X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=1e071ebd17c1e233c8ee188df74a5c4ac21f6694;hb=87b3c589498941332029a8a9da35e94a6139f0eb;hp=e17d0b007275a8e95fb4a75d8fdb7fc5c9dafdff;hpb=ac704fcac946590eef0ec91ae19f3b47d779a75f;p=ghc-hetmet.git diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index e17d0b0..1e071eb 100644 --- a/compiler/types/Coercion.lhs +++ b/compiler/types/Coercion.lhs @@ -25,13 +25,23 @@ module Coercion ( mkSymCoercion, mkTransCoercion, mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion, mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion, - mkNewTypeCoercion, mkDataInstCoercion, mkAppsCoercion, + mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion, splitNewTypeRepCo_maybe, decomposeCo, unsafeCoercionTyCon, symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, - rightCoercionTyCon, instCoercionTyCon -- needed by TysWiredIn + rightCoercionTyCon, instCoercionTyCon, -- needed by TysWiredIn + + -- CoercionI + CoercionI(..), + isIdentityCoercion, + mkSymCoI, mkTransCoI, + mkTyConAppCoI, mkAppTyCoI, mkFunTyCoI, + mkNoteTyCoI, mkForAllTyCoI, + fromCoI, + mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI, + ) where #include "HsVersions.h" @@ -39,6 +49,7 @@ module Coercion ( import TypeRep import Type import TyCon +import Class import Var import Name import OccName @@ -156,61 +167,71 @@ 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 | otherwise = mkCoercion rightCoercionTyCon [co] -mkTransCoercion co1 co2 = mkCoercion transCoercionTyCon [co1, co2] - -mkInstCoercion co ty = mkCoercion instCoercionTyCon [co, ty] +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 @@ -275,8 +296,8 @@ mkUnsafeCoercion ty1 ty2 -- See note [Newtype coercions] in TyCon -mkNewTypeCoercion :: Name -> TyCon -> ([TyVar], Type) -> TyCon -mkNewTypeCoercion name tycon (tvs, rhs_ty) +mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon +mkNewTypeCoercion name tycon tvs rhs_ty = mkCoercionTyCon name co_con_arity rule where co_con_arity = length tvs @@ -284,18 +305,18 @@ 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 @@ -411,3 +432,92 @@ splitNewTypeRepCo_maybe (TyConApp tc tys) co_con = maybe (pprPanic "splitNewTypeRepCo_maybe" (ppr tc)) id (newTyConCo_maybe tc) splitNewTypeRepCo_maybe other = Nothing \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 + +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 = + let (anyAcon,co_args) = f tys cois + in if anyAcon + then ACo (TyConApp tyCon co_args) + else IdCo + where + f [] [] = (False,[]) + f (x:xs) (y:ys) = + let (b,cos) = f xs ys + in case y of + IdCo -> (b,x:cos) + ACo co -> (True,co:cos) + +mkAppTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +mkAppTyCoI ty1 IdCo ty2 IdCo = IdCo +mkAppTyCoI ty1 coi1 ty2 coi2 = + ACo $ AppTy (fromCoI coi1 ty1) (fromCoI coi2 ty2) + +mkFunTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +mkFunTyCoI ty1 IdCo ty2 IdCo = IdCo +mkFunTyCoI ty1 coi1 ty2 coi2 = + ACo $ FunTy (fromCoI coi1 ty1) (fromCoI coi2 ty2) + +mkNoteTyCoI :: TyNote -> CoercionI -> CoercionI +mkNoteTyCoI _ IdCo = IdCo +mkNoteTyCoI note (ACo co) = ACo $ NoteTy note co + +mkForAllTyCoI :: TyVar -> CoercionI -> CoercionI +mkForAllTyCoI _ IdCo = IdCo +mkForAllTyCoI tv (ACo co) = ACo $ ForAllTy tv co + +fromCoI IdCo ty = ty +fromCoI (ACo co) ty = co + +mkClassPPredCoI :: Class -> [Type] -> [CoercionI] -> CoercionI +mkClassPPredCoI cls tys cois = + let (anyAcon,co_args) = f tys cois + in if anyAcon + then ACo $ PredTy $ ClassP cls co_args + else IdCo + where + f [] [] = (False,[]) + f (x:xs) (y:ys) = + let (b,cos) = f xs ys + in case y of + IdCo -> (b,x:cos) + ACo co -> (True,co:cos) + +mkIParamPredCoI :: (IPName Name) -> CoercionI -> CoercionI +mkIParamPredCoI ipn IdCo = IdCo +mkIParamPredCoI ipn (ACo co) = ACo $ PredTy $ IParam ipn co + +mkEqPredCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI +mkEqPredCoI _ IdCo _ IdCo = IdCo +mkEqPredCoI ty1 IdCo _ (ACo co2) = ACo $ PredTy $ EqPred ty1 co2 +mkEqPredCoI ty1 (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi2 ty2) + +\end{code} +