X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=3bc5d84541e201edeecfa5338efdde1bb318cb76;hb=8604da0136707cc14845d14a88c2272fe576b6d0;hp=c2261adcd472743d6327b5ba9874703ba0eba06f;hpb=fd6ccd023fe4c1d4124a4fe504e07a23bf433722;p=ghc-hetmet.git diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index c2261ad..3bc5d84 100644 --- a/compiler/types/Coercion.lhs +++ b/compiler/types/Coercion.lhs @@ -12,6 +12,13 @@ The coercion kind constructor is a special TyCon that must always be saturated typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type] \begin{code} +{-# OPTIONS -fno-warn-incomplete-patterns #-} +-- 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 Coercion ( Coercion, @@ -22,16 +29,31 @@ module Coercion ( isEqPred, mkEqPred, getEqPredTys, isEqPredTy, -- Coercion transformations + mkCoercion, mkSymCoercion, mkTransCoercion, - mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion, + mkLeftCoercion, mkRightCoercion, mkRightCoercions, + mkInstCoercion, mkAppCoercion, mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion, - mkNewTypeCoercion, mkDataInstCoercion, mkAppsCoercion, + mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion, - splitNewTypeRepCo_maybe, decomposeCo, + splitNewTypeRepCo_maybe, instNewTyCon_maybe, decomposeCo, unsafeCoercionTyCon, symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, - rightCoercionTyCon, instCoercionTyCon -- needed by TysWiredIn + rightCoercionTyCon, instCoercionTyCon, -- needed by TysWiredIn + + -- Comparison + coreEqCoercion, + + -- CoercionI + CoercionI(..), + isIdentityCoercion, + mkSymCoI, mkTransCoI, + mkTyConAppCoI, mkAppTyCoI, mkFunTyCoI, + mkForAllTyCoI, + fromCoI, fromACo, + mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI + ) where #include "HsVersions.h" @@ -39,6 +61,7 @@ module Coercion ( import TypeRep import Type import TyCon +import Class import Var import Name import OccName @@ -47,7 +70,10 @@ import Util import Unique import BasicTypes import Outputable +import FastString +type Coercion = Type +type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2) ------------------------------ decomposeCo :: Arity -> Coercion -> [Coercion] @@ -57,7 +83,7 @@ decomposeCo :: Arity -> Coercion -> [Coercion] decomposeCo n co = go n co [] where - go 0 co cos = cos + go 0 _ cos = cos go n co cos = go (n-1) (mkLeftCoercion co) (mkRightCoercion co : cos) @@ -66,8 +92,9 @@ decomposeCo n co ------------------------------------------------------- -- and some coercion kind stuff +isEqPredTy :: Type -> Bool isEqPredTy (PredTy pred) = isEqPred pred -isEqPredTy other = False +isEqPredTy _ = False mkEqPred :: (Type, Type) -> PredType mkEqPred (ty1, ty2) = EqPred ty1 ty2 @@ -89,10 +116,7 @@ splitCoercionKind (PredTy (EqPred ty1 ty2)) = (ty1, ty2) splitCoercionKind_maybe :: Kind -> Maybe (Type, Type) splitCoercionKind_maybe co | Just co' <- kindView co = splitCoercionKind_maybe co' splitCoercionKind_maybe (PredTy (EqPred ty1 ty2)) = Just (ty1, ty2) -splitCoercionKind_maybe other = Nothing - -type Coercion = Type -type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2) +splitCoercionKind_maybe _ = Nothing coercionKind :: Coercion -> (Type, Type) -- c :: (t1 :=: t2) @@ -121,7 +145,6 @@ coercionKind (FunTy ty1 ty2) coercionKind (ForAllTy tv ty) = let (ty1, ty2) = coercionKind ty in (ForAllTy tv ty1, ForAllTy tv ty2) -coercionKind (NoteTy _ ty) = coercionKind ty coercionKind (PredTy (EqPred c1 c2)) = let k1 = coercionKindPredTy c1 k2 = coercionKindPredTy c2 in @@ -143,11 +166,14 @@ coercionKinds tys = unzip $ map coercionKind tys -- Coercion kind and type mk's -- (make saturated TyConApp CoercionTyCon{...} args) +mkCoercion :: TyCon -> [Type] -> Coercion mkCoercion coCon args = ASSERT( tyConArity coCon == length args ) TyConApp coCon args mkAppCoercion, mkFunCoercion, mkTransCoercion, mkInstCoercion :: Coercion -> Coercion -> Coercion mkSymCoercion, mkLeftCoercion, mkRightCoercion :: Coercion -> Coercion +mkAppsCoercion, mkInstsCoercion :: Coercion -> [Coercion] -> Coercion +mkForAllCoercion :: Var -> Coercion -> Coercion mkAppCoercion co1 co2 = mkAppTy co1 co2 mkAppsCoercion co1 tys = foldl mkAppTy co1 tys @@ -156,70 +182,94 @@ mkForAllCoercion tv co = ASSERT ( isTyVar tv ) mkForAllTy tv co mkFunCoercion co1 co2 = mkFunTy co1 co2 +------------------------------- -- This smart constructor creates a sym'ed version its argument, -- but tries to push the sym's down to the leaves. If we come to -- sym tv or sym tycon then we can drop the sym because tv and tycon -- are reflexive coercions mkSymCoercion co - | Just co2 <- splitSymCoercion_maybe co = co2 - -- sym (sym co) --> co - | Just (co1, arg_tys) <- splitTyConApp_maybe co - , not (isCoercionTyCon co1) = mkTyConApp co1 (map mkSymCoercion arg_tys) - -- we can drop the sym for a TyCon - -- sym (ty [t1, ..., tn]) --> ty [sym t1, ..., sym tn] - | (co1, arg_tys) <- splitAppTys co - , isTyVarTy co1 = mkAppTys (maybe_drop co1) (map mkSymCoercion arg_tys) - -- sym (tv [t1, ..., tn]) --> tv [sym t1, ..., sym tn] - -- if tv type variable - -- sym (cv [t1, ..., tn]) --> (sym cv) [sym t1, ..., sym tn] - -- if cv is a coercion variable - -- fall through if head is a CoercionTyCon - | Just (co1, co2) <- splitTransCoercion_maybe co + | Just co' <- coreView co = mkSymCoercion co' + +mkSymCoercion (ForAllTy tv ty) = ForAllTy tv (mkSymCoercion ty) +mkSymCoercion (AppTy co1 co2) = AppTy (mkSymCoercion co1) (mkSymCoercion co2) +mkSymCoercion (FunTy co1 co2) = FunTy (mkSymCoercion co1) (mkSymCoercion co2) + +mkSymCoercion (TyConApp tc cos) + | not (isCoercionTyCon tc) = mkTyConApp tc (map mkSymCoercion cos) + +mkSymCoercion (TyConApp tc [co]) + | tc `hasKey` symCoercionTyConKey = co -- sym (sym co) --> co + | tc `hasKey` leftCoercionTyConKey = mkLeftCoercion (mkSymCoercion co) + | tc `hasKey` rightCoercionTyConKey = mkRightCoercion (mkSymCoercion co) + +mkSymCoercion (TyConApp tc [co1,co2]) + | tc `hasKey` transCoercionTyConKey -- sym (co1 `trans` co2) --> (sym co2) `trans (sym co2) + -- Note reversal of arguments! = mkTransCoercion (mkSymCoercion co2) (mkSymCoercion co1) - | Just (co, ty) <- splitInstCoercion_maybe co + + | tc `hasKey` instCoercionTyConKey -- sym (co @ ty) --> (sym co) @ ty - = mkInstCoercion (mkSymCoercion co) ty - | Just co <- splitLeftCoercion_maybe co - -- sym (left co) --> left (sym co) - = mkLeftCoercion (mkSymCoercion co) - | Just co <- splitRightCoercion_maybe co - -- sym (right co) --> right (sym co) - = mkRightCoercion (mkSymCoercion co) - where - maybe_drop (TyVarTy tv) - | isCoVar tv = mkCoercion symCoercionTyCon [TyVarTy tv] - | otherwise = TyVarTy tv - maybe_drop other = other -mkSymCoercion (ForAllTy tv ty) = ForAllTy tv (mkSymCoercion ty) --- for atomic types and constructors, we can just ignore sym since these --- are reflexive coercions + -- Note: sym is not applied to 'ty' + = mkInstCoercion (mkSymCoercion co1) co2 + +mkSymCoercion (TyConApp tc cos) -- Other coercion tycons, such as those + = mkCoercion symCoercionTyCon [TyConApp tc cos] -- arising from newtypes + mkSymCoercion (TyVarTy tv) | isCoVar tv = mkCoercion symCoercionTyCon [TyVarTy tv] - | otherwise = TyVarTy tv -mkSymCoercion co = mkCoercion symCoercionTyCon [co] + | otherwise = TyVarTy tv -- Reflexive + +------------------------------- +-- ToDo: we should be cleverer about transitivity +mkTransCoercion g1 g2 -- sym g `trans` g = id + | (t1,_) <- coercionKind g1 + , (_,t2) <- coercionKind g2 + , t1 `coreEqType` t2 + = t1 + + | otherwise + = mkCoercion transCoercionTyCon [g1, g2] + +------------------------------- -- Smart constructors for left and right mkLeftCoercion co | Just (co', _) <- splitAppCoercion_maybe co = co' - | otherwise = mkCoercion leftCoercionTyCon [co] + | otherwise = mkCoercion leftCoercionTyCon [co] mkRightCoercion co - | Just (co1, co2) <- splitAppCoercion_maybe co = co2 + | Just (_, co2) <- splitAppCoercion_maybe co = co2 | otherwise = mkCoercion rightCoercionTyCon [co] -mkTransCoercion co1 co2 = mkCoercion transCoercionTyCon [co1, co2] - -mkInstCoercion co ty = mkCoercion instCoercionTyCon [co, ty] +mkRightCoercions :: Int -> Coercion -> [Coercion] +mkRightCoercions n co + = go n co [] + where + go n co acc + | n > 0 + = case splitAppCoercion_maybe co of + Just (co1,co2) -> go (n-1) co1 (co2:acc) + Nothing -> go (n-1) (mkCoercion leftCoercionTyCon [co]) (mkCoercion rightCoercionTyCon [co]:acc) + | otherwise + = acc + +mkInstCoercion co ty + | Just (tv,co') <- splitForAllTy_maybe co + = substTyWith [tv] [ty] co' -- (forall a.co) @ ty --> co[ty/a] + | otherwise + = mkCoercion instCoercionTyCon [co, ty] mkInstsCoercion co tys = foldl mkInstCoercion co tys +{- splitSymCoercion_maybe :: Coercion -> Maybe Coercion splitSymCoercion_maybe (TyConApp tc [co]) = if tc `hasKey` symCoercionTyConKey then Just co else Nothing splitSymCoercion_maybe co = Nothing +-} splitAppCoercion_maybe :: Coercion -> Maybe (Coercion, Coercion) -- Splits a coercion application, being careful *not* to split (left c), etc @@ -232,8 +282,9 @@ splitAppCoercion_maybe (TyConApp tc tys) = case snocView tys of Just (tys', ty') -> Just (TyConApp tc tys', ty') Nothing -> Nothing -splitAppCoercion_maybe co = Nothing +splitAppCoercion_maybe _ = Nothing +{- splitTransCoercion_maybe :: Coercion -> Maybe (Coercion, Coercion) splitTransCoercion_maybe (TyConApp tc [ty1, ty2]) = if tc `hasKey` transCoercionTyConKey then @@ -265,6 +316,7 @@ splitRightCoercion_maybe (TyConApp tc [co]) else Nothing splitRightCoercion_maybe other = Nothing +-} -- Unsafe coercion is not safe, it is used when we know we are dealing with -- bottom, which is one case in which it is safe. It is also used to @@ -284,18 +336,18 @@ mkNewTypeCoercion name tycon tvs rhs_ty rule args = ASSERT( co_con_arity == length args ) (TyConApp tycon args, substTyWith tvs args rhs_ty) --- Coercion identifying a data/newtype representation type and its family --- instance. It has the form `Co tvs :: F ts :=: R tvs', where `Co' is the --- coercion tycon built here, `F' the family tycon and `R' the (derived) +-- Coercion identifying a data/newtype/synonym representation type and its +-- family instance. It has the form `Co tvs :: F ts :=: R tvs', where `Co' is +-- the coercion tycon built here, `F' the family tycon and `R' the (derived) -- representation tycon. -- -mkDataInstCoercion :: Name -- unique name for the coercion tycon - -> [TyVar] -- type parameters of the coercion (`tvs') - -> TyCon -- family tycon (`F') - -> [Type] -- type instance (`ts') - -> TyCon -- representation tycon (`R') - -> TyCon -- => coercion tycon (`Co') -mkDataInstCoercion name tvs family instTys rep_tycon +mkFamInstCoercion :: Name -- unique name for the coercion tycon + -> [TyVar] -- type parameters of the coercion (`tvs') + -> TyCon -- family tycon (`F') + -> [Type] -- type instance (`ts') + -> TyCon -- representation tycon (`R') + -> TyCon -- => coercion tycon (`Co') +mkFamInstCoercion name tvs family instTys rep_tycon = mkCoercionTyCon name coArity rule where coArity = length tvs @@ -313,7 +365,7 @@ mkDataInstCoercion name tvs family instTys rep_tycon -- sym e :: p3=q3 -- then ((sym c) (sym d) (sym e)) :: (p1 p2 p3)=(q1 q2 q3) -symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon :: TyCon +symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon, unsafeCoercionTyCon :: TyCon -- Each coercion TyCon is built with the special CoercionTyCon record and -- carries its own kinding rule. Such CoercionTyCons must be fully applied -- by any TyConApp in which they are applied, however they may also be over @@ -330,7 +382,10 @@ transCoercionTyCon = where composeCoercionKindsOf (co1:co2:rest) = ASSERT( null rest ) - WARN( not (r1 `coreEqType` a2), text "Strange! Type mismatch in trans coercion, probably a bug") + WARN( not (r1 `coreEqType` a2), + text "Strange! Type mismatch in trans coercion, probably a bug" + $$ + ppr r1 <+> text "=/=" <+> ppr a2) (a1, r2) where (a1, r1) = coercionKind co1 @@ -360,6 +415,9 @@ splitCoercionKindOf co , Just (ty_fun1, ty_arg1) <- splitAppTy_maybe ty1 , Just (ty_fun2, ty_arg2) <- splitAppTy_maybe ty2 = ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2)) +splitCoercionKindOf co + = pprPanic "Coercion.splitCoercionKindOf" + (ppr co $$ ppr (coercionKindPredTy co)) instCoercionTyCon = mkCoercionTyCon instCoercionTyConName 2 instCoercionKind @@ -380,34 +438,134 @@ unsafeCoercionTyCon -------------------------------------- -- ...and their names +mkCoConName :: FastString -> Unique -> TyCon -> Name mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ) key (ATyCon coCon) BuiltInSyntax -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 -unsafeCoercionTyConName = mkCoConName FSLIT("CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon +transCoercionTyConName, symCoercionTyConName, leftCoercionTyConName, rightCoercionTyConName, instCoercionTyConName, unsafeCoercionTyConName :: 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 +unsafeCoercionTyConName = mkCoConName (fsLit "CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon +instNewTyCon_maybe :: TyCon -> [Type] -> Maybe (Type, CoercionI) +-- instNewTyCon_maybe T ts +-- = Just (rep_ty, co) if co : T ts ~ rep_ty +instNewTyCon_maybe tc tys + | Just (tvs, ty, mb_co_tc) <- unwrapNewTyCon_maybe tc + = ASSERT( tys `lengthIs` tyConArity tc ) + Just (substTyWith tvs tys ty, + case mb_co_tc of + Nothing -> IdCo + Just co_tc -> ACo (mkTyConApp co_tc tys)) + | otherwise + = Nothing + -- this is here to avoid module loops splitNewTypeRepCo_maybe :: Type -> Maybe (Type, Coercion) -- Sometimes we want to look through a newtype and get its associated coercion -- It only strips *one layer* off, so the caller will usually call itself recursively -- Only applied to types of kind *, hence the newtype is always saturated +-- splitNewTypeRepCo_maybe ty +-- = Just (ty', co) if co : ty ~ ty' +-- Returns Nothing for non-newtypes or fully-transparent newtypes splitNewTypeRepCo_maybe ty | Just ty' <- coreView ty = splitNewTypeRepCo_maybe ty' splitNewTypeRepCo_maybe (TyConApp tc tys) - | isClosedNewTyCon tc - = ASSERT( tys `lengthIs` tyConArity tc ) -- splitNewTypeRepCo_maybe only be applied - -- to *types* (of kind *) - case newTyConRhs tc of - (tvs, rep_ty) -> - ASSERT( length tvs == length tys ) - Just (substTyWith tvs tys rep_ty, mkTyConApp co_con tys) - where - co_con = maybe (pprPanic "splitNewTypeRepCo_maybe" (ppr tc)) id (newTyConCo_maybe tc) -splitNewTypeRepCo_maybe other = Nothing + | Just (ty', coi) <- instNewTyCon_maybe tc tys + = case coi of + ACo co -> Just (ty', co) + IdCo -> panic "splitNewTypeRepCo_maybe" + -- This case handled by coreView +splitNewTypeRepCo_maybe _ + = Nothing + +------------------------------------- +-- Syntactic equality of coercions + +coreEqCoercion :: Coercion -> Coercion -> Bool +coreEqCoercion = coreEqType +\end{code} + + +-------------------------------------- +-- CoercionI smart constructors +-- lifted smart constructors of ordinary coercions + +\begin{code} + -- CoercionI is either + -- (a) proper coercion + -- (b) the identity coercion +data CoercionI = IdCo | ACo Coercion + +isIdentityCoercion :: CoercionI -> Bool +isIdentityCoercion IdCo = True +isIdentityCoercion _ = False + +allIdCos :: [CoercionI] -> Bool +allIdCos = all isIdentityCoercion + +zipCoArgs :: [CoercionI] -> [Type] -> [Coercion] +zipCoArgs cois tys = zipWith fromCoI cois tys + +fromCoI :: CoercionI -> Type -> Type +fromCoI IdCo ty = ty -- Identity coercion represented +fromCoI (ACo co) _ = co -- by the type itself + +mkSymCoI :: CoercionI -> CoercionI +mkSymCoI IdCo = IdCo +mkSymCoI (ACo co) = ACo $ mkCoercion symCoercionTyCon [co] + -- the smart constructor + -- is too smart with tyvars + +mkTransCoI :: CoercionI -> CoercionI -> CoercionI +mkTransCoI IdCo aco = aco +mkTransCoI aco IdCo = aco +mkTransCoI (ACo co1) (ACo co2) = ACo $ mkTransCoercion co1 co2 + +mkTyConAppCoI :: TyCon -> [Type] -> [CoercionI] -> CoercionI +mkTyConAppCoI tyCon tys cois + | allIdCos cois = IdCo + | otherwise = ACo (TyConApp tyCon (zipCoArgs cois tys)) + +mkAppTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +mkAppTyCoI _ IdCo _ IdCo = IdCo +mkAppTyCoI ty1 coi1 ty2 coi2 = + ACo $ AppTy (fromCoI coi1 ty1) (fromCoI coi2 ty2) + +mkFunTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +mkFunTyCoI _ IdCo _ IdCo = IdCo +mkFunTyCoI ty1 coi1 ty2 coi2 = + ACo $ FunTy (fromCoI coi1 ty1) (fromCoI coi2 ty2) + +mkForAllTyCoI :: TyVar -> CoercionI -> CoercionI +mkForAllTyCoI _ IdCo = IdCo +mkForAllTyCoI tv (ACo co) = ACo $ ForAllTy tv co + +fromACo :: CoercionI -> Coercion +fromACo (ACo co) = co + +mkClassPPredCoI :: Class -> [Type] -> [CoercionI] -> CoercionI +-- mkClassPPredCoI cls tys cois = coi +-- coi : PredTy (cls tys) ~ predTy (cls (tys `cast` cois)) +mkClassPPredCoI cls tys cois + | allIdCos cois = IdCo + | otherwise = ACo $ PredTy $ ClassP cls (zipCoArgs cois tys) + +mkIParamPredCoI :: (IPName Name) -> CoercionI -> CoercionI +-- Similar invariant to mkclassPPredCoI +mkIParamPredCoI _ IdCo = IdCo +mkIParamPredCoI ipn (ACo co) = ACo $ PredTy $ IParam ipn co + +mkEqPredCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +-- Similar invariant to mkclassPPredCoI +mkEqPredCoI _ IdCo _ IdCo = IdCo +mkEqPredCoI ty1 IdCo _ (ACo co2) = ACo $ PredTy $ EqPred ty1 co2 +mkEqPredCoI _ (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi2 ty2) \end{code} +