X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=fa4a6b7340a92d6b80e28f366a4e2cf4b16ce829;hp=d715016352cb4b2da0074a5890b79a9a5f192fc8;hb=7fc749a43b4b6b85d234fa95d4928648259584f4;hpb=909d2dd885f5eebaf7c12cf15d5ac153d646566e diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index d715016..fa4a6b7 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. @@ -9,6 +12,13 @@ The coercion kind constructor is a special TyCon that must always be saturated typeKind (symCoercion type) :: TyConApp CoercionTyCon{...} [type, type] \begin{code} +{-# OPTIONS -w #-} +-- 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, @@ -19,45 +29,48 @@ module Coercion ( isEqPred, mkEqPred, getEqPredTys, isEqPredTy, -- Coercion transformations + mkCoercion, mkSymCoercion, mkTransCoercion, - mkLeftCoercion, mkRightCoercion, mkInstCoercion, mkAppCoercion, + mkLeftCoercion, mkRightCoercion, mkRightCoercions, + mkInstCoercion, mkAppCoercion, mkForAllCoercion, mkFunCoercion, mkInstsCoercion, mkUnsafeCoercion, - mkNewTypeCoercion, mkDataInstCoercion, mkAppsCoercion, + mkNewTypeCoercion, mkFamInstCoercion, mkAppsCoercion, - splitNewTypeRepCo_maybe, decomposeCo, + splitNewTypeRepCo_maybe, instNewTyCon_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, fromACo, + 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 - ) -import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isNewTyCon, - newTyConRhs, newTyConCo, - 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 +type Coercion = Type +type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2) ------------------------------ decomposeCo :: Arity -> Coercion -> [Coercion] @@ -101,17 +114,11 @@ 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 +126,11 @@ 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 +176,82 @@ 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] +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] + | otherwise + = mkCoercion instCoercionTyCon [co, ty] mkInstsCoercion co tys = foldl mkInstCoercion co tys @@ -288,65 +317,32 @@ 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 - - n_eta_tys = count_eta (reverse rhs_args) (reverse tvs) - - 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 - + co_con_arity = length tvs - eqVar (TyVarTy tv) tv' = tv == tv' - eqVar _ _ = False + rule args = ASSERT( co_con_arity == length args ) + (TyConApp tycon args, substTyWith tvs args rhs_ty) - 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], - TyConApp family instTys, -- sigma (F ts) - TyConApp rep_tycon instTys, -- :=: R tys - rest) -- surplus arguments - where - tys = take coArity args - rest = drop coArity args + rule args = (substTyWith tvs args $ -- with sigma = [tys/tvs], + TyConApp family instTys, -- sigma (F ts) + TyConApp rep_tycon args) -- :=: R tys -------------------------------------- -- Coercion Type Constructors... @@ -357,14 +353,6 @@ 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 +360,34 @@ 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 +403,26 @@ 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 @@ -443,22 +433,117 @@ unsafeCoercionTyConName = mkCoConName FSLIT("CoUnsafe") unsafeCoercionTyConKey u +instNewTyCon_maybe :: TyCon -> [Type] -> Maybe (Type, CoercionI) +-- instNewTyCon_maybe T ts +-- = Just (rep_ty, co) if co : T ts ~ rep_ty +instNewTyCon_maybe tc tys + | Just (tvs, ty, mb_co_tc) <- unwrapNewTyCon_maybe tc + = 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)) + | otherwise + = Nothing + -- 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', co) if co : ty ~ ty' +-- Returns Nothing for non-newtypes or fully-transparent newtypes splitNewTypeRepCo_maybe ty | Just ty' <- coreView ty = splitNewTypeRepCo_maybe ty' splitNewTypeRepCo_maybe (TyConApp tc tys) - | isNewTyCon 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 tc) -splitNewTypeRepCo_maybe other = Nothing + | Just (ty', coi) <- instNewTyCon_maybe tc tys + = case coi of + ACo co -> Just (ty', co) + IdCo -> panic "splitNewTypeRepCo_maybe" + -- This case handled by coreView +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 + +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) ty = co -- by the type itself + +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 + | allIdCos cois = IdCo + | otherwise = ACo (TyConApp tyCon (zipCoArgs cois tys)) + +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 + +fromACo (ACo co) = co + + +mkClassPPredCoI :: Class -> [Type] -> [CoercionI] -> CoercionI +-- 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 +-- Similar invariant to mkclassPPredCoI +mkIParamPredCoI ipn 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) +\end{code} +