ghc-7.0.3: The GHC API

Id

Contents

- The main types
  - Simple construction
  - Taking an Id apart
  - Modifying an Id
  - Predicates on Ids
  - Inline pragma stuff
  - One-shot lambdas
  - Reading `IdInfo` fields
  - Writing `IdInfo` fields

Description

GHC uses several kinds of name internally:

- `OccName.OccName`: see OccName
- `RdrName.RdrName`: see RdrName
- `Name`: see Name
- `Id.Id` represents names that not only have a `Name` but also a `TypeRep.Type` and some additional details (a `IdInfo` and one of `Var.LocalIdDetails` or `IdInfo.GlobalIdDetails`) that are added, modified and inspected by various compiler passes. These `Var` names may either be global or local, see Var
- `Var`: see Var

Synopsis

- type Id = Var
- type DictId = EvId
- mkGlobalId :: IdDetails -> Name -> Type -> IdInfo -> Id
- mkVanillaGlobal :: Name -> Type -> Id
- mkVanillaGlobalWithInfo :: Name -> Type -> IdInfo -> Id
- mkLocalId :: Name -> Type -> Id
- mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id
- mkExportedLocalId :: Name -> Type -> Id
- mkSysLocal :: FastString -> Unique -> Type -> Id
- mkSysLocalM :: MonadUnique m => FastString -> Type -> m Id
- mkUserLocal :: OccName -> Unique -> Type -> SrcSpan -> Id
- mkUserLocalM :: MonadUnique m => OccName -> Type -> SrcSpan -> m Id
- mkTemplateLocals :: [Type] -> [Id]
- mkTemplateLocalsNum :: Int -> [Type] -> [Id]
- mkTemplateLocal :: Int -> Type -> Id
- mkWorkerId :: Unique -> Id -> Type -> Id
- mkWiredInIdName :: Module -> FastString -> Unique -> Id -> Name
- idName :: Id -> Name
- idType :: Id -> Kind
- idUnique :: Id -> Unique
- idInfo :: Id -> IdInfo
- idDetails :: Id -> IdDetails
- isId :: Var -> Bool
- idPrimRep :: Id -> PrimRep
- recordSelectorFieldLabel :: Id -> (TyCon, FieldLabel)
- setIdName :: Id -> Name -> Id
- setIdUnique :: Id -> Unique -> Id
- setIdType :: Id -> Type -> Id
- setIdExported :: Id -> Id
- setIdNotExported :: Id -> Id
- globaliseId :: Id -> Id
- localiseId :: Id -> Id
- setIdInfo :: Id -> IdInfo -> Id
- lazySetIdInfo :: Id -> IdInfo -> Id
- modifyIdInfo :: (IdInfo -> IdInfo) -> Id -> Id
- maybeModifyIdInfo :: Maybe IdInfo -> Id -> Id
- zapLamIdInfo :: Id -> Id
- zapDemandIdInfo :: Id -> Id
- zapFragileIdInfo :: Id -> Id
- transferPolyIdInfo :: Id -> [Var] -> Id -> Id
- isImplicitId :: Id -> Bool
- isDeadBinder :: Id -> Bool
- isDictId :: Id -> Bool
- isStrictId :: Id -> Bool
- isExportedId :: Var -> Bool
- isLocalId :: Var -> Bool
- isGlobalId :: Var -> Bool
- isRecordSelector :: Id -> Bool
- isNaughtyRecordSelector :: Id -> Bool
- isClassOpId_maybe :: Id -> Maybe Class
- isDFunId :: Id -> Bool
- dfunNSilent :: Id -> Int
- isPrimOpId :: Id -> Bool
- isPrimOpId_maybe :: Id -> Maybe PrimOp
- isFCallId :: Id -> Bool
- isFCallId_maybe :: Id -> Maybe ForeignCall
- isDataConWorkId :: Id -> Bool
- isDataConWorkId_maybe :: Id -> Maybe DataCon
- isDataConId_maybe :: Id -> Maybe DataCon
- idDataCon :: Id -> DataCon
- isConLikeId :: Id -> Bool
- isBottomingId :: Id -> Bool
- idIsFrom :: Module -> Id -> Bool
- isTickBoxOp :: Id -> Bool
- isTickBoxOp_maybe :: Id -> Maybe TickBoxOp
- hasNoBinding :: Id -> Bool
- idInlinePragma :: Id -> InlinePragma
- setInlinePragma :: Id -> InlinePragma -> Id
- modifyInlinePragma :: Id -> (InlinePragma -> InlinePragma) -> Id
- idInlineActivation :: Id -> Activation
- setInlineActivation :: Id -> Activation -> Id
- idRuleMatchInfo :: Id -> RuleMatchInfo
- isOneShotBndr :: Id -> Bool
- isOneShotLambda :: Id -> Bool
- isStateHackType :: Type -> Bool
- setOneShotLambda :: Id -> Id
- clearOneShotLambda :: Id -> Id
- idArity :: Id -> Arity
- idDemandInfo :: Id -> Demand
- idDemandInfo_maybe :: Id -> Maybe Demand
- idStrictness :: Id -> StrictSig
- idStrictness_maybe :: Id -> Maybe StrictSig
- idUnfolding :: Id -> Unfolding
- realIdUnfolding :: Id -> Unfolding
- idSpecialisation :: Id -> SpecInfo
- idCoreRules :: Id -> [CoreRule]
- idHasRules :: Id -> Bool
- idCafInfo :: Id -> CafInfo
- idLBVarInfo :: Id -> LBVarInfo
- idOccInfo :: Id -> OccInfo
- setIdUnfoldingLazily :: Id -> Unfolding -> Id
- setIdUnfolding :: Id -> Unfolding -> Id
- setIdArity :: Id -> Arity -> Id
- setIdDemandInfo :: Id -> Demand -> Id
- setIdStrictness :: Id -> StrictSig -> Id
- zapIdStrictness :: Id -> Id
- setIdSpecialisation :: Id -> SpecInfo -> Id
- setIdCafInfo :: Id -> CafInfo -> Id
- setIdOccInfo :: Id -> OccInfo -> Id
- zapIdOccInfo :: Id -> Id

# The main types

type Id = Var

type DictId = EvId

## Simple construction

mkGlobalId :: IdDetails -> Name -> Type -> IdInfo -> Id

For an explanation of global vs. local `Id`s, see Var

mkVanillaGlobal :: Name -> Type -> Id

Make a global `Id` without any extra information at all

mkVanillaGlobalWithInfo :: Name -> Type -> IdInfo -> Id

Make a global `Id` with no global information but some generic `IdInfo`

mkLocalId :: Name -> Type -> Id

For an explanation of global vs. local `Id`s, see Var

mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id

mkExportedLocalId :: Name -> Type -> Id

Create a local `Id` that is marked as exported. This prevents things attached to it from being removed as dead code.

mkSysLocal :: FastString -> Unique -> Type -> Id

Create a system local `Id`. These are local `Id`s (see Var) that are created by the compiler out of thin air

mkSysLocalM :: MonadUnique m => FastString -> Type -> m Id

mkUserLocal :: OccName -> Unique -> Type -> SrcSpan -> Id

Create a user local `Id`. These are local `Id`s (see Var) with a name and location that the user might recognize

mkUserLocalM :: MonadUnique m => OccName -> Type -> SrcSpan -> m Id

mkTemplateLocals :: [Type] -> [Id]

Create a template local for a series of types

mkTemplateLocalsNum :: Int -> [Type] -> [Id]

Create a template local for a series of type, but start from a specified template local

mkTemplateLocal :: Int -> Type -> Id

Create a template local: a family of system local `Id`s in bijection with `Int`s, typically used in unfoldings

mkWorkerId :: Unique -> Id -> Type -> Id

Workers get local names. CoreTidy will externalise these if necessary

mkWiredInIdName :: Module -> FastString -> Unique -> Id -> Name

## Taking an Id apart

idName :: Id -> Name

idType :: Id -> Kind

idUnique :: Id -> Unique

idInfo :: Id -> IdInfo

idDetails :: Id -> IdDetails

isId :: Var -> Bool

idPrimRep :: Id -> PrimRep

recordSelectorFieldLabel :: Id -> (TyCon, FieldLabel)

If the `Id` is that for a record selector, extract the `sel_tycon` and label. Panic otherwise

## Modifying an Id

setIdName :: Id -> Name -> Id

setIdUnique :: Id -> Unique -> Id

setIdType :: Id -> Type -> Id

Not only does this set the `Id` `Type`, it also evaluates the type to try and reduce space usage

setIdExported :: Id -> Id

setIdNotExported :: Id -> Id

globaliseId :: Id -> Id

If it's a local, make it global

localiseId :: Id -> Id

setIdInfo :: Id -> IdInfo -> Id

lazySetIdInfo :: Id -> IdInfo -> Id

modifyIdInfo :: (IdInfo -> IdInfo) -> Id -> Id

maybeModifyIdInfo :: Maybe IdInfo -> Id -> Id

zapLamIdInfo :: Id -> Id

zapDemandIdInfo :: Id -> Id

zapFragileIdInfo :: Id -> Id

transferPolyIdInfo :: Id -> [Var] -> Id -> Id

## Predicates on Ids

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.

isDeadBinder :: Id -> Bool

isDictId :: Id -> Bool

isStrictId :: Id -> Bool

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`.

isExportedId :: Var -> Bool

`isExportedIdVar` means "don't throw this away"

isLocalId :: Var -> Bool

isGlobalId :: Var -> Bool

isRecordSelector :: Id -> Bool

isNaughtyRecordSelector :: Id -> Bool

isClassOpId_maybe :: Id -> Maybe Class

isDFunId :: Id -> Bool

dfunNSilent :: Id -> Int

isPrimOpId :: Id -> Bool

isPrimOpId_maybe :: Id -> Maybe PrimOp

isFCallId :: Id -> Bool

isFCallId_maybe :: Id -> Maybe ForeignCall

isDataConWorkId :: Id -> Bool

isDataConWorkId_maybe :: Id -> Maybe DataCon

isDataConId_maybe :: Id -> Maybe DataCon

idDataCon :: Id -> DataCon

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

isConLikeId :: Id -> Bool

isBottomingId :: Id -> Bool

Returns true if an application to n args would diverge

idIsFrom :: Module -> Id -> Bool

isTickBoxOp :: Id -> Bool

isTickBoxOp_maybe :: Id -> Maybe TickBoxOp

hasNoBinding :: Id -> Bool

Returns `True` of an `Id` which may not have a binding, even though it is defined in this module.

## Inline pragma stuff

idInlinePragma :: Id -> InlinePragma

setInlinePragma :: Id -> InlinePragma -> Id

modifyInlinePragma :: Id -> (InlinePragma -> InlinePragma) -> Id

idInlineActivation :: Id -> Activation

setInlineActivation :: Id -> Activation -> Id

idRuleMatchInfo :: Id -> RuleMatchInfo

## One-shot lambdas

isOneShotBndr :: Id -> Bool

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`

isOneShotLambda :: Id -> Bool

Returns whether the lambda associated with the `Id` is certainly applied at most once. You probably want to use `isOneShotBndr` instead

isStateHackType :: Type -> Bool

Should we apply the state hack to values of this `Type`?

setOneShotLambda :: Id -> Id

clearOneShotLambda :: Id -> Id

## Reading `IdInfo` fields

idArity :: Id -> Arity

idDemandInfo :: Id -> Demand

idDemandInfo_maybe :: Id -> Maybe Demand

idStrictness :: Id -> StrictSig

idStrictness_maybe :: Id -> Maybe StrictSig

idUnfolding :: Id -> Unfolding

realIdUnfolding :: Id -> Unfolding

idSpecialisation :: Id -> SpecInfo

idCoreRules :: Id -> [CoreRule]

idHasRules :: Id -> Bool

idCafInfo :: Id -> CafInfo

idLBVarInfo :: Id -> LBVarInfo

idOccInfo :: Id -> OccInfo

## Writing `IdInfo` fields

setIdUnfoldingLazily :: Id -> Unfolding -> Id

setIdUnfolding :: Id -> Unfolding -> Id

setIdArity :: Id -> Arity -> Id

setIdDemandInfo :: Id -> Demand -> Id

setIdStrictness :: Id -> StrictSig -> Id

zapIdStrictness :: Id -> Id

setIdSpecialisation :: Id -> SpecInfo -> Id

setIdCafInfo :: Id -> CafInfo -> Id

setIdOccInfo :: Id -> OccInfo -> Id

zapIdOccInfo :: Id -> Id