diff options
Diffstat (limited to 'compiler/GHC/Types/Var.hs')
| -rw-r--r-- | compiler/GHC/Types/Var.hs | 71 |
1 files changed, 14 insertions, 57 deletions
diff --git a/compiler/GHC/Types/Var.hs b/compiler/GHC/Types/Var.hs index 0e7e806656..a3974a92bd 100644 --- a/compiler/GHC/Types/Var.hs +++ b/compiler/GHC/Types/Var.hs @@ -65,11 +65,10 @@ module GHC.Types.Var ( -- * ArgFlags ArgFlag(Invisible,Required,Specified,Inferred), isVisibleArgFlag, isInvisibleArgFlag, sameVis, - AnonArgFlag(..), ForallVisFlag(..), argToForallVisFlag, - Specificity(..), + AnonArgFlag(..), Specificity(..), -- * TyVar's - VarBndr(..), TyCoVarBinder, TyVarBinder, InvisTVBinder, + VarBndr(..), TyCoVarBinder, TyVarBinder, InvisTVBinder, ReqTVBinder, binderVar, binderVars, binderArgFlag, binderType, mkTyCoVarBinder, mkTyCoVarBinders, mkTyVarBinder, mkTyVarBinders, @@ -405,7 +404,6 @@ data ArgFlag = Invisible Specificity -- (<) on ArgFlag means "is less visible than" -- | Whether an 'Invisible' argument may appear in source Haskell. --- see Note [Specificity in HsForAllTy] in GHC.Hs.Type data Specificity = InferredSpec -- ^ the argument may not appear in source Haskell, it is -- only inferred. @@ -469,7 +467,6 @@ instance Binary ArgFlag where -- Appears here partly so that it's together with its friends ArgFlag -- and ForallVisFlag, but also because it is used in IfaceType, rather -- early in the compilation chain --- See Note [AnonArgFlag vs. ForallVisFlag] data AnonArgFlag = VisArg -- ^ Used for @(->)@: an ordinary non-dependent arrow. -- The argument is visible in source code. @@ -491,26 +488,6 @@ instance Binary AnonArgFlag where 0 -> return VisArg _ -> return InvisArg --- | Is a @forall@ invisible (e.g., @forall a b. {...}@, with a dot) or visible --- (e.g., @forall a b -> {...}@, with an arrow)? - --- See Note [AnonArgFlag vs. ForallVisFlag] -data ForallVisFlag - = ForallVis -- ^ A visible @forall@ (with an arrow) - | ForallInvis -- ^ An invisible @forall@ (with a dot) - deriving (Eq, Ord, Data) - -instance Outputable ForallVisFlag where - ppr f = text $ case f of - ForallVis -> "ForallVis" - ForallInvis -> "ForallInvis" - --- | Convert an 'ArgFlag' to its corresponding 'ForallVisFlag'. -argToForallVisFlag :: ArgFlag -> ForallVisFlag -argToForallVisFlag Required = ForallVis -argToForallVisFlag Specified = ForallInvis -argToForallVisFlag Inferred = ForallInvis - {- Note [AnonArgFlag] ~~~~~~~~~~~~~~~~~~~~~ AnonArgFlag is used principally in the FunTy constructor of Type. @@ -564,30 +541,7 @@ Conclusion: the easiest thing is to make mkLamType build (c => ty) when the argument is a predicate type. See GHC.Core.TyCo.Rep Note [Types for coercions, predicates, and evidence] - -Note [AnonArgFlag vs. ForallVisFlag] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -The AnonArgFlag and ForallVisFlag data types are quite similar at a first -glance: - - data AnonArgFlag = VisArg | InvisArg - data ForallVisFlag = ForallVis | ForallInvis - -Both data types keep track of visibility of some sort. AnonArgFlag tracks -whether a FunTy has a visible argument (->) or an invisible predicate argument -(=>). ForallVisFlag tracks whether a `forall` quantifier in a user-specified -HsType is - visible: forall a -> {...} - invisible: forall a. {...} -In fact the visible form can currently only appear in kinds. - -Given their similarities, it's tempting to want to combine these two -data types into one, but they actually represent distinct -concepts. AnonArgFlag reflects a property of *Core* types, whereas -ForallVisFlag reflects a property of the HsSyn source-code AST. In -other words, AnonArgFlag is all about internals, whereas ForallVisFlag -is all about surface syntax. Therefore, they are kept as separate data -types. -} +-} {- ********************************************************************* * * @@ -598,14 +552,16 @@ types. -} -- Variable Binder -- -- VarBndr is polymorphic in both var and visibility fields. --- Currently there are sevenv different uses of 'VarBndr': --- * Var.TyVarBinder = VarBndr TyVar ArgFlag --- * Var.InvisTVBinder = VarBndr TyVar Specificity --- * Var.TyCoVarBinder = VarBndr TyCoVar ArgFlag --- * TyCon.TyConBinder = VarBndr TyVar TyConBndrVis --- * TyCon.TyConTyCoBinder = VarBndr TyCoVar TyConBndrVis --- * IfaceType.IfaceForAllBndr = VarBndr IfaceBndr ArgFlag --- * IfaceType.IfaceTyConBinder = VarBndr IfaceBndr TyConBndrVis +-- Currently there are nine different uses of 'VarBndr': +-- * Var.TyVarBinder = VarBndr TyVar ArgFlag +-- * Var.TyCoVarBinder = VarBndr TyCoVar ArgFlag +-- * Var.InvisTVBinder = VarBndr TyVar Specificity +-- * Var.ReqTVBinder = VarBndr TyVar () +-- * TyCon.TyConBinder = VarBndr TyVar TyConBndrVis +-- * TyCon.TyConTyCoBinder = VarBndr TyCoVar TyConBndrVis +-- * IfaceType.IfaceForAllBndr = VarBndr IfaceBndr ArgFlag +-- * IfaceType.IfaceTyConBinder = VarBndr IfaceBndr TyConBndrVis +-- * IfaceType.IfaceForAllSpecBndr = VarBndr IfaceBndr Specificity data VarBndr var argf = Bndr var argf deriving( Data ) @@ -619,6 +575,7 @@ data VarBndr var argf = Bndr var argf type TyCoVarBinder = VarBndr TyCoVar ArgFlag type TyVarBinder = VarBndr TyVar ArgFlag type InvisTVBinder = VarBndr TyVar Specificity +type ReqTVBinder = VarBndr TyVar () tyVarSpecToBinders :: [VarBndr a Specificity] -> [VarBndr a ArgFlag] tyVarSpecToBinders = map tyVarSpecToBinder |