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,
isEqPred, mkEqPred, getEqPredTys, isEqPredTy,
-- Coercion transformations
+ mkCoercion,
mkSymCoercion, mkTransCoercion,
- mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion,
+ mkLeftCoercion, mkRightCoercion, mkRightCoercions,
+ mkInstCoercion, mkAppCoercion,
mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion,
mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion,
transCoercionTyCon, leftCoercionTyCon,
rightCoercionTyCon, instCoercionTyCon, -- needed by TysWiredIn
+ -- Comparison
+ coreEqCoercion,
+
-- CoercionI
CoercionI(..),
isIdentityCoercion,
mkSymCoI, mkTransCoI,
mkTyConAppCoI, mkAppTyCoI, mkFunTyCoI,
- mkNoteTyCoI, mkForAllTyCoI,
- fromCoI,
- mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI,
+ mkForAllTyCoI,
+ fromCoI, fromACo,
+ mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI
) where
import Outputable
+type Coercion = Type
+type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2)
+
------------------------------
decomposeCo :: Arity -> Coercion -> [Coercion]
-- (decomposeCo 3 c) = [right (left (left c)), right (left c), right c]
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)
-------------------------------------------------------
-- 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
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)
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
-- 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
| otherwise = mkCoercion leftCoercionTyCon [co]
mkRightCoercion co
- | Just (co1, co2) <- splitAppCoercion_maybe co = co2
+ | Just (_, co2) <- splitAppCoercion_maybe co = co2
| otherwise = mkCoercion rightCoercionTyCon [co]
+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]
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
= 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
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
-- 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
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"
+ $$
+ ppr r1 <+> text "=/=" <+> ppr a2)
(a1, r2)
where
(a1, r1) = coercionKind co1
, Just (ty_fun1, ty_arg1) <- splitAppTy_maybe ty1
, Just (ty_fun2, ty_arg2) <- splitAppTy_maybe ty2
= ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2))
+splitCoercionKindOf co
+ = pprPanic "Coercion.splitCoercionKindOf"
+ (ppr co $$ ppr (coercionKindPredTy co))
instCoercionTyCon
= mkCoercionTyCon instCoercionTyConName 2 instCoercionKind
--------------------------------------
-- ...and their names
+mkCoConName :: FS.FastString -> Unique -> TyCon -> Name
mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ)
key (ATyCon coCon) BuiltInSyntax
+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
ACo co -> Just (ty', co)
IdCo -> panic "splitNewTypeRepCo_maybe"
-- This case handled by coreView
-splitNewTypeRepCo_maybe other
+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
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]
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)
+mkTyConAppCoI tyCon tys cois
+ | allIdCos cois = IdCo
+ | otherwise = ACo (TyConApp tyCon (zipCoArgs cois tys))
mkAppTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI
-mkAppTyCoI ty1 IdCo ty2 IdCo = IdCo
+mkAppTyCoI _ IdCo _ 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 _ IdCo _ 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
+fromACo :: CoercionI -> Coercion
+fromACo (ACo co) = 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)
+-- 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
-mkIParamPredCoI ipn IdCo = IdCo
+-- 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 ty1 (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi2 ty2)
-
+mkEqPredCoI _ (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi2 ty2)
\end{code}
projects / ghc-hetmet.git / blobdiff