{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 \section{@Vars@: Variables} -} {-# LANGUAGE CPP, FlexibleContexts, MultiWayIf, FlexibleInstances, DeriveDataTypeable, PatternSynonyms, BangPatterns #-} {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-} {-# OPTIONS_GHC -Wno-incomplete-record-updates #-} -- | -- #name_types# -- GHC uses several kinds of name internally: -- -- * 'GHC.Types.Name.Occurrence.OccName': see "GHC.Types.Name.Occurrence#name_types" -- -- * 'GHC.Types.Name.Reader.RdrName': see "GHC.Types.Name.Reader#name_types" -- -- * 'GHC.Types.Name.Name': see "GHC.Types.Name#name_types" -- -- * 'GHC.Types.Id.Id': see "GHC.Types.Id#name_types" -- -- * 'GHC.Types.Var.Var' is a synonym for the 'GHC.Types.Id.Id' type but it may additionally -- potentially contain type variables, which have a 'GHC.Core.TyCo.Rep.Kind' -- rather than a 'GHC.Core.TyCo.Rep.Type' and only contain some extra -- details during typechecking. -- -- These 'Var' names may either be global or local, see "GHC.Types.Var#globalvslocal" -- -- #globalvslocal# -- Global 'Id's and 'Var's are those that are imported or correspond -- to a data constructor, primitive operation, or record selectors. -- Local 'Id's and 'Var's are those bound within an expression -- (e.g. by a lambda) or at the top level of the module being compiled. module GHC.Types.Var ( -- * The main data type and synonyms Var, CoVar, Id, NcId, DictId, DFunId, EvVar, EqVar, EvId, IpId, JoinId, TyVar, TcTyVar, TypeVar, KindVar, TKVar, TyCoVar, -- * In and Out variants InVar, InCoVar, InId, InTyVar, OutVar, OutCoVar, OutId, OutTyVar, -- ** Taking 'Var's apart varName, varUnique, varType, varMult, varMultMaybe, -- ** Modifying 'Var's setVarName, setVarUnique, setVarType, updateVarType, updateVarTypeM, -- ** Constructing, taking apart, modifying 'Id's mkGlobalVar, mkLocalVar, mkExportedLocalVar, mkCoVar, idInfo, idDetails, lazySetIdInfo, setIdDetails, globaliseId, setIdExported, setIdNotExported, setIdMult, updateIdTypeButNotMult, updateIdTypeAndMult, updateIdTypeAndMultM, -- ** Predicates isId, isTyVar, isTcTyVar, isLocalVar, isLocalId, isCoVar, isNonCoVarId, isTyCoVar, isGlobalId, isExportedId, mustHaveLocalBinding, -- * ArgFlags ArgFlag(Invisible,Required,Specified,Inferred), isVisibleArgFlag, isInvisibleArgFlag, sameVis, AnonArgFlag(..), Specificity(..), -- * TyVar's VarBndr(..), TyCoVarBinder, TyVarBinder, InvisTVBinder, ReqTVBinder, binderVar, binderVars, binderArgFlag, binderType, mkTyCoVarBinder, mkTyCoVarBinders, mkTyVarBinder, mkTyVarBinders, isTyVarBinder, tyVarSpecToBinder, tyVarSpecToBinders, mapVarBndr, mapVarBndrs, lookupVarBndr, -- ** Constructing TyVar's mkTyVar, mkTcTyVar, -- ** Taking 'TyVar's apart tyVarName, tyVarKind, tcTyVarDetails, setTcTyVarDetails, -- ** Modifying 'TyVar's setTyVarName, setTyVarUnique, setTyVarKind, updateTyVarKind, updateTyVarKindM, nonDetCmpVar ) where #include "HsVersions.h" import GHC.Prelude import {-# SOURCE #-} GHC.Core.TyCo.Rep( Type, Kind, Mult ) import {-# SOURCE #-} GHC.Core.TyCo.Ppr( pprKind ) import {-# SOURCE #-} GHC.Tc.Utils.TcType( TcTyVarDetails, pprTcTyVarDetails, vanillaSkolemTv ) import {-# SOURCE #-} GHC.Types.Id.Info( IdDetails, IdInfo, coVarDetails, isCoVarDetails, vanillaIdInfo, pprIdDetails ) import {-# SOURCE #-} GHC.Builtin.Types ( manyDataConTy ) import GHC.Types.Name hiding (varName) import GHC.Types.Unique ( Uniquable, Unique, getKey, getUnique , mkUniqueGrimily, nonDetCmpUnique ) import GHC.Utils.Misc import GHC.Utils.Binary import GHC.Utils.Outputable import Data.Data {- ************************************************************************ * * Synonyms * * ************************************************************************ -- These synonyms are here and not in Id because otherwise we need a very -- large number of SOURCE imports of "GHC.Types.Id" :-( -} -- | Identifier type Id = Var -- A term-level identifier -- predicate: isId -- | Coercion Variable type CoVar = Id -- See Note [Evidence: EvIds and CoVars] -- predicate: isCoVar -- | type NcId = Id -- A term-level (value) variable that is -- /not/ an (unlifted) coercion -- predicate: isNonCoVarId -- | Type or kind Variable type TyVar = Var -- Type *or* kind variable (historical) -- | Type or Kind Variable type TKVar = Var -- Type *or* kind variable (historical) -- | Type variable that might be a metavariable type TcTyVar = Var -- | Type Variable type TypeVar = Var -- Definitely a type variable -- | Kind Variable type KindVar = Var -- Definitely a kind variable -- See Note [Kind and type variables] -- See Note [Evidence: EvIds and CoVars] -- | Evidence Identifier type EvId = Id -- Term-level evidence: DictId, IpId, or EqVar -- | Evidence Variable type EvVar = EvId -- ...historical name for EvId -- | Dictionary Function Identifier type DFunId = Id -- A dictionary function -- | Dictionary Identifier type DictId = EvId -- A dictionary variable -- | Implicit parameter Identifier type IpId = EvId -- A term-level implicit parameter -- | Equality Variable type EqVar = EvId -- Boxed equality evidence type JoinId = Id -- A join variable -- | Type or Coercion Variable type TyCoVar = Id -- Type, *or* coercion variable -- predicate: isTyCoVar {- Many passes apply a substitution, and it's very handy to have type synonyms to remind us whether or not the substitution has been applied -} type InVar = Var type InTyVar = TyVar type InCoVar = CoVar type InId = Id type OutVar = Var type OutTyVar = TyVar type OutCoVar = CoVar type OutId = Id {- Note [Evidence: EvIds and CoVars] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * An EvId (evidence Id) is a term-level evidence variable (dictionary, implicit parameter, or equality). Could be boxed or unboxed. * DictId, IpId, and EqVar are synonyms when we know what kind of evidence we are talking about. For example, an EqVar has type (t1 ~ t2). * A CoVar is always an un-lifted coercion, of type (t1 ~# t2) or (t1 ~R# t2) Note [Kind and type variables] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Before kind polymorphism, TyVar were used to mean type variables. Now they are used to mean kind *or* type variables. KindVar is used when we know for sure that it is a kind variable. In future, we might want to go over the whole compiler code to use: - TKVar to mean kind or type variables - TypeVar to mean type variables only - KindVar to mean kind variables ************************************************************************ * * \subsection{The main data type declarations} * * ************************************************************************ Every @Var@ has a @Unique@, to uniquify it and for fast comparison, a @Type@, and an @IdInfo@ (non-essential info about it, e.g., strictness). The essential info about different kinds of @Vars@ is in its @VarDetails@. -} -- | Variable -- -- Essentially a typed 'Name', that may also contain some additional information -- about the 'Var' and its use sites. data Var = TyVar { -- Type and kind variables -- see Note [Kind and type variables] varName :: !Name, realUnique :: {-# UNPACK #-} !Int, -- ^ Key for fast comparison -- Identical to the Unique in the name, -- cached here for speed varType :: Kind -- ^ The type or kind of the 'Var' in question } | TcTyVar { -- Used only during type inference -- Used for kind variables during -- inference, as well varName :: !Name, realUnique :: {-# UNPACK #-} !Int, varType :: Kind, tc_tv_details :: TcTyVarDetails } | Id { varName :: !Name, realUnique :: {-# UNPACK #-} !Int, varType :: Type, varMult :: Mult, -- See Note [Multiplicity of let binders] idScope :: IdScope, id_details :: IdDetails, -- Stable, doesn't change id_info :: IdInfo } -- Unstable, updated by simplifier -- | Identifier Scope data IdScope -- See Note [GlobalId/LocalId] = GlobalId | LocalId ExportFlag data ExportFlag -- See Note [ExportFlag on binders] = NotExported -- ^ Not exported: may be discarded as dead code. | Exported -- ^ Exported: kept alive {- Note [ExportFlag on binders] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ An ExportFlag of "Exported" on a top-level binder says "keep this binding alive; do not drop it as dead code". This transitively keeps alive all the other top-level bindings that this binding refers to. This property is persisted all the way down the pipeline, so that the binding will be compiled all the way to object code, and its symbols will appear in the linker symbol table. However, note that this use of "exported" is quite different to the export list on a Haskell module. Setting the ExportFlag on an Id does /not/ mean that if you import the module (in Haskell source code) you will see this Id. Of course, things that appear in the export list of the source Haskell module do indeed have their ExportFlag set. But many other things, such as dictionary functions, are kept alive by having their ExportFlag set, even though they are not exported in the source-code sense. We should probably use a different term for ExportFlag, like KeepAlive. Note [GlobalId/LocalId] ~~~~~~~~~~~~~~~~~~~~~~~ A GlobalId is * always a constant (top-level) * imported, or data constructor, or primop, or record selector * has a Unique that is globally unique across the whole GHC invocation (a single invocation may compile multiple modules) * never treated as a candidate by the free-variable finder; it's a constant! A LocalId is * bound within an expression (lambda, case, local let(rec)) * or defined at top level in the module being compiled * always treated as a candidate by the free-variable finder After CoreTidy, top-level LocalIds are turned into GlobalIds Note [Multiplicity of let binders] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In Core, let-binders' multiplicity is always completely determined by syntax: a recursive let will always have multiplicity Many (it's a prerequisite for being recursive), and non-recursive let doesn't have a conventional multiplicity, instead they act, for the purpose of multiplicity, as an alias for their right-hand side. Therefore, the `varMult` field of identifier is only used by binders in lambda and case expressions. In a let expression the `varMult` field holds an arbitrary value which will (and must!) be ignored. -} instance Outputable Var where ppr var = sdocOption sdocSuppressVarKinds $ \supp_var_kinds -> getPprDebug $ \debug -> getPprStyle $ \sty -> let ppr_var = case var of (TyVar {}) | debug -> brackets (text "tv") (TcTyVar {tc_tv_details = d}) | dumpStyle sty || debug -> brackets (pprTcTyVarDetails d) (Id { idScope = s, id_details = d }) | debug -> brackets (ppr_id_scope s <> pprIdDetails d) _ -> empty in if | debug && (not supp_var_kinds) -> parens (ppr (varName var) <+> ppr (varMultMaybe var) <+> ppr_var <+> dcolon <+> pprKind (tyVarKind var)) | otherwise -> ppr (varName var) <> ppr_var ppr_id_scope :: IdScope -> SDoc ppr_id_scope GlobalId = text "gid" ppr_id_scope (LocalId Exported) = text "lidx" ppr_id_scope (LocalId NotExported) = text "lid" instance NamedThing Var where getName = varName instance Uniquable Var where getUnique = varUnique instance Eq Var where a == b = realUnique a == realUnique b instance Ord Var where a <= b = realUnique a <= realUnique b a < b = realUnique a < realUnique b a >= b = realUnique a >= realUnique b a > b = realUnique a > realUnique b a `compare` b = a `nonDetCmpVar` b -- | Compare Vars by their Uniques. -- This is what Ord Var does, provided here to make it explicit at the -- call-site that it can introduce non-determinism. -- See Note [Unique Determinism] nonDetCmpVar :: Var -> Var -> Ordering nonDetCmpVar a b = varUnique a `nonDetCmpUnique` varUnique b instance Data Var where -- don't traverse? toConstr _ = abstractConstr "Var" gunfold _ _ = error "gunfold" dataTypeOf _ = mkNoRepType "Var" instance HasOccName Var where occName = nameOccName . varName varUnique :: Var -> Unique varUnique var = mkUniqueGrimily (realUnique var) varMultMaybe :: Id -> Maybe Mult varMultMaybe (Id { varMult = mult }) = Just mult varMultMaybe _ = Nothing setVarUnique :: Var -> Unique -> Var setVarUnique var uniq = var { realUnique = getKey uniq, varName = setNameUnique (varName var) uniq } setVarName :: Var -> Name -> Var setVarName var new_name = var { realUnique = getKey (getUnique new_name), varName = new_name } setVarType :: Var -> Type -> Var setVarType id ty = id { varType = ty } -- | Update a 'Var's type. Does not update the /multiplicity/ -- stored in an 'Id', if any. Because of the possibility for -- abuse, ASSERTs that there is no multiplicity to update. updateVarType :: (Type -> Type) -> Var -> Var updateVarType upd var | debugIsOn = case var of Id { id_details = details } -> ASSERT( isCoVarDetails details ) result _ -> result | otherwise = result where result = var { varType = upd (varType var) } -- | Update a 'Var's type monadically. Does not update the /multiplicity/ -- stored in an 'Id', if any. Because of the possibility for -- abuse, ASSERTs that there is no multiplicity to update. updateVarTypeM :: Monad m => (Type -> m Type) -> Var -> m Var updateVarTypeM upd var | debugIsOn = case var of Id { id_details = details } -> ASSERT( isCoVarDetails details ) result _ -> result | otherwise = result where result = do { ty' <- upd (varType var) ; return (var { varType = ty' }) } {- ********************************************************************* * * * ArgFlag * * ********************************************************************* -} -- | Argument Flag -- -- Is something required to appear in source Haskell ('Required'), -- permitted by request ('Specified') (visible type application), or -- prohibited entirely from appearing in source Haskell ('Inferred')? -- See Note [VarBndrs, TyCoVarBinders, TyConBinders, and visibility] in "GHC.Core.TyCo.Rep" data ArgFlag = Invisible Specificity | Required deriving (Eq, Ord, Data) -- (<) on ArgFlag means "is less visible than" -- | Whether an 'Invisible' argument may appear in source Haskell. data Specificity = InferredSpec -- ^ the argument may not appear in source Haskell, it is -- only inferred. | SpecifiedSpec -- ^ the argument may appear in source Haskell, but isn't -- required. deriving (Eq, Ord, Data) pattern Inferred, Specified :: ArgFlag pattern Inferred = Invisible InferredSpec pattern Specified = Invisible SpecifiedSpec {-# COMPLETE Required, Specified, Inferred #-} -- | Does this 'ArgFlag' classify an argument that is written in Haskell? isVisibleArgFlag :: ArgFlag -> Bool isVisibleArgFlag Required = True isVisibleArgFlag _ = False -- | Does this 'ArgFlag' classify an argument that is not written in Haskell? isInvisibleArgFlag :: ArgFlag -> Bool isInvisibleArgFlag = not . isVisibleArgFlag -- | Do these denote the same level of visibility? 'Required' -- arguments are visible, others are not. So this function -- equates 'Specified' and 'Inferred'. Used for printing. sameVis :: ArgFlag -> ArgFlag -> Bool sameVis Required Required = True sameVis (Invisible _) (Invisible _) = True sameVis _ _ = False instance Outputable ArgFlag where ppr Required = text "[req]" ppr Specified = text "[spec]" ppr Inferred = text "[infrd]" instance Binary Specificity where put_ bh SpecifiedSpec = putByte bh 0 put_ bh InferredSpec = putByte bh 1 get bh = do h <- getByte bh case h of 0 -> return SpecifiedSpec _ -> return InferredSpec instance Binary ArgFlag where put_ bh Required = putByte bh 0 put_ bh Specified = putByte bh 1 put_ bh Inferred = putByte bh 2 get bh = do h <- getByte bh case h of 0 -> return Required 1 -> return Specified _ -> return Inferred -- | The non-dependent version of 'ArgFlag'. -- See Note [AnonArgFlag] -- 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 data AnonArgFlag = VisArg -- ^ Used for @(->)@: an ordinary non-dependent arrow. -- The argument is visible in source code. | InvisArg -- ^ Used for @(=>)@: a non-dependent predicate arrow. -- The argument is invisible in source code. deriving (Eq, Ord, Data) instance Outputable AnonArgFlag where ppr VisArg = text "[vis]" ppr InvisArg = text "[invis]" instance Binary AnonArgFlag where put_ bh VisArg = putByte bh 0 put_ bh InvisArg = putByte bh 1 get bh = do h <- getByte bh case h of 0 -> return VisArg _ -> return InvisArg {- Note [AnonArgFlag] ~~~~~~~~~~~~~~~~~~~~~ AnonArgFlag is used principally in the FunTy constructor of Type. FunTy VisArg t1 t2 means t1 -> t2 FunTy InvisArg t1 t2 means t1 => t2 However, the AnonArgFlag in a FunTy is just redundant, cached information. In (FunTy { ft_af = af, ft_arg = t1, ft_res = t2 }) * if (isPredTy t1 = True) then af = InvisArg * if (isPredTy t1 = False) then af = VisArg where isPredTy is defined in GHC.Core.Type, and sees if t1's kind is Constraint. See GHC.Core.TyCo.Rep Note [Types for coercions, predicates, and evidence] GHC.Core.Utils.mkFunctionType :: Mult -> Type -> Type -> Type uses isPredTy to decide the AnonArgFlag for the FunTy. The term (Lam b e), and coercion (FunCo co1 co2) don't carry AnonArgFlags; instead they use mkFunctionType when we want to get their types; see mkLamType and coercionLKind/RKind resp. This is just an engineering choice; we could cache here too if we wanted. Why bother with all this? After all, we are in Core, where (=>) and (->) behave the same. We maintain this distinction throughout Core so that we can cheaply and conveniently determine * How to print a type * How to split up a type: tcSplitSigmaTy * How to specialise it (over type classes; GHC.Core.Opt.Specialise) For the specialisation point, consider (\ (d :: Ord a). blah). We want to give it type (Ord a => blah_ty) with a fat arrow; that is, using mkInvisFunTy, not mkVisFunTy. Why? Because the /specialiser/ treats dictionary arguments specially. Suppose we do w/w on 'foo', thus (#11272, #6056) foo :: Ord a => Int -> blah foo a d x = case x of I# x' -> $wfoo @a d x' $wfoo :: Ord a => Int# -> blah Now, at a call we see (foo @Int dOrdInt). The specialiser will specialise this to $sfoo, where $sfoo :: Int -> blah $sfoo x = case x of I# x' -> $wfoo @Int dOrdInt x' Now we /must/ also specialise $wfoo! But it wasn't user-written, and has a type built with mkLamTypes. 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] -} {- ********************************************************************* * * * VarBndr, TyCoVarBinder * * ********************************************************************* -} -- Variable Binder -- -- VarBndr is polymorphic in both var and visibility fields. -- 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 ) -- | Variable Binder -- -- A 'TyCoVarBinder' is the binder of a ForAllTy -- It's convenient to define this synonym here rather its natural -- home in "GHC.Core.TyCo.Rep", because it's used in GHC.Core.DataCon.hs-boot -- -- A 'TyVarBinder' is a binder with only TyVar 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 tyVarSpecToBinder :: (VarBndr a Specificity) -> (VarBndr a ArgFlag) tyVarSpecToBinder (Bndr tv vis) = Bndr tv (Invisible vis) binderVar :: VarBndr tv argf -> tv binderVar (Bndr v _) = v binderVars :: [VarBndr tv argf] -> [tv] binderVars tvbs = map binderVar tvbs binderArgFlag :: VarBndr tv argf -> argf binderArgFlag (Bndr _ argf) = argf binderType :: VarBndr TyCoVar argf -> Type binderType (Bndr tv _) = varType tv -- | Make a named binder mkTyCoVarBinder :: vis -> TyCoVar -> (VarBndr TyCoVar vis) mkTyCoVarBinder vis var = Bndr var vis -- | Make a named binder -- 'var' should be a type variable mkTyVarBinder :: vis -> TyVar -> (VarBndr TyVar vis) mkTyVarBinder vis var = ASSERT( isTyVar var ) Bndr var vis -- | Make many named binders mkTyCoVarBinders :: vis -> [TyCoVar] -> [VarBndr TyCoVar vis] mkTyCoVarBinders vis = map (mkTyCoVarBinder vis) -- | Make many named binders -- Input vars should be type variables mkTyVarBinders :: vis -> [TyVar] -> [VarBndr TyVar vis] mkTyVarBinders vis = map (mkTyVarBinder vis) isTyVarBinder :: TyCoVarBinder -> Bool isTyVarBinder (Bndr v _) = isTyVar v mapVarBndr :: (var -> var') -> (VarBndr var flag) -> (VarBndr var' flag) mapVarBndr f (Bndr v fl) = Bndr (f v) fl mapVarBndrs :: (var -> var') -> [VarBndr var flag] -> [VarBndr var' flag] mapVarBndrs f = map (mapVarBndr f) lookupVarBndr :: Eq var => var -> [VarBndr var flag] -> Maybe flag lookupVarBndr var bndrs = lookup var zipped_bndrs where zipped_bndrs = map (\(Bndr v f) -> (v,f)) bndrs instance Outputable tv => Outputable (VarBndr tv ArgFlag) where ppr (Bndr v Required) = ppr v ppr (Bndr v Specified) = char '@' <> ppr v ppr (Bndr v Inferred) = braces (ppr v) instance Outputable tv => Outputable (VarBndr tv Specificity) where ppr = ppr . tyVarSpecToBinder instance (Binary tv, Binary vis) => Binary (VarBndr tv vis) where put_ bh (Bndr tv vis) = do { put_ bh tv; put_ bh vis } get bh = do { tv <- get bh; vis <- get bh; return (Bndr tv vis) } instance NamedThing tv => NamedThing (VarBndr tv flag) where getName (Bndr tv _) = getName tv {- ************************************************************************ * * * Type and kind variables * * * ************************************************************************ -} tyVarName :: TyVar -> Name tyVarName = varName tyVarKind :: TyVar -> Kind tyVarKind = varType setTyVarUnique :: TyVar -> Unique -> TyVar setTyVarUnique = setVarUnique setTyVarName :: TyVar -> Name -> TyVar setTyVarName = setVarName setTyVarKind :: TyVar -> Kind -> TyVar setTyVarKind tv k = tv {varType = k} updateTyVarKind :: (Kind -> Kind) -> TyVar -> TyVar updateTyVarKind update tv = tv {varType = update (tyVarKind tv)} updateTyVarKindM :: (Monad m) => (Kind -> m Kind) -> TyVar -> m TyVar updateTyVarKindM update tv = do { k' <- update (tyVarKind tv) ; return $ tv {varType = k'} } mkTyVar :: Name -> Kind -> TyVar mkTyVar name kind = TyVar { varName = name , realUnique = getKey (nameUnique name) , varType = kind } mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar mkTcTyVar name kind details = -- NB: 'kind' may be a coercion kind; cf, 'GHC.Tc.Utils.TcMType.newMetaCoVar' TcTyVar { varName = name, realUnique = getKey (nameUnique name), varType = kind, tc_tv_details = details } tcTyVarDetails :: TyVar -> TcTyVarDetails -- See Note [TcTyVars in the typechecker] in GHC.Tc.Utils.TcType tcTyVarDetails (TcTyVar { tc_tv_details = details }) = details tcTyVarDetails (TyVar {}) = vanillaSkolemTv tcTyVarDetails var = pprPanic "tcTyVarDetails" (ppr var <+> dcolon <+> pprKind (tyVarKind var)) setTcTyVarDetails :: TyVar -> TcTyVarDetails -> TyVar setTcTyVarDetails tv details = tv { tc_tv_details = details } {- %************************************************************************ %* * \subsection{Ids} * * ************************************************************************ -} idInfo :: HasDebugCallStack => Id -> IdInfo idInfo (Id { id_info = info }) = info idInfo other = pprPanic "idInfo" (ppr other) idDetails :: Id -> IdDetails idDetails (Id { id_details = details }) = details idDetails other = pprPanic "idDetails" (ppr other) -- The next three have a 'Var' suffix even though they always build -- Ids, because "GHC.Types.Id" uses 'mkGlobalId' etc with different types mkGlobalVar :: IdDetails -> Name -> Type -> IdInfo -> Id mkGlobalVar details name ty info = mk_id name manyDataConTy ty GlobalId details info -- There is no support for linear global variables yet. They would require -- being checked at link-time, which can be useful, but is not a priority. mkLocalVar :: IdDetails -> Name -> Mult -> Type -> IdInfo -> Id mkLocalVar details name w ty info = mk_id name w ty (LocalId NotExported) details info mkCoVar :: Name -> Type -> CoVar -- Coercion variables have no IdInfo mkCoVar name ty = mk_id name manyDataConTy ty (LocalId NotExported) coVarDetails vanillaIdInfo -- | Exported 'Var's will not be removed as dead code mkExportedLocalVar :: IdDetails -> Name -> Type -> IdInfo -> Id mkExportedLocalVar details name ty info = mk_id name manyDataConTy ty (LocalId Exported) details info -- There is no support for exporting linear variables. See also [mkGlobalVar] mk_id :: Name -> Mult -> Type -> IdScope -> IdDetails -> IdInfo -> Id mk_id name !w ty scope details info = Id { varName = name, realUnique = getKey (nameUnique name), varMult = w, varType = ty, idScope = scope, id_details = details, id_info = info } ------------------- lazySetIdInfo :: Id -> IdInfo -> Var lazySetIdInfo id info = id { id_info = info } setIdDetails :: Id -> IdDetails -> Id setIdDetails id details = id { id_details = details } globaliseId :: Id -> Id -- ^ If it's a local, make it global globaliseId id = id { idScope = GlobalId } setIdExported :: Id -> Id -- ^ Exports the given local 'Id'. Can also be called on global 'Id's, such as data constructors -- and class operations, which are born as global 'Id's and automatically exported setIdExported id@(Id { idScope = LocalId {} }) = id { idScope = LocalId Exported } setIdExported id@(Id { idScope = GlobalId }) = id setIdExported tv = pprPanic "setIdExported" (ppr tv) setIdNotExported :: Id -> Id -- ^ We can only do this to LocalIds setIdNotExported id = ASSERT( isLocalId id ) id { idScope = LocalId NotExported } ----------------------- updateIdTypeButNotMult :: (Type -> Type) -> Id -> Id updateIdTypeButNotMult f id = id { varType = f (varType id) } updateIdTypeAndMult :: (Type -> Type) -> Id -> Id updateIdTypeAndMult f id@(Id { varType = ty , varMult = mult }) = id { varType = ty' , varMult = mult' } where !ty' = f ty !mult' = f mult updateIdTypeAndMult _ other = pprPanic "updateIdTypeAndMult" (ppr other) updateIdTypeAndMultM :: Monad m => (Type -> m Type) -> Id -> m Id updateIdTypeAndMultM f id@(Id { varType = ty , varMult = mult }) = do { !ty' <- f ty ; !mult' <- f mult ; return (id { varType = ty', varMult = mult' }) } updateIdTypeAndMultM _ other = pprPanic "updateIdTypeAndMultM" (ppr other) setIdMult :: Id -> Mult -> Id setIdMult id !r | isId id = id { varMult = r } | otherwise = pprPanic "setIdMult" (ppr id <+> ppr r) {- ************************************************************************ * * \subsection{Predicates over variables} * * ************************************************************************ -} -- | Is this a type-level (i.e., computationally irrelevant, thus erasable) -- variable? Satisfies @isTyVar = not . isId@. isTyVar :: Var -> Bool -- True of both TyVar and TcTyVar isTyVar (TyVar {}) = True isTyVar (TcTyVar {}) = True isTyVar _ = False isTcTyVar :: Var -> Bool -- True of TcTyVar only isTcTyVar (TcTyVar {}) = True isTcTyVar _ = False isTyCoVar :: Var -> Bool isTyCoVar v = isTyVar v || isCoVar v -- | Is this a value-level (i.e., computationally relevant) 'Id'entifier? -- Satisfies @isId = not . isTyVar@. isId :: Var -> Bool isId (Id {}) = True isId _ = False -- | Is this a coercion variable? -- Satisfies @'isId' v ==> 'isCoVar' v == not ('isNonCoVarId' v)@. isCoVar :: Var -> Bool isCoVar (Id { id_details = details }) = isCoVarDetails details isCoVar _ = False -- | Is this a term variable ('Id') that is /not/ a coercion variable? -- Satisfies @'isId' v ==> 'isCoVar' v == not ('isNonCoVarId' v)@. isNonCoVarId :: Var -> Bool isNonCoVarId (Id { id_details = details }) = not (isCoVarDetails details) isNonCoVarId _ = False isLocalId :: Var -> Bool isLocalId (Id { idScope = LocalId _ }) = True isLocalId _ = False -- | 'isLocalVar' returns @True@ for type variables as well as local 'Id's -- These are the variables that we need to pay attention to when finding free -- variables, or doing dependency analysis. isLocalVar :: Var -> Bool isLocalVar v = not (isGlobalId v) isGlobalId :: Var -> Bool isGlobalId (Id { idScope = GlobalId }) = True isGlobalId _ = False -- | 'mustHaveLocalBinding' returns @True@ of 'Id's and 'TyVar's -- that must have a binding in this module. The converse -- is not quite right: there are some global 'Id's that must have -- bindings, such as record selectors. But that doesn't matter, -- because it's only used for assertions mustHaveLocalBinding :: Var -> Bool mustHaveLocalBinding var = isLocalVar var -- | 'isExportedIdVar' means \"don't throw this away\" isExportedId :: Var -> Bool isExportedId (Id { idScope = GlobalId }) = True isExportedId (Id { idScope = LocalId Exported}) = True isExportedId _ = False