X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fiface%2FBuildTyCl.lhs;h=eabe8c45aa42da1eefd91253f619c9c624bffe71;hp=f81f2e7d07c3be91dcc7f977666d7c6bfb847272;hb=86add45dbfb6f962b65e371143dd467ae783f9e7;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1 diff --git a/compiler/iface/BuildTyCl.lhs b/compiler/iface/BuildTyCl.lhs index f81f2e7..eabe8c4 100644 --- a/compiler/iface/BuildTyCl.lhs +++ b/compiler/iface/BuildTyCl.lhs @@ -1,150 +1,186 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \begin{code} module BuildTyCl ( - buildSynTyCon, buildAlgTyCon, buildDataCon, - buildClass, - mkAbstractTyConRhs, mkNewTyConRhs, mkDataTyConRhs + buildSynTyCon, + buildAlgTyCon, + buildDataCon, + TcMethInfo, buildClass, + mkAbstractTyConRhs, + mkNewTyConRhs, mkDataTyConRhs, + newImplicitBinder ) where #include "HsVersions.h" -import IfaceEnv ( newImplicitBinder ) -import TcRnMonad +import IfaceEnv -import DataCon ( DataCon, isNullarySrcDataCon, dataConTyVars, - mkDataCon, dataConFieldLabels, dataConOrigArgTys ) -import Var ( tyVarKind, TyVar, Id ) -import VarSet ( isEmptyVarSet, intersectVarSet, elemVarSet ) -import TysWiredIn ( unitTy ) -import BasicTypes ( RecFlag, StrictnessMark(..) ) -import Name ( Name ) -import OccName ( mkDataConWrapperOcc, mkDataConWorkerOcc, mkClassTyConOcc, - mkClassDataConOcc, mkSuperDictSelOcc ) -import MkId ( mkDataConIds, mkRecordSelId, mkDictSelId ) -import Class ( mkClass, Class( classTyCon), FunDep, DefMeth(..) ) -import TyCon ( mkSynTyCon, mkAlgTyCon, visibleDataCons, tyConStupidTheta, - tyConDataCons, isNewTyCon, mkClassTyCon, TyCon( tyConTyVars ), - isRecursiveTyCon, - ArgVrcs, AlgTyConRhs(..), newTyConRhs ) -import Type ( mkArrowKinds, liftedTypeKind, typeKind, - tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, - splitTyConApp_maybe, splitAppTy_maybe, getTyVar_maybe, - mkPredTys, mkTyVarTys, ThetaType, Type, - substTyWith, zipTopTvSubst, substTheta ) -import Outputable -import List ( nub ) +import DataCon +import Var +import VarSet +import BasicTypes +import Name +import MkId +import Class +import TyCon +import Type +import Coercion +import TcRnMonad +import Data.List ( partition ) +import Outputable \end{code} \begin{code} ------------------------------------------------------ -buildSynTyCon name tvs rhs_ty arg_vrcs - = mkSynTyCon name kind tvs rhs_ty arg_vrcs +buildSynTyCon :: Name -> [TyVar] + -> SynTyConRhs + -> Kind -- ^ Kind of the RHS + -> TyConParent + -> Maybe (TyCon, [Type]) -- ^ family instance if applicable + -> TcRnIf m n 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) (typeKind rhs_ty) - + kind = mkArrowKinds (map tyVarKind tvs) rhs_kind ------------------------------------------------------ buildAlgTyCon :: Name -> [TyVar] - -> ThetaType -- Stupid theta + -> ThetaType -- ^ Stupid theta -> AlgTyConRhs - -> ArgVrcs -> RecFlag - -> Bool -- True <=> want generics functions + -> RecFlag + -> 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 arg_vrcs is_rec want_generics - = do { let { tycon = mkAlgTyCon tc_name kind tvs arg_vrcs stupid_theta - rhs fields is_rec want_generics - ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind - ; fields = mkTyConSelIds tycon rhs - } - ; return tycon } - +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, +-- `F' the family tycon and `R' the (derived) representation tycon, +-- and +-- (2) produce a `TyConParent' value containing the parent and coercion +-- information. +-- +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 mkDataTyConRhs :: [DataCon] -> AlgTyConRhs mkDataTyConRhs cons - = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons } - -mkNewTyConRhs :: TyCon -> DataCon -> AlgTyConRhs -mkNewTyConRhs tycon con - = NewTyCon { data_con = con, - nt_rhs = rhs_ty, - nt_etad_rhs = eta_reduce tvs rhs_ty, - nt_rep = mkNewTyConRep tycon rhs_ty } + = DataTyCon { + data_cons = cons, + is_enum = not (null cons) && all is_enum_con cons + -- See Note [Enumeration types] in TyCon + } where - tvs = dataConTyVars con - rhs_ty = head (dataConOrigArgTys con) - -- Newtypes are guaranteed vanilla, so OrigArgTys will do - - eta_reduce [] ty = ([], ty) - eta_reduce (a:as) ty | null as', - Just (fun, arg) <- splitAppTy_maybe ty', + 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. +mkNewTyConRhs tycon_name tycon con + = do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc + ; 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 = co_tycon } ) } + -- Coreview looks through newtypes with a Nothing + -- for nt_co, or uses explicit coercions otherwise + where + tvs = tyConTyVars tycon + 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 + -- 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 + + eta_reduce :: [TyVar] -- Reversed + -> Type -- Rhs type + -> ([TyVar], Type) -- Eta-reduced version (tyvars in normal order) + eta_reduce (a:as) ty | Just (fun, arg) <- splitAppTy_maybe ty, Just tv <- getTyVar_maybe arg, tv == a, not (a `elemVarSet` tyVarsOfType fun) - = ([], fun) -- Successful eta reduction - | otherwise - = (a:as', ty') - where - (as', ty') = eta_reduce as ty + = eta_reduce as fun + 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. --- --- The non-recursive newtypes are easy, because they look transparent --- to splitTyConApp_maybe, but recursive ones really are represented as --- TyConApps (see TypeRep). --- --- 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 -> ASSERT( isRecursiveTyCon tc ) - -- Non-recursive ones have been - -- dealt with by splitTyConApp_maybe - go (tc:tcs) (substTyWith tvs tys rhs_ty) - where - (tvs, rhs_ty) = newTyConRhs tc - - other -> rep_ty ------------------------------------------------------ -buildDataCon :: Name -> Bool -> Bool - -> [StrictnessMark] +buildDataCon :: Name -> Bool + -> [HsBang] -> [Name] -- Field labels - -> [TyVar] + -> [TyVar] -> [TyVar] -- Univ and ext + -> [(TyVar,Type)] -- Equality spec -> ThetaType -- Does not include the "stupid theta" - -> [Type] -> TyCon -> [Type] + -- or the GADT equalities + -> [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 vanilla arg_stricts field_lbls - tyvars ctxt arg_tys tycon res_tys +buildDataCon src_name declared_infix arg_stricts field_lbls + 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 @@ -152,105 +188,163 @@ buildDataCon src_name declared_infix vanilla arg_stricts field_lbls -- space, and puts it into the VarName name space ; let - stupid_ctxt = mkDataConStupidTheta tycon arg_tys res_tys - data_con = mkDataCon src_name declared_infix vanilla + stupid_ctxt = mkDataConStupidTheta rep_tycon arg_tys univ_tvs + data_con = mkDataCon src_name declared_infix arg_stricts field_lbls - tyvars stupid_ctxt ctxt - arg_tys tycon res_tys dc_ids + univ_tvs ex_tvs eq_spec ctxt + 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 -mkDataConStupidTheta tycon arg_tys res_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 where - tc_subst = zipTopTvSubst (tyConTyVars tycon) res_tys - stupid_theta = substTheta tc_subst (tyConStupidTheta tycon) + tc_subst = zipTopTvSubst (tyConTyVars tycon) (mkTyVarTys univ_tvs) + stupid_theta = substTheta tc_subst (tyConStupidTheta tycon) -- Start by instantiating the master copy of the -- stupid theta, taken from the TyCon 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. + tyVarsOfPred pred `intersectVarSet` arg_tyvars \end{code} ------------------------------------------------------ \begin{code} -buildClass :: Name -> [TyVar] -> ThetaType - -> [FunDep TyVar] -- Functional dependencies - -> [(Name, DefMeth, Type)] -- Method info - -> RecFlag -> ArgVrcs -- 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 sig_stuff tc_isrec tc_vrcs - = 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 + + ; fixM (\ rec_clas -> do { -- Only name generation inside loop + + ; 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!) - - ; fixM (\ clas -> do { -- Only name generation inside loop - - let { op_tys = [ty | (_,_,ty) <- 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] - ; op_items = [ (mkDictSelId op_name clas, dm_info) - | (op_name, dm_info, _) <- sig_stuff ] } - -- Build the selector id and default method id - - ; dict_con <- buildDataCon datacon_name + + ; 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 - True -- Is vanilla; tyvars same as tycon - (map (const NotMarkedStrict) dict_component_tys) - [{- No labelled fields -}] - tvs [{-No context-}] dict_component_tys - (classTyCon clas) (mkTyVarTys tvs) - - ; let { clas = mkClass class_name tvs fds - sc_theta sc_sel_ids op_items - tycon - - ; tycon = mkClassTyCon tycon_name clas_kind tvs - tc_vrcs rhs clas tc_isrec + (map (const HsNoBang) args) + [{- No fields -}] + tvs [{- no existentials -}] + [{- No GADT equalities -}] + eq_theta + arg_tys + (mkTyConApp rec_tycon (mkTyVarTys tvs)) + rec_tycon + + ; 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 + + ; tycon = mkClassTyCon tycon_name clas_kind tvs + rhs rec_clas tc_isrec -- A class can be recursive, and in the case of newtypes -- this matters. For example -- class C a where { op :: C b => a -> b -> Int } -- Because C has only one operation, it is represented by -- a newtype, and it should be a *recursive* newtype. -- [If we don't make it a recursive newtype, we'll expand the - -- newtype like a synonym, but that will lead to an infinite type] - - ; clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind - - ; rhs = case dict_component_tys of - [rep_ty] -> mkNewTyConRhs tycon dict_con - other -> mkDataTyConRhs [dict_con] + -- 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 clas + ; 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