-\r
- Module for type coercions, as in System FC.\r
-\r
-Coercions are represented as types, and their kinds tell what types the \r
-coercion works on. \r
-\r
-The coercion kind constructor is a special TyCon that must always be saturated\r
-\r
- typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type]\r
-\r
-\begin{code}\r
-module Coercion (\r
- Coercion,\r
- \r
- mkCoKind, mkReflCoKind, splitCoercionKind_maybe, splitCoercionKind,\r
- coercionKind, coercionKinds, coercionKindPredTy,\r
-\r
- -- Equality predicates\r
- isEqPred, mkEqPred, getEqPredTys, isEqPredTy, \r
-\r
- -- Coercion transformations\r
- mkSymCoercion, mkTransCoercion,\r
- mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion,\r
- mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion,\r
- mkNewTypeCoercion, mkAppsCoercion,\r
-\r
- splitNewTypeRepCo_maybe, decomposeCo,\r
-\r
- unsafeCoercionTyCon, symCoercionTyCon,\r
- transCoercionTyCon, leftCoercionTyCon, \r
- rightCoercionTyCon, instCoercionTyCon -- needed by TysWiredIn\r
- ) where \r
-\r
-#include "HsVersions.h"\r
-\r
-import TypeRep\r
-import Type ( Type, Kind, PredType, substTyWith, mkAppTy, mkForAllTy,\r
- mkFunTy, splitAppTy_maybe, splitForAllTy_maybe, coreView,\r
- kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys\r
- )\r
-import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isNewTyCon,\r
- newTyConRhs, newTyConCo, \r
- isCoercionTyCon, isCoercionTyCon_maybe )\r
-import Var ( Var, TyVar, isTyVar, tyVarKind )\r
-import Name ( BuiltInSyntax(..), Name, mkWiredInName, tcName )\r
-import OccName ( mkOccNameFS )\r
-import PrelNames ( symCoercionTyConKey, \r
- transCoercionTyConKey, leftCoercionTyConKey,\r
- rightCoercionTyConKey, instCoercionTyConKey, \r
- unsafeCoercionTyConKey, gHC_PRIM\r
- )\r
-import Util ( lengthIs, snocView )\r
-import Unique ( hasKey )\r
-import BasicTypes ( Arity )\r
-import Outputable\r
-\r
-\r
-\r
-------------------------------\r
-decomposeCo :: Arity -> Coercion -> [Coercion]\r
--- (decomposeCo 3 c) = [right (left (left c)), right (left c), right c]\r
-decomposeCo n co\r
- = go n co []\r
- where\r
- go 0 co cos = cos\r
- go n co cos = go (n-1) (mkLeftCoercion co)\r
- (mkRightCoercion co : cos)\r
-\r
-------------------------------\r
-\r
--------------------------------------------------------\r
--- and some coercion kind stuff\r
-\r
-isEqPredTy (PredTy pred) = isEqPred pred\r
-isEqPredTy other = False\r
-\r
-mkEqPred :: (Type, Type) -> PredType\r
-mkEqPred (ty1, ty2) = EqPred ty1 ty2\r
-\r
-getEqPredTys :: PredType -> (Type,Type)\r
-getEqPredTys (EqPred ty1 ty2) = (ty1, ty2)\r
-getEqPredTys other = pprPanic "getEqPredTys" (ppr other)\r
-\r
-mkCoKind :: Type -> Type -> CoercionKind\r
-mkCoKind ty1 ty2 = PredTy (EqPred ty1 ty2)\r
-\r
-mkReflCoKind :: Type -> CoercionKind\r
-mkReflCoKind ty = mkCoKind ty ty\r
-\r
-splitCoercionKind :: CoercionKind -> (Type, Type)\r
-splitCoercionKind co | Just co' <- kindView co = splitCoercionKind co'\r
-splitCoercionKind (PredTy (EqPred ty1 ty2)) = (ty1, ty2)\r
-\r
-splitCoercionKind_maybe :: Kind -> Maybe (Type, Type)\r
-splitCoercionKind_maybe co | Just co' <- kindView co = splitCoercionKind_maybe co'\r
-splitCoercionKind_maybe (PredTy (EqPred ty1 ty2)) = Just (ty1, ty2)\r
-splitCoercionKind_maybe other = Nothing\r
-\r
-isCoVar :: Var -> Bool\r
-isCoVar tv = isTyVar tv && isCoercionKind (tyVarKind tv)\r
-\r
-type Coercion = Type\r
-type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2)\r
-\r
-coercionKind :: Coercion -> (Type, Type)\r
--- c :: (t1 :=: t2)\r
--- Then (coercionKind c) = (t1,t2)\r
-\r
-coercionKind (TyVarTy a) | isCoVar a = splitCoercionKind (tyVarKind a)\r
- | otherwise = let t = (TyVarTy a) in (t, t)\r
-coercionKind (AppTy ty1 ty2) \r
- = let (t1, t2) = coercionKind ty1\r
- (s1, s2) = coercionKind ty2 in\r
- (mkAppTy t1 s1, mkAppTy t2 s2)\r
-coercionKind (TyConApp tc args)\r
- | Just (ar, rule) <- isCoercionTyCon_maybe tc \r
- = if length args >= ar \r
- then splitCoercionKind (rule args)\r
- else pprPanic ("arity/arguments mismatch in coercionKind:") \r
- (ppr ar $$ ppr tc <+> ppr args)\r
- | otherwise\r
- = let (lArgs, rArgs) = coercionKinds args in\r
- (TyConApp tc lArgs, TyConApp tc rArgs)\r
-coercionKind (FunTy ty1 ty2) \r
- = let (t1, t2) = coercionKind ty1\r
- (s1, s2) = coercionKind ty2 in\r
- (mkFunTy t1 s1, mkFunTy t2 s2)\r
-coercionKind (ForAllTy tv ty) \r
- = let (ty1, ty2) = coercionKind ty in\r
- (ForAllTy tv ty1, ForAllTy tv ty2)\r
-coercionKind (NoteTy _ ty) = coercionKind ty\r
-coercionKind (PredTy (EqPred c1 c2)) \r
- = let k1 = coercionKindPredTy c1\r
- k2 = coercionKindPredTy c2 in\r
- (k1,k2)\r
-coercionKind (PredTy (ClassP cl args)) \r
- = let (lArgs, rArgs) = coercionKinds args in\r
- (PredTy (ClassP cl lArgs), PredTy (ClassP cl rArgs))\r
-coercionKind (PredTy (IParam name ty))\r
- = let (ty1, ty2) = coercionKind ty in\r
- (PredTy (IParam name ty1), PredTy (IParam name ty2))\r
-\r
-coercionKindPredTy :: Coercion -> CoercionKind\r
-coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2\r
-\r
-coercionKinds :: [Coercion] -> ([Type], [Type])\r
-coercionKinds tys = unzip $ map coercionKind tys\r
-\r
--------------------------------------\r
--- Coercion kind and type mk's\r
--- (make saturated TyConApp CoercionTyCon{...} args)\r
-\r
-mkCoercion coCon args = ASSERT( tyConArity coCon == length args ) \r
- TyConApp coCon args\r
-\r
-mkAppCoercion, mkFunCoercion, mkTransCoercion, mkInstCoercion :: Coercion -> Coercion -> Coercion\r
-mkSymCoercion, mkLeftCoercion, mkRightCoercion :: Coercion -> Coercion\r
-\r
-mkAppCoercion co1 co2 = mkAppTy co1 co2\r
-mkAppsCoercion co1 tys = foldl mkAppTy co1 tys\r
--- note that a TyVar should be used here, not a CoVar (nor a TcTyVar)\r
-mkForAllCoercion tv co = ASSERT ( isTyVar tv ) mkForAllTy tv co\r
-mkFunCoercion co1 co2 = mkFunTy co1 co2\r
-\r
-mkSymCoercion co \r
- | Just co2 <- splitSymCoercion_maybe co = co2\r
- | Just (co1, co2) <- splitAppCoercion_maybe co \r
- -- should make this case better\r
- = mkAppCoercion (mkSymCoercion co1) (mkSymCoercion co2)\r
- | Just (co1, co2) <- splitTransCoercion_maybe co\r
- = mkTransCoercion (mkSymCoercion co1) (mkSymCoercion co2)\r
- | Just (co, ty) <- splitInstCoercion_maybe co\r
- = mkInstCoercion (mkSymCoercion co) ty\r
- | Just co <- splitLeftCoercion_maybe co\r
- = mkLeftCoercion (mkSymCoercion co)\r
- | Just co <- splitRightCoercion_maybe co\r
- = mkRightCoercion (mkSymCoercion co)\r
-mkSymCoercion (ForAllTy tv ty) = ForAllTy tv (mkSymCoercion ty)\r
--- for atomic types and constructors, we can just ignore sym since these\r
--- are reflexive coercions\r
-mkSymCoercion (TyVarTy tv) \r
- | isCoVar tv = mkCoercion symCoercionTyCon [TyVarTy tv]\r
- | otherwise = TyVarTy tv\r
-mkSymCoercion co = mkCoercion symCoercionTyCon [co] \r
- -- this should not happen but does\r
-\r
--- Smart constructors for left and right\r
-mkLeftCoercion co \r
- | Just (co', _) <- splitAppCoercion_maybe co = co'\r
- | otherwise = mkCoercion leftCoercionTyCon [co]\r
-\r
-mkRightCoercion co \r
- | Just (co1, co2) <- splitAppCoercion_maybe co = co2\r
- | otherwise = mkCoercion rightCoercionTyCon [co]\r
-\r
-mkTransCoercion co1 co2 = mkCoercion transCoercionTyCon [co1, co2]\r
-\r
-mkInstCoercion co ty = mkCoercion instCoercionTyCon [co, ty]\r
-\r
-mkInstsCoercion co tys = foldl mkInstCoercion co tys\r
-\r
-splitSymCoercion_maybe :: Coercion -> Maybe Coercion\r
-splitSymCoercion_maybe (TyConApp tc [co]) = \r
- if tc `hasKey` symCoercionTyConKey\r
- then Just co\r
- else Nothing\r
-splitSymCoercion_maybe co = Nothing\r
-\r
-splitAppCoercion_maybe :: Coercion -> Maybe (Coercion, Coercion)\r
--- Splits a coercion application, being careful *not* to split (left c), etc\r
--- which are really sytactic constructs, not applications\r
-splitAppCoercion_maybe co | Just co' <- coreView co = splitAppCoercion_maybe co'\r
-splitAppCoercion_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)\r
-splitAppCoercion_maybe (AppTy ty1 ty2) = Just (ty1, ty2)\r
-splitAppCoercion_maybe (TyConApp tc tys) \r
- | not (isCoercionTyCon tc)\r
- = case snocView tys of\r
- Just (tys', ty') -> Just (TyConApp tc tys', ty')\r
- Nothing -> Nothing\r
-splitAppCoercion_maybe co = Nothing\r
-\r
-splitTransCoercion_maybe :: Coercion -> Maybe (Coercion, Coercion)\r
-splitTransCoercion_maybe (TyConApp tc [ty1, ty2]) \r
- = if tc `hasKey` transCoercionTyConKey then\r
- Just (ty1, ty2)\r
- else\r
- Nothing\r
-splitTransCoercion_maybe other = Nothing\r
-\r
-splitInstCoercion_maybe :: Coercion -> Maybe (Coercion, Type)\r
-splitInstCoercion_maybe (TyConApp tc [ty1, ty2])\r
- = if tc `hasKey` instCoercionTyConKey then\r
- Just (ty1, ty2)\r
- else\r
- Nothing\r
-splitInstCoercion_maybe other = Nothing\r
-\r
-splitLeftCoercion_maybe :: Coercion -> Maybe Coercion\r
-splitLeftCoercion_maybe (TyConApp tc [co])\r
- = if tc `hasKey` leftCoercionTyConKey then\r
- Just co\r
- else\r
- Nothing\r
-splitLeftCoercion_maybe other = Nothing\r
-\r
-splitRightCoercion_maybe :: Coercion -> Maybe Coercion\r
-splitRightCoercion_maybe (TyConApp tc [co])\r
- = if tc `hasKey` rightCoercionTyConKey then\r
- Just co\r
- else\r
- Nothing\r
-splitRightCoercion_maybe other = Nothing\r
-\r
--- Unsafe coercion is not safe, it is used when we know we are dealing with\r
--- bottom, which is the one case in which it is safe\r
-mkUnsafeCoercion :: Type -> Type -> Coercion\r
-mkUnsafeCoercion ty1 ty2 \r
- = mkCoercion unsafeCoercionTyCon [ty1, ty2]\r
-\r
-\r
--- make the coercion associated with a newtype\r
-mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon\r
-mkNewTypeCoercion name tycon tvs rhs_ty \r
- = ASSERT (length tvs == tyConArity tycon)\r
- mkCoercionTyCon name (tyConArity tycon) rule\r
- where\r
- rule args = mkCoKind (substTyWith tvs args rhs_ty) (TyConApp tycon args)\r
-\r
---------------------------------------\r
--- Coercion Type Constructors...\r
-\r
--- Example. The coercion ((sym c) (sym d) (sym e))\r
--- will be represented by (TyConApp sym [c, sym d, sym e])\r
--- If sym c :: p1=q1\r
--- sym d :: p2=q2\r
--- sym e :: p3=q3\r
--- then ((sym c) (sym d) (sym e)) :: (p1 p2 p3)=(q1 q2 q3)\r
---\r
--- (mkKindingFun f) is given the args [c, sym d, sym e]\r
-mkKindingFun :: ([Type] -> (Type, Type, [Type])) -> [Type] -> Kind\r
-mkKindingFun f args = \r
- let (ty1, ty2, rest) = f args in \r
- let (argtys1, argtys2) = unzip (map coercionKind rest) in\r
- mkCoKind (mkAppTys ty1 argtys1) (mkAppTys ty2 argtys2)\r
- \r
-\r
-symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon :: TyCon\r
--- Each coercion TyCon is built with the special CoercionTyCon record and\r
--- carries its won kinding rule. Such CoercionTyCons must be fully applied\r
--- by any TyConApp in which they are applied, however they may also be over\r
--- applied (see example above) and the kinding function must deal with this.\r
-symCoercionTyCon = \r
- mkCoercionTyCon symCoercionTyConName 1 (mkKindingFun flipCoercionKindOf)\r
- where\r
- flipCoercionKindOf (co:rest) = (ty2, ty1, rest)\r
- where\r
- (ty1, ty2) = coercionKind co\r
-\r
-transCoercionTyCon = \r
- mkCoercionTyCon transCoercionTyConName 2 (mkKindingFun composeCoercionKindsOf)\r
- where\r
- composeCoercionKindsOf (co1:co2:rest) = (a1, r2, rest)\r
- where\r
- (a1, r1) = coercionKind co1\r
- (a2, r2) = coercionKind co2 \r
-\r
-leftCoercionTyCon =\r
- mkCoercionTyCon leftCoercionTyConName 1 (mkKindingFun leftProjectCoercionKindOf)\r
- where\r
- leftProjectCoercionKindOf (co:rest) = (ty1, ty2, rest)\r
- where\r
- (ty1,ty2) = fst (splitCoercionKindOf co)\r
-\r
-rightCoercionTyCon =\r
- mkCoercionTyCon rightCoercionTyConName 1 (mkKindingFun rightProjectCoercionKindOf)\r
- where\r
- rightProjectCoercionKindOf (co:rest) = (ty1, ty2, rest)\r
- where\r
- (ty1,ty2) = snd (splitCoercionKindOf co)\r
-\r
-splitCoercionKindOf :: Type -> ((Type,Type), (Type,Type))\r
--- Helper for left and right. Finds coercion kind of its input and\r
--- returns the left and right projections of the coercion...\r
---\r
--- if c :: t1 s1 :=: t2 s2 then splitCoercionKindOf c = ((t1, t2), (s1, s2))\r
-splitCoercionKindOf co\r
- | Just (ty1, ty2) <- splitCoercionKind_maybe (coercionKindPredTy co)\r
- , Just (ty_fun1, ty_arg1) <- splitAppTy_maybe ty1\r
- , Just (ty_fun2, ty_arg2) <- splitAppTy_maybe ty2\r
- = ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2))\r
-\r
-instCoercionTyCon \r
- = mkCoercionTyCon instCoercionTyConName 2 (mkKindingFun instCoercionKind)\r
- where\r
- instantiateCo t s =\r
- let Just (tv, ty) = splitForAllTy_maybe t in\r
- substTyWith [tv] [s] ty\r
-\r
- instCoercionKind (co1:ty:rest) = (instantiateCo t1 ty, instantiateCo t2 ty, rest)\r
- where (t1, t2) = coercionKind co1\r
-\r
-unsafeCoercionTyCon \r
- = mkCoercionTyCon unsafeCoercionTyConName 2 (mkKindingFun unsafeCoercionKind)\r
- where\r
- unsafeCoercionKind (ty1:ty2:rest) = (ty1,ty2,rest) \r
- \r
---------------------------------------\r
--- ...and their names\r
-\r
-mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ)\r
- key Nothing (ATyCon coCon) BuiltInSyntax\r
-\r
-transCoercionTyConName = mkCoConName FSLIT("trans") transCoercionTyConKey transCoercionTyCon\r
-symCoercionTyConName = mkCoConName FSLIT("sym") symCoercionTyConKey symCoercionTyCon\r
-leftCoercionTyConName = mkCoConName FSLIT("left") leftCoercionTyConKey leftCoercionTyCon\r
-rightCoercionTyConName = mkCoConName FSLIT("right") rightCoercionTyConKey rightCoercionTyCon\r
-instCoercionTyConName = mkCoConName FSLIT("inst") instCoercionTyConKey instCoercionTyCon\r
-unsafeCoercionTyConName = mkCoConName FSLIT("CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon\r
-\r
-\r
-\r
--- this is here to avoid module loops\r
-splitNewTypeRepCo_maybe :: Type -> Maybe (Type, Coercion) \r
--- Sometimes we want to look through a recursive newtype, and that's what happens here\r
--- It only strips *one layer* off, so the caller will usually call itself recursively\r
--- Only applied to types of kind *, hence the newtype is always saturated\r
-splitNewTypeRepCo_maybe ty \r
- | Just ty' <- coreView ty = splitNewTypeRepCo_maybe ty'\r
-splitNewTypeRepCo_maybe (TyConApp tc tys)\r
- | isNewTyCon tc \r
- = ASSERT( tys `lengthIs` tyConArity tc ) -- splitNewTypeRepCo_maybe only be applied \r
- -- to *types* (of kind *)\r
- case newTyConRhs tc of\r
- (tvs, rep_ty) -> \r
- ASSERT( length tvs == length tys )\r
- Just (substTyWith tvs tys rep_ty, mkTyConApp co_con tys)\r
- where\r
- co_con = maybe (pprPanic "splitNewTypeRepCo_maybe" (ppr tc)) id (newTyConCo tc)\r
-\r
-splitNewTypeRepCo_maybe other = Nothing\r
-\end{code}
\ No newline at end of file
+
+ Module for type coercions, as in System FC.
+
+Coercions are represented as types, and their kinds tell what types the
+coercion works on.
+
+The coercion kind constructor is a special TyCon that must always be saturated
+
+ typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type]
+
+\begin{code}
+module Coercion (
+ Coercion,
+
+ mkCoKind, mkReflCoKind, splitCoercionKind_maybe, splitCoercionKind,
+ coercionKind, coercionKinds, coercionKindPredTy,
+
+ -- Equality predicates
+ isEqPred, mkEqPred, getEqPredTys, isEqPredTy,
+
+ -- Coercion transformations
+ mkSymCoercion, mkTransCoercion,
+ mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion,
+ mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion,
+ mkNewTypeCoercion, mkDataInstCoercion, mkAppsCoercion,
+
+ splitNewTypeRepCo_maybe, decomposeCo,
+
+ unsafeCoercionTyCon, symCoercionTyCon,
+ transCoercionTyCon, leftCoercionTyCon,
+ rightCoercionTyCon, instCoercionTyCon -- needed by TysWiredIn
+ ) 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
+ )
+import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isClosedNewTyCon,
+ newTyConRhs, newTyConCo_maybe,
+ isCoercionTyCon, isCoercionTyCon_maybe )
+import Var ( Var, TyVar, isTyVar, tyVarKind )
+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 Outputable
+
+
+
+------------------------------
+decomposeCo :: Arity -> Coercion -> [Coercion]
+-- (decomposeCo 3 c) = [right (left (left c)), right (left c), right c]
+-- So this breaks a coercion with kind T A B C :=: T D E F into
+-- a list of coercions of kinds A :=: D, B :=: E and E :=: F
+decomposeCo n co
+ = go n co []
+ where
+ go 0 co cos = cos
+ go n co cos = go (n-1) (mkLeftCoercion co)
+ (mkRightCoercion co : cos)
+
+------------------------------
+
+-------------------------------------------------------
+-- and some coercion kind stuff
+
+isEqPredTy (PredTy pred) = isEqPred pred
+isEqPredTy other = False
+
+mkEqPred :: (Type, Type) -> PredType
+mkEqPred (ty1, ty2) = EqPred ty1 ty2
+
+getEqPredTys :: PredType -> (Type,Type)
+getEqPredTys (EqPred ty1 ty2) = (ty1, ty2)
+getEqPredTys other = pprPanic "getEqPredTys" (ppr other)
+
+mkCoKind :: Type -> Type -> CoercionKind
+mkCoKind ty1 ty2 = PredTy (EqPred ty1 ty2)
+
+mkReflCoKind :: Type -> CoercionKind
+mkReflCoKind ty = mkCoKind ty ty
+
+splitCoercionKind :: CoercionKind -> (Type, Type)
+splitCoercionKind co | Just co' <- kindView co = splitCoercionKind co'
+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
+
+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 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
+ (mkAppTy t1 s1, mkAppTy t2 s2)
+coercionKind (TyConApp tc args)
+ | Just (ar, rule) <- isCoercionTyCon_maybe tc
+ -- CoercionTyCons carry their kinding rule, so we use it here
+ = 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)
+coercionKind (FunTy ty1 ty2)
+ = let (t1, t2) = coercionKind ty1
+ (s1, s2) = coercionKind ty2 in
+ (mkFunTy t1 s1, mkFunTy t2 s2)
+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
+ (k1,k2)
+coercionKind (PredTy (ClassP cl args))
+ = let (lArgs, rArgs) = coercionKinds args in
+ (PredTy (ClassP cl lArgs), PredTy (ClassP cl rArgs))
+coercionKind (PredTy (IParam name ty))
+ = let (ty1, ty2) = coercionKind ty in
+ (PredTy (IParam name ty1), PredTy (IParam name ty2))
+
+coercionKindPredTy :: Coercion -> CoercionKind
+coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2
+
+coercionKinds :: [Coercion] -> ([Type], [Type])
+coercionKinds tys = unzip $ map coercionKind tys
+
+-------------------------------------
+-- Coercion kind and type mk's
+-- (make saturated TyConApp CoercionTyCon{...} args)
+
+mkCoercion coCon args = ASSERT( tyConArity coCon == length args )
+ TyConApp coCon args
+
+mkAppCoercion, mkFunCoercion, mkTransCoercion, mkInstCoercion :: Coercion -> Coercion -> Coercion
+mkSymCoercion, mkLeftCoercion, mkRightCoercion :: Coercion -> Coercion
+
+mkAppCoercion co1 co2 = mkAppTy co1 co2
+mkAppsCoercion co1 tys = foldl mkAppTy co1 tys
+-- note that a TyVar should be used here, not a CoVar (nor a TcTyVar)
+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
+ -- sym (co1 `trans` co2) --> (sym co2) `trans (sym co2)
+ = mkTransCoercion (mkSymCoercion co2) (mkSymCoercion co1)
+ | Just (co, ty) <- splitInstCoercion_maybe co
+ -- 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
+mkSymCoercion (TyVarTy tv)
+ | isCoVar tv = mkCoercion symCoercionTyCon [TyVarTy tv]
+ | otherwise = TyVarTy tv
+mkSymCoercion co = mkCoercion symCoercionTyCon [co]
+
+-- Smart constructors for left and right
+mkLeftCoercion co
+ | Just (co', _) <- splitAppCoercion_maybe co = 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]
+
+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
+-- which are really sytactic constructs, not applications
+splitAppCoercion_maybe co | Just co' <- coreView co = splitAppCoercion_maybe co'
+splitAppCoercion_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
+splitAppCoercion_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
+splitAppCoercion_maybe (TyConApp tc tys)
+ | not (isCoercionTyCon tc)
+ = case snocView tys of
+ Just (tys', ty') -> Just (TyConApp tc tys', ty')
+ Nothing -> Nothing
+splitAppCoercion_maybe co = Nothing
+
+splitTransCoercion_maybe :: Coercion -> Maybe (Coercion, Coercion)
+splitTransCoercion_maybe (TyConApp tc [ty1, ty2])
+ = if tc `hasKey` transCoercionTyConKey then
+ Just (ty1, ty2)
+ else
+ Nothing
+splitTransCoercion_maybe other = Nothing
+
+splitInstCoercion_maybe :: Coercion -> Maybe (Coercion, Type)
+splitInstCoercion_maybe (TyConApp tc [ty1, ty2])
+ = if tc `hasKey` instCoercionTyConKey then
+ Just (ty1, ty2)
+ else
+ Nothing
+splitInstCoercion_maybe other = Nothing
+
+splitLeftCoercion_maybe :: Coercion -> Maybe Coercion
+splitLeftCoercion_maybe (TyConApp tc [co])
+ = if tc `hasKey` leftCoercionTyConKey then
+ Just co
+ else
+ Nothing
+splitLeftCoercion_maybe other = Nothing
+
+splitRightCoercion_maybe :: Coercion -> Maybe Coercion
+splitRightCoercion_maybe (TyConApp tc [co])
+ = if tc `hasKey` rightCoercionTyConKey then
+ Just 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
+-- implement the unsafeCoerce# primitive.
+mkUnsafeCoercion :: Type -> Type -> Coercion
+mkUnsafeCoercion ty1 ty2
+ = mkCoercion unsafeCoercionTyCon [ty1, ty2]
+
+
+-- 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.
+--
+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
+ 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...
+
+-- Example. The coercion ((sym c) (sym d) (sym e))
+-- will be represented by (TyConApp sym [c, sym d, sym e])
+-- If sym c :: p1=q1
+-- sym d :: p2=q2
+-- sym e :: p3=q3
+-- then ((sym c) (sym d) (sym e)) :: (p1 p2 p3)=(q1 q2 q3)
+
+symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon :: 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
+-- applied (see example above) and the kinding function must deal with this.
+symCoercionTyCon =
+ mkCoercionTyCon symCoercionTyConName 1 flipCoercionKindOf
+ where
+ flipCoercionKindOf (co:rest) = ASSERT( null rest ) (ty2, ty1)
+ where
+ (ty1, ty2) = coercionKind co
+
+transCoercionTyCon =
+ mkCoercionTyCon transCoercionTyConName 2 composeCoercionKindsOf
+ where
+ composeCoercionKindsOf (co1:co2:rest)
+ = ASSERT( null rest )
+ WARN( not (r1 `coreEqType` a2), text "Strange! Type mismatch in trans coercion, probably a bug")
+ (a1, r2)
+ where
+ (a1, r1) = coercionKind co1
+ (a2, r2) = coercionKind co2
+
+leftCoercionTyCon =
+ mkCoercionTyCon leftCoercionTyConName 1 leftProjectCoercionKindOf
+ where
+ leftProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2)
+ where
+ (ty1,ty2) = fst (splitCoercionKindOf co)
+
+rightCoercionTyCon =
+ mkCoercionTyCon rightCoercionTyConName 1 rightProjectCoercionKindOf
+ where
+ rightProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2)
+ where
+ (ty1,ty2) = snd (splitCoercionKindOf co)
+
+splitCoercionKindOf :: Type -> ((Type,Type), (Type,Type))
+-- Helper for left and right. Finds coercion kind of its input and
+-- returns the left and right projections of the coercion...
+--
+-- if c :: t1 s1 :=: t2 s2 then splitCoercionKindOf c = ((t1, t2), (s1, s2))
+splitCoercionKindOf co
+ | Just (ty1, ty2) <- splitCoercionKind_maybe (coercionKindPredTy 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))
+
+instCoercionTyCon
+ = mkCoercionTyCon instCoercionTyConName 2 instCoercionKind
+ where
+ instantiateCo t s =
+ let Just (tv, ty) = splitForAllTy_maybe t in
+ substTyWith [tv] [s] ty
+
+ instCoercionKind (co1:ty:rest) = ASSERT( null rest )
+ (instantiateCo t1 ty, instantiateCo t2 ty)
+ where (t1, t2) = coercionKind co1
+
+unsafeCoercionTyCon
+ = mkCoercionTyCon unsafeCoercionTyConName 2 unsafeCoercionKind
+ where
+ unsafeCoercionKind (ty1:ty2:rest) = ASSERT( null rest ) (ty1,ty2)
+
+--------------------------------------
+-- ...and their names
+
+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
+
+
+
+-- 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' <- 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
+\end{code}
projects / ghc-hetmet.git / blobdiff