ tycon_rec -> do + { fam_parent <- mkFamInstParentInfo tc_name tvs fam_inst_info tycon_rec + ; return (mkSynTyCon tc_name kind tvs rhs fam_parent) } + + | otherwise + = return (mkSynTyCon tc_name kind tvs rhs parent) + where + kind = mkArrowKinds (map tyVarKind tvs) rhs_kind ------------------------------------------------------ buildAlgTyCon :: Name -> [TyVar] - -> ThetaType -- Stupid theta + -> ThetaType -- ^ Stupid theta -> AlgTyConRhs -> RecFlag - -> Bool -- True <=> want generics functions - -> Bool -- True <=> was declared in GADT syntax - -> Maybe (TyCon, [Type]) -- family instance if applicable + -> Bool -- ^ True <=> was declared in GADT syntax + -> TyConParent + -> Maybe (TyCon, [Type]) -- ^ family instance if applicable -> TcRnIf m n TyCon -buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn - mb_family - = do { -- We need to tie a knot as the coercion of a data instance depends - -- on the instance representation tycon and vice versa. - ; tycon <- fixM (\ tycon_rec -> do - { parent <- mkParentInfo mb_family tc_name tvs tycon_rec - ; let { tycon = mkAlgTyCon tc_name kind tvs stupid_theta rhs - fields parent is_rec want_generics gadt_syn - ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind - ; fields = mkTyConSelIds tycon rhs - } - ; return tycon - }) - ; return tycon - } - --- If a family tycon with instance types is given, the current tycon is an +buildAlgTyCon tc_name tvs stupid_theta rhs is_rec gadt_syn + parent mb_family + | Just fam_inst_info <- mb_family + = -- We need to tie a knot as the coercion of a data instance depends + -- on the instance representation tycon and vice versa. + ASSERT( isNoParent parent ) + fixM $ \ tycon_rec -> do + { fam_parent <- mkFamInstParentInfo tc_name tvs fam_inst_info tycon_rec + ; return (mkAlgTyCon tc_name kind tvs stupid_theta rhs + fam_parent is_rec gadt_syn) } + + | otherwise + = return (mkAlgTyCon tc_name kind tvs stupid_theta rhs + parent is_rec gadt_syn) + where + kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind + +-- | If a family tycon with instance types is given, the current tycon is an -- instance of that family and we need to -- -- (1) create a coercion that identifies the family instance type and the -- representation type from Step (1); ie, it is of the form --- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion, +-- `Co tvs :: F ts ~ R tvs', where `Co' is the name of the coercion, -- `F' the family tycon and `R' the (derived) representation tycon, -- and -- (2) produce a `TyConParent' value containing the parent and coercion -- information. -- -mkParentInfo :: Maybe (TyCon, [Type]) - -> Name -> [TyVar] - -> TyCon - -> TcRnIf m n TyConParent -mkParentInfo Nothing _ _ _ = - return NoParentTyCon -mkParentInfo (Just (family, instTys)) tc_name tvs rep_tycon = - do { -- Create the coercion - ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc - ; let co_tycon = mkFamInstCoercion co_tycon_name tvs - family instTys rep_tycon - ; return $ FamilyTyCon family instTys co_tycon - } +mkFamInstParentInfo :: Name -> [TyVar] + -> (TyCon, [Type]) + -> TyCon + -> TcRnIf m n TyConParent +mkFamInstParentInfo tc_name tvs (family, instTys) rep_tycon + = do { -- Create the coercion + ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc + ; let co_tycon = mkFamInstCo co_tycon_name tvs + family instTys rep_tycon + ; return $ FamInstTyCon family instTys co_tycon } ------------------------------------------------------ mkAbstractTyConRhs :: AlgTyConRhs mkAbstractTyConRhs = AbstractTyCon -mkOpenDataTyConRhs :: AlgTyConRhs -mkOpenDataTyConRhs = OpenTyCon Nothing False - -mkOpenNewTyConRhs :: AlgTyConRhs -mkOpenNewTyConRhs = OpenTyCon Nothing True - mkDataTyConRhs :: [DataCon] -> AlgTyConRhs mkDataTyConRhs cons - = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons } + = DataTyCon { + data_cons = cons, + is_enum = not (null cons) && all is_enum_con cons + -- See Note [Enumeration types] in TyCon + } + where + is_enum_con con + | (_tvs, theta, arg_tys, _res) <- dataConSig con + = null theta && null arg_tys + mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs --- Monadic because it makes a Name for the coercion TyCon --- We pass the Name of the parent TyCon, as well as the TyCon itself, --- because the latter is part of a knot, whereas the former is not. +-- ^ Monadic because it makes a Name for the coercion TyCon +-- We pass the Name of the parent TyCon, as well as the TyCon itself, +-- because the latter is part of a knot, whereas the former is not. mkNewTyConRhs tycon_name tycon con = do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc - ; let co_tycon = mkNewTypeCoercion co_tycon_name tycon etad_tvs etad_rhs - cocon_maybe | all_coercions || isRecursiveTyCon tycon - = Just co_tycon - | otherwise - = Nothing + ; let co_tycon = mkNewTypeCo co_tycon_name tycon etad_tvs etad_rhs + ; traceIf (text "mkNewTyConRhs" <+> ppr co_tycon) ; return (NewTyCon { data_con = con, nt_rhs = rhs_ty, nt_etad_rhs = (etad_tvs, etad_rhs), - nt_co = cocon_maybe, + nt_co = co_tycon } ) } -- Coreview looks through newtypes with a Nothing -- for nt_co, or uses explicit coercions otherwise - nt_rep = mkNewTyConRep tycon rhs_ty }) } where - -- If all_coercions is True then we use coercions for all newtypes - -- otherwise we use coercions for recursive newtypes and look through - -- non-recursive newtypes - all_coercions = True tvs = tyConTyVars tycon - rhs_ty = head (dataConInstOrigArgTys con (mkTyVarTys tvs)) + inst_con_ty = applyTys (dataConUserType con) (mkTyVarTys tvs) + rhs_ty = ASSERT( isFunTy inst_con_ty ) funArgTy inst_con_ty -- Instantiate the data con with the -- type variables from the tycon - - etad_tvs :: [TyVar] -- Matched lazily, so that mkNewTypeCoercion can + -- NB: a newtype DataCon has a type that must look like + -- forall tvs. -> T tvs + -- Note that we *can't* use dataConInstOrigArgTys here because + -- the newtype arising from class Foo a => Bar a where {} + -- has a single argument (Foo a) that is a *type class*, so + -- dataConInstOrigArgTys returns []. + + etad_tvs :: [TyVar] -- Matched lazily, so that mkNewTypeCo can etad_rhs :: Type -- return a TyCon without pulling on rhs_ty -- See Note [Tricky iface loop] in LoadIface (etad_tvs, etad_rhs) = eta_reduce (reverse tvs) rhs_ty @@ -168,58 +164,23 @@ mkNewTyConRhs tycon_name tycon con eta_reduce tvs ty = (reverse tvs, ty) -mkNewTyConRep :: TyCon -- The original type constructor - -> Type -- The arg type of its constructor - -> Type -- Chosen representation type --- The "representation type" is guaranteed not to be another newtype --- at the outermost level; but it might have newtypes in type arguments - --- Find the representation type for this newtype TyCon --- Remember that the representation type is the *ultimate* representation --- type, looking through other newtypes. --- --- splitTyConApp_maybe no longer looks through newtypes, so we must --- deal explicitly with this case --- --- The trick is to to deal correctly with recursive newtypes --- such as newtype T = MkT T - -mkNewTyConRep tc rhs_ty - | null (tyConDataCons tc) = unitTy - -- External Core programs can have newtypes with no data constructors - | otherwise = go [tc] rhs_ty - where - -- Invariant: tcs have been seen before - go tcs rep_ty - = case splitTyConApp_maybe rep_ty of - Just (tc, tys) - | tc `elem` tcs -> unitTy -- Recursive loop - | isNewTyCon tc -> - if isRecursiveTyCon tc then - go (tc:tcs) (substTyWith tvs tys rhs_ty) - else - substTyWith tvs tys rhs_ty - where - (tvs, rhs_ty) = newTyConRhs tc - - other -> rep_ty - ------------------------------------------------------ buildDataCon :: Name -> Bool - -> [StrictnessMark] + -> [HsBang] -> [Name] -- Field labels -> [TyVar] -> [TyVar] -- Univ and ext -> [(TyVar,Type)] -- Equality spec -> ThetaType -- Does not include the "stupid theta" -- or the GADT equalities - -> [Type] -> TyCon + -> [Type] -> Type -- Argument and result types + -> TyCon -- Rep tycon -> TcRnIf m n DataCon -- A wrapper for DataCon.mkDataCon that -- a) makes the worker Id -- b) makes the wrapper Id if necessary, including -- allocating its unique (hence monadic) buildDataCon src_name declared_infix arg_stricts field_lbls - univ_tvs ex_tvs eq_spec ctxt arg_tys tycon + univ_tvs ex_tvs eq_spec ctxt arg_tys res_ty rep_tycon = do { wrap_name <- newImplicitBinder src_name mkDataConWrapperOcc ; work_name <- newImplicitBinder src_name mkDataConWorkerOcc -- This last one takes the name of the data constructor in the source @@ -227,21 +188,22 @@ buildDataCon src_name declared_infix arg_stricts field_lbls -- space, and puts it into the VarName name space ; let - stupid_ctxt = mkDataConStupidTheta tycon arg_tys univ_tvs + stupid_ctxt = mkDataConStupidTheta rep_tycon arg_tys univ_tvs data_con = mkDataCon src_name declared_infix arg_stricts field_lbls univ_tvs ex_tvs eq_spec ctxt - arg_tys tycon + arg_tys res_ty rep_tycon stupid_ctxt dc_ids dc_ids = mkDataConIds wrap_name work_name data_con - ; returnM data_con } + ; return data_con } -- The stupid context for a data constructor should be limited to -- the type variables mentioned in the arg_tys -- ToDo: Or functionally dependent on? -- This whole stupid theta thing is, well, stupid. +mkDataConStupidTheta :: TyCon -> [Type] -> [TyVar] -> [PredType] mkDataConStupidTheta tycon arg_tys univ_tvs | null stupid_theta = [] -- The common case | otherwise = filter in_arg_tys stupid_theta @@ -254,65 +216,86 @@ mkDataConStupidTheta tycon arg_tys univ_tvs arg_tyvars = tyVarsOfTypes arg_tys in_arg_tys pred = not $ isEmptyVarSet $ tyVarsOfPred pred `intersectVarSet` arg_tyvars - ------------------------------------------------------- -mkTyConSelIds :: TyCon -> AlgTyConRhs -> [Id] -mkTyConSelIds tycon rhs - = [ mkRecordSelId tycon fld - | fld <- nub (concatMap dataConFieldLabels (visibleDataCons rhs)) ] - -- We'll check later that fields with the same name - -- from different constructors have the same type. \end{code} ------------------------------------------------------ \begin{code} -buildClass :: Name -> [TyVar] -> ThetaType - -> [FunDep TyVar] -- Functional dependencies - -> [TyThing] -- Associated types - -> [(Name, DefMeth, Type)] -- Method info - -> RecFlag -- Info for type constructor +type TcMethInfo = (Name, DefMethSpec, Type) + -- A temporary intermediate, to communicate between + -- tcClassSigs and buildClass. + +buildClass :: Bool -- True <=> do not include unfoldings + -- on dict selectors + -- Used when importing a class without -O + -> Name -> [TyVar] -> ThetaType + -> [FunDep TyVar] -- Functional dependencies + -> [TyThing] -- Associated types + -> [TcMethInfo] -- Method info + -> RecFlag -- Info for type constructor -> TcRnIf m n Class -buildClass class_name tvs sc_theta fds ats sig_stuff tc_isrec - = do { tycon_name <- newImplicitBinder class_name mkClassTyConOcc +buildClass no_unf class_name tvs sc_theta fds ats sig_stuff tc_isrec + = do { traceIf (text "buildClass") + ; tycon_name <- newImplicitBinder class_name mkClassTyConOcc ; datacon_name <- newImplicitBinder class_name mkClassDataConOcc -- The class name is the 'parent' for this datacon, not its tycon, -- because one should import the class to get the binding for -- the datacon - ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc) - [1..length sc_theta] - -- We number off the superclass selectors, 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!) ; fixM (\ rec_clas -> do { -- Only name generation inside loop - let { rec_tycon = classTyCon rec_clas - ; op_tys = [ty | (_,_,ty) <- sig_stuff] - ; sc_tys = mkPredTys sc_theta - ; dict_component_tys = sc_tys ++ op_tys - ; sc_sel_ids = [mkDictSelId sc_name rec_clas | sc_name <- sc_sel_names] - ; op_items = [ (mkDictSelId op_name rec_clas, dm_info) - | (op_name, dm_info, _) <- sig_stuff ] } + ; op_items <- mapM (mk_op_item rec_clas) sig_stuff -- Build the selector id and default method id + ; let (eq_theta, dict_theta) = partition isEqPred sc_theta + + -- We only make selectors for the *value* superclasses, + -- not equality predicates + ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc) + [1..length dict_theta] + ; let sc_sel_ids = [ mkDictSelId no_unf sc_name rec_clas + | sc_name <- sc_sel_names] + -- We number off the Dict superclass selectors, 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!) + + ; let use_newtype = null eq_theta && (length dict_theta + length sig_stuff == 1) + -- Use a newtype if the data constructor has + -- (a) exactly one value field + -- (b) no existential or equality-predicate fields + -- i.e. exactly one operation or superclass taken together + -- See note [Class newtypes and equality predicates] + + -- We play a bit fast and loose by treating the dictionary + -- superclasses as ordinary arguments. That means that in + -- the case of + -- class C a => D a + -- we don't get a newtype with no arguments! + args = sc_sel_names ++ op_names + op_tys = [ty | (_,_,ty) <- sig_stuff] + op_names = [op | (op,_,_) <- sig_stuff] + arg_tys = map mkPredTy dict_theta ++ op_tys + rec_tycon = classTyCon rec_clas + ; dict_con <- buildDataCon datacon_name False -- Not declared infix - (map (const NotMarkedStrict) dict_component_tys) - [{- No labelled fields -}] + (map (const HsNoBang) args) + [{- No fields -}] tvs [{- no existentials -}] - [{- No equalities -}] [{-No context-}] - dict_component_tys + [{- No GADT equalities -}] + eq_theta + arg_tys + (mkTyConApp rec_tycon (mkTyVarTys tvs)) rec_tycon - ; rhs <- case dict_component_tys of - [rep_ty] -> mkNewTyConRhs tycon_name rec_tycon dict_con - other -> return (mkDataTyConRhs [dict_con]) + ; rhs <- if use_newtype + then mkNewTyConRhs tycon_name rec_tycon dict_con + else return (mkDataTyConRhs [dict_con]) ; let { clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind @@ -327,11 +310,41 @@ buildClass class_name tvs sc_theta fds ats sig_stuff tc_isrec -- newtype like a synonym, but that will lead to an infinite -- type] ; atTyCons = [tycon | ATyCon tycon <- ats] + + ; result = mkClass class_name tvs fds + (eq_theta ++ dict_theta) -- Equalities first + (length eq_theta) -- Number of equalities + sc_sel_ids atTyCons + op_items tycon } - ; return (mkClass class_name tvs fds - sc_theta sc_sel_ids atTyCons op_items - tycon) + ; traceIf (text "buildClass" <+> ppr tycon) + ; return result })} + where + mk_op_item :: Class -> TcMethInfo -> TcRnIf n m ClassOpItem + mk_op_item rec_clas (op_name, dm_spec, _) + = do { dm_info <- case dm_spec of + NoDM -> return NoDefMeth + GenericDM -> do { dm_name <- newImplicitBinder op_name mkGenDefMethodOcc + ; return (GenDefMeth dm_name) } + VanillaDM -> do { dm_name <- newImplicitBinder op_name mkDefaultMethodOcc + ; return (DefMeth dm_name) } + ; return (mkDictSelId no_unf op_name rec_clas, dm_info) } \end{code} +Note [Class newtypes and equality predicates] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider + class (a ~ F b) => C a b where + op :: a -> b + +We cannot represent this by a newtype, even though it's not +existential, and there's only one value field, because we do +capture an equality predicate: + + data C a b where + MkC :: forall a b. (a ~ F b) => (a->b) -> C a b + +We need to access this equality predicate when we get passes a C +dictionary. See Trac #2238