X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=bc93372e0f4041531d13682bd1a5b81a5f5078b2;hp=2b0f1b3223d148fc507131a4b948d9772a763a45;hb=b06d623b2e367a572de5daf06d6a0b12c2740471;hpb=3029576129e31d23e749be21c6a5a6f376ba28cd diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index 2b0f1b3..bc93372 100644 --- a/compiler/types/Coercion.lhs +++ b/compiler/types/Coercion.lhs @@ -3,23 +3,32 @@ % \begin{code} --- The above warning supression flag is a temporary kludge. --- While working on this module you are encouraged to remove it and fix --- any warnings in the module. See --- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings --- for details - --- | Module for type coercions, as used in System FC. See 'CoreSyn.Expr' for +-- | Module for (a) type kinds and (b) type coercions, +-- as used in System FC. See 'CoreSyn.Expr' for -- more on System FC and how coercions fit into it. -- -- Coercions are represented as types, and their kinds tell what types the --- coercion works on. The coercion kind constructor is a special TyCon that must always be saturated, like so: +-- coercion works on. The coercion kind constructor is a special TyCon that +-- must always be saturated, like so: -- --- > typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type] +-- > typeKind (symCoercion type) :: TyConApp CoTyCon{...} [type, type] module Coercion ( -- * Main data type - Coercion, - + Coercion, Kind, + typeKind, + + -- ** Deconstructing Kinds + kindFunResult, splitKindFunTys, splitKindFunTysN, splitKindFunTy_maybe, + + -- ** Predicates on Kinds + isLiftedTypeKind, isUnliftedTypeKind, isOpenTypeKind, + isUbxTupleKind, isArgTypeKind, isKind, isTySuperKind, + isCoSuperKind, isSuperKind, isCoercionKind, + mkArrowKind, mkArrowKinds, + + isSubArgTypeKind, isSubOpenTypeKind, isSubKind, defaultKind, eqKind, + isSubKindCon, + mkCoKind, mkCoPredTy, coVarKind, coVarKind_maybe, coercionKind, coercionKinds, isIdentityCoercion, @@ -35,7 +44,6 @@ module Coercion ( mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion, mkCsel1Coercion, mkCsel2Coercion, mkCselRCoercion, - splitNewTypeRepCo_maybe, instNewTyCon_maybe, decomposeCo, unsafeCoercionTyCon, symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, @@ -44,9 +52,8 @@ module Coercion ( -- ** Decomposition decompLR_maybe, decompCsel_maybe, decompInst_maybe, - - -- ** Optimisation - optCoercion, + splitCoPredTy_maybe, + splitNewTypeRepCo_maybe, instNewTyCon_maybe, decomposeCo, -- ** Comparison coreEqCoercion, coreEqCoercion2, @@ -73,12 +80,140 @@ import VarEnv import Name import PrelNames import Util -import Control.Monad import BasicTypes -import MonadUtils import Outputable import FastString +\end{code} + +%************************************************************************ +%* * + Functions over Kinds +%* * +%************************************************************************ +\begin{code} +-- | Essentially 'funResultTy' on kinds +kindFunResult :: Kind -> Kind +kindFunResult k = funResultTy k + +-- | Essentially 'splitFunTys' on kinds +splitKindFunTys :: Kind -> ([Kind],Kind) +splitKindFunTys k = splitFunTys k + +splitKindFunTy_maybe :: Kind -> Maybe (Kind,Kind) +splitKindFunTy_maybe = splitFunTy_maybe + +-- | Essentially 'splitFunTysN' on kinds +splitKindFunTysN :: Int -> Kind -> ([Kind],Kind) +splitKindFunTysN k = splitFunTysN k + +-- | See "Type#kind_subtyping" for details of the distinction between these 'Kind's +isUbxTupleKind, isOpenTypeKind, isArgTypeKind, isUnliftedTypeKind :: Kind -> Bool +isOpenTypeKindCon, isUbxTupleKindCon, isArgTypeKindCon, + isUnliftedTypeKindCon, isSubArgTypeKindCon :: TyCon -> Bool + +isOpenTypeKindCon tc = tyConUnique tc == openTypeKindTyConKey + +isOpenTypeKind (TyConApp tc _) = isOpenTypeKindCon tc +isOpenTypeKind _ = False + +isUbxTupleKindCon tc = tyConUnique tc == ubxTupleKindTyConKey + +isUbxTupleKind (TyConApp tc _) = isUbxTupleKindCon tc +isUbxTupleKind _ = False + +isArgTypeKindCon tc = tyConUnique tc == argTypeKindTyConKey + +isArgTypeKind (TyConApp tc _) = isArgTypeKindCon tc +isArgTypeKind _ = False + +isUnliftedTypeKindCon tc = tyConUnique tc == unliftedTypeKindTyConKey + +isUnliftedTypeKind (TyConApp tc _) = isUnliftedTypeKindCon tc +isUnliftedTypeKind _ = False + +isSubOpenTypeKind :: Kind -> Bool +-- ^ True of any sub-kind of OpenTypeKind (i.e. anything except arrow) +isSubOpenTypeKind (FunTy k1 k2) = ASSERT2 ( isKind k1, text "isSubOpenTypeKind" <+> ppr k1 <+> text "::" <+> ppr (typeKind k1) ) + ASSERT2 ( isKind k2, text "isSubOpenTypeKind" <+> ppr k2 <+> text "::" <+> ppr (typeKind k2) ) + False +isSubOpenTypeKind (TyConApp kc []) = ASSERT( isKind (TyConApp kc []) ) True +isSubOpenTypeKind other = ASSERT( isKind other ) False + -- This is a conservative answer + -- It matters in the call to isSubKind in + -- checkExpectedKind. + +isSubArgTypeKindCon kc + | isUnliftedTypeKindCon kc = True + | isLiftedTypeKindCon kc = True + | isArgTypeKindCon kc = True + | otherwise = False + +isSubArgTypeKind :: Kind -> Bool +-- ^ True of any sub-kind of ArgTypeKind +isSubArgTypeKind (TyConApp kc []) = isSubArgTypeKindCon kc +isSubArgTypeKind _ = False + +-- | Is this a super-kind (i.e. a type-of-kinds)? +isSuperKind :: Type -> Bool +isSuperKind (TyConApp (skc) []) = isSuperKindTyCon skc +isSuperKind _ = False + +-- | Is this a kind (i.e. a type-of-types)? +isKind :: Kind -> Bool +isKind k = isSuperKind (typeKind k) + +isSubKind :: Kind -> Kind -> Bool +-- ^ @k1 \`isSubKind\` k2@ checks that @k1@ <: @k2@ +isSubKind (TyConApp kc1 []) (TyConApp kc2 []) = kc1 `isSubKindCon` kc2 +isSubKind (FunTy a1 r1) (FunTy a2 r2) = (a2 `isSubKind` a1) && (r1 `isSubKind` r2) +isSubKind (PredTy (EqPred ty1 ty2)) (PredTy (EqPred ty1' ty2')) + = ty1 `tcEqType` ty1' && ty2 `tcEqType` ty2' +isSubKind _ _ = False + +eqKind :: Kind -> Kind -> Bool +eqKind = tcEqType + +isSubKindCon :: TyCon -> TyCon -> Bool +-- ^ @kc1 \`isSubKindCon\` kc2@ checks that @kc1@ <: @kc2@ +isSubKindCon kc1 kc2 + | isLiftedTypeKindCon kc1 && isLiftedTypeKindCon kc2 = True + | isUnliftedTypeKindCon kc1 && isUnliftedTypeKindCon kc2 = True + | isUbxTupleKindCon kc1 && isUbxTupleKindCon kc2 = True + | isOpenTypeKindCon kc2 = True + -- we already know kc1 is not a fun, its a TyCon + | isArgTypeKindCon kc2 && isSubArgTypeKindCon kc1 = True + | otherwise = False + +defaultKind :: Kind -> Kind +-- ^ Used when generalising: default kind ? and ?? to *. See "Type#kind_subtyping" for more +-- information on what that means + +-- When we generalise, we make generic type variables whose kind is +-- simple (* or *->* etc). So generic type variables (other than +-- built-in constants like 'error') always have simple kinds. This is important; +-- consider +-- f x = True +-- We want f to get type +-- f :: forall (a::*). a -> Bool +-- Not +-- f :: forall (a::??). a -> Bool +-- because that would allow a call like (f 3#) as well as (f True), +--and the calling conventions differ. This defaulting is done in TcMType.zonkTcTyVarBndr. +defaultKind k + | isSubOpenTypeKind k = liftedTypeKind + | isSubArgTypeKind k = liftedTypeKind + | otherwise = k +\end{code} + +%************************************************************************ +%* * + Coercions +%* * +%************************************************************************ + + +\begin{code} -- | A 'Coercion' represents a 'Type' something should be coerced to. type Coercion = Type @@ -154,83 +289,6 @@ getEqPredTys :: PredType -> (Type,Type) getEqPredTys (EqPred ty1 ty2) = (ty1, ty2) getEqPredTys other = pprPanic "getEqPredTys" (ppr other) --- | If it is the case that --- --- > c :: (t1 ~ t2) --- --- i.e. the kind of @c@ is a 'CoercionKind' relating @t1@ and @t2@, then @coercionKind c = (t1, t2)@. -coercionKind :: Coercion -> (Type, Type) -coercionKind ty@(TyVarTy a) | isCoVar a = coVarKind a - | otherwise = (ty, ty) -coercionKind (AppTy ty1 ty2) - = let (s1, t1) = coercionKind ty1 - (s2, t2) = coercionKind ty2 in - (mkAppTy s1 s2, mkAppTy t1 t2) -coercionKind co@(TyConApp tc args) - | Just (ar, rule) <- isCoercionTyCon_maybe tc - -- CoercionTyCons carry their kinding rule, so we use it here - = WARN( not (length args >= ar), ppr co ) -- Always saturated - (let (ty1,ty2) = runID (rule (return . typeKind) - (return . coercionKind) - False (take ar args)) - -- Apply the rule to the right number of args - -- Always succeeds (if term is well-kinded!) - (tys1, tys2) = coercionKinds (drop ar args) - in (mkAppTys ty1 tys1, mkAppTys ty2 tys2)) - - | otherwise - = let (lArgs, rArgs) = coercionKinds args in - (TyConApp tc lArgs, TyConApp tc rArgs) -coercionKind (FunTy ty1 ty2) - = let (t1, t2) = coercionKind ty1 - (s1, s2) = coercionKind ty2 in - (mkFunTy t1 s1, mkFunTy t2 s2) - -coercionKind (ForAllTy tv ty) - | isCoVar tv --- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2 --- ---------------------------------------------- --- c1~c2 => c3 :: (s1~t1) => r1 ~ (s2~t2) => r2 --- or --- forall (_:c1~c2) - = let (c1,c2) = coVarKind tv - (s1,s2) = coercionKind c1 - (t1,t2) = coercionKind c2 - (r1,r2) = coercionKind ty - in - (mkCoPredTy s1 t1 r1, mkCoPredTy s2 t2 r2) - - | otherwise --- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2 --- ---------------------------------------------- --- forall a:k. c :: forall a:k. t1 ~ forall a:k. t2 - = let (ty1, ty2) = coercionKind ty in - (ForAllTy tv ty1, ForAllTy tv ty2) - -coercionKind (PredTy (EqPred c1 c2)) - = pprTrace "coercionKind" (pprEqPred (c1,c2)) $ - let k1 = coercionKindPredTy c1 - k2 = coercionKindPredTy c2 in - (k1,k2) - -- These should not show up in coercions at all - -- becuase they are in the form of for-alls - where - coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2 - - - -coercionKind (PredTy (ClassP cl args)) - = let (lArgs, rArgs) = coercionKinds args in - (PredTy (ClassP cl lArgs), PredTy (ClassP cl rArgs)) -coercionKind (PredTy (IParam name ty)) - = let (ty1, ty2) = coercionKind ty in - (PredTy (IParam name ty1), PredTy (IParam name ty2)) - --- | Apply 'coercionKind' to multiple 'Coercion's -coercionKinds :: [Coercion] -> ([Type], [Type]) -coercionKinds tys = unzip $ map coercionKind tys - -------------------------------------- isIdentityCoercion :: Coercion -> Bool isIdentityCoercion co = case coercionKind co of @@ -322,8 +380,7 @@ mkInstsCoercion co tys = foldl mkInstCoercion co tys -- but it is used when we know we are dealing with bottom, which is one case in which -- it is safe. This is also used implement the @unsafeCoerce#@ primitive. mkUnsafeCoercion :: Type -> Type -> Coercion -mkUnsafeCoercion ty1 ty2 - = mkCoercion unsafeCoercionTyCon [ty1, ty2] +mkUnsafeCoercion ty1 ty2 = mkCoercion unsafeCoercionTyCon [ty1, ty2] -- See note [Newtype coercions] in TyCon @@ -334,16 +391,12 @@ mkUnsafeCoercion ty1 ty2 -- a subset of those 'TyVar's. mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon mkNewTypeCoercion name tycon tvs rhs_ty - = mkCoercionTyCon name co_con_arity rule + = mkCoercionTyCon name arity desc where - co_con_arity = length tvs - - rule :: CoTyConKindChecker - rule kc_ty _kc_co checking args - = do { ks <- mapM kc_ty args - ; unless (not checking || kindAppOk (tyConKind tycon) ks) - (fail "Argument kind mis-match") - ; return (TyConApp tycon args, substTyWith tvs args rhs_ty) } + arity = length tvs + desc = CoAxiom { co_ax_tvs = tvs + , co_ax_lhs = mkTyConApp tycon (mkTyVarTys tvs) + , co_ax_rhs = rhs_ty } -- | Create a coercion identifying a @data@, @newtype@ or @type@ representation type -- and its family instance. It has the form @Co tvs :: F ts ~ R tvs@, where @Co@ is @@ -355,26 +408,13 @@ mkFamInstCoercion :: Name -- ^ Unique name for the coercion tycon -> [Type] -- ^ Type instance (@ts@) -> TyCon -- ^ Representation tycon (@R@) -> TyCon -- ^ Coercion tycon (@Co@) -mkFamInstCoercion name tvs family instTys rep_tycon - = mkCoercionTyCon name coArity rule +mkFamInstCoercion name tvs family inst_tys rep_tycon + = mkCoercionTyCon name arity desc where - coArity = length tvs - - rule :: CoTyConKindChecker - rule kc_ty _kc_co checking args - = do { ks <- mapM kc_ty args - ; unless (not checking || kindAppOk (tyConKind rep_tycon) ks) - (fail "Argument kind mis-match") - ; return (substTyWith tvs args $ -- with sigma = [tys/tvs], - TyConApp family instTys -- sigma (F ts) - , TyConApp rep_tycon args) } -- ~ R tys - -kindAppOk :: Kind -> [Kind] -> Bool -kindAppOk _ [] = True -kindAppOk kfn (k:ks) - = case splitKindFunTy_maybe kfn of - Just (kfa, kfb) | k `isSubKind` kfa -> kindAppOk kfb ks - _other -> False + arity = length tvs + desc = CoAxiom { co_ax_tvs = tvs + , co_ax_lhs = mkTyConApp family inst_tys + , co_ax_rhs = mkTyConApp rep_tycon (mkTyVarTys tvs) } \end{code} @@ -403,137 +443,67 @@ symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon, unsafeCoercionTyCon, csel1CoercionTyCon, csel2CoercionTyCon, cselRCoercionTyCon :: TyCon -symCoercionTyCon - = mkCoercionTyCon symCoercionTyConName 1 kc_sym - where - kc_sym :: CoTyConKindChecker - kc_sym _kc_ty kc_co _ (co:_) - = do { (ty1,ty2) <- kc_co co - ; return (ty2,ty1) } - kc_sym _ _ _ _ = panic "kc_sym" - -transCoercionTyCon - = mkCoercionTyCon transCoercionTyConName 2 kc_trans - where - kc_trans :: CoTyConKindChecker - kc_trans _kc_ty kc_co checking (co1:co2:_) - = do { (a1, r1) <- kc_co co1 - ; (a2, r2) <- kc_co co2 - ; unless (not checking || (r1 `coreEqType` a2)) - (fail "Trans coercion mis-match") - ; return (a1, r2) } - kc_trans _ _ _ _ = panic "kc_sym" - ---------------------------------------------------- -leftCoercionTyCon = mkCoercionTyCon leftCoercionTyConName 1 (kcLR_help fst) -rightCoercionTyCon = mkCoercionTyCon rightCoercionTyConName 1 (kcLR_help snd) - -kcLR_help :: (forall a. (a,a)->a) -> CoTyConKindChecker -kcLR_help select _kc_ty kc_co _checking (co : _) - = do { (ty1, ty2) <- kc_co co - ; case decompLR_maybe ty1 ty2 of - Nothing -> fail "decompLR" - Just res -> return (select res) } -kcLR_help _ _ _ _ _ = panic "kcLR_help" - -decompLR_maybe :: Type -> Type -> Maybe ((Type,Type), (Type,Type)) +symCoercionTyCon = mkCoercionTyCon symCoercionTyConName 1 CoSym +transCoercionTyCon = mkCoercionTyCon transCoercionTyConName 2 CoTrans +leftCoercionTyCon = mkCoercionTyCon leftCoercionTyConName 1 CoLeft +rightCoercionTyCon = mkCoercionTyCon rightCoercionTyConName 1 CoRight +instCoercionTyCon = mkCoercionTyCon instCoercionTyConName 2 CoInst +csel1CoercionTyCon = mkCoercionTyCon csel1CoercionTyConName 1 CoCsel1 +csel2CoercionTyCon = mkCoercionTyCon csel2CoercionTyConName 1 CoCsel2 +cselRCoercionTyCon = mkCoercionTyCon cselRCoercionTyConName 1 CoCselR +unsafeCoercionTyCon = mkCoercionTyCon unsafeCoercionTyConName 2 CoUnsafe + +transCoercionTyConName, symCoercionTyConName, leftCoercionTyConName, + rightCoercionTyConName, instCoercionTyConName, unsafeCoercionTyConName, + csel1CoercionTyConName, csel2CoercionTyConName, cselRCoercionTyConName :: Name + +transCoercionTyConName = mkCoConName (fsLit "trans") transCoercionTyConKey transCoercionTyCon +symCoercionTyConName = mkCoConName (fsLit "sym") symCoercionTyConKey symCoercionTyCon +leftCoercionTyConName = mkCoConName (fsLit "left") leftCoercionTyConKey leftCoercionTyCon +rightCoercionTyConName = mkCoConName (fsLit "right") rightCoercionTyConKey rightCoercionTyCon +instCoercionTyConName = mkCoConName (fsLit "inst") instCoercionTyConKey instCoercionTyCon +csel1CoercionTyConName = mkCoConName (fsLit "csel1") csel1CoercionTyConKey csel1CoercionTyCon +csel2CoercionTyConName = mkCoConName (fsLit "csel2") csel2CoercionTyConKey csel2CoercionTyCon +cselRCoercionTyConName = mkCoConName (fsLit "cselR") cselRCoercionTyConKey cselRCoercionTyCon +unsafeCoercionTyConName = mkCoConName (fsLit "CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon + +mkCoConName :: FastString -> Unique -> TyCon -> Name +mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkTcOccFS occ) + key (ATyCon coCon) BuiltInSyntax +\end{code} + +\begin{code} +------------ +decompLR_maybe :: (Type,Type) -> Maybe ((Type,Type), (Type,Type)) -- Helper for left and right. Finds coercion kind of its input and -- returns the left and right projections of the coercion... -- -- if c :: t1 s1 ~ t2 s2 then splitCoercionKindOf c = ((t1, t2), (s1, s2)) -decompLR_maybe ty1 ty2 +decompLR_maybe (ty1,ty2) | Just (ty_fun1, ty_arg1) <- splitAppTy_maybe ty1 , Just (ty_fun2, ty_arg2) <- splitAppTy_maybe ty2 = Just ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2)) -decompLR_maybe _ _ = Nothing +decompLR_maybe _ = Nothing ---------------------------------------------------- -instCoercionTyCon - = mkCoercionTyCon instCoercionTyConName 2 kcInst_help - where - kcInst_help :: CoTyConKindChecker - kcInst_help kc_ty kc_co checking (co : ty : _) - = do { (t1,t2) <- kc_co co - ; k <- kc_ty ty - ; case decompInst_maybe t1 t2 of - Nothing -> fail "decompInst" - Just ((tv1,tv2), (ty1,ty2)) -> do - { unless (not checking || (k `isSubKind` tyVarKind tv1)) - (fail "Coercion instantation kind mis-match") - ; return (substTyWith [tv1] [ty] ty1, - substTyWith [tv2] [ty] ty2) } } - kcInst_help _ _ _ _ = panic "kcInst_help" - -decompInst_maybe :: Type -> Type -> Maybe ((TyVar,TyVar), (Type,Type)) -decompInst_maybe ty1 ty2 +------------ +decompInst_maybe :: (Type, Type) -> Maybe ((TyVar,TyVar), (Type,Type)) +decompInst_maybe (ty1, ty2) | Just (tv1,r1) <- splitForAllTy_maybe ty1 , Just (tv2,r2) <- splitForAllTy_maybe ty2 = Just ((tv1,tv2), (r1,r2)) -decompInst_maybe _ _ = Nothing +decompInst_maybe _ = Nothing ---------------------------------------------------- -unsafeCoercionTyCon - = mkCoercionTyCon unsafeCoercionTyConName 2 kc_unsafe - where - kc_unsafe kc_ty _kc_co _checking (ty1:ty2:_) - = do { _ <- kc_ty ty1 - ; _ <- kc_ty ty2 - ; return (ty1,ty2) } - kc_unsafe _ _ _ _ = panic "kc_unsafe" - ---------------------------------------------------- --- The csel* family - -csel1CoercionTyCon = mkCoercionTyCon csel1CoercionTyConName 1 (kcCsel_help fstOf3) -csel2CoercionTyCon = mkCoercionTyCon csel2CoercionTyConName 1 (kcCsel_help sndOf3) -cselRCoercionTyCon = mkCoercionTyCon cselRCoercionTyConName 1 (kcCsel_help thirdOf3) - -kcCsel_help :: (forall a. (a,a,a) -> a) -> CoTyConKindChecker -kcCsel_help select _kc_ty kc_co _checking (co : _) - = do { (ty1,ty2) <- kc_co co - ; case decompCsel_maybe ty1 ty2 of - Nothing -> fail "decompCsel" - Just res -> return (select res) } -kcCsel_help _ _ _ _ _ = panic "kcCsel_help" - -decompCsel_maybe :: Type -> Type -> Maybe ((Type,Type), (Type,Type), (Type,Type)) +------------ +decompCsel_maybe :: (Type, Type) -> Maybe ((Type,Type), (Type,Type), (Type,Type)) -- If co :: (s1~t1 => r1) ~ (s2~t2 => r2) -- Then csel1 co :: s1 ~ s2 -- csel2 co :: t1 ~ t2 -- cselR co :: r1 ~ r2 -decompCsel_maybe ty1 ty2 +decompCsel_maybe (ty1, ty2) | Just (s1, t1, r1) <- splitCoPredTy_maybe ty1 , Just (s2, t2, r2) <- splitCoPredTy_maybe ty2 = Just ((s1,s2), (t1,t2), (r1,r2)) -decompCsel_maybe _ _ = Nothing - -fstOf3 :: (a,b,c) -> a -sndOf3 :: (a,b,c) -> b -thirdOf3 :: (a,b,c) -> c -fstOf3 (a,_,_) = a -sndOf3 (_,b,_) = b -thirdOf3 (_,_,c) = c - --------------------------------------- --- Their Names - -transCoercionTyConName, symCoercionTyConName, leftCoercionTyConName, - rightCoercionTyConName, instCoercionTyConName, unsafeCoercionTyConName, - csel1CoercionTyConName, csel2CoercionTyConName, cselRCoercionTyConName :: Name - -transCoercionTyConName = mkCoConName (fsLit "trans") transCoercionTyConKey transCoercionTyCon -symCoercionTyConName = mkCoConName (fsLit "sym") symCoercionTyConKey symCoercionTyCon -leftCoercionTyConName = mkCoConName (fsLit "left") leftCoercionTyConKey leftCoercionTyCon -rightCoercionTyConName = mkCoConName (fsLit "right") rightCoercionTyConKey rightCoercionTyCon -instCoercionTyConName = mkCoConName (fsLit "inst") instCoercionTyConKey instCoercionTyCon -csel1CoercionTyConName = mkCoConName (fsLit "csel1") csel1CoercionTyConKey csel1CoercionTyCon -csel2CoercionTyConName = mkCoConName (fsLit "csel2") csel2CoercionTyConKey csel2CoercionTyCon -cselRCoercionTyConName = mkCoConName (fsLit "cselR") cselRCoercionTyConKey cselRCoercionTyCon -unsafeCoercionTyConName = mkCoConName (fsLit "CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon - -mkCoConName :: FastString -> Unique -> TyCon -> Name -mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkTcOccFS occ) - key (ATyCon coCon) BuiltInSyntax +decompCsel_maybe _ = Nothing \end{code} @@ -693,233 +663,148 @@ mkEqPredCoI _ (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi \end{code} %************************************************************************ -%* * - Optimising coercions -%* * +%* * + The kind of a type, and of a coercion +%* * %************************************************************************ \begin{code} -optCoercion :: TvSubst -> Coercion -> NormalCo --- ^ optCoercion applies a substitution to a coercion, --- *and* optimises it to reduce its size -optCoercion env co = opt_co env False co - -type NormalCo = Coercion - -- Invariants: - -- * The substitution has been fully applied - -- * For trans coercions (co1 `trans` co2) - -- co1 is not a trans, and neither co1 nor co2 is identity - -- * If the coercion is the identity, it has no CoVars of CoTyCons in it (just types) - -type NormalNonIdCo = NormalCo -- Extra invariant: not the identity - -opt_co, opt_co' :: TvSubst - -> Bool -- True <=> return (sym co) - -> Coercion - -> NormalCo -opt_co = opt_co' --- opt_co sym co = pprTrace "opt_co {" (ppr sym <+> ppr co) $ --- co1 `seq` --- pprTrace "opt_co done }" (ppr co1) --- WARN( not same_co_kind, ppr co <+> dcolon <+> pprEqPred (s1,t1) --- $$ ppr co1 <+> dcolon <+> pprEqPred (s2,t2) ) --- co1 --- where --- co1 = opt_co' sym co --- same_co_kind = s1 `coreEqType` s2 && t1 `coreEqType` t2 --- (s,t) = coercionKind co --- (s1,t1) | sym = (t,s) --- | otherwise = (s,t) --- (s2,t2) = coercionKind co1 - -opt_co' env sym (AppTy ty1 ty2) = mkAppTy (opt_co env sym ty1) (opt_co env sym ty2) -opt_co' env sym (FunTy ty1 ty2) = FunTy (opt_co env sym ty1) (opt_co env sym ty2) -opt_co' env sym (PredTy (ClassP cls tys)) = PredTy (ClassP cls (map (opt_co env sym) tys)) -opt_co' env sym (PredTy (IParam n ty)) = PredTy (IParam n (opt_co env sym ty)) -opt_co' _ _ co@(PredTy (EqPred {})) = pprPanic "optCoercion" (ppr co) - -opt_co' env sym co@(TyVarTy tv) - | Just ty <- lookupTyVar env tv = opt_co' (zapTvSubstEnv env) sym ty - | not (isCoVar tv) = co -- Identity; does not mention a CoVar - | ty1 `coreEqType` ty2 = ty1 -- Identity; ..ditto.. - | not sym = co - | otherwise = mkSymCoercion co - where - (ty1,ty2) = coVarKind tv +typeKind :: Type -> Kind +typeKind ty@(TyConApp tc tys) + | isCoercionTyCon tc = typeKind (fst (coercionKind ty)) + | otherwise = foldr (\_ k -> kindFunResult k) (tyConKind tc) tys + -- During coercion optimisation we *do* match a type + -- against a coercion (see OptCoercion.matchesAxiomLhs) + -- So the use of typeKind in Unify.match_kind must work on coercions too + -- Hence the isCoercionTyCon case above + +typeKind (PredTy pred) = predKind pred +typeKind (AppTy fun _) = kindFunResult (typeKind fun) +typeKind (ForAllTy _ ty) = typeKind ty +typeKind (TyVarTy tyvar) = tyVarKind tyvar +typeKind (FunTy _arg res) + -- Hack alert. The kind of (Int -> Int#) is liftedTypeKind (*), + -- not unliftedTypKind (#) + -- The only things that can be after a function arrow are + -- (a) types (of kind openTypeKind or its sub-kinds) + -- (b) kinds (of super-kind TY) (e.g. * -> (* -> *)) + | isTySuperKind k = k + | otherwise = ASSERT( isSubOpenTypeKind k) liftedTypeKind + where + k = typeKind res + +------------------ +predKind :: PredType -> Kind +predKind (EqPred {}) = coSuperKind -- A coercion kind! +predKind (ClassP {}) = liftedTypeKind -- Class and implicitPredicates are +predKind (IParam {}) = liftedTypeKind -- always represented by lifted types + +------------------ +-- | If it is the case that +-- +-- > c :: (t1 ~ t2) +-- +-- i.e. the kind of @c@ is a 'CoercionKind' relating @t1@ and @t2@, then @coercionKind c = (t1, t2)@. +coercionKind :: Coercion -> (Type, Type) +coercionKind ty@(TyVarTy a) | isCoVar a = coVarKind a + | otherwise = (ty, ty) +coercionKind (AppTy ty1 ty2) + = let (s1, t1) = coercionKind ty1 + (s2, t2) = coercionKind ty2 in + (mkAppTy s1 s2, mkAppTy t1 t2) +coercionKind co@(TyConApp tc args) + | Just (ar, desc) <- isCoercionTyCon_maybe tc + -- CoercionTyCons carry their kinding rule, so we use it here + = WARN( not (length args >= ar), ppr co ) -- Always saturated + (let (ty1, ty2) = coTyConAppKind desc (take ar args) + (tys1, tys2) = coercionKinds (drop ar args) + in (mkAppTys ty1 tys1, mkAppTys ty2 tys2)) -opt_co' env sym (ForAllTy tv cor) - | isCoVar tv = mkCoPredTy (opt_co env sym co1) (opt_co env sym co2) (opt_co env sym cor) - | otherwise = case substTyVarBndr env tv of - (env', tv') -> ForAllTy tv' (opt_co env' sym cor) - where - (co1,co2) = coVarKind tv + | otherwise + = let (lArgs, rArgs) = coercionKinds args in + (TyConApp tc lArgs, TyConApp tc rArgs) + +coercionKind (FunTy ty1 ty2) + = let (t1, t2) = coercionKind ty1 + (s1, s2) = coercionKind ty2 in + (mkFunTy t1 s1, mkFunTy t2 s2) + +coercionKind (ForAllTy tv ty) + | isCoVar tv +-- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2 +-- ---------------------------------------------- +-- c1~c2 => c3 :: (s1~t1) => r1 ~ (s2~t2) => r2 +-- or +-- forall (_:c1~c2) + = let (c1,c2) = coVarKind tv + (s1,s2) = coercionKind c1 + (t1,t2) = coercionKind c2 + (r1,r2) = coercionKind ty + in + (mkCoPredTy s1 t1 r1, mkCoPredTy s2 t2 r2) -opt_co' env sym (TyConApp tc cos) - | isCoercionTyCon tc - = foldl mkAppTy - (opt_co_tc_app env sym tc (take arity cos)) - (map (opt_co env sym) (drop arity cos)) | otherwise - = TyConApp tc (map (opt_co env sym) cos) - where - arity = tyConArity tc - --------- -opt_co_tc_app :: TvSubst -> Bool -> TyCon -> [Coercion] -> NormalCo --- Used for CoercionTyCons only --- Arguments are *not* already simplified/substituted -opt_co_tc_app env sym tc cos - | tc `hasKey` symCoercionTyConKey - = opt_co env (not sym) co1 - - | tc `hasKey` transCoercionTyConKey - = if sym then opt_trans opt_co2 opt_co1 -- sym (g `o` h) = sym h `o` sym g - else opt_trans opt_co1 opt_co2 - - | tc `hasKey` leftCoercionTyConKey - , Just (opt_co1_left, _) <- splitAppTy_maybe opt_co1 - = opt_co1_left -- sym (left g) = left (sym g) - -- The opt_co has the sym pushed into it - - | tc `hasKey` rightCoercionTyConKey - , Just (_, opt_co1_right) <- splitAppTy_maybe opt_co1 - = opt_co1_right - - | tc `hasKey` csel1CoercionTyConKey - , Just (s1,_,_) <- splitCoPredTy_maybe opt_co1 - = s1 - - | tc `hasKey` csel2CoercionTyConKey - , Just (_,s2,_) <- splitCoPredTy_maybe opt_co1 - = s2 - - | tc `hasKey` cselRCoercionTyConKey - , Just (_,_,r) <- splitCoPredTy_maybe opt_co1 - = r - - | tc `hasKey` instCoercionTyConKey -- See if the first arg - -- is already a forall - , Just (tv, co1_body) <- splitForAllTy_maybe co1 - , let ty = substTy env co2 - = opt_co (extendTvSubst env tv ty) sym co1_body - - | tc `hasKey` instCoercionTyConKey -- See if is *now* a forall - , Just (tv, opt_co1_body) <- splitForAllTy_maybe opt_co1 - , let ty = substTy env co2 - = substTyWith [tv] [ty] opt_co1_body -- An inefficient one-variable substitution - - | otherwise -- Do *not* push sym inside top-level axioms - -- e.g. if g is a top-level axiom - -- g a : F a ~ a - -- Then (sym (g ty)) /= g (sym ty) !! - = if sym then mkSymCoercion the_co - else the_co +-- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2 +-- ---------------------------------------------- +-- forall a:k. c :: forall a:k. t1 ~ forall a:k. t2 + = let (ty1, ty2) = coercionKind ty in + (ForAllTy tv ty1, ForAllTy tv ty2) + +coercionKind (PredTy (ClassP cl args)) + = let (lArgs, rArgs) = coercionKinds args in + (PredTy (ClassP cl lArgs), PredTy (ClassP cl rArgs)) +coercionKind (PredTy (IParam name ty)) + = let (ty1, ty2) = coercionKind ty in + (PredTy (IParam name ty1), PredTy (IParam name ty2)) +coercionKind (PredTy (EqPred c1 c2)) + = pprTrace "coercionKind" (pprEqPred (c1,c2)) $ + -- These should not show up in coercions at all + -- becuase they are in the form of for-alls + let k1 = coercionKindPredTy c1 + k2 = coercionKindPredTy c2 in + (k1,k2) where - (co1 : cos1) = cos - (co2 : _) = cos1 - - -- These opt_cos have the sym pushed into them - opt_co1 = opt_co env sym co1 - opt_co2 = opt_co env sym co2 - - -- However the_co does *not* have sym pushed into it - the_co = TyConApp tc (map (opt_co env False) cos) - -------------- -opt_trans :: NormalCo -> NormalCo -> NormalCo -opt_trans co1 co2 - | isIdNormCo co1 = co2 - | otherwise = opt_trans1 co1 co2 - -opt_trans1 :: NormalNonIdCo -> NormalCo -> NormalCo --- First arg is not the identity -opt_trans1 co1 co2 - | isIdNormCo co2 = co1 - | otherwise = opt_trans2 co1 co2 - -opt_trans2 :: NormalNonIdCo -> NormalNonIdCo -> NormalCo --- Neither arg is the identity -opt_trans2 (TyConApp tc [co1a,co1b]) co2 - | tc `hasKey` transCoercionTyConKey - = opt_trans1 co1a (opt_trans2 co1b co2) - -opt_trans2 co1 co2 - | Just co <- opt_trans_rule co1 co2 - = co - -opt_trans2 co1 (TyConApp tc [co2a,co2b]) - | tc `hasKey` transCoercionTyConKey - , Just co1_2a <- opt_trans_rule co1 co2a - = if isIdNormCo co1_2a - then co2b - else opt_trans2 co1_2a co2b - -opt_trans2 co1 co2 - = mkTransCoercion co1 co2 - ------- -opt_trans_rule :: NormalNonIdCo -> NormalNonIdCo -> Maybe NormalCo -opt_trans_rule (TyConApp tc [co1]) co2 - | tc `hasKey` symCoercionTyConKey - , co1 `coreEqType` co2 - , (_,ty2) <- coercionKind co2 - = Just ty2 - -opt_trans_rule co1 (TyConApp tc [co2]) - | tc `hasKey` symCoercionTyConKey - , co1 `coreEqType` co2 - , (ty1,_) <- coercionKind co1 - = Just ty1 - -opt_trans_rule (TyConApp tc1 [co1,ty1]) (TyConApp tc2 [co2,ty2]) - | tc1 `hasKey` instCoercionTyConKey - , tc1 == tc2 - , ty1 `coreEqType` ty2 - = Just (mkInstCoercion (opt_trans2 co1 co2) ty1) - -opt_trans_rule (TyConApp tc1 cos1) (TyConApp tc2 cos2) - | not (isCoercionTyCon tc1) || - getUnique tc1 `elem` [ leftCoercionTyConKey, rightCoercionTyConKey - , csel1CoercionTyConKey, csel2CoercionTyConKey - , cselRCoercionTyConKey ] --Yuk! - , tc1 == tc2 -- Works for left,right, and csel* family - -- BUT NOT equality axioms - -- E.g. (g Int) `trans` (g Bool) - -- /= g (Int . Bool) - = Just (TyConApp tc1 (zipWith opt_trans cos1 cos2)) - -opt_trans_rule co1 co2 - | Just (co1a, co1b) <- splitAppTy_maybe co1 - , Just (co2a, co2b) <- splitAppTy_maybe co2 - = Just (mkAppTy (opt_trans co1a co2a) (opt_trans co1b co2b)) - - | Just (s1,t1,r1) <- splitCoPredTy_maybe co1 - , Just (s2,t2,r2) <- splitCoPredTy_maybe co1 - = Just (mkCoPredTy (opt_trans s1 s2) - (opt_trans t1 t2) - (opt_trans r1 r2)) - - | Just (tv1,r1) <- splitForAllTy_maybe co1 - , Just (tv2,r2) <- splitForAllTy_maybe co2 - , not (isCoVar tv1) -- Both have same kind - , let r2' = substTyWith [tv2] [TyVarTy tv1] r2 - = Just (ForAllTy tv1 (opt_trans2 r1 r2')) - -opt_trans_rule _ _ = Nothing - - -------------- -isIdNormCo :: NormalCo -> Bool --- Cheap identity test: look for coercions with no coercion variables at all --- So it'll return False for (sym g `trans` g) -isIdNormCo ty = go ty + coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2 + +------------------ +-- | Apply 'coercionKind' to multiple 'Coercion's +coercionKinds :: [Coercion] -> ([Type], [Type]) +coercionKinds tys = unzip $ map coercionKind tys + +------------------ +-- | 'coTyConAppKind' is given a list of the type arguments to the 'CoTyCon', +-- and constructs the types that the resulting coercion relates. +-- Fails (in the monad) if ill-kinded. +-- Typically the monad is +-- either the Lint monad (with the consistency-check flag = True), +-- or the ID monad with a panic on failure (and the consistency-check flag = False) +coTyConAppKind + :: CoTyConDesc + -> [Type] -- Exactly right number of args + -> (Type, Type) -- Kind of this application +coTyConAppKind CoUnsafe (ty1:ty2:_) + = (ty1,ty2) +coTyConAppKind CoSym (co:_) + | (ty1,ty2) <- coercionKind co = (ty2,ty1) +coTyConAppKind CoTrans (co1:co2:_) + = (fst (coercionKind co1), snd (coercionKind co2)) +coTyConAppKind CoLeft (co:_) + | Just (res,_) <- decompLR_maybe (coercionKind co) = res +coTyConAppKind CoRight (co:_) + | Just (_,res) <- decompLR_maybe (coercionKind co) = res +coTyConAppKind CoCsel1 (co:_) + | Just (res,_,_) <- decompCsel_maybe (coercionKind co) = res +coTyConAppKind CoCsel2 (co:_) + | Just (_,res,_) <- decompCsel_maybe (coercionKind co) = res +coTyConAppKind CoCselR (co:_) + | Just (_,_,res) <- decompCsel_maybe (coercionKind co) = res +coTyConAppKind CoInst (co:ty:_) + | Just ((tv1,tv2), (ty1,ty2)) <- decompInst_maybe (coercionKind co) + = (substTyWith [tv1] [ty] ty1, substTyWith [tv2] [ty] ty2) +coTyConAppKind (CoAxiom { co_ax_tvs = tvs + , co_ax_lhs = lhs_ty, co_ax_rhs = rhs_ty }) cos + = (substTyWith tvs tys1 lhs_ty, substTyWith tvs tys2 rhs_ty) where - go (TyVarTy tv) = not (isCoVar tv) - go (AppTy t1 t2) = go t1 && go t2 - go (FunTy t1 t2) = go t1 && go t2 - go (ForAllTy tv ty) = go (tyVarKind tv) && go ty - go (TyConApp tc tys) = not (isCoercionTyCon tc) && all go tys - go (PredTy (IParam _ ty)) = go ty - go (PredTy (ClassP _ tys)) = all go tys - go (PredTy (EqPred t1 t2)) = go t1 && go t2 -\end{code} + (tys1, tys2) = coercionKinds cos +coTyConAppKind desc cos = pprPanic "coTyConAppKind" (ppr desc $$ ppr cos) +\end{code}