%
\begin{code}
--- 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 for type coercions, as used in System FC. See 'CoreSyn.Expr' for
+-- | Module for (a) type kinds and (b) type coercions,
+-- as used in System FC. See 'CoreSyn.Expr' for
-- more on System FC and how coercions fit into it.
--
-- 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, like so:
+-- coercion works on. The coercion kind constructor is a special TyCon that
+-- must always be saturated, like so:
--
--- > typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type]
+-- > typeKind (symCoercion type) :: TyConApp CoTyCon{...} [type, type]
module Coercion (
-- * Main data type
- Coercion,
-
+ Coercion, Kind,
+ typeKind,
+
+ -- ** Deconstructing Kinds
+ kindFunResult, kindAppResult, synTyConResKind,
+ splitKindFunTys, splitKindFunTysN, splitKindFunTy_maybe,
+
+ -- ** Predicates on Kinds
+ isLiftedTypeKind, isUnliftedTypeKind, isOpenTypeKind,
+ isUbxTupleKind, isArgTypeKind, isKind, isTySuperKind,
+ isCoSuperKind, isSuperKind, isCoercionKind,
+ mkArrowKind, mkArrowKinds,
+
+ isSubArgTypeKind, isSubOpenTypeKind, isSubKind, defaultKind, eqKind,
+ isSubKindCon,
+
mkCoKind, mkCoPredTy, coVarKind, coVarKind_maybe,
coercionKind, coercionKinds, isIdentityCoercion,
mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion,
mkCsel1Coercion, mkCsel2Coercion, mkCselRCoercion,
- splitNewTypeRepCo_maybe, instNewTyCon_maybe, decomposeCo,
+ mkClassPPredCo, mkIParamPredCo, mkEqPredCo,
+ mkCoVarCoercion, mkCoPredCo,
+
unsafeCoercionTyCon, symCoercionTyCon,
transCoercionTyCon, leftCoercionTyCon,
-- ** Decomposition
decompLR_maybe, decompCsel_maybe, decompInst_maybe,
-
- -- ** Optimisation
- optCoercion,
+ splitCoPredTy_maybe,
+ splitNewTypeRepCo_maybe, instNewTyCon_maybe, decomposeCo,
-- ** Comparison
coreEqCoercion, coreEqCoercion2,
mkSymCoI, mkTransCoI,
mkTyConAppCoI, mkAppTyCoI, mkFunTyCoI,
mkForAllTyCoI,
- fromCoI, fromACo,
- mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI
+ fromCoI,
+ mkClassPPredCoI, mkIParamPredCoI, mkEqPredCoI, mkCoPredCoI
) where
import Class
import Var
import VarEnv
+import VarSet
import Name
import PrelNames
import Util
-import Control.Monad
import BasicTypes
-import MonadUtils
import Outputable
import FastString
+\end{code}
+
+%************************************************************************
+%* *
+ Functions over Kinds
+%* *
+%************************************************************************
+\begin{code}
+-- | Essentially 'funResultTy' on kinds
+kindFunResult :: Kind -> Kind
+kindFunResult k = funResultTy k
+
+kindAppResult :: Kind -> [arg] -> Kind
+kindAppResult k [] = k
+kindAppResult k (_:as) = kindAppResult (kindFunResult k) as
+
+-- | Essentially 'splitFunTys' on kinds
+splitKindFunTys :: Kind -> ([Kind],Kind)
+splitKindFunTys k = splitFunTys k
+
+splitKindFunTy_maybe :: Kind -> Maybe (Kind,Kind)
+splitKindFunTy_maybe = splitFunTy_maybe
+
+-- | Essentially 'splitFunTysN' on kinds
+splitKindFunTysN :: Int -> Kind -> ([Kind],Kind)
+splitKindFunTysN k = splitFunTysN k
+
+-- | Find the result 'Kind' of a type synonym,
+-- after applying it to its 'arity' number of type variables
+-- Actually this function works fine on data types too,
+-- but they'd always return '*', so we never need to ask
+synTyConResKind :: TyCon -> Kind
+synTyConResKind tycon = kindAppResult (tyConKind tycon) (tyConTyVars tycon)
+
+-- | See "Type#kind_subtyping" for details of the distinction between these 'Kind's
+isUbxTupleKind, isOpenTypeKind, isArgTypeKind, isUnliftedTypeKind :: Kind -> Bool
+isOpenTypeKindCon, isUbxTupleKindCon, isArgTypeKindCon,
+ isUnliftedTypeKindCon, isSubArgTypeKindCon :: TyCon -> Bool
+
+isOpenTypeKindCon tc = tyConUnique tc == openTypeKindTyConKey
+
+isOpenTypeKind (TyConApp tc _) = isOpenTypeKindCon tc
+isOpenTypeKind _ = False
+
+isUbxTupleKindCon tc = tyConUnique tc == ubxTupleKindTyConKey
+
+isUbxTupleKind (TyConApp tc _) = isUbxTupleKindCon tc
+isUbxTupleKind _ = False
+
+isArgTypeKindCon tc = tyConUnique tc == argTypeKindTyConKey
+
+isArgTypeKind (TyConApp tc _) = isArgTypeKindCon tc
+isArgTypeKind _ = False
+
+isUnliftedTypeKindCon tc = tyConUnique tc == unliftedTypeKindTyConKey
+
+isUnliftedTypeKind (TyConApp tc _) = isUnliftedTypeKindCon tc
+isUnliftedTypeKind _ = False
+
+isSubOpenTypeKind :: Kind -> Bool
+-- ^ True of any sub-kind of OpenTypeKind (i.e. anything except arrow)
+isSubOpenTypeKind (FunTy k1 k2) = ASSERT2 ( isKind k1, text "isSubOpenTypeKind" <+> ppr k1 <+> text "::" <+> ppr (typeKind k1) )
+ ASSERT2 ( isKind k2, text "isSubOpenTypeKind" <+> ppr k2 <+> text "::" <+> ppr (typeKind k2) )
+ False
+isSubOpenTypeKind (TyConApp kc []) = ASSERT( isKind (TyConApp kc []) ) True
+isSubOpenTypeKind other = ASSERT( isKind other ) False
+ -- This is a conservative answer
+ -- It matters in the call to isSubKind in
+ -- checkExpectedKind.
+
+isSubArgTypeKindCon kc
+ | isUnliftedTypeKindCon kc = True
+ | isLiftedTypeKindCon kc = True
+ | isArgTypeKindCon kc = True
+ | otherwise = False
+
+isSubArgTypeKind :: Kind -> Bool
+-- ^ True of any sub-kind of ArgTypeKind
+isSubArgTypeKind (TyConApp kc []) = isSubArgTypeKindCon kc
+isSubArgTypeKind _ = False
+
+-- | Is this a super-kind (i.e. a type-of-kinds)?
+isSuperKind :: Type -> Bool
+isSuperKind (TyConApp (skc) []) = isSuperKindTyCon skc
+isSuperKind _ = False
+
+-- | Is this a kind (i.e. a type-of-types)?
+isKind :: Kind -> Bool
+isKind k = isSuperKind (typeKind k)
+
+isSubKind :: Kind -> Kind -> Bool
+-- ^ @k1 \`isSubKind\` k2@ checks that @k1@ <: @k2@
+isSubKind (TyConApp kc1 []) (TyConApp kc2 []) = kc1 `isSubKindCon` kc2
+isSubKind (FunTy a1 r1) (FunTy a2 r2) = (a2 `isSubKind` a1) && (r1 `isSubKind` r2)
+isSubKind (PredTy (EqPred ty1 ty2)) (PredTy (EqPred ty1' ty2'))
+ = ty1 `tcEqType` ty1' && ty2 `tcEqType` ty2'
+isSubKind _ _ = False
+
+eqKind :: Kind -> Kind -> Bool
+eqKind = tcEqType
+
+isSubKindCon :: TyCon -> TyCon -> Bool
+-- ^ @kc1 \`isSubKindCon\` kc2@ checks that @kc1@ <: @kc2@
+isSubKindCon kc1 kc2
+ | isLiftedTypeKindCon kc1 && isLiftedTypeKindCon kc2 = True
+ | isUnliftedTypeKindCon kc1 && isUnliftedTypeKindCon kc2 = True
+ | isUbxTupleKindCon kc1 && isUbxTupleKindCon kc2 = True
+ | isOpenTypeKindCon kc2 = True
+ -- we already know kc1 is not a fun, its a TyCon
+ | isArgTypeKindCon kc2 && isSubArgTypeKindCon kc1 = True
+ | otherwise = False
+
+defaultKind :: Kind -> Kind
+-- ^ Used when generalising: default kind ? and ?? to *. See "Type#kind_subtyping" for more
+-- information on what that means
+
+-- When we generalise, we make generic type variables whose kind is
+-- simple (* or *->* etc). So generic type variables (other than
+-- built-in constants like 'error') always have simple kinds. This is important;
+-- consider
+-- f x = True
+-- We want f to get type
+-- f :: forall (a::*). a -> Bool
+-- Not
+-- f :: forall (a::??). a -> Bool
+-- because that would allow a call like (f 3#) as well as (f True),
+--and the calling conventions differ. This defaulting is done in TcMType.zonkTcTyVarBndr.
+defaultKind k
+ | isSubOpenTypeKind k = liftedTypeKind
+ | isSubArgTypeKind k = liftedTypeKind
+ | otherwise = k
+\end{code}
+
+%************************************************************************
+%* *
+ Coercions
+%* *
+%************************************************************************
+
+
+\begin{code}
-- | A 'Coercion' represents a 'Type' something should be coerced to.
type Coercion = Type
go n co cos = go (n-1) (mkLeftCoercion co)
(mkRightCoercion co : cos)
-------------------------------
-------------------------------------------------------
-- and some coercion kind stuff
-- | (mkCoPredTy s t r) produces the type: (s~t) => r
mkCoPredTy :: Type -> Type -> Type -> Type
-mkCoPredTy s t r = ForAllTy (mkWildCoVar (mkCoKind s t)) r
+mkCoPredTy s t r = ASSERT( not (co_var `elemVarSet` tyVarsOfType r) )
+ ForAllTy co_var r
+ where
+ co_var = mkWildCoVar (mkCoKind s t)
+
+mkCoPredCo :: Coercion -> Coercion -> Coercion -> Coercion
+-- Creates a coercion between (s1~t1) => r1 and (s2~t2) => r2
+mkCoPredCo = mkCoPredTy
+
splitCoPredTy_maybe :: Type -> Maybe (Type, Type, Type)
splitCoPredTy_maybe ty
getEqPredTys (EqPred ty1 ty2) = (ty1, ty2)
getEqPredTys other = pprPanic "getEqPredTys" (ppr other)
--- | If it is the case that
---
--- > c :: (t1 ~ t2)
---
--- i.e. the kind of @c@ is a 'CoercionKind' relating @t1@ and @t2@, then @coercionKind c = (t1, t2)@.
-coercionKind :: Coercion -> (Type, Type)
-coercionKind ty@(TyVarTy a) | isCoVar a = coVarKind a
- | otherwise = (ty, ty)
-coercionKind (AppTy ty1 ty2)
- = let (s1, t1) = coercionKind ty1
- (s2, t2) = coercionKind ty2 in
- (mkAppTy s1 s2, mkAppTy t1 t2)
-coercionKind co@(TyConApp tc args)
- | Just (ar, rule) <- isCoercionTyCon_maybe tc
- -- CoercionTyCons carry their kinding rule, so we use it here
- = WARN( not (length args >= ar), ppr co ) -- Always saturated
- (let (ty1,ty2) = runID (rule (return . typeKind)
- (return . coercionKind)
- False (take ar args))
- -- Apply the rule to the right number of args
- -- Always succeeds (if term is well-kinded!)
- (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)
- | isCoVar tv
--- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2
--- ----------------------------------------------
--- c1~c2 => c3 :: (s1~t1) => r1 ~ (s2~t2) => r2
--- or
--- forall (_:c1~c2)
- = let (c1,c2) = coVarKind tv
- (s1,s2) = coercionKind c1
- (t1,t2) = coercionKind c2
- (r1,r2) = coercionKind ty
- in
- (mkCoPredTy s1 t1 r1, mkCoPredTy s2 t2 r2)
-
- | otherwise
--- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2
--- ----------------------------------------------
--- forall a:k. c :: forall a:k. t1 ~ forall a:k. t2
- = let (ty1, ty2) = coercionKind ty in
- (ForAllTy tv ty1, ForAllTy tv ty2)
-
-coercionKind (PredTy (EqPred c1 c2))
- = pprTrace "coercionKind" (pprEqPred (c1,c2)) $
- let k1 = coercionKindPredTy c1
- k2 = coercionKindPredTy c2 in
- (k1,k2)
- -- These should not show up in coercions at all
- -- becuase they are in the form of for-alls
- where
- coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2
-
-
-
-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))
-
--- | Apply 'coercionKind' to multiple 'Coercion's
-coercionKinds :: [Coercion] -> ([Type], [Type])
-coercionKinds tys = unzip $ map coercionKind tys
-
--------------------------------------
isIdentityCoercion :: Coercion -> Bool
isIdentityCoercion co
= case coercionKind co of
mkCoercion coCon args = ASSERT( tyConArity coCon == length args )
TyConApp coCon args
+mkCoVarCoercion :: CoVar -> Coercion
+mkCoVarCoercion cv = mkTyVarTy cv
+
-- | Apply a 'Coercion' to another 'Coercion', which is presumably a
-- 'Coercion' constructor of some kind
mkAppCoercion :: Coercion -> Coercion -> Coercion
-- | Make a function 'Coercion' between two other 'Coercion's
mkFunCoercion :: Coercion -> Coercion -> Coercion
-mkFunCoercion co1 co2 = mkFunTy co1 co2
+mkFunCoercion co1 co2 = mkFunTy co1 co2 -- NB: Handles correctly the forall for eqpreds!
-- | Make a 'Coercion' which binds a variable within an inner 'Coercion'
mkForAllCoercion :: Var -> Coercion -> Coercion
-- note that a TyVar should be used here, not a CoVar (nor a TcTyVar)
-mkForAllCoercion tv co = ASSERT ( isTyVar tv ) mkForAllTy tv co
+mkForAllCoercion tv co = ASSERT ( isTyCoVar tv ) mkForAllTy tv co
-------------------------------
-- | Manufacture a coercion from this air. Needless to say, this is not usually safe,
-- but it is used when we know we are dealing with bottom, which is one case in which
-- it is safe. This is also used implement the @unsafeCoerce#@ primitive.
+-- Optimise by pushing down through type constructors
mkUnsafeCoercion :: Type -> Type -> Coercion
-mkUnsafeCoercion ty1 ty2
- = mkCoercion unsafeCoercionTyCon [ty1, ty2]
+mkUnsafeCoercion (TyConApp tc1 tys1) (TyConApp tc2 tys2)
+ | tc1 == tc2
+ = TyConApp tc1 (zipWith mkUnsafeCoercion tys1 tys2)
+mkUnsafeCoercion (FunTy a1 r1) (FunTy a2 r2)
+ = FunTy (mkUnsafeCoercion a1 a2) (mkUnsafeCoercion r1 r2)
+
+mkUnsafeCoercion ty1 ty2
+ | ty1 `coreEqType` ty2 = ty1
+ | otherwise = mkCoercion unsafeCoercionTyCon [ty1, ty2]
-- See note [Newtype coercions] in TyCon
-- a subset of those 'TyVar's.
mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon
mkNewTypeCoercion name tycon tvs rhs_ty
- = mkCoercionTyCon name co_con_arity rule
+ = mkCoercionTyCon name arity desc
where
- co_con_arity = length tvs
-
- rule :: CoTyConKindChecker
- rule kc_ty _kc_co checking args
- = do { ks <- mapM kc_ty args
- ; unless (not checking || kindAppOk (tyConKind tycon) ks)
- (fail "Argument kind mis-match")
- ; return (TyConApp tycon args, substTyWith tvs args rhs_ty) }
+ arity = length tvs
+ desc = CoAxiom { co_ax_tvs = tvs
+ , co_ax_lhs = mkTyConApp tycon (mkTyVarTys tvs)
+ , co_ax_rhs = rhs_ty }
-- | Create a coercion identifying a @data@, @newtype@ or @type@ representation type
-- and its family instance. It has the form @Co tvs :: F ts ~ R tvs@, where @Co@ is
-> [Type] -- ^ Type instance (@ts@)
-> TyCon -- ^ Representation tycon (@R@)
-> TyCon -- ^ Coercion tycon (@Co@)
-mkFamInstCoercion name tvs family instTys rep_tycon
- = mkCoercionTyCon name coArity rule
+mkFamInstCoercion name tvs family inst_tys rep_tycon
+ = mkCoercionTyCon name arity desc
where
- coArity = length tvs
-
- rule :: CoTyConKindChecker
- rule kc_ty _kc_co checking args
- = do { ks <- mapM kc_ty args
- ; unless (not checking || kindAppOk (tyConKind rep_tycon) ks)
- (fail "Argument kind mis-match")
- ; return (substTyWith tvs args $ -- with sigma = [tys/tvs],
- TyConApp family instTys -- sigma (F ts)
- , TyConApp rep_tycon args) } -- ~ R tys
-
-kindAppOk :: Kind -> [Kind] -> Bool
-kindAppOk _ [] = True
-kindAppOk kfn (k:ks)
- = case splitKindFunTy_maybe kfn of
- Just (kfa, kfb) | k `isSubKind` kfa -> kindAppOk kfb ks
- _other -> False
+ arity = length tvs
+ desc = CoAxiom { co_ax_tvs = tvs
+ , co_ax_lhs = mkTyConApp family inst_tys
+ , co_ax_rhs = mkTyConApp rep_tycon (mkTyVarTys tvs) }
+
+
+mkClassPPredCo :: Class -> [Coercion] -> Coercion
+mkClassPPredCo cls = (PredTy . ClassP cls)
+
+mkIParamPredCo :: (IPName Name) -> Coercion -> Coercion
+mkIParamPredCo ipn = (PredTy . IParam ipn)
+
+mkEqPredCo :: Coercion -> Coercion -> Coercion
+mkEqPredCo co1 co2 = PredTy (EqPred co1 co2)
+
+
\end{code}
rightCoercionTyCon, instCoercionTyCon, unsafeCoercionTyCon,
csel1CoercionTyCon, csel2CoercionTyCon, cselRCoercionTyCon :: TyCon
-symCoercionTyCon
- = mkCoercionTyCon symCoercionTyConName 1 kc_sym
- where
- kc_sym :: CoTyConKindChecker
- kc_sym _kc_ty kc_co _ (co:_)
- = do { (ty1,ty2) <- kc_co co
- ; return (ty2,ty1) }
- kc_sym _ _ _ _ = panic "kc_sym"
-
-transCoercionTyCon
- = mkCoercionTyCon transCoercionTyConName 2 kc_trans
- where
- kc_trans :: CoTyConKindChecker
- kc_trans _kc_ty kc_co checking (co1:co2:_)
- = do { (a1, r1) <- kc_co co1
- ; (a2, r2) <- kc_co co2
- ; unless (not checking || (r1 `coreEqType` a2))
- (fail "Trans coercion mis-match")
- ; return (a1, r2) }
- kc_trans _ _ _ _ = panic "kc_sym"
-
----------------------------------------------------
-leftCoercionTyCon = mkCoercionTyCon leftCoercionTyConName 1 (kcLR_help fst)
-rightCoercionTyCon = mkCoercionTyCon rightCoercionTyConName 1 (kcLR_help snd)
-
-kcLR_help :: (forall a. (a,a)->a) -> CoTyConKindChecker
-kcLR_help select _kc_ty kc_co _checking (co : _)
- = do { (ty1, ty2) <- kc_co co
- ; case decompLR_maybe ty1 ty2 of
- Nothing -> fail "decompLR"
- Just res -> return (select res) }
-kcLR_help _ _ _ _ _ = panic "kcLR_help"
-
-decompLR_maybe :: Type -> Type -> Maybe ((Type,Type), (Type,Type))
+symCoercionTyCon = mkCoercionTyCon symCoercionTyConName 1 CoSym
+transCoercionTyCon = mkCoercionTyCon transCoercionTyConName 2 CoTrans
+leftCoercionTyCon = mkCoercionTyCon leftCoercionTyConName 1 CoLeft
+rightCoercionTyCon = mkCoercionTyCon rightCoercionTyConName 1 CoRight
+instCoercionTyCon = mkCoercionTyCon instCoercionTyConName 2 CoInst
+csel1CoercionTyCon = mkCoercionTyCon csel1CoercionTyConName 1 CoCsel1
+csel2CoercionTyCon = mkCoercionTyCon csel2CoercionTyConName 1 CoCsel2
+cselRCoercionTyCon = mkCoercionTyCon cselRCoercionTyConName 1 CoCselR
+unsafeCoercionTyCon = mkCoercionTyCon unsafeCoercionTyConName 2 CoUnsafe
+
+transCoercionTyConName, symCoercionTyConName, leftCoercionTyConName,
+ rightCoercionTyConName, instCoercionTyConName, unsafeCoercionTyConName,
+ csel1CoercionTyConName, csel2CoercionTyConName, cselRCoercionTyConName :: Name
+
+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
+csel1CoercionTyConName = mkCoConName (fsLit "csel1") csel1CoercionTyConKey csel1CoercionTyCon
+csel2CoercionTyConName = mkCoConName (fsLit "csel2") csel2CoercionTyConKey csel2CoercionTyCon
+cselRCoercionTyConName = mkCoConName (fsLit "cselR") cselRCoercionTyConKey cselRCoercionTyCon
+unsafeCoercionTyConName = mkCoConName (fsLit "CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon
+
+mkCoConName :: FastString -> Unique -> TyCon -> Name
+mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkTcOccFS occ)
+ key (ATyCon coCon) BuiltInSyntax
+\end{code}
+
+\begin{code}
+------------
+decompLR_maybe :: (Type,Type) -> Maybe ((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))
-decompLR_maybe ty1 ty2
+decompLR_maybe (ty1,ty2)
| Just (ty_fun1, ty_arg1) <- splitAppTy_maybe ty1
, Just (ty_fun2, ty_arg2) <- splitAppTy_maybe ty2
= Just ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2))
-decompLR_maybe _ _ = Nothing
+decompLR_maybe _ = Nothing
----------------------------------------------------
-instCoercionTyCon
- = mkCoercionTyCon instCoercionTyConName 2 kcInst_help
- where
- kcInst_help :: CoTyConKindChecker
- kcInst_help kc_ty kc_co checking (co : ty : _)
- = do { (t1,t2) <- kc_co co
- ; k <- kc_ty ty
- ; case decompInst_maybe t1 t2 of
- Nothing -> fail "decompInst"
- Just ((tv1,tv2), (ty1,ty2)) -> do
- { unless (not checking || (k `isSubKind` tyVarKind tv1))
- (fail "Coercion instantation kind mis-match")
- ; return (substTyWith [tv1] [ty] ty1,
- substTyWith [tv2] [ty] ty2) } }
- kcInst_help _ _ _ _ = panic "kcInst_help"
-
-decompInst_maybe :: Type -> Type -> Maybe ((TyVar,TyVar), (Type,Type))
-decompInst_maybe ty1 ty2
+------------
+decompInst_maybe :: (Type, Type) -> Maybe ((TyVar,TyVar), (Type,Type))
+decompInst_maybe (ty1, ty2)
| Just (tv1,r1) <- splitForAllTy_maybe ty1
, Just (tv2,r2) <- splitForAllTy_maybe ty2
= Just ((tv1,tv2), (r1,r2))
-decompInst_maybe _ _ = Nothing
+decompInst_maybe _ = Nothing
----------------------------------------------------
-unsafeCoercionTyCon
- = mkCoercionTyCon unsafeCoercionTyConName 2 kc_unsafe
- where
- kc_unsafe kc_ty _kc_co _checking (ty1:ty2:_)
- = do { _ <- kc_ty ty1
- ; _ <- kc_ty ty2
- ; return (ty1,ty2) }
- kc_unsafe _ _ _ _ = panic "kc_unsafe"
-
----------------------------------------------------
--- The csel* family
-
-csel1CoercionTyCon = mkCoercionTyCon csel1CoercionTyConName 1 (kcCsel_help fstOf3)
-csel2CoercionTyCon = mkCoercionTyCon csel2CoercionTyConName 1 (kcCsel_help sndOf3)
-cselRCoercionTyCon = mkCoercionTyCon cselRCoercionTyConName 1 (kcCsel_help thirdOf3)
-
-kcCsel_help :: (forall a. (a,a,a) -> a) -> CoTyConKindChecker
-kcCsel_help select _kc_ty kc_co _checking (co : _)
- = do { (ty1,ty2) <- kc_co co
- ; case decompCsel_maybe ty1 ty2 of
- Nothing -> fail "decompCsel"
- Just res -> return (select res) }
-kcCsel_help _ _ _ _ _ = panic "kcCsel_help"
-
-decompCsel_maybe :: Type -> Type -> Maybe ((Type,Type), (Type,Type), (Type,Type))
+------------
+decompCsel_maybe :: (Type, Type) -> Maybe ((Type,Type), (Type,Type), (Type,Type))
-- If co :: (s1~t1 => r1) ~ (s2~t2 => r2)
-- Then csel1 co :: s1 ~ s2
-- csel2 co :: t1 ~ t2
-- cselR co :: r1 ~ r2
-decompCsel_maybe ty1 ty2
+decompCsel_maybe (ty1, ty2)
| Just (s1, t1, r1) <- splitCoPredTy_maybe ty1
, Just (s2, t2, r2) <- splitCoPredTy_maybe ty2
= Just ((s1,s2), (t1,t2), (r1,r2))
-decompCsel_maybe _ _ = Nothing
-
-fstOf3 :: (a,b,c) -> a
-sndOf3 :: (a,b,c) -> b
-thirdOf3 :: (a,b,c) -> c
-fstOf3 (a,_,_) = a
-sndOf3 (_,b,_) = b
-thirdOf3 (_,_,c) = c
-
---------------------------------------
--- Their Names
-
-transCoercionTyConName, symCoercionTyConName, leftCoercionTyConName,
- rightCoercionTyConName, instCoercionTyConName, unsafeCoercionTyConName,
- csel1CoercionTyConName, csel2CoercionTyConName, cselRCoercionTyConName :: Name
-
-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
-csel1CoercionTyConName = mkCoConName (fsLit "csel1") csel1CoercionTyConKey csel1CoercionTyCon
-csel2CoercionTyConName = mkCoConName (fsLit "csel2") csel2CoercionTyConKey csel2CoercionTyCon
-cselRCoercionTyConName = mkCoConName (fsLit "cselR") cselRCoercionTyConKey cselRCoercionTyCon
-unsafeCoercionTyConName = mkCoConName (fsLit "CoUnsafe") unsafeCoercionTyConKey unsafeCoercionTyCon
-
-mkCoConName :: FastString -> Unique -> TyCon -> Name
-mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkTcOccFS occ)
- key (ATyCon coCon) BuiltInSyntax
+decompCsel_maybe _ = Nothing
\end{code}
= ASSERT( tys `lengthIs` tyConArity tc )
Just (substTyWith tvs tys ty,
case mb_co_tc of
- Nothing -> IdCo
- Just co_tc -> ACo (mkTyConApp co_tc tys))
+ Nothing -> IdCo (mkTyConApp tc tys)
+ Just co_tc -> ACo (mkTyConApp co_tc tys))
| otherwise
= Nothing
| Just (ty', coi) <- instNewTyCon_maybe tc tys
= case coi of
ACo co -> Just (ty', co)
- IdCo -> panic "splitNewTypeRepCo_maybe"
+ IdCo _ -> panic "splitNewTypeRepCo_maybe"
-- This case handled by coreView
splitNewTypeRepCo_maybe _
= Nothing
-- 1. A proper 'Coercion'
--
-- 2. The identity coercion
-data CoercionI = IdCo | ACo Coercion
+data CoercionI = IdCo Type | ACo Coercion
+
+liftCoI :: (Type -> Type) -> CoercionI -> CoercionI
+liftCoI f (IdCo ty) = IdCo (f ty)
+liftCoI f (ACo ty) = ACo (f ty)
+
+liftCoI2 :: (Type -> Type -> Type) -> CoercionI -> CoercionI -> CoercionI
+liftCoI2 f (IdCo ty1) (IdCo ty2) = IdCo (f ty1 ty2)
+liftCoI2 f coi1 coi2 = ACo (f (fromCoI coi1) (fromCoI coi2))
+
+liftCoIs :: ([Type] -> Type) -> [CoercionI] -> CoercionI
+liftCoIs f cois = go_id [] cois
+ where
+ go_id rev_tys [] = IdCo (f (reverse rev_tys))
+ go_id rev_tys (IdCo ty : cois) = go_id (ty:rev_tys) cois
+ go_id rev_tys (ACo co : cois) = go_aco (co:rev_tys) cois
+
+ go_aco rev_tys [] = ACo (f (reverse rev_tys))
+ go_aco rev_tys (IdCo ty : cois) = go_aco (ty:rev_tys) cois
+ go_aco rev_tys (ACo co : cois) = go_aco (co:rev_tys) cois
instance Outputable CoercionI where
- ppr IdCo = ptext (sLit "IdCo")
+ ppr (IdCo _) = ptext (sLit "IdCo")
ppr (ACo co) = ppr co
isIdentityCoI :: CoercionI -> Bool
-isIdentityCoI IdCo = True
-isIdentityCoI _ = False
-
--- | Tests whether all the given 'CoercionI's represent the identity coercion
-allIdCoIs :: [CoercionI] -> Bool
-allIdCoIs = all isIdentityCoI
-
--- | For each 'CoercionI' in the input list, return either the 'Coercion' it
--- contains or the corresponding 'Type' from the other list
-zipCoArgs :: [CoercionI] -> [Type] -> [Coercion]
-zipCoArgs cois tys = zipWith fromCoI cois tys
+isIdentityCoI (IdCo _) = True
+isIdentityCoI (ACo _) = False
-- | Return either the 'Coercion' contained within the 'CoercionI' or the given
-- 'Type' if the 'CoercionI' is the identity 'Coercion'
-fromCoI :: CoercionI -> Type -> Type
-fromCoI IdCo ty = ty -- Identity coercion represented
-fromCoI (ACo co) _ = co -- by the type itself
+fromCoI :: CoercionI -> Type
+fromCoI (IdCo ty) = ty -- Identity coercion represented
+fromCoI (ACo co) = co -- by the type itself
-- | Smart constructor for @sym@ on 'CoercionI', see also 'mkSymCoercion'
mkSymCoI :: CoercionI -> CoercionI
-mkSymCoI IdCo = IdCo
-mkSymCoI (ACo co) = ACo $ mkCoercion symCoercionTyCon [co]
+mkSymCoI (IdCo ty) = IdCo ty
+mkSymCoI (ACo co) = ACo $ mkCoercion symCoercionTyCon [co]
-- the smart constructor
-- is too smart with tyvars
-- | Smart constructor for @trans@ on 'CoercionI', see also 'mkTransCoercion'
mkTransCoI :: CoercionI -> CoercionI -> CoercionI
-mkTransCoI IdCo aco = aco
-mkTransCoI aco IdCo = aco
+mkTransCoI (IdCo _) aco = aco
+mkTransCoI aco (IdCo _) = aco
mkTransCoI (ACo co1) (ACo co2) = ACo $ mkTransCoercion co1 co2
-- | Smart constructor for type constructor application on 'CoercionI', see also 'mkAppCoercion'
-mkTyConAppCoI :: TyCon -> [Type] -> [CoercionI] -> CoercionI
-mkTyConAppCoI tyCon tys cois
- | allIdCoIs cois = IdCo
- | otherwise = ACo (TyConApp tyCon (zipCoArgs cois tys))
+mkTyConAppCoI :: TyCon -> [CoercionI] -> CoercionI
+mkTyConAppCoI tyCon cois = liftCoIs (mkTyConApp tyCon) cois
-- | Smart constructor for honest-to-god 'Coercion' application on 'CoercionI', see also 'mkAppCoercion'
-mkAppTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI
-mkAppTyCoI _ IdCo _ IdCo = IdCo
-mkAppTyCoI ty1 coi1 ty2 coi2 =
- ACo $ AppTy (fromCoI coi1 ty1) (fromCoI coi2 ty2)
-
+mkAppTyCoI :: CoercionI -> CoercionI -> CoercionI
+mkAppTyCoI = liftCoI2 mkAppTy
-mkFunTyCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI
-mkFunTyCoI _ IdCo _ IdCo = IdCo
-mkFunTyCoI ty1 coi1 ty2 coi2 =
- ACo $ FunTy (fromCoI coi1 ty1) (fromCoI coi2 ty2)
+mkFunTyCoI :: CoercionI -> CoercionI -> CoercionI
+mkFunTyCoI = liftCoI2 mkFunTy
-- | Smart constructor for quantified 'Coercion's on 'CoercionI', see also 'mkForAllCoercion'
mkForAllTyCoI :: TyVar -> CoercionI -> CoercionI
-mkForAllTyCoI _ IdCo = IdCo
-mkForAllTyCoI tv (ACo co) = ACo $ ForAllTy tv co
-
--- | Extract a 'Coercion' from a 'CoercionI' if it represents one. If it is the identity coercion,
--- panic
-fromACo :: CoercionI -> Coercion
-fromACo (ACo co) = co
-fromACo (IdCo {}) = panic "fromACo"
+mkForAllTyCoI tv = liftCoI (ForAllTy tv)
-- | Smart constructor for class 'Coercion's on 'CoercionI'. Satisfies:
--
-- > mkClassPPredCoI cls tys cois :: PredTy (cls tys) ~ PredTy (cls (tys `cast` cois))
-mkClassPPredCoI :: Class -> [Type] -> [CoercionI] -> CoercionI
-mkClassPPredCoI cls tys cois
- | allIdCoIs cois = IdCo
- | otherwise = ACo $ PredTy $ ClassP cls (zipCoArgs cois tys)
+mkClassPPredCoI :: Class -> [CoercionI] -> CoercionI
+mkClassPPredCoI cls = liftCoIs (PredTy . ClassP cls)
-- | Smart constructor for implicit parameter 'Coercion's on 'CoercionI'. Similar to 'mkClassPPredCoI'
mkIParamPredCoI :: (IPName Name) -> CoercionI -> CoercionI
-mkIParamPredCoI _ IdCo = IdCo
-mkIParamPredCoI ipn (ACo co) = ACo $ PredTy $ IParam ipn co
+mkIParamPredCoI ipn = liftCoI (PredTy . IParam ipn)
-- | Smart constructor for type equality 'Coercion's on 'CoercionI'. Similar to 'mkClassPPredCoI'
-mkEqPredCoI :: Type -> CoercionI -> Type -> CoercionI -> CoercionI
-mkEqPredCoI _ IdCo _ IdCo = IdCo
-mkEqPredCoI ty1 IdCo _ (ACo co2) = ACo $ PredTy $ EqPred ty1 co2
-mkEqPredCoI _ (ACo co1) ty2 coi2 = ACo $ PredTy $ EqPred co1 (fromCoI coi2 ty2)
+mkEqPredCoI :: CoercionI -> CoercionI -> CoercionI
+mkEqPredCoI = liftCoI2 (\t1 t2 -> PredTy (EqPred t1 t2))
+
+mkCoPredCoI :: CoercionI -> CoercionI -> CoercionI -> CoercionI
+mkCoPredCoI coi1 coi2 coi3 = mkFunTyCoI (mkEqPredCoI coi1 coi2) coi3
+
+
\end{code}
%************************************************************************
-%* *
- Optimising coercions
-%* *
+%* *
+ The kind of a type, and of a coercion
+%* *
%************************************************************************
\begin{code}
-type NormalCo = Coercion
- -- Invariants:
- -- * For trans coercions (co1 `trans` co2)
- -- co1 is not a trans, and neither co1 nor co2 is identity
- -- * If the coercion is the identity, it has no CoVars of CoTyCons in it (just types)
-
-type NormalNonIdCo = NormalCo -- Extra invariant: not the identity
-
-optCoercion :: Coercion -> NormalCo
-optCoercion co = opt_co False co
-
-opt_co :: Bool -- True <=> return (sym co)
- -> Coercion
- -> NormalCo
-opt_co = opt_co'
--- opt_co sym co = pprTrace "opt_co {" (ppr sym <+> ppr co) $
--- co1 `seq`
--- pprTrace "opt_co done }" (ppr co1)
--- WARN( not same_co_kind, ppr co <+> dcolon <+> pprEqPred (s1,t1)
--- $$ ppr co1 <+> dcolon <+> pprEqPred (s2,t2) )
--- co1
--- where
--- co1 = opt_co' sym co
--- same_co_kind = s1 `coreEqType` s2 && t1 `coreEqType` t2
--- (s,t) = coercionKind co
--- (s1,t1) | sym = (t,s)
--- | otherwise = (s,t)
--- (s2,t2) = coercionKind co1
-
-opt_co' sym (AppTy ty1 ty2) = mkAppTy (opt_co sym ty1) (opt_co sym ty2)
-opt_co' sym (FunTy ty1 ty2) = FunTy (opt_co sym ty1) (opt_co sym ty2)
-opt_co' sym (PredTy (ClassP cls tys)) = PredTy (ClassP cls (map (opt_co sym) tys))
-opt_co' sym (PredTy (IParam n ty)) = PredTy (IParam n (opt_co sym ty))
-
-opt_co' sym co@(TyVarTy tv)
- | not (isCoVar tv) = co -- Identity; does not mention a CoVar
- | ty1 `coreEqType` ty2 = ty1 -- Identity; ..ditto..
- | not sym = co
- | otherwise = mkSymCoercion co
- where
- (ty1,ty2) = coVarKind tv
+typeKind :: Type -> Kind
+typeKind ty@(TyConApp tc tys)
+ | isCoercionTyCon tc = typeKind (fst (coercionKind ty))
+ | otherwise = kindAppResult (tyConKind tc) tys
+ -- During coercion optimisation we *do* match a type
+ -- against a coercion (see OptCoercion.matchesAxiomLhs)
+ -- So the use of typeKind in Unify.match_kind must work on coercions too
+ -- Hence the isCoercionTyCon case above
+
+typeKind (PredTy pred) = predKind pred
+typeKind (AppTy fun _) = kindFunResult (typeKind fun)
+typeKind (ForAllTy _ ty) = typeKind ty
+typeKind (TyVarTy tyvar) = tyVarKind tyvar
+typeKind (FunTy _arg res)
+ -- Hack alert. The kind of (Int -> Int#) is liftedTypeKind (*),
+ -- not unliftedTypKind (#)
+ -- The only things that can be after a function arrow are
+ -- (a) types (of kind openTypeKind or its sub-kinds)
+ -- (b) kinds (of super-kind TY) (e.g. * -> (* -> *))
+ | isTySuperKind k = k
+ | otherwise = ASSERT( isSubOpenTypeKind k) liftedTypeKind
+ where
+ k = typeKind res
+
+------------------
+predKind :: PredType -> Kind
+predKind (EqPred {}) = coSuperKind -- A coercion kind!
+predKind (ClassP {}) = liftedTypeKind -- Class and implicitPredicates are
+predKind (IParam {}) = liftedTypeKind -- always represented by lifted types
+
+------------------
+-- | If it is the case that
+--
+-- > c :: (t1 ~ t2)
+--
+-- i.e. the kind of @c@ is a 'CoercionKind' relating @t1@ and @t2@,
+-- then @coercionKind c = (t1, t2)@.
+coercionKind :: Coercion -> (Type, Type)
+coercionKind ty@(TyVarTy a) | isCoVar a = coVarKind a
+ | otherwise = (ty, ty)
+coercionKind (AppTy ty1 ty2)
+ = let (s1, t1) = coercionKind ty1
+ (s2, t2) = coercionKind ty2 in
+ (mkAppTy s1 s2, mkAppTy t1 t2)
+coercionKind co@(TyConApp tc args)
+ | Just (ar, desc) <- isCoercionTyCon_maybe tc
+ -- CoercionTyCons carry their kinding rule, so we use it here
+ = WARN( not (length args >= ar), ppr co ) -- Always saturated
+ (let (ty1, ty2) = coTyConAppKind desc (take ar args)
+ (tys1, tys2) = coercionKinds (drop ar args)
+ in (mkAppTys ty1 tys1, mkAppTys ty2 tys2))
-opt_co' sym (ForAllTy tv cor)
- | isCoVar tv = mkCoPredTy (opt_co sym co1) (opt_co sym co2) (opt_co sym cor)
- | otherwise = ForAllTy tv (opt_co sym cor)
- where
- (co1,co2) = coVarKind tv
+ | 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)
+ | isCoVar tv
+-- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2
+-- ----------------------------------------------
+-- c1~c2 => c3 :: (s1~t1) => r1 ~ (s2~t2) => r2
+-- or
+-- forall (_:c1~c2)
+ = let (c1,c2) = coVarKind tv
+ (s1,s2) = coercionKind c1
+ (t1,t2) = coercionKind c2
+ (r1,r2) = coercionKind ty
+ in
+ (mkCoPredTy s1 t1 r1, mkCoPredTy s2 t2 r2)
-opt_co' sym (TyConApp tc cos)
- | isCoercionTyCon tc
- = foldl mkAppTy opt_co_tc
- (map (opt_co sym) (drop arity cos))
| otherwise
- = TyConApp tc (map (opt_co sym) cos)
- where
- arity = tyConArity tc
- opt_co_tc :: NormalCo
- opt_co_tc = opt_co_tc_app sym tc (take arity cos)
-
---------
-opt_co_tc_app :: Bool -> TyCon -> [Type] -> NormalCo
--- Used for CoercionTyCons only
-opt_co_tc_app sym tc cos
- | tc `hasKey` symCoercionTyConKey
- = opt_co (not sym) co1
-
- | tc `hasKey` transCoercionTyConKey
- = if sym then opt_trans opt_co2 opt_co1
- else opt_trans opt_co1 opt_co2
-
- | tc `hasKey` leftCoercionTyConKey
- , Just (co1, _) <- splitAppTy_maybe opt_co1
- = co1
-
- | tc `hasKey` rightCoercionTyConKey
- , Just (_, co2) <- splitAppTy_maybe opt_co1
- = co2
-
- | tc `hasKey` csel1CoercionTyConKey
- , Just (s1,_,_) <- splitCoPredTy_maybe opt_co1
- = s1
-
- | tc `hasKey` csel2CoercionTyConKey
- , Just (_,s2,_) <- splitCoPredTy_maybe opt_co1
- = s2
-
- | tc `hasKey` cselRCoercionTyConKey
- , Just (_,_,r) <- splitCoPredTy_maybe opt_co1
- = r
-
- | tc `hasKey` instCoercionTyConKey
- , Just (tv, co'') <- splitForAllTy_maybe opt_co1
- , let ty = co2
- = substTyWith [tv] [ty] co''
-
- | otherwise -- Do not push sym inside top-level axioms
- -- e.g. if g is a top-level axiom
- -- g a : F a ~ a
- -- Then (sym (g ty)) /= g (sym ty) !!
- = if sym then mkSymCoercion the_co
- else the_co
+-- c1 :: s1~s2 c2 :: t1~t2 c3 :: r1~r2
+-- ----------------------------------------------
+-- forall a:k. c :: forall a:k. t1 ~ forall a:k. t2
+ = let (ty1, ty2) = coercionKind ty in
+ (ForAllTy tv ty1, ForAllTy tv ty2)
+
+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))
+coercionKind (PredTy (EqPred c1 c2))
+ = pprTrace "coercionKind" (pprEqPred (c1,c2)) $
+ -- These should not show up in coercions at all
+ -- becuase they are in the form of for-alls
+ let k1 = coercionKindPredTy c1
+ k2 = coercionKindPredTy c2 in
+ (k1,k2)
where
- the_co = TyConApp tc cos
- (co1 : cos1) = cos
- (co2 : _) = cos1
- opt_co1 = opt_co sym co1
- opt_co2 = opt_co sym co2
-
--------------
-opt_trans :: NormalCo -> NormalCo -> NormalCo
-opt_trans co1 co2
- | isIdNormCo co1 = co2
- | otherwise = opt_trans1 co1 co2
-
-opt_trans1 :: NormalNonIdCo -> NormalCo -> NormalCo
--- First arg is not the identity
-opt_trans1 co1 co2
- | isIdNormCo co2 = co1
- | otherwise = opt_trans2 co1 co2
-
-opt_trans2 :: NormalNonIdCo -> NormalNonIdCo -> NormalCo
--- Neither arg is the identity
-opt_trans2 (TyConApp tc [co1a,co1b]) co2
- | tc `hasKey` transCoercionTyConKey
- = opt_trans1 co1a (opt_trans2 co1b co2)
-
-opt_trans2 co1 co2
- | Just co <- opt_trans_rule co1 co2
- = co
-
-opt_trans2 co1 (TyConApp tc [co2a,co2b])
- | tc `hasKey` transCoercionTyConKey
- , Just co1_2a <- opt_trans_rule co1 co2a
- = if isIdNormCo co1_2a
- then co2b
- else opt_trans2 co1_2a co2b
-
-opt_trans2 co1 co2
- = mkTransCoercion co1 co2
-
-------
-opt_trans_rule :: NormalNonIdCo -> NormalNonIdCo -> Maybe NormalCo
-opt_trans_rule (TyConApp tc [co1]) co2
- | tc `hasKey` symCoercionTyConKey
- , co1 `coreEqType` co2
- , (_,ty2) <- coercionKind co2
- = Just ty2
-
-opt_trans_rule co1 (TyConApp tc [co2])
- | tc `hasKey` symCoercionTyConKey
- , co1 `coreEqType` co2
- , (ty1,_) <- coercionKind co1
- = Just ty1
-
-opt_trans_rule (TyConApp tc1 [co1,ty1]) (TyConApp tc2 [co2,ty2])
- | tc1 `hasKey` instCoercionTyConKey
- , tc1 == tc2
- , ty1 `coreEqType` ty2
- = Just (mkInstCoercion (opt_trans2 co1 co2) ty1)
-
-opt_trans_rule (TyConApp tc1 cos1) (TyConApp tc2 cos2)
- | not (isCoercionTyCon tc1) ||
- getUnique tc1 `elem` [ leftCoercionTyConKey, rightCoercionTyConKey
- , csel1CoercionTyConKey, csel2CoercionTyConKey
- , cselRCoercionTyConKey ] --Yuk!
- , tc1 == tc2 -- Works for left,right, and csel* family
- -- BUT NOT equality axioms
- -- E.g. (g Int) `trans` (g Bool)
- -- /= g (Int . Bool)
- = Just (TyConApp tc1 (zipWith opt_trans cos1 cos2))
-
-opt_trans_rule co1 co2
- | Just (co1a, co1b) <- splitAppTy_maybe co1
- , Just (co2a, co2b) <- splitAppTy_maybe co2
- = Just (mkAppTy (opt_trans co1a co2a) (opt_trans co1b co2b))
-
- | Just (s1,t1,r1) <- splitCoPredTy_maybe co1
- , Just (s2,t2,r2) <- splitCoPredTy_maybe co1
- = Just (mkCoPredTy (opt_trans s1 s2)
- (opt_trans t1 t2)
- (opt_trans r1 r2))
-
- | Just (tv1,r1) <- splitForAllTy_maybe co1
- , Just (tv2,r2) <- splitForAllTy_maybe co2
- , not (isCoVar tv1) -- Both have same kind
- , let r2' = substTyWith [tv2] [TyVarTy tv1] r2
- = Just (ForAllTy tv1 (opt_trans2 r1 r2'))
-
-opt_trans_rule _ _ = Nothing
-
-
--------------
-isIdNormCo :: NormalCo -> Bool
--- Cheap identity test: look for coercions with no coercion variables at all
--- So it'll return False for (sym g `trans` g)
-isIdNormCo ty = go ty
+ coercionKindPredTy c = let (t1, t2) = coercionKind c in mkCoKind t1 t2
+
+------------------
+-- | Apply 'coercionKind' to multiple 'Coercion's
+coercionKinds :: [Coercion] -> ([Type], [Type])
+coercionKinds tys = unzip $ map coercionKind tys
+
+------------------
+-- | 'coTyConAppKind' is given a list of the type arguments to the 'CoTyCon',
+-- and constructs the types that the resulting coercion relates.
+-- Fails (in the monad) if ill-kinded.
+-- Typically the monad is
+-- either the Lint monad (with the consistency-check flag = True),
+-- or the ID monad with a panic on failure (and the consistency-check flag = False)
+coTyConAppKind
+ :: CoTyConDesc
+ -> [Type] -- Exactly right number of args
+ -> (Type, Type) -- Kind of this application
+coTyConAppKind CoUnsafe (ty1:ty2:_)
+ = (ty1,ty2)
+coTyConAppKind CoSym (co:_)
+ | (ty1,ty2) <- coercionKind co = (ty2,ty1)
+coTyConAppKind CoTrans (co1:co2:_)
+ = (fst (coercionKind co1), snd (coercionKind co2))
+coTyConAppKind CoLeft (co:_)
+ | Just (res,_) <- decompLR_maybe (coercionKind co) = res
+coTyConAppKind CoRight (co:_)
+ | Just (_,res) <- decompLR_maybe (coercionKind co) = res
+coTyConAppKind CoCsel1 (co:_)
+ | Just (res,_,_) <- decompCsel_maybe (coercionKind co) = res
+coTyConAppKind CoCsel2 (co:_)
+ | Just (_,res,_) <- decompCsel_maybe (coercionKind co) = res
+coTyConAppKind CoCselR (co:_)
+ | Just (_,_,res) <- decompCsel_maybe (coercionKind co) = res
+coTyConAppKind CoInst (co:ty:_)
+ | Just ((tv1,tv2), (ty1,ty2)) <- decompInst_maybe (coercionKind co)
+ = (substTyWith [tv1] [ty] ty1, substTyWith [tv2] [ty] ty2)
+coTyConAppKind (CoAxiom { co_ax_tvs = tvs
+ , co_ax_lhs = lhs_ty, co_ax_rhs = rhs_ty }) cos
+ = (substTyWith tvs tys1 lhs_ty, substTyWith tvs tys2 rhs_ty)
where
- go (TyVarTy tv) = not (isCoVar tv)
- go (AppTy t1 t2) = go t1 && go t2
- go (FunTy t1 t2) = go t1 && go t2
- go (ForAllTy tv ty) = go (tyVarKind tv) && go ty
- go (TyConApp tc tys) = not (isCoercionTyCon tc) && all go tys
- go (PredTy (IParam _ ty)) = go ty
- go (PredTy (ClassP _ tys)) = all go tys
- go (PredTy (EqPred t1 t2)) = go t1 && go t2
-\end{code}
+ (tys1, tys2) = coercionKinds cos
+coTyConAppKind desc cos = pprTrace "coTyConAppKind" (ppr desc $$ braces (vcat
+ [ ppr co <+> dcolon <+> pprEqPred (coercionKind co)
+ | co <- cos ])) $
+ coercionKind (head cos)
+\end{code}
projects / ghc-hetmet.git / blobdiff