\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,
- -- Simple construction
- mkGlobalId, mkLocalId, mkLocalIdWithInfo,
- mkSysLocal, mkUserLocal, mkVanillaGlobal,
- mkTemplateLocals, mkTemplateLocalsNum, mkWildId, mkTemplateLocal,
+ -- ** Simple construction
+ mkGlobalId, mkVanillaGlobal, mkVanillaGlobalWithInfo,
+ mkLocalId, mkLocalIdWithInfo,
+ mkSysLocal, mkSysLocalM, mkUserLocal, mkUserLocalM,
+ mkTemplateLocals, mkTemplateLocalsNum, mkTemplateLocal,
mkWorkerId, mkExportedLocalId,
- -- Taking an Id apart
+ -- ** Taking an Id apart
idName, idType, idUnique, idInfo,
isId, globalIdDetails, idPrimRep,
recordSelectorFieldLabel,
- -- Modifying an Id
- setIdName, setIdUnique, Id.setIdType, setIdExported, setIdNotExported,
+ -- ** Modifying an Id
+ setIdName, setIdUnique, Id.setIdType,
+ setIdExported, setIdNotExported,
+ globaliseId, localiseId,
setIdInfo, lazySetIdInfo, modifyIdInfo, maybeModifyIdInfo,
- zapLamIdInfo, zapDemandIdInfo,
+ zapLamIdInfo, zapDemandIdInfo, zapFragileIdInfo, transferPolyIdInfo,
+
- -- Predicates
- isImplicitId, isDeadBinder, isDictId,
+ -- ** Predicates on Ids
+ isImplicitId, isDeadBinder, isDictId, isStrictId,
isExportedId, isLocalId, isGlobalId,
isRecordSelector, isNaughtyRecordSelector,
isClassOpId_maybe,
isFCallId, isFCallId_maybe,
isDataConWorkId, isDataConWorkId_maybe, isDataConId_maybe, idDataCon,
isBottomingId, idIsFrom,
+ isTickBoxOp, isTickBoxOp_maybe,
hasNoBinding,
- -- Inline pragma stuff
+ -- ** Inline pragma stuff
idInlinePragma, setInlinePragma, modifyInlinePragma,
-
- -- One shot lambda stuff
+ -- ** One-shot lambdas
isOneShotBndr, isOneShotLambda, isStateHackType,
setOneShotLambda, clearOneShotLambda,
- -- IdInfo stuff
- setIdUnfolding,
- setIdArity,
- setIdNewDemandInfo,
- setIdNewStrictness, zapIdNewStrictness,
- setIdWorkerInfo,
- setIdSpecialisation,
- setIdCafInfo,
- setIdOccInfo,
-
-#ifdef OLD_STRICTNESS
- idDemandInfo,
- idStrictness,
- idCprInfo,
- setIdStrictness,
- setIdDemandInfo,
- setIdCprInfo,
-#endif
-
+ -- ** Reading 'IdInfo' fields
idArity,
idNewDemandInfo, idNewDemandInfo_maybe,
idNewStrictness, idNewStrictness_maybe,
- idWorkerInfo,
idUnfolding,
idSpecialisation, idCoreRules, idHasRules,
idCafInfo,
idOccInfo,
#ifdef OLD_STRICTNESS
- newStrictnessFromOld -- Temporary
+ idDemandInfo,
+ idStrictness,
+ idCprInfo,
#endif
+ -- ** Writing 'IdInfo' fields
+ setIdUnfolding,
+ setIdArity,
+ setIdNewDemandInfo,
+ setIdNewStrictness, zapIdNewStrictness,
+ setIdSpecialisation,
+ setIdCafInfo,
+ setIdOccInfo, zapIdOccInfo,
+
+#ifdef OLD_STRICTNESS
+ setIdStrictness,
+ setIdDemandInfo,
+ setIdCprInfo,
+#endif
) where
#include "HsVersions.h"
-import CoreSyn
+import CoreSyn ( CoreRule, Unfolding )
+
+import IdInfo
import BasicTypes
import qualified Var
-import Var hiding (mkLocalId, mkGlobalId, mkExportedLocalId)
+import Var
import TyCon
import Type
import TcType
import TysPrim
-import IdInfo
#ifdef OLD_STRICTNESS
import qualified Demand
#endif
import NewDemand
import Name
import Module
+import Class
+import PrimOp
+import ForeignCall
import OccName
import Maybes
import SrcLoc
import Outputable
import Unique
+import UniqSupply
import FastString
import StaticFlags
`setIdArity`,
`setIdNewDemandInfo`,
`setIdNewStrictness`,
- `setIdWorkerInfo`,
`setIdSpecialisation`,
`setInlinePragma`,
`idCafInfo`
#endif
\end{code}
+%************************************************************************
+%* *
+\subsection{Basic Id manipulation}
+%* *
+%************************************************************************
+
+\begin{code}
+idName :: Id -> Name
+idName = Var.varName
+
+idUnique :: Id -> Unique
+idUnique = varUnique
+
+idType :: Id -> Kind
+idType = varType
+
+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
+
+setIdExported :: Id -> Id
+setIdExported = setIdVarExported
+
+setIdNotExported :: Id -> Id
+setIdNotExported = setIdVarNotExported
+
+localiseId :: Id -> Id
+-- Make an with the same unique and type as the
+-- incoming Id, but with an *Internal* Name and *LocalId* flavour
+localiseId id
+ | isLocalId id && isInternalName name
+ = id
+ | otherwise
+ = mkLocalIdWithInfo (localiseName name) (idType id) (idInfo id)
+ where
+ name = idName id
+
+globaliseId :: GlobalIdDetails -> Id -> Id
+globaliseId = globaliseIdVar
+
+lazySetIdInfo :: Id -> IdInfo -> Id
+lazySetIdInfo = lazySetVarIdInfo
+setIdInfo :: Id -> IdInfo -> Id
+setIdInfo id info = seqIdInfo info `seq` (lazySetIdInfo id info)
+ -- Try to avoid spack leaks by seq'ing
+
+modifyIdInfo :: (IdInfo -> IdInfo) -> Id -> Id
+modifyIdInfo fn id = setIdInfo id (fn (idInfo id))
+
+-- maybeModifyIdInfo tries to avoid unnecesary thrashing
+maybeModifyIdInfo :: Maybe IdInfo -> Id -> Id
+maybeModifyIdInfo (Just new_info) id = lazySetIdInfo id new_info
+maybeModifyIdInfo Nothing id = id
+\end{code}
%************************************************************************
%* *
but in addition it pins free-tyvar-info onto the Id's type,
where it can easily be found.
+Note [Free type variables]
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+At one time we cached the free type variables of the type of an Id
+at the root of the type in a TyNote. The idea was to avoid repeating
+the free-type-variable calculation. But it turned out to slow down
+the compiler overall. I don't quite know why; perhaps finding free
+type variables of an Id isn't all that common whereas applying a
+substitution (which changes the free type variables) is more common.
+Anyway, we removed it in March 2008.
+
\begin{code}
-mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id
-mkLocalIdWithInfo name ty info = Var.mkLocalId name (addFreeTyVars ty) info
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
+mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
+mkGlobalId = mkGlobalIdVar
-mkExportedLocalId :: Name -> Type -> Id
-mkExportedLocalId name ty = Var.mkExportedLocalId name (addFreeTyVars ty) vanillaIdInfo
+-- | Make a global 'Id' without any extra information at all
+mkVanillaGlobal :: Name -> Type -> Id
+mkVanillaGlobal name ty = mkVanillaGlobalWithInfo name ty vanillaIdInfo
-mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
-mkGlobalId details name ty info = Var.mkGlobalId details name (addFreeTyVars ty) info
-\end{code}
+-- | Make a global 'Id' with no global information but some generic 'IdInfo'
+mkVanillaGlobalWithInfo :: Name -> Type -> IdInfo -> Id
+mkVanillaGlobalWithInfo = mkGlobalId VanillaGlobal
-\begin{code}
+
+-- | For an explanation of global vs. local 'Id's, see "Var#globalvslocal"
mkLocalId :: Name -> Type -> Id
mkLocalId name ty = mkLocalIdWithInfo name ty vanillaIdInfo
--- SysLocal: for an Id being created by the compiler out of thin air...
+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.
+mkExportedLocalId :: Name -> Type -> Id
+mkExportedLocalId name ty = mkExportedLocalIdVar name ty vanillaIdInfo
+ -- Note [Free type variables]
+
+
+-- | 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 :: MonadUnique m => FastString -> Type -> m Id
+mkSysLocalM fs ty = getUniqueM >>= (\uniq -> return (mkSysLocal fs uniq ty))
+
--- UserLocal: an Id with a name the user might recognize...
-mkUserLocal :: OccName -> Unique -> Type -> SrcLoc -> Id
-mkVanillaGlobal :: Name -> Type -> IdInfo -> Id
+-- | 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))
-mkUserLocal occ uniq ty loc = mkLocalId (mkInternalName uniq occ loc) ty
-mkVanillaGlobal = mkGlobalId VanillaGlobal
\end{code}
Make some local @Ids@ for a template @CoreExpr@. These have bogus
instantiated before use.
\begin{code}
--- "Wild Id" 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
--- A worker gets a local name. CoreTidy will externalise it if necessary.
mkWorkerId uniq unwrkr ty
= mkLocalId wkr_name ty
where
- wkr_name = mkInternalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcLoc unwrkr)
+ wkr_name = mkInternalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcSpan unwrkr)
--- "Template locals" 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 types
mkTemplateLocals :: [Type] -> [Id]
-mkTemplateLocals tys = zipWith mkTemplateLocal [1..] tys
+mkTemplateLocals = mkTemplateLocalsNum 1
+-- | 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
-
-mkTemplateLocal :: Int -> Type -> Id
-mkTemplateLocal i ty = mkSysLocal FSLIT("tpl") (mkBuiltinUnique i) ty
\end{code}
%************************************************************************
%* *
-\subsection[Id-general-funs]{General @Id@-related functions}
+\subsection{Basic predicates on @Id@s}
%* *
%************************************************************************
\begin{code}
-setIdType :: Id -> Type -> Id
- -- Add free tyvar info to the type
-setIdType id ty = seqType ty `seq` Var.setIdType id (addFreeTyVars ty)
+isId :: Id -> Bool
+isId = isIdVar
-idPrimRep :: Id -> PrimRep
-idPrimRep id = typePrimRep (idType id)
-\end{code}
+-- | 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
+-- | Determines whether an 'Id' is marked as exported and hence will not be considered dead code
+isExportedId :: Id -> Bool
+isExportedId = isExportedIdVar
+\end{code}
%************************************************************************
%* *
%************************************************************************
\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
- RecordSelId tycon lbl _ -> (tycon,lbl)
- other -> panic "recordSelectorFieldLabel"
+recordSelectorFieldLabel id
+ = case globalIdDetails id of
+ RecordSelId { sel_tycon = tycon, sel_label = lbl } -> (tycon,lbl)
+ _ -> panic "recordSelectorFieldLabel"
+
+isRecordSelector :: Id -> Bool
+isNaughtyRecordSelector :: Id -> Bool
+isPrimOpId :: Id -> Bool
+isFCallId :: Id -> Bool
+isDataConWorkId :: Id -> Bool
+
+isClassOpId_maybe :: Id -> Maybe Class
+isPrimOpId_maybe :: Id -> Maybe PrimOp
+isFCallId_maybe :: Id -> Maybe ForeignCall
+isDataConWorkId_maybe :: Id -> Maybe DataCon
isRecordSelector id = case globalIdDetails id of
- RecordSelId {} -> True
- other -> False
+ RecordSelId {} -> True
+ _ -> False
isNaughtyRecordSelector id = case globalIdDetails id of
- RecordSelId { sel_naughty = n } -> n
- other -> False
+ RecordSelId { sel_naughty = n } -> n
+ _ -> False
isClassOpId_maybe id = case globalIdDetails id of
ClassOpId cls -> Just cls
_other -> Nothing
isPrimOpId id = case globalIdDetails id of
- PrimOpId op -> True
- other -> False
+ PrimOpId _ -> True
+ _ -> False
isPrimOpId_maybe id = case globalIdDetails id of
- PrimOpId op -> Just op
- other -> Nothing
+ PrimOpId op -> Just op
+ _ -> Nothing
isFCallId id = case globalIdDetails id of
- FCallId call -> True
- other -> False
+ FCallId _ -> True
+ _ -> False
isFCallId_maybe id = case globalIdDetails id of
- FCallId call -> Just call
- other -> Nothing
+ FCallId call -> Just call
+ _ -> Nothing
isDataConWorkId id = case globalIdDetails id of
- DataConWorkId _ -> True
- other -> False
+ DataConWorkId _ -> True
+ _ -> False
isDataConWorkId_maybe id = case globalIdDetails id of
- DataConWorkId con -> Just con
- other -> Nothing
+ DataConWorkId con -> Just con
+ _ -> Nothing
isDataConId_maybe :: Id -> Maybe DataCon
isDataConId_maybe id = case globalIdDetails id of
- DataConWorkId con -> Just con
- DataConWrapId con -> Just con
- other -> Nothing
+ DataConWorkId con -> Just con
+ DataConWrapId con -> Just con
+ _ -> 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
--- (Remember, dataConWrapId can return either the wrapper or the worker.)
-idDataCon id = case globalIdDetails id of
- DataConWorkId con -> con
- DataConWrapId con -> con
- other -> pprPanic "idDataCon" (ppr id)
+-- ^ Get from either the worker or the wrapper 'Id' to the 'DataCon'. Currently used only in the desugarer.
+--
+-- 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 returns True of an Id which may not have a
--- binding, even though it is defined in this module.
+hasNoBinding :: Id -> Bool
+-- ^ 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.
-- EXCEPT: unboxed tuples, which definitely have no binding
hasNoBinding id = case globalIdDetails id of
- PrimOpId _ -> True
+ PrimOpId _ -> True -- See Note [Primop wrappers]
FCallId _ -> True
DataConWorkId dc -> isUnboxedTupleCon dc
- other -> False
+ _ -> False
isImplicitId :: Id -> Bool
- -- 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' 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
= case globalIdDetails id of
RecordSelId {} -> True
-- remember that all type and class decls appear in the interface file.
-- The dfun id is not an implicit Id; it must *not* be omitted, because
-- it carries version info for the instance decl
- other -> False
+ _ -> False
idIsFrom :: Module -> Id -> Bool
idIsFrom mod id = nameIsLocalOrFrom mod (idName id)
\end{code}
+Note [Primop wrappers]
+~~~~~~~~~~~~~~~~~~~~~~
+Currently hasNoBinding claims that PrimOpIds don't have a curried
+function definition. But actually they do, in GHC.PrimopWrappers,
+which is auto-generated from prelude/primops.txt.pp. So actually, hasNoBinding
+could return 'False' for PrimOpIds.
+
+But we'd need to add something in CoreToStg to swizzle any unsaturated
+applications of GHC.Prim.plusInt# to GHC.PrimopWrappers.plusInt#.
+
+Nota Bene: GHC.PrimopWrappers is needed *regardless*, because it's
+used by GHCi, which does not implement primops direct at all.
+
+
+
\begin{code}
isDeadBinder :: Id -> Bool
isDeadBinder bndr | isId bndr = isDeadOcc (idOccInfo bndr)
| otherwise = False -- TyVars count as not dead
\end{code}
+\begin{code}
+isTickBoxOp :: Id -> Bool
+isTickBoxOp id =
+ case globalIdDetails id of
+ TickBoxOpId _ -> True
+ _ -> False
+
+isTickBoxOp_maybe :: Id -> Maybe TickBoxOp
+isTickBoxOp_maybe id =
+ case globalIdDetails id of
+ TickBoxOpId tick -> Just tick
+ _ -> Nothing
+\end{code}
%************************************************************************
%* *
setIdStrictness id strict_info = modifyIdInfo (`setStrictnessInfo` strict_info) id
#endif
--- isBottomingId returns true if an application to n args would diverge
+-- | Returns true if an application to n args would diverge
isBottomingId :: Id -> Bool
isBottomingId id = isBottomingSig (idNewStrictness id)
zapIdNewStrictness :: Id -> Id
zapIdNewStrictness id = modifyIdInfo (`setNewStrictnessInfo` Nothing) id
- ---------------------------------
- -- WORKER ID
-idWorkerInfo :: Id -> WorkerInfo
-idWorkerInfo id = workerInfo (idInfo id)
-
-setIdWorkerInfo :: Id -> WorkerInfo -> Id
-setIdWorkerInfo id work_info = modifyIdInfo (`setWorkerInfo` work_info) id
+-- | 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 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 )
+ (isStrictDmd (idNewDemandInfo id)) ||
+ (isStrictType (idType id))
---------------------------------
-- UNFOLDING
setIdOccInfo :: Id -> OccInfo -> Id
setIdOccInfo id occ_info = modifyIdInfo (`setOccInfo` occ_info) id
+
+zapIdOccInfo :: Id -> Id
+zapIdOccInfo b = b `setIdOccInfo` NoOccInfo
\end{code}
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
| otherwise
= case splitTyConApp_maybe ty of
Just (tycon,_) -> tycon == statePrimTyCon
- other -> False
+ _ -> False
-- This is a gross hack. It claims that
-- every function over realWorldStatePrimTy is a one-shot
-- function. This is pretty true in practice, and makes a big
-- 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
\end{code}
\begin{code}
+zapInfo :: (IdInfo -> Maybe IdInfo) -> Id -> Id
+zapInfo zapper id = maybeModifyIdInfo (zapper (idInfo id)) id
+
zapLamIdInfo :: Id -> Id
-zapLamIdInfo id = maybeModifyIdInfo (zapLamInfo (idInfo id)) id
+zapLamIdInfo = zapInfo zapLamInfo
+
+zapDemandIdInfo :: Id -> Id
+zapDemandIdInfo = zapInfo zapDemandInfo
-zapDemandIdInfo id = maybeModifyIdInfo (zapDemandInfo (idInfo id)) id
+zapFragileIdInfo :: Id -> Id
+zapFragileIdInfo = zapInfo zapFragileInfo
\end{code}
+Note [transferPolyIdInfo]
+~~~~~~~~~~~~~~~~~~~~~~~~~
+Suppose we have
+
+ f = /\a. let g = rhs in ...
+
+where g has interesting strictness information. Then if we float thus
+
+ g' = /\a. rhs
+ f = /\a. ...[g' a/g]
+
+we *do not* want to lose the strictness information on g. Nor arity.
+
+It's simple to retain strictness and arity, but not so simple to retain
+ worker info
+ rules
+so we simply discard those. Sooner or later this may bite us.
+
+This transfer is used in two places:
+ FloatOut (long-distance let-floating)
+ SimplUtils.abstractFloats (short-distance let-floating)
+
+\begin{code}
+transferPolyIdInfo :: Id -> Id -> Id
+transferPolyIdInfo old_id new_id
+ = modifyIdInfo transfer new_id
+ where
+ old_info = idInfo old_id
+ transfer new_info = new_info `setNewStrictnessInfo` (newStrictnessInfo old_info)
+ `setArityInfo` (arityInfo old_info)
+\end{code}
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