\section[Id]{@Ids@: Value and constructor identifiers}
\begin{code}
+-- |
+-- #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' represents names that not only have a 'Name.Name' but also a 'TypeRep.Type' and some additional
+-- details (a 'IdInfo.IdInfo' and one of 'Var.LocalIdDetails' or 'IdInfo.GlobalIdDetails') that
+-- are added, modified and inspected by various compiler passes. These 'Var.Var' names may either
+-- be global or local, see "Var#globalvslocal"
+--
+-- * 'Var.Var': see "Var#name_types"
module Id (
-- * The main types
Id, DictId,
mkGlobalId, mkVanillaGlobal, mkVanillaGlobalWithInfo,
mkLocalId, mkLocalIdWithInfo,
mkSysLocal, mkSysLocalM, mkUserLocal, mkUserLocalM,
+ mkTemplateLocals, mkTemplateLocalsNum, mkWildId, mkTemplateLocal,
+ mkWorkerId, mkExportedLocalId,
-- ** Taking an Id apart
idName, idType, idUnique, idInfo,
-- ** Inline pragma stuff
idInlinePragma, setInlinePragma, modifyInlinePragma,
-
- -- ** One shot lambda stuff
+ -- ** One-shot lambdas
isOneShotBndr, isOneShotLambda, isStateHackType,
setOneShotLambda, clearOneShotLambda,
- -- ** IdInfo stuff
+ -- ** Reading 'IdInfo' fields
+ idArity,
+ idNewDemandInfo, idNewDemandInfo_maybe,
+ idNewStrictness, idNewStrictness_maybe,
+ idWorkerInfo,
+ idUnfolding,
+ idSpecialisation, idCoreRules, idHasRules,
+ idCafInfo,
+ idLBVarInfo,
+ idOccInfo,
+
+#ifdef OLD_STRICTNESS
+ idDemandInfo,
+ idStrictness,
+ idCprInfo,
+#endif
+
+ -- ** Writing 'IdInfo' fields
setIdUnfolding,
setIdArity,
setIdNewDemandInfo,
setIdCafInfo,
setIdOccInfo,
- -- ** Id demand information
#ifdef OLD_STRICTNESS
- idDemandInfo,
- idStrictness,
- idCprInfo,
setIdStrictness,
setIdDemandInfo,
setIdCprInfo,
#endif
-
- idArity,
- idNewDemandInfo, idNewDemandInfo_maybe,
- idNewStrictness, idNewStrictness_maybe,
- idWorkerInfo,
- idUnfolding,
- idSpecialisation, idCoreRules, idHasRules,
- idCafInfo,
- idLBVarInfo,
- idOccInfo,
-
-#ifdef OLD_STRICTNESS
- newStrictnessFromOld -- Temporary
-#endif
-
) where
#include "HsVersions.h"
import TyCon
import Type
import TcType
-import TysPrim
+import TysPrim
#ifdef OLD_STRICTNESS
import qualified Demand
#endif
,`setIdDemandInfo`
#endif
\end{code}
+
%************************************************************************
%* *
\subsection{Basic Id manipulation}
idType :: Id -> Kind
idType = varType
-setIdUnique :: Id -> Unique -> Id
-setIdUnique = setVarUnique
+idInfo :: Id -> IdInfo
+idInfo = varIdInfo
+
+idPrimRep :: Id -> PrimRep
+idPrimRep id = typePrimRep (idType id)
+
+globalIdDetails :: Id -> GlobalIdDetails
+globalIdDetails = globalIdVarDetails
+
setIdName :: Id -> Name -> Id
setIdName = setVarName
+setIdUnique :: Id -> Unique -> Id
+setIdUnique = setVarUnique
+
+-- | Not only does this set the 'Id' 'Type', it also evaluates the type to try and
+-- reduce space usage
setIdType :: Id -> Type -> Id
setIdType id ty = seqType ty `seq` Var.setVarType id ty
globaliseId :: GlobalIdDetails -> Id -> Id
globaliseId = globaliseIdVar
-idInfo :: Id -> IdInfo
-idInfo = varIdInfo
-
lazySetIdInfo :: Id -> IdInfo -> Id
lazySetIdInfo = lazySetVarIdInfo
Anyway, we removed it in March 2008.
\begin{code}
--- | Create a global Id. Global identifiers are those that are imported or are data constructors/destructors.
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
mkGlobalId = mkGlobalIdVar
+-- | Make a global 'Id' without any extra information at all
mkVanillaGlobal :: Name -> Type -> Id
mkVanillaGlobal name ty = mkVanillaGlobalWithInfo name ty vanillaIdInfo
+-- | Make a global 'Id' with no global information but some generic 'IdInfo'
mkVanillaGlobalWithInfo :: Name -> Type -> IdInfo -> Id
mkVanillaGlobalWithInfo = mkGlobalId VanillaGlobal
--- | Create a local Id. Local identifiers are those bound at the top level of the current module or in an expression.
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
mkLocalId :: Name -> Type -> Id
mkLocalId name ty = mkLocalIdWithInfo name ty vanillaIdInfo
mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id
mkLocalIdWithInfo = mkLocalIdVar
+ -- Note [Free type variables]
--- | Create a local Id that is marked as exported. This prevents things attached to it from being removed as dead code.
+-- | Create a local 'Id' that is marked as exported. This prevents things attached to it from being removed as dead code.
mkExportedLocalId :: Name -> Type -> Id
mkExportedLocalId name ty = mkExportedLocalIdVar name ty vanillaIdInfo
-- Note [Free type variables]
--- | Create a system local Id. These are local Ids that are created by the compiler out of thin air
+-- | Create a system local 'Id'. These are local 'Id's (see "Var#globalvslocal") that are created by the compiler out of thin air
mkSysLocal :: FastString -> Unique -> Type -> Id
mkSysLocal fs uniq ty = mkLocalId (mkSystemVarName uniq fs) ty
mkSysLocalM fs ty = getUniqueM >>= (\uniq -> return (mkSysLocal fs uniq ty))
--- | Create a user local Id. These are local Id with a name and location that the user might recognize
+-- | Create a user local 'Id'. These are local 'Id's (see "Var#globalvslocal") with a name and location that the user might recognize
mkUserLocal :: OccName -> Unique -> Type -> SrcSpan -> Id
mkUserLocal occ uniq ty loc = mkLocalId (mkInternalName uniq occ loc) ty
mkUserLocalM :: MonadUnique m => OccName -> Type -> SrcSpan -> m Id
mkUserLocalM occ ty loc = getUniqueM >>= (\uniq -> return (mkUserLocal occ uniq ty loc))
+
\end{code}
Make some local @Ids@ for a template @CoreExpr@. These have bogus
instantiated before use.
\begin{code}
--- | Make a "wild Id". This is typically used when you need a binder that you don't expect to use
+-- | Make a /wild Id/. This is typically used when you need a binder that you don't expect to use
mkWildId :: Type -> Id
mkWildId ty = mkSysLocal (fsLit "wild") (mkBuiltinUnique 1) ty
+-- | Workers get local names. "CoreTidy" will externalise these if necessary
mkWorkerId :: Unique -> Id -> Type -> Id
--- | Workers get local names. CoreTidy will externalise these if necessary
mkWorkerId uniq unwrkr ty
= mkLocalId wkr_name ty
where
wkr_name = mkInternalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcSpan unwrkr)
--- | Create a "template local": a family of system local Ids in bijection with Ints, typically used in unfoldings
+-- | Create a /template local/: a family of system local 'Id's in bijection with @Int@s, typically used in unfoldings
mkTemplateLocal :: Int -> Type -> Id
mkTemplateLocal i ty = mkSysLocal (fsLit "tpl") (mkBuiltinUnique i) ty
-- | Create a template local for a series of type, but start from a specified template local
mkTemplateLocalsNum :: Int -> [Type] -> [Id]
--- The Int gives the starting point for unique allocation
mkTemplateLocalsNum n tys = zipWith mkTemplateLocal [n..] tys
\end{code}
%************************************************************************
%* *
-\subsection[Id-general-funs]{General @Id@-related functions}
+\subsection{Basic predicates on @Id@s}
%* *
%************************************************************************
\begin{code}
-idPrimRep :: Id -> PrimRep
-idPrimRep id = typePrimRep (idType id)
-
-globalIdDetails :: Id -> GlobalIdDetails
-globalIdDetails = globalIdVarDetails
-
isId :: Id -> Bool
isId = isIdVar
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
isLocalId :: Id -> Bool
isLocalId = isLocalIdVar
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
isGlobalId :: Id -> Bool
isGlobalId = isGlobalIdVar
-isExportedId :: Var -> Bool
+-- | Determines whether an 'Id' is marked as exported and hence will not be considered dead code
+isExportedId :: Id -> Bool
isExportedId = isExportedIdVar
\end{code}
-
%************************************************************************
%* *
\subsection{Special Ids}
%************************************************************************
\begin{code}
+-- | If the 'Id' is that for a record selector, extract the 'sel_tycon' and label. Panic otherwise
recordSelectorFieldLabel :: Id -> (TyCon, FieldLabel)
recordSelectorFieldLabel id
= case globalIdDetails id of
_ -> Nothing
idDataCon :: Id -> DataCon
--- ^ Get from either the worker or the wrapper to the DataCon.
--- Currently used only in the desugarer.
---
--- INVARIANT: @idDataCon (dataConWrapId d) = d@
+-- ^ Get from either the worker or the wrapper 'Id' to the 'DataCon'. Currently used only in the desugarer.
--
--- (Remember, dataConWrapId can return either the wrapper or the worker.)
-idDataCon id = isDataConId_maybe id `orElse` pprPanic "idDataCon" (ppr id
+-- INVARIANT: @idDataCon (dataConWrapId d) = d@: remember, 'dataConWrapId' can return either the wrapper or the worker
+idDataCon id = isDataConId_maybe id `orElse` pprPanic "idDataCon" (ppr id)
isDictId :: Id -> Bool
isDictId id = isDictTy (idType id)
hasNoBinding :: Id -> Bool
--- ^ Returns True of an Id which may not have a
--- binding, even though it is defined in this module.
+-- ^ Returns @True@ of an 'Id' which may not have a
+-- binding, even though it is defined in this module.
+
-- Data constructor workers used to be things of this kind, but
-- they aren't any more. Instead, we inject a binding for
-- them at the CorePrep stage.
_ -> False
isImplicitId :: Id -> Bool
--- ^ isImplicitId tells whether an Id's info is implied by other
+-- ^ 'isImplicitId' tells whether an 'Id's info is implied by other
-- declarations, so we don't need to put its signature in an interface
-- file, even if it's mentioned in some other interface unfolding.
isImplicitId id
zapIdNewStrictness :: Id -> Id
zapIdNewStrictness id = modifyIdInfo (`setNewStrictnessInfo` Nothing) id
--- | This predicate says whether the id has a strict demand placed on it or
+-- | This predicate says whether the 'Id' has a strict demand placed on it or
-- has a type such that it can always be evaluated strictly (e.g., an
-- unlifted type, but see the comment for 'isStrictType'). We need to
--- check separately whether <id> has a so-called "strict type" because if
--- the demand for <id> hasn't been computed yet but <id> has a strict
--- type, we still want @isStrictId <id>@ to be True.
+-- check separately whether the 'Id' has a so-called \"strict type\" because if
+-- the demand for the given @id@ hasn't been computed yet but @id@ has a strict
+-- type, we still want @isStrictId id@ to be @True@.
isStrictId :: Id -> Bool
isStrictId id
= ASSERT2( isId id, text "isStrictId: not an id: " <+> ppr id )
idLBVarInfo :: Id -> LBVarInfo
idLBVarInfo id = lbvarInfo (idInfo id)
+-- | Returns whether the lambda associated with the 'Id' is certainly applied at most once
+-- OR we are applying the \"state hack\" which makes it appear as if theis is the case for
+-- lambdas used in @IO@. You should prefer using this over 'isOneShotLambda'
isOneShotBndr :: Id -> Bool
-- This one is the "business end", called externally.
-- Its main purpose is to encapsulate the Horrible State Hack
isOneShotBndr id = isOneShotLambda id || isStateHackType (idType id)
+-- | Should we apply the state hack to values of this 'Type'?
isStateHackType :: Type -> Bool
isStateHackType ty
| opt_NoStateHack
-- spot that fill_in has arity 2 (and when Keith is done, we will) but we can't yet.
--- The OneShotLambda functions simply fiddle with the IdInfo flag
+-- | Returns whether the lambda associated with the 'Id' is certainly applied at most once.
+-- You probably want to use 'isOneShotBndr' instead
isOneShotLambda :: Id -> Bool
isOneShotLambda id = case idLBVarInfo id of
IsOneShotLambda -> True
| isOneShotLambda id = modifyIdInfo (`setLBVarInfo` NoLBVarInfo) id
| otherwise = id
+-- The OneShotLambda functions simply fiddle with the IdInfo flag
-- But watch out: this may change the type of something else
-- f = \x -> e
-- If we change the one-shot-ness of x, f's type changes
transfer new_info = new_info `setNewStrictnessInfo` (newStrictnessInfo old_info)
`setArityInfo` (arityInfo old_info)
\end{code}
-
projects / ghc-hetmet.git / commitdiff