\section{@Vars@: Variables}
\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
+-- |
+-- #name_types#
+-- GHC uses several kinds of name internally:
+--
+-- * 'OccName.OccName': see "OccName#name_types"
+--
+-- * 'RdrName.RdrName': see "RdrName#name_types"
+--
+-- * 'Name.Name': see "Name#name_types"
+--
+-- * 'Id.Id': see "Id#name_types"
+--
+-- * 'Var.Var' is a synonym for the 'Id.Id' type but it may additionally
+-- potentially contain type variables, which have a 'TypeRep.Kind'
+-- rather than a 'TypeRep.Type' and only contain some extra
+-- details during typechecking.
+--
+-- These 'Var.Var' names may either be global or local, see "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 Var (
- Var,
- varName, varUnique, varType,
- setVarName, setVarUnique,
-
- -- TyVars
- TyVar, mkTyVar, mkTcTyVar, mkWildCoVar,
- tyVarName, tyVarKind,
- setTyVarName, setTyVarUnique, setTyVarKind,
- tcTyVarDetails,
-
- -- CoVars
- CoVar, coVarName, setCoVarUnique, setCoVarName, mkCoVar, isCoVar,
-
- -- Ids
- Id, DictId,
- idName, idType, idUnique, idInfo, modifyIdInfo, maybeModifyIdInfo,
- setIdName, setIdUnique, setIdType, setIdInfo, lazySetIdInfo,
+ -- * The main data type and synonyms
+ Var, TyVar, CoVar, TyCoVar, Id, DictId, DFunId, EvVar, EvId, IpId,
+
+ -- ** Taking 'Var's apart
+ varName, varUnique, varType,
+
+ -- ** Modifying 'Var's
+ setVarName, setVarUnique, setVarType,
+
+ -- ** Constructing, taking apart, modifying 'Id's
+ mkGlobalVar, mkLocalVar, mkExportedLocalVar, mkCoVar,
+ idInfo, idDetails,
+ lazySetIdInfo, setIdDetails, globaliseId,
setIdExported, setIdNotExported,
- globalIdDetails, globaliseId,
+ -- ** Predicates
+ isId, isTyVar, isTcTyVar,
+ isLocalVar, isLocalId,
+ isGlobalId, isExportedId,
+ mustHaveLocalBinding,
+
+ -- ** Constructing 'TyVar's
+ mkTyVar, mkTcTyVar,
- mkLocalId, mkExportedLocalId, mkGlobalId,
+ -- ** Taking 'TyVar's apart
+ tyVarName, tyVarKind, tcTyVarDetails, setTcTyVarDetails,
+
+ -- ** Modifying 'TyVar's
+ setTyVarName, setTyVarUnique, setTyVarKind
- isTyVar, isTcTyVar, isId, isLocalVar, isLocalId,
- isGlobalId, isExportedId,
- mustHaveLocalBinding
) where
#include "HsVersions.h"
+#include "Typeable.h"
import {-# SOURCE #-} TypeRep( Type, Kind )
import {-# SOURCE #-} TcType( TcTyVarDetails, pprTcTyVarDetails )
-import {-# SOURCE #-} IdInfo( GlobalIdDetails, notGlobalId,
- IdInfo, seqIdInfo )
-import {-# SOURCE #-} TypeRep( isCoercionKind )
+import {-# SOURCE #-} IdInfo( IdDetails, IdInfo, coVarDetails, vanillaIdInfo, pprIdDetails )
import Name hiding (varName)
import Unique
+import Util
import FastTypes
import FastString
-import Outputable
+import Outputable
+
+import Data.Data
\end{code}
%************************************************************************
%* *
+ Synonyms
+%* *
+%************************************************************************
+-- These synonyms are here and not in Id because otherwise we need a very
+-- large number of SOURCE imports of Id.hs :-(
+
+\begin{code}
+type EvVar = Var -- An evidence variable: dictionary or equality constraint
+ -- Could be an DictId or a CoVar
+
+type Id = Var -- A term-level identifier
+type DFunId = Id -- A dictionary function
+type EvId = Id -- Term-level evidence: DictId or IpId
+type DictId = EvId -- A dictionary variable
+type IpId = EvId -- A term-level implicit parameter
+
+type TyVar = Var
+type CoVar = Id -- A coercion variable is simply an Id
+ -- variable of kind @ty1 ~ ty2@. Hence its
+ -- 'varType' is always @PredTy (EqPred t1 t2)@
+type TyCoVar = TyVar -- Something that is a type OR coercion variable.
+\end{code}
+
+%************************************************************************
+%* *
\subsection{The main data type declarations}
%* *
%************************************************************************
in its @VarDetails@.
\begin{code}
+-- | Essentially a typed 'Name', that may also contain some additional information
+-- about the 'Var' and it's use sites.
data Var
= TyVar {
varName :: !Name,
realUnique :: FastInt, -- Key for fast comparison
-- Identical to the Unique in the name,
-- cached here for speed
- varType :: Kind,
- isCoercionVar :: Bool
+ varType :: Kind -- ^ The type or kind of the 'Var' in question
}
| TcTyVar { -- Used only during type inference
varName :: !Name,
realUnique :: FastInt,
varType :: Kind,
- tcTyVarDetails :: TcTyVarDetails }
-
- | GlobalId { -- Used for imported Ids, dict selectors etc
- -- See Note [GlobalId/LocalId] below
- varName :: !Name, -- Always an External or WiredIn Name
- realUnique :: FastInt,
- varType :: Type,
- idInfo_ :: IdInfo,
- gblDetails :: GlobalIdDetails }
+ tc_tv_details :: TcTyVarDetails }
- | LocalId { -- Used for locally-defined Ids
- -- See Note [GlobalId/LocalId] below
+ | Id {
varName :: !Name,
realUnique :: FastInt,
varType :: Type,
- idInfo_ :: IdInfo,
- lclDetails :: LocalIdDetails }
-
-data LocalIdDetails
- = NotExported -- Not exported
- | Exported -- Exported
- -- Exported Ids are kept alive;
- -- NotExported things may be discarded as dead code.
+ idScope :: IdScope,
+ id_details :: IdDetails, -- Stable, doesn't change
+ id_info :: IdInfo } -- Unstable, updated by simplifier
+ deriving Typeable
+
+data IdScope -- See Note [GlobalId/LocalId]
+ = GlobalId
+ | LocalId ExportFlag
+
+data ExportFlag
+ = NotExported -- ^ Not exported: may be discarded as dead code.
+ | Exported -- ^ Exported: kept alive
\end{code}
Note [GlobalId/LocalId]
* always treated as a candidate by the free-variable finder
After CoreTidy, top-level LocalIds are turned into GlobalIds
-
\begin{code}
instance Outputable Var where
- ppr var = ppr (varName var) <+> ifPprDebug (brackets extra)
- where
- extra = case var of
- GlobalId {} -> ptext SLIT("gid")
- LocalId {} -> ptext SLIT("lid")
- TyVar {} -> ptext SLIT("tv")
- TcTyVar {tcTyVarDetails = details} -> pprTcTyVarDetails details
+ ppr var = ppr (varName var) <+> ifPprDebug (brackets (ppr_debug var))
+
+ppr_debug :: Var -> SDoc
+ppr_debug (TyVar {}) = ptext (sLit "tv")
+ppr_debug (TcTyVar {tc_tv_details = d}) = pprTcTyVarDetails d
+ppr_debug (Id { idScope = s, id_details = d }) = ppr_id_scope s <> pprIdDetails d
+
+ppr_id_scope :: IdScope -> SDoc
+ppr_id_scope GlobalId = ptext (sLit "gid")
+ppr_id_scope (LocalId Exported) = ptext (sLit "lidx")
+ppr_id_scope (LocalId NotExported) = ptext (sLit "lid")
instance Show Var where
showsPrec p var = showsPrecSDoc p (ppr var)
a >= b = realUnique a >=# realUnique b
a > b = realUnique a ># realUnique b
a `compare` b = varUnique a `compare` varUnique b
+
+instance Data Var where
+ -- don't traverse?
+ toConstr _ = abstractConstr "Var"
+ gunfold _ _ = error "gunfold"
+ dataTypeOf _ = mkNoRepType "Var"
\end{code}
setVarName var new_name
= var { realUnique = getKeyFastInt (getUnique new_name),
varName = new_name }
+
+setVarType :: Id -> Type -> Id
+setVarType id ty = id { varType = ty }
\end{code}
%************************************************************************
\begin{code}
-type TyVar = Var
-
+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
\begin{code}
mkTyVar :: Name -> Kind -> TyVar
-mkTyVar name kind = ASSERT( not (isCoercionKind kind ) )
- TyVar { varName = name
+mkTyVar name kind = TyVar { varName = name
, realUnique = getKeyFastInt (nameUnique name)
, varType = kind
- , isCoercionVar = False
}
mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar
mkTcTyVar name kind details
- = -- TOM: no longer valid assertion?
- -- ASSERT( not (isCoercionKind kind) )
+ = -- NB: 'kind' may be a coercion kind; cf, 'TcMType.newMetaCoVar'
TcTyVar { varName = name,
realUnique = getKeyFastInt (nameUnique name),
varType = kind,
- tcTyVarDetails = details
+ tc_tv_details = details
}
-\end{code}
-
-%************************************************************************
-%* *
-\subsection{Coercion variables}
-%* *
-%************************************************************************
-\begin{code}
-type CoVar = Var -- A coercion variable is simply a type
- -- variable of kind (ty1 :=: ty2)
-coVarName = varName
-
-setCoVarUnique = setVarUnique
-setCoVarName = setVarName
-
-mkCoVar :: Name -> Kind -> CoVar
-mkCoVar name kind = ASSERT( isCoercionKind kind )
- TyVar { varName = name
- , realUnique = getKeyFastInt (nameUnique name)
- , varType = kind
- -- varType is always PredTy (EqPred t1 t2)
- , isCoercionVar = True
- }
+tcTyVarDetails :: TyVar -> TcTyVarDetails
+tcTyVarDetails (TcTyVar { tc_tv_details = details }) = details
+tcTyVarDetails var = pprPanic "tcTyVarDetails" (ppr var)
-mkWildCoVar :: Kind -> TyVar
--- A type variable that is never referred to,
--- so its unique doesn't matter
-mkWildCoVar kind
- = ASSERT( isCoercionKind kind )
- TyVar { varName = mkSysTvName wild_uniq FSLIT("co_wild"),
- realUnique = _ILIT(1),
- varType = kind,
- isCoercionVar = True }
- where
- wild_uniq = mkBuiltinUnique 1
+setTcTyVarDetails :: TyVar -> TcTyVarDetails -> TyVar
+setTcTyVarDetails tv details = tv { tc_tv_details = details }
\end{code}
%************************************************************************
%* *
-\subsection{Id Construction}
+\subsection{Ids}
%* *
%************************************************************************
-Most Id-related functions are in Id.lhs and MkId.lhs
-
\begin{code}
-type Id = Var
-type DictId = Id
-\end{code}
-
-\begin{code}
-idName = varName
-idUnique = varUnique
-idType = varType
-
-setIdUnique :: Id -> Unique -> Id
-setIdUnique = setVarUnique
-
-setIdName :: Id -> Name -> Id
-setIdName = setVarName
-
-setIdType :: Id -> Type -> Id
-setIdType id ty = id {varType = ty}
+idInfo :: 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, becuase Id.lhs uses 'mkGlobalId' etc with different types
+mkGlobalVar :: IdDetails -> Name -> Type -> IdInfo -> Id
+mkGlobalVar details name ty info
+ = mk_id name ty GlobalId details info
+
+mkLocalVar :: IdDetails -> Name -> Type -> IdInfo -> Id
+mkLocalVar details name ty info
+ = mk_id name ty (LocalId NotExported) details info
+
+mkCoVar :: Name -> Type -> CoVar
+-- Coercion variables have no IdInfo
+mkCoVar name ty = mk_id name 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 ty (LocalId Exported) details info
+
+mk_id :: Name -> Type -> IdScope -> IdDetails -> IdInfo -> Id
+mk_id name ty scope details info
+ = Id { varName = name,
+ realUnique = getKeyFastInt (nameUnique name),
+ 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
--- Can be called on GlobalIds, such as data cons and class ops,
--- which are "born" as GlobalIds and automatically exported
-setIdExported id@(LocalId {}) = id { lclDetails = Exported }
-setIdExported other_id = ASSERT( isId other_id ) other_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 { lclDetails = NotExported }
-
-globaliseId :: GlobalIdDetails -> Id -> Id
--- If it's a local, make it global
-globaliseId details id = GlobalId { varName = varName id,
- realUnique = realUnique id,
- varType = varType id,
- idInfo_ = idInfo id,
- gblDetails = details }
-
-idInfo :: Id -> IdInfo
-idInfo (GlobalId {idInfo_ = info}) = info
-idInfo (LocalId {idInfo_ = info}) = info
-idInfo other_var = pprPanic "idInfo" (ppr other_var)
-
-lazySetIdInfo :: Id -> IdInfo -> Id
-lazySetIdInfo id info = id {idInfo_ = info}
-
-setIdInfo :: Id -> IdInfo -> Id
-setIdInfo id info = seqIdInfo info `seq` id {idInfo_ = info}
- -- Try to avoid spack leaks by seq'ing
-
-modifyIdInfo :: (IdInfo -> IdInfo) -> Id -> Id
-modifyIdInfo fn id
- = seqIdInfo new_info `seq` id {idInfo_ = new_info}
- where
- new_info = fn (idInfo id)
-
--- maybeModifyIdInfo tries to avoid unnecesary thrashing
-maybeModifyIdInfo :: Maybe IdInfo -> Id -> Id
-maybeModifyIdInfo (Just new_info) id = id {idInfo_ = new_info}
-maybeModifyIdInfo Nothing id = id
+-- ^ We can only do this to LocalIds
+setIdNotExported id = ASSERT( isLocalId id )
+ id { idScope = LocalId NotExported }
\end{code}
%************************************************************************
%* *
-\subsection{Predicates over variables
+\subsection{Predicates over variables}
%* *
%************************************************************************
\begin{code}
-mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
-mkGlobalId details name ty info
- = GlobalId { varName = name,
- realUnique = getKeyFastInt (nameUnique name), -- Cache the unique
- varType = ty,
- gblDetails = details,
- idInfo_ = info }
-
-mk_local_id :: Name -> Type -> LocalIdDetails -> IdInfo -> Id
-mk_local_id name ty details info
- = LocalId { varName = name,
- realUnique = getKeyFastInt (nameUnique name), -- Cache the unique
- varType = ty,
- lclDetails = details,
- idInfo_ = info }
-
-mkLocalId :: Name -> Type -> IdInfo -> Id
-mkLocalId name ty info = mk_local_id name ty NotExported info
-
-mkExportedLocalId :: Name -> Type -> IdInfo -> Id
-mkExportedLocalId name ty info = mk_local_id name ty Exported info
-\end{code}
-
-\begin{code}
-isTyVar, isTcTyVar :: Var -> Bool
-isId, isLocalVar, isLocalId :: Var -> Bool
-isGlobalId, isExportedId :: Var -> Bool
-mustHaveLocalBinding :: Var -> Bool
-
+isTyVar :: Var -> Bool -- True of both type variables only
isTyVar (TyVar {}) = True
isTyVar (TcTyVar {}) = True
-isTyVar other = False
+isTyVar _ = False
+isTcTyVar :: Var -> Bool
isTcTyVar (TcTyVar {}) = True
-isTcTyVar other = False
-
-isId (LocalId {}) = True
-isId (GlobalId {}) = True
-isId other = False
+isTcTyVar _ = False
-isLocalId (LocalId {}) = True
-isLocalId other = False
+isId :: Var -> Bool
+isId (Id {}) = True
+isId _ = False
-isCoVar (v@(TyVar {})) = isCoercionVar v
-isCoVar other = False
+isLocalId :: Var -> Bool
+isLocalId (Id { idScope = LocalId _ }) = True
+isLocalId _ = False
--- isLocalVar returns True for type variables as well as local Ids
+-- | '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 (GlobalId {}) = False
-isLocalVar other = True
+isLocalVar :: Var -> Bool
+isLocalVar v = not (isGlobalId v)
--- mustHaveLocalBinding returns True of Ids and TyVars
+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 GlobalIds that must have
+-- 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
-isGlobalId (GlobalId {}) = True
-isGlobalId other = False
-
--- isExportedId means "don't throw this away"
-isExportedId (GlobalId {}) = True
-isExportedId (LocalId {lclDetails = details})
- = case details of
- Exported -> True
- other -> False
-isExportedId other = False
+-- | 'isExportedIdVar' means \"don't throw this away\"
+isExportedId :: Var -> Bool
+isExportedId (Id { idScope = GlobalId }) = True
+isExportedId (Id { idScope = LocalId Exported}) = True
+isExportedId _ = False
\end{code}
-
-\begin{code}
-globalIdDetails :: Var -> GlobalIdDetails
--- Works OK on local Ids too, returning notGlobalId
-globalIdDetails (GlobalId {gblDetails = details}) = details
-globalIdDetails other = notGlobalId
-\end{code}
-
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