X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=1e071ebd17c1e233c8ee188df74a5c4ac21f6694;hb=87b3c589498941332029a8a9da35e94a6139f0eb;hp=1dbd7f3eab1a1a6316a9eabee06c192d12a88d17;hpb=d76c18e05f6366c23144624b696a02fbaa6d26e8;p=ghc-hetmet.git diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index 1dbd7f3..1e071eb 100644 --- a/compiler/types/Coercion.lhs +++ b/compiler/types/Coercion.lhs @@ -1,5 +1,8 @@ +% +% (c) The University of Glasgow 2006 +% - Module for type coercions, as in System FC. +Module for type coercions, as in System FC. Coercions are represented as types, and their kinds tell what types the coercion works on. @@ -22,43 +25,41 @@ 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" import TypeRep -import Type ( Type, Kind, PredType, substTyWith, mkAppTy, mkForAllTy, - mkFunTy, splitAppTy_maybe, splitForAllTy_maybe, coreView, - kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys, - coreEqType, splitAppTys, isTyVarTy, splitTyConApp_maybe, - tyVarsOfType, mkTyVarTys - ) -import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isClosedNewTyCon, - newTyConRhs, newTyConCo_maybe, - isCoercionTyCon, isCoercionTyCon_maybe ) -import Var ( Var, TyVar, isTyVar, tyVarKind ) -import VarSet ( elemVarSet ) -import Name ( BuiltInSyntax(..), Name, mkWiredInName, tcName ) -import OccName ( mkOccNameFS ) -import PrelNames ( symCoercionTyConKey, - transCoercionTyConKey, leftCoercionTyConKey, - rightCoercionTyConKey, instCoercionTyConKey, - unsafeCoercionTyConKey, gHC_PRIM - ) -import Util ( lengthIs, snocView ) -import Unique ( hasKey ) -import BasicTypes ( Arity ) +import Type +import TyCon +import Class +import Var +import Name +import OccName +import PrelNames +import Util +import Unique +import BasicTypes import Outputable - ------------------------------ decomposeCo :: Arity -> Coercion -> [Coercion] -- (decomposeCo 3 c) = [right (left (left c)), right (left c), right c] @@ -101,17 +102,14 @@ splitCoercionKind_maybe co | Just co' <- kindView co = splitCoercionKind_maybe c splitCoercionKind_maybe (PredTy (EqPred ty1 ty2)) = Just (ty1, ty2) splitCoercionKind_maybe other = Nothing -isCoVar :: Var -> Bool -isCoVar tv = isTyVar tv && isCoercionKind (tyVarKind tv) - type Coercion = Type type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2) coercionKind :: Coercion -> (Type, Type) -- c :: (t1 :=: t2) -- Then (coercionKind c) = (t1,t2) -coercionKind (TyVarTy a) | isCoVar a = splitCoercionKind (tyVarKind a) - | otherwise = let t = (TyVarTy a) in (t, t) +coercionKind ty@(TyVarTy a) | isCoVar a = splitCoercionKind (tyVarKind a) + | otherwise = (ty, ty) coercionKind (AppTy ty1 ty2) = let (t1, t2) = coercionKind ty1 (s1, s2) = coercionKind ty2 in @@ -119,10 +117,11 @@ coercionKind (AppTy ty1 ty2) coercionKind (TyConApp tc args) | Just (ar, rule) <- isCoercionTyCon_maybe tc -- CoercionTyCons carry their kinding rule, so we use it here - = if length args >= ar - then splitCoercionKind (rule args) - else pprPanic ("arity/arguments mismatch in coercionKind:") - (ppr ar $$ ppr tc <+> ppr args) + = ASSERT( length args >= ar ) -- Always saturated + let (ty1,ty2) = rule (take ar args) -- Apply the rule to the right number of args + (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) @@ -168,61 +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 @@ -288,65 +297,32 @@ mkUnsafeCoercion ty1 ty2 -- See note [Newtype coercions] in TyCon mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon -mkNewTypeCoercion name tycon tvs rhs_ty - = ASSERT (length tvs == tyConArity tycon) - mkCoercionTyCon name co_con_arity (mkKindingFun rule) +mkNewTypeCoercion name tycon tvs rhs_ty + = mkCoercionTyCon name co_con_arity rule where - rule args = (TyConApp tycon tys, substTyWith tvs_eta tys rhs_eta, rest) - where - tys = take co_con_arity args - rest = drop co_con_arity args - - -- if the rhs_ty is a type application and it has a tail equal to a tail - -- of the tvs, then we eta-contract the type of the coercion - rhs_args = let (ty, ty_args) = splitAppTys rhs_ty in ty_args + co_con_arity = length tvs - n_eta_tys = count_eta (reverse rhs_args) (reverse tvs) + rule args = ASSERT( co_con_arity == length args ) + (TyConApp tycon args, substTyWith tvs args rhs_ty) - count_eta ((TyVarTy tv):rest_ty) (tv':rest_tv) - | tv == tv' && (not $ any (elemVarSet tv . tyVarsOfType) rest_ty) - -- if the last types are the same, and not free anywhere else - -- then eta contract - = 1 + (count_eta rest_ty rest_tv) - | otherwise -- don't - = 0 - count_eta _ _ = 0 - - - eqVar (TyVarTy tv) tv' = tv == tv' - eqVar _ _ = False - - co_con_arity = (tyConArity tycon) - n_eta_tys - - tvs_eta = (reverse (drop n_eta_tys (reverse tvs))) - - rhs_eta - | (ty, ty_args) <- splitAppTys rhs_ty - = mkAppTys ty (reverse (drop n_eta_tys (reverse ty_args))) - --- 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 - = mkCoercionTyCon name coArity (mkKindingFun rule) +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 - - rule args = (substTyWith tvs tys $ -- with sigma = [tys/tvs], + rule args = (substTyWith tvs args $ -- with sigma = [tys/tvs], TyConApp family instTys, -- sigma (F ts) - TyConApp rep_tycon tys, -- :=: R tys - rest) -- surplus arguments - where - tys = take coArity args - rest = drop coArity args + TyConApp rep_tycon args) -- :=: R tys -------------------------------------- -- Coercion Type Constructors... @@ -357,14 +333,6 @@ mkDataInstCoercion name tvs family instTys rep_tycon -- sym d :: p2=q2 -- sym e :: p3=q3 -- then ((sym c) (sym d) (sym e)) :: (p1 p2 p3)=(q1 q2 q3) --- --- (mkKindingFun f) is given the args [c, sym d, sym e] -mkKindingFun :: ([Type] -> (Type, Type, [Type])) -> [Type] -> Kind -mkKindingFun f args = - let (ty1, ty2, rest) = f args in - let (argtys1, argtys2) = unzip (map coercionKind rest) in - mkCoKind (mkAppTys ty1 argtys1) (mkAppTys ty2 argtys2) - symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon :: TyCon -- Each coercion TyCon is built with the special CoercionTyCon record and @@ -372,33 +340,34 @@ symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, ins -- by any TyConApp in which they are applied, however they may also be over -- applied (see example above) and the kinding function must deal with this. symCoercionTyCon = - mkCoercionTyCon symCoercionTyConName 1 (mkKindingFun flipCoercionKindOf) + mkCoercionTyCon symCoercionTyConName 1 flipCoercionKindOf where - flipCoercionKindOf (co:rest) = (ty2, ty1, rest) + flipCoercionKindOf (co:rest) = ASSERT( null rest ) (ty2, ty1) where (ty1, ty2) = coercionKind co transCoercionTyCon = - mkCoercionTyCon transCoercionTyConName 2 (mkKindingFun composeCoercionKindsOf) + mkCoercionTyCon transCoercionTyConName 2 composeCoercionKindsOf where - composeCoercionKindsOf (co1:co2:rest) = + composeCoercionKindsOf (co1:co2:rest) + = ASSERT( null rest ) WARN( not (r1 `coreEqType` a2), text "Strange! Type mismatch in trans coercion, probably a bug") - (a1, r2, rest) + (a1, r2) where (a1, r1) = coercionKind co1 (a2, r2) = coercionKind co2 leftCoercionTyCon = - mkCoercionTyCon leftCoercionTyConName 1 (mkKindingFun leftProjectCoercionKindOf) + mkCoercionTyCon leftCoercionTyConName 1 leftProjectCoercionKindOf where - leftProjectCoercionKindOf (co:rest) = (ty1, ty2, rest) + leftProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2) where (ty1,ty2) = fst (splitCoercionKindOf co) rightCoercionTyCon = - mkCoercionTyCon rightCoercionTyConName 1 (mkKindingFun rightProjectCoercionKindOf) + mkCoercionTyCon rightCoercionTyConName 1 rightProjectCoercionKindOf where - rightProjectCoercionKindOf (co:rest) = (ty1, ty2, rest) + rightProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2) where (ty1,ty2) = snd (splitCoercionKindOf co) @@ -414,25 +383,26 @@ splitCoercionKindOf co = ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2)) instCoercionTyCon - = mkCoercionTyCon instCoercionTyConName 2 (mkKindingFun instCoercionKind) + = mkCoercionTyCon instCoercionTyConName 2 instCoercionKind where instantiateCo t s = let Just (tv, ty) = splitForAllTy_maybe t in substTyWith [tv] [s] ty - instCoercionKind (co1:ty:rest) = (instantiateCo t1 ty, instantiateCo t2 ty, rest) + instCoercionKind (co1:ty:rest) = ASSERT( null rest ) + (instantiateCo t1 ty, instantiateCo t2 ty) where (t1, t2) = coercionKind co1 unsafeCoercionTyCon - = mkCoercionTyCon unsafeCoercionTyConName 2 (mkKindingFun unsafeCoercionKind) + = mkCoercionTyCon unsafeCoercionTyConName 2 unsafeCoercionKind where - unsafeCoercionKind (ty1:ty2:rest) = (ty1,ty2,rest) + unsafeCoercionKind (ty1:ty2:rest) = ASSERT( null rest ) (ty1,ty2) -------------------------------------- -- ...and their names mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ) - key Nothing (ATyCon coCon) BuiltInSyntax + key (ATyCon coCon) BuiltInSyntax transCoercionTyConName = mkCoConName FSLIT("trans") transCoercionTyConKey transCoercionTyCon symCoercionTyConName = mkCoConName FSLIT("sym") symCoercionTyConKey symCoercionTyCon @@ -462,3 +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} +