X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fiface%2FBuildTyCl.lhs;h=8459edf98ad5ec54933f884af52260d3f8fb7dfd;hb=a08b4f85df5fbebc237bb7798cabe3812500e921;hp=8093c083c11e6b364c8a65d7efd5f9fd218f789b;hpb=d76c18e05f6366c23144624b696a02fbaa6d26e8;p=ghc-hetmet.git diff --git a/compiler/iface/BuildTyCl.lhs b/compiler/iface/BuildTyCl.lhs index 8093c08..8459edf 100644 --- a/compiler/iface/BuildTyCl.lhs +++ b/compiler/iface/BuildTyCl.lhs @@ -1,4 +1,5 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % @@ -6,61 +7,59 @@ module BuildTyCl ( buildSynTyCon, buildAlgTyCon, buildDataCon, buildClass, - mkAbstractTyConRhs, mkOpenDataTyConRhs, mkOpenNewTyConRhs, + mkAbstractTyConRhs, mkOpenDataTyConRhs, mkNewTyConRhs, mkDataTyConRhs ) where #include "HsVersions.h" -import IfaceEnv ( newImplicitBinder ) -import TcRnMonad +import IfaceEnv + +import DataCon +import Var +import VarSet +import BasicTypes +import Name +import OccName +import MkId +import Class +import TyCon +import Type +import Coercion -import DataCon ( DataCon, isNullarySrcDataCon, dataConUnivTyVars, - mkDataCon, dataConFieldLabels, dataConInstOrigArgTys, - dataConTyCon ) -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, mkNewTyCoOcc, mkInstTyTcOcc, - mkInstTyCoOcc ) -import MkId ( mkDataConIds, mkRecordSelId, mkDictSelId ) -import Class ( mkClass, Class( classTyCon), FunDep, DefMeth(..) ) -import TyCon ( mkSynTyCon, mkAlgTyCon, visibleDataCons, - tyConStupidTheta, tyConDataCons, isNewTyCon, - mkClassTyCon, TyCon( tyConTyVars ), - isRecursiveTyCon, tyConArity, AlgTyConRhs(..), - SynTyConRhs(..), newTyConRhs, AlgTyConParent(..) ) -import Type ( mkArrowKinds, liftedTypeKind, typeKind, - tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, - splitTyConApp_maybe, splitAppTy_maybe, - getTyVar_maybe, - mkPredTys, mkTyVarTys, ThetaType, Type, Kind, - TyThing(..), - substTyWith, zipTopTvSubst, substTheta, mkForAllTys, - mkTyConApp, mkTyVarTy ) -import Coercion ( mkNewTypeCoercion, mkDataInstCoercion ) +import TcRnMonad +import Util ( count ) import Outputable -import List ( nub ) +import Data.List \end{code} \begin{code} ------------------------------------------------------ -buildSynTyCon :: Name -> [TyVar] -> SynTyConRhs -> TyCon -buildSynTyCon name tvs rhs@(OpenSynTyCon rhs_ki) - = mkSynTyCon name kind tvs rhs - where - kind = mkArrowKinds (map tyVarKind tvs) rhs_ki -buildSynTyCon name tvs rhs@(SynonymTyCon rhs_ty) - = mkSynTyCon name kind tvs rhs - where - kind = mkArrowKinds (map tyVarKind tvs) (typeKind rhs_ty) - +buildSynTyCon :: Name -> [TyVar] + -> SynTyConRhs + -> 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 + } ------------------------------------------------------ buildAlgTyCon :: Name -> [TyVar] @@ -69,9 +68,7 @@ buildAlgTyCon :: Name -> [TyVar] -> RecFlag -> Bool -- True <=> want generics functions -> Bool -- True <=> was declared in GADT syntax - -> Maybe (TyCon, [Type], - Int) -- Just (family, tys, index) - -- <=> instance of `family' at `tys' + -> Maybe (TyCon, [Type]) -- family instance if applicable -> TcRnIf m n TyCon buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn @@ -79,8 +76,8 @@ buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn = 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 - { (final_name, parent) <- maybeComputeFamilyInfo mb_family tycon_rec - ; let { tycon = mkAlgTyCon final_name kind tvs stupid_theta rhs + { 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 @@ -89,45 +86,38 @@ buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn }) ; return tycon } - where - -- If a family tycon with instance types is given, the current tycon is an - -- instance of that family and we have to perform three extra tasks: - -- - -- (1) The instance tycon (representing the family at a particular type - -- instance) need to get a new, derived name - we may not reuse the - -- family name. - -- (2) 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. - -- (3) Produce a `AlgTyConParent' value containing the parent and coercion - -- information. - -- - maybeComputeFamilyInfo Nothing rep_tycon = - return (tc_name, NoParentTyCon) - maybeComputeFamilyInfo (Just (family, instTys, index)) rep_tycon = - do { -- (1) New, derived name for the instance tycon - ; final_name <- newImplicitBinder tc_name (mkInstTyTcOcc index) - - -- (2) Create the coercion. - ; co_tycon_name <- newImplicitBinder tc_name (mkInstTyCoOcc index) - ; let co_tycon = mkDataInstCoercion co_tycon_name tvs - family instTys rep_tycon - - -- (3) Produce parent information. - ; return (final_name, FamilyTyCon family instTys co_tycon index) - } - +-- 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. +-- +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 + } + ------------------------------------------------------ mkAbstractTyConRhs :: AlgTyConRhs mkAbstractTyConRhs = AbstractTyCon mkOpenDataTyConRhs :: AlgTyConRhs -mkOpenDataTyConRhs = OpenDataTyCon - -mkOpenNewTyConRhs :: AlgTyConRhs -mkOpenNewTyConRhs = OpenNewTyCon +mkOpenDataTyConRhs = OpenTyCon Nothing mkDataTyConRhs :: [DataCon] -> AlgTyConRhs mkDataTyConRhs cons @@ -139,76 +129,47 @@ mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs -- 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 tvs rhs_ty - cocon_maybe - | all_coercions || isRecursiveTyCon tycon - = Just co_tycon - | otherwise - = Nothing - ; return (NewTyCon { data_con = con, - nt_co = cocon_maybe, + ; let co_tycon = mkNewTypeCoercion co_tycon_name tycon etad_tvs etad_rhs + cocon_maybe | all_coercions || isRecursiveTyCon tycon + = Just co_tycon + | otherwise + = Nothing + ; traceIf (text "mkNewTyConRhs" <+> ppr cocon_maybe) + ; return (NewTyCon { data_con = con, + nt_rhs = rhs_ty, + nt_etad_rhs = (etad_tvs, etad_rhs), + nt_co = cocon_maybe } ) } -- Coreview looks through newtypes with a Nothing -- for nt_co, or uses explicit coercions otherwise - nt_rhs = rhs_ty, - nt_etad_rhs = eta_reduce tvs rhs_ty, - nt_rep = mkNewTyConRep tycon rhs_ty }) } where - -- if all_coercions is True then we use coercions for all newtypes + -- 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)) + rhs_ty = ASSERT(not (null (dataConInstOrigDictsAndArgTys con (mkTyVarTys tvs)))) + -- head (dataConInstOrigArgTys con (mkTyVarTys tvs)) + head (dataConInstOrigDictsAndArgTys con (mkTyVarTys tvs)) -- Instantiate the data con with the -- type variables from the tycon - - eta_reduce [] ty = ([], ty) - eta_reduce (a:as) ty | null as', - Just (fun, arg) <- splitAppTy_maybe ty', + -- NB: a newtype DataCon has no existentials; hence the + -- call to dataConInstOrigArgTys has the right type args + + etad_tvs :: [TyVar] -- Matched lazily, so that mkNewTypeCoercion 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. --- --- 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 @@ -241,13 +202,14 @@ buildDataCon src_name declared_infix arg_stricts field_lbls 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 @@ -273,57 +235,73 @@ mkTyConSelIds tycon rhs ------------------------------------------------------ \begin{code} -buildClass :: Name -> [TyVar] -> ThetaType +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 -> [(Name, DefMeth, Type)] -- 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 ] } + let { rec_tycon = classTyCon rec_clas + ; op_tys = [ty | (_,_,ty) <- sig_stuff] + ; op_items = [ (mkDictSelId no_unf op_name rec_clas, dm_info) + | (op_name, dm_info, _) <- sig_stuff ] } -- Build the selector id and default method id ; dict_con <- buildDataCon datacon_name False -- Not declared infix - (map (const NotMarkedStrict) dict_component_tys) + (map (const NotMarkedStrict) op_tys) [{- No labelled fields -}] tvs [{- no existentials -}] - [{- No equalities -}] [{-No context-}] - dict_component_tys + [{- No GADT equalities -}] sc_theta + op_tys rec_tycon - ; rhs <- case dict_component_tys of - [rep_ty] -> mkNewTyConRhs tycon_name rec_tycon dict_con - other -> return (mkDataTyConRhs [dict_con]) + ; let n_value_preds = count (not . isEqPred) sc_theta + all_value_preds = n_value_preds == length sc_theta + -- We only make selectors for the *value* superclasses, + -- not equality predicates + + ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc) + [1..n_value_preds] + ; 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 = (n_value_preds + length sig_stuff == 1) && all_value_preds + -- 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] + + ; 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 + 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 } @@ -333,11 +311,29 @@ 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 + sc_theta 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 })} \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