ghc-7.4.2: The GHC API

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Var

Contents

- The main data type and synonyms
  - Taking `Var`s apart
  - Modifying `Var`s
  - Constructing, taking apart, modifying `Id`s
  - Predicates
  - Constructing `TyVar`s
  - Taking `TyVar`s apart
  - Modifying `TyVar`s

Description

GHC uses several kinds of name internally:

- `OccName`: see OccName
- `RdrName`: see RdrName
- `Name`: see Name
- `Id`: see Id
- `Var` is a synonym for the `Id` type but it may additionally potentially contain type variables, which have a `Kind` rather than a `Type` and only contain some extra details during typechecking.

These `Var` names may either be global or local, see Var

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.

Synopsis

- data Var
- type TyVar = Var
- type CoVar = Id
- type Id = Var
- type KindVar = Var
- type DictId = EvId
- type DFunId = Id
- type EvVar = EvId
- type EqVar = EvId
- type EvId = Id
- type IpId = EvId
- varName :: Var -> Name
- varUnique :: Var -> Unique
- varType :: Var -> Kind
- setVarName :: Var -> Name -> Var
- setVarUnique :: Var -> Unique -> Var
- setVarType :: Id -> Type -> Id
- mkGlobalVar :: IdDetails -> Name -> Type -> IdInfo -> Id
- mkLocalVar :: IdDetails -> Name -> Type -> IdInfo -> Id
- mkExportedLocalVar :: IdDetails -> Name -> Type -> IdInfo -> Id
- mkCoVar :: Name -> Type -> CoVar
- idInfo :: Id -> IdInfo
- idDetails :: Id -> IdDetails
- lazySetIdInfo :: Id -> IdInfo -> Var
- setIdDetails :: Id -> IdDetails -> Id
- globaliseId :: Id -> Id
- setIdExported :: Id -> Id
- setIdNotExported :: Id -> Id
- isId :: Var -> Bool
- isTyVar :: Var -> Bool
- isTcTyVar :: Var -> Bool
- isLocalVar :: Var -> Bool
- isLocalId :: Var -> Bool
- isGlobalId :: Var -> Bool
- isExportedId :: Var -> Bool
- mustHaveLocalBinding :: Var -> Bool
- mkTyVar :: Name -> Kind -> TyVar
- mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar
- mkKindVar :: Name -> SuperKind -> KindVar
- tyVarName :: TyVar -> Name
- tyVarKind :: TyVar -> Kind
- tcTyVarDetails :: TyVar -> TcTyVarDetails
- setTcTyVarDetails :: TyVar -> TcTyVarDetails -> TyVar
- setTyVarName :: TyVar -> Name -> TyVar
- setTyVarUnique :: TyVar -> Unique -> TyVar
- setTyVarKind :: TyVar -> Kind -> TyVar
- updateTyVarKind :: (Kind -> Kind) -> TyVar -> TyVar
- updateTyVarKindM :: Monad m => (Kind -> m Kind) -> TyVar -> m TyVar

# The main data type and synonyms

data Var

Essentially a typed `Name`, that may also contain some additional information about the `Var` and it's use sites.

Instances

Eq Var |
Data Var |
Ord Var |
Show Var |
Typeable Var |
OutputableBndr Var |
Outputable Var |
Uniquable Var |
NamedThing Var |

type TyVar = Var

type CoVar = Id

type Id = Var

type KindVar = Var

type DictId = EvId

type DFunId = Id

type EvVar = EvId

type EqVar = EvId

type EvId = Id

type IpId = EvId

## Taking `Var`s apart

varName :: Var -> Name

varUnique :: Var -> Unique

varType :: Var -> Kind

The type or kind of the `Var` in question

## Modifying `Var`s

setVarName :: Var -> Name -> Var

setVarUnique :: Var -> Unique -> Var

setVarType :: Id -> Type -> Id

## Constructing, taking apart, modifying `Id`s

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

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

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

Exported `Var`s will not be removed as dead code

mkCoVar :: Name -> Type -> CoVar

idInfo :: Id -> IdInfo

idDetails :: Id -> IdDetails

lazySetIdInfo :: Id -> IdInfo -> Var

setIdDetails :: Id -> IdDetails -> Id

globaliseId :: Id -> Id

If it's a local, make it global

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

setIdNotExported :: Id -> Id

We can only do this to LocalIds

## Predicates

isId :: Var -> Bool

isTyVar :: Var -> Bool

isTcTyVar :: Var -> Bool

isLocalVar :: Var -> Bool

`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.

isLocalId :: Var -> Bool

isGlobalId :: Var -> Bool

isExportedId :: Var -> Bool

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

mustHaveLocalBinding :: Var -> Bool

`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

## Constructing `TyVar`s

mkTyVar :: Name -> Kind -> TyVar

mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar

mkKindVar :: Name -> SuperKind -> KindVar

## Taking `TyVar`s apart

tyVarName :: TyVar -> Name

tyVarKind :: TyVar -> Kind

tcTyVarDetails :: TyVar -> TcTyVarDetails

setTcTyVarDetails :: TyVar -> TcTyVarDetails -> TyVar

## Modifying `TyVar`s

setTyVarName :: TyVar -> Name -> TyVar

setTyVarUnique :: TyVar -> Unique -> TyVar

setTyVarKind :: TyVar -> Kind -> TyVar

updateTyVarKind :: (Kind -> Kind) -> TyVar -> TyVar

updateTyVarKindM :: Monad m => (Kind -> m Kind) -> TyVar -> m TyVar