diff options
Diffstat (limited to 'compiler/GHC/Core/TyCon.hs')
| -rw-r--r-- | compiler/GHC/Core/TyCon.hs | 93 |
1 files changed, 22 insertions, 71 deletions
diff --git a/compiler/GHC/Core/TyCon.hs b/compiler/GHC/Core/TyCon.hs index f08d18ffc2..0311ba32bd 100644 --- a/compiler/GHC/Core/TyCon.hs +++ b/compiler/GHC/Core/TyCon.hs @@ -20,10 +20,10 @@ module GHC.Core.TyCon( PromDataConInfo(..), TyConFlavour(..), -- * TyConBinder - TyConBinder, TyConBndrVis(..), TyConPiTyBinder, + TyConBinder, TyConBndrVis(..), mkNamedTyConBinder, mkNamedTyConBinders, mkRequiredTyConBinder, - mkAnonTyConBinder, mkAnonTyConBinders, mkInvisAnonTyConBinder, + mkAnonTyConBinder, mkAnonTyConBinders, tyConBinderForAllTyFlag, tyConBndrVisForAllTyFlag, isNamedTyConBinder, isVisibleTyConBinder, isInvisibleTyConBinder, isVisibleTcbVis, @@ -445,38 +445,29 @@ See #19367. ************************************************************************ * * - TyConBinder, TyConPiTyBinder + TyConBinder * * ************************************************************************ -} type TyConBinder = VarBndr TyVar TyConBndrVis -type TyConPiTyBinder = VarBndr TyCoVar TyConBndrVis - -- Only PromotedDataCon has TyConPiTyBinders - -- See Note [Promoted GADT data constructors] data TyConBndrVis - = NamedTCB ForAllTyFlag - | AnonTCB FunTyFlag + = NamedTCB ForAllTyFlag -- ^ A named, forall-bound variable (invisible or not) + | AnonTCB -- ^ an ordinary, visible type argument instance Outputable TyConBndrVis where ppr (NamedTCB flag) = ppr flag - ppr (AnonTCB af) = ppr af + ppr AnonTCB = text "AnonTCB" mkAnonTyConBinder :: TyVar -> TyConBinder -- Make a visible anonymous TyCon binder mkAnonTyConBinder tv = assert (isTyVar tv) $ - Bndr tv (AnonTCB visArgTypeLike) + Bndr tv AnonTCB mkAnonTyConBinders :: [TyVar] -> [TyConBinder] mkAnonTyConBinders tvs = map mkAnonTyConBinder tvs -mkInvisAnonTyConBinder :: TyVar -> TyConBinder --- Make an /invisible/ anonymous TyCon binder --- Not used much -mkInvisAnonTyConBinder tv = assert (isTyVar tv) $ - Bndr tv (AnonTCB invisArgTypeLike) - mkNamedTyConBinder :: ForAllTyFlag -> TyVar -> TyConBinder -- The odd argument order supports currying mkNamedTyConBinder vis tv = assert (isTyVar tv) $ @@ -499,10 +490,8 @@ tyConBinderForAllTyFlag :: TyConBinder -> ForAllTyFlag tyConBinderForAllTyFlag (Bndr _ vis) = tyConBndrVisForAllTyFlag vis tyConBndrVisForAllTyFlag :: TyConBndrVis -> ForAllTyFlag -tyConBndrVisForAllTyFlag (NamedTCB vis) = vis -tyConBndrVisForAllTyFlag (AnonTCB af) -- See Note [AnonTCB with constraint arg] - | isVisibleFunArg af = Required - | otherwise = Inferred +tyConBndrVisForAllTyFlag (NamedTCB vis) = vis +tyConBndrVisForAllTyFlag AnonTCB = Required isNamedTyConBinder :: TyConBinder -> Bool -- Identifies kind variables @@ -517,7 +506,7 @@ isVisibleTyConBinder (Bndr _ tcb_vis) = isVisibleTcbVis tcb_vis isVisibleTcbVis :: TyConBndrVis -> Bool isVisibleTcbVis (NamedTCB vis) = isVisibleForAllTyFlag vis -isVisibleTcbVis (AnonTCB af) = isVisibleFunArg af +isVisibleTcbVis AnonTCB = True isInvisibleTyConBinder :: VarBndr tv TyConBndrVis -> Bool -- Works for IfaceTyConBinder too @@ -530,7 +519,7 @@ mkTyConKind bndrs res_kind = foldr mk res_kind bndrs where mk :: TyConBinder -> Kind -> Kind mk (Bndr tv (NamedTCB vis)) k = mkForAllTy (Bndr tv vis) k - mk (Bndr tv (AnonTCB af)) k = mkNakedFunTy af (varType tv) k + mk (Bndr tv AnonTCB) k = mkNakedFunTy FTF_T_T (varType tv) k -- mkNakedFunTy: see Note [Naked FunTy] in GHC.Builtin.Types -- | (mkTyConTy tc) returns (TyConApp tc []) @@ -549,9 +538,7 @@ tyConInvisTVBinders tc_bndrs mk_binder (Bndr tv tc_vis) = mkTyVarBinder vis tv where vis = case tc_vis of - AnonTCB af -- Note [AnonTCB with constraint arg] - | isInvisibleFunArg af -> InferredSpec - | otherwise -> SpecifiedSpec + AnonTCB -> SpecifiedSpec NamedTCB Required -> SpecifiedSpec NamedTCB (Invisible vis) -> vis @@ -561,35 +548,7 @@ tyConVisibleTyVars tc = [ tv | Bndr tv vis <- tyConBinders tc , isVisibleTcbVis vis ] -{- Note [AnonTCB with constraint arg] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -It's pretty rare to have an (AnonTCB af) binder with af=FTF_C_T or FTF_C_C. -The only way it can occur is through equality constraints in kinds. These -can arise in one of two ways: - -* In a PromotedDataCon whose kind has an equality constraint: - - 'MkT :: forall a b. (a~b) => blah - - See Note [Constraints in kinds] in GHC.Core.TyCo.Rep, and - Note [Promoted data constructors] in this module. - -* In a data type whose kind has an equality constraint, as in the - following example from #12102: - - data T :: forall a. (IsTypeLit a ~ 'True) => a -> Type - -When mapping an (AnonTCB FTF_C_x) to an ForAllTyFlag, in -tyConBndrVisForAllTyFlag, we use "Inferred" to mean "the user cannot -specify this arguments, even with visible type/kind application; -instead the type checker must fill it in. - -We map (AnonTCB FTF_T_x) to Required, of course: the user must -provide it. It would be utterly wrong to do this for constraint -arguments, which is why AnonTCB must have the FunTyFlag in -the first place. - -Note [Building TyVarBinders from TyConBinders] +{- Note [Building TyVarBinders from TyConBinders] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We sometimes need to build the quantified type of a value from the TyConBinders of a type or class. For that we need not @@ -645,7 +604,7 @@ in GHC.Core.TyCo.Rep), so we change it to Specified when making MkT's PiTyBinder {- Note [The binders/kind/arity fields of a TyCon] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ All TyCons have this group of fields - tyConBinders :: [TyConBinder/TyConPiTyBinder] + tyConBinders :: [TyConBinder] tyConResKind :: Kind tyConTyVars :: [TyVar] -- Cached = binderVars tyConBinders -- NB: Currently (Aug 2018), TyCons that own this @@ -656,7 +615,7 @@ All TyCons have this group of fields They fit together like so: -* tyConBinders gives the telescope of type/coercion variables on the LHS of the +* tyConBinders gives the telescope of type variables on the LHS of the type declaration. For example: type App a (b :: k) = a b @@ -673,7 +632,7 @@ They fit together like so: * See Note [VarBndrs, ForAllTyBinders, TyConBinders, and visibility] in GHC.Core.TyCo.Rep for what the visibility flag means. -* Each TyConBinder tyConBinders has a TyVar (sometimes it is TyCoVar), and +* Each TyConBinder in tyConBinders has a TyVar, and that TyVar may scope over some other part of the TyCon's definition. Eg type T a = a -> a we have @@ -745,12 +704,12 @@ instance OutputableBndr tv => Outputable (VarBndr tv TyConBndrVis) where ppr (Bndr v bi) = ppr bi <+> parens (pprBndr LetBind v) instance Binary TyConBndrVis where - put_ bh (AnonTCB af) = do { putByte bh 0; put_ bh af } + put_ bh AnonTCB = do { putByte bh 0 } put_ bh (NamedTCB vis) = do { putByte bh 1; put_ bh vis } get bh = do { h <- getByte bh ; case h of - 0 -> do { af <- get bh; return (AnonTCB af) } + 0 -> return AnonTCB _ -> do { vis <- get bh; return (NamedTCB vis) } } @@ -915,6 +874,9 @@ data TyConDetails = } -- | Represents promoted data constructor. + -- The kind of a promoted data constructor is the *wrapper* type of + -- the original data constructor. This type must not have constraints + -- (as checked in GHC.Tc.Gen.HsType.tcTyVar). | PromotedDataCon { -- See Note [Promoted data constructors] dataCon :: DataCon, -- ^ Corresponding data constructor tcRepName :: TyConRepName, @@ -958,17 +920,6 @@ where tcTyConScopedTyVars are used only for MonoTcTyCons, not PolyTcTyCons. See Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon] in GHC.Tc.Utils.TcType. -Note [Promoted GADT data constructors] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Any promoted GADT data constructor will have a type with equality -constraints in its type; e.g. - K :: forall a b. (a ~# [b]) => a -> b -> T a - -So, when promoted to become a type constructor, the tyConBinders -will include CoVars. That is why we use [TyConPiTyBinder] for the -tyconBinders field. TyConPiTyBinder is a synonym for TyConBinder, -but with the clue that the binder can be a CoVar not just a TyVar. - Note [Representation-polymorphic TyCons] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To check for representation-polymorphism directly in the typechecker, @@ -1946,7 +1897,7 @@ mkFamilyTyCon name binders res_kind resVar flav parent inj -- as the data constructor itself; when we pretty-print -- the TyCon we add a quote; see the Outputable TyCon instance mkPromotedDataCon :: DataCon -> Name -> TyConRepName - -> [TyConPiTyBinder] -> Kind -> [Role] + -> [TyConBinder] -> Kind -> [Role] -> PromDataConInfo -> TyCon mkPromotedDataCon con name rep_name binders res_kind roles rep_info = mkTyCon name binders res_kind roles $ |