mkSymCoercion, mkTransCoercion,
mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion,
mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion,
- mkNewTypeCoercion, mkAppsCoercion,
+ mkNewTypeCoercion, mkDataInstCoercion, mkAppsCoercion,
splitNewTypeRepCo_maybe, decomposeCo,
kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys,
coreEqType, splitAppTys, isTyVarTy, splitTyConApp_maybe
)
-import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isNewTyCon,
- newTyConRhs, newTyConCo,
+import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isClosedNewTyCon,
+ newTyConRhs, newTyConCo_maybe,
isCoercionTyCon, isCoercionTyCon_maybe )
import Var ( Var, TyVar, isTyVar, tyVarKind )
import Name ( BuiltInSyntax(..), Name, mkWiredInName, tcName )
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
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)
splitRightCoercion_maybe other = Nothing
-- Unsafe coercion is not safe, it is used when we know we are dealing with
--- bottom, which is the one case in which it is safe. It is also used to
+-- bottom, which is one case in which it is safe. It is also used to
-- implement the unsafeCoerce# primitive.
mkUnsafeCoercion :: Type -> Type -> Coercion
mkUnsafeCoercion ty1 ty2
= mkCoercion unsafeCoercionTyCon [ty1, ty2]
--- Make the coercion associated with a newtype. If we have
---
--- newtype T a b = MkT (Int, a, b)
---
--- Then (mkNewTypeCoercion CoT T [a,b] (Int, a, b)) creates the coercion
--- CoT, such kinding rule such that
+-- See note [Newtype coercions] in TyCon
+mkNewTypeCoercion :: Name -> TyCon -> ([TyVar], Type) -> TyCon
+mkNewTypeCoercion name tycon (tvs, rhs_ty)
+ = mkCoercionTyCon name co_con_arity rule
+ where
+ co_con_arity = length tvs
+
+ 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)
+-- representation tycon.
--
--- CoT S U :: (Int, S, U) :=: T S U
-mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon
-mkNewTypeCoercion name tycon tvs rhs_ty
- = ASSERT (length tvs == tyConArity tycon)
- mkCoercionTyCon name (tyConArity tycon) rule
+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 rule
where
- rule args = mkCoKind (substTyWith tvs args rhs_ty) (TyConApp tycon args)
+ coArity = length tvs
+ rule args = (substTyWith tvs args $ -- with sigma = [tys/tvs],
+ TyConApp family instTys, -- sigma (F ts)
+ TyConApp rep_tycon args) -- :=: R tys
--------------------------------------
-- Coercion Type Constructors...
-- 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
-- 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)
= ((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
splitNewTypeRepCo_maybe ty
| Just ty' <- coreView ty = splitNewTypeRepCo_maybe ty'
splitNewTypeRepCo_maybe (TyConApp tc tys)
- | isNewTyCon tc
+ | isClosedNewTyCon tc
= ASSERT( tys `lengthIs` tyConArity tc ) -- splitNewTypeRepCo_maybe only be applied
-- to *types* (of kind *)
case newTyConRhs tc of
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 tc)
+ co_con = maybe (pprPanic "splitNewTypeRepCo_maybe" (ppr tc)) id (newTyConCo_maybe tc)
splitNewTypeRepCo_maybe other = Nothing
\end{code}
projects / ghc-hetmet.git / blobdiff