Data.Void

A logically uninhabited data type, used to indicate that a given term should not exist.

Since: base-4.8.0.0

Documentation

data Void

Uninhabited data type

Since: base-4.8.0.0

Instances

Semigroup Void

Since: base-4.9.0.0

Defined in GHC.Internal.Base

Methods

(<>) :: Void -> Void -> Void

sconcat :: NonEmpty Void -> Void

stimes :: Integral b => b -> Void -> Void

Data Void

Since: base-4.8.0.0

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Void -> c Void

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Void

toConstr :: Void -> Constr

dataTypeOf :: Void -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Void)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Void)

gmapT :: (forall b. Data b => b -> b) -> Void -> Void

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Void -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Void -> r

gmapQ :: (forall d. Data d => d -> u) -> Void -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Void -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Void -> m Void

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Void -> m Void

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Void -> m Void

Exception Void

Since: base-4.8.0.0

Defined in GHC.Internal.Exception.Type

Methods

toException :: Void -> SomeException

fromException :: SomeException -> Maybe Void

displayException :: Void -> String

backtraceDesired :: Void -> Bool

Generic Void

Defined in GHC.Internal.Generics

Associated Types

type Rep Void

Since: base-4.8.0.0

Defined in GHC.Internal.Generics

type Rep Void = D1 ('MetaData "Void" "GHC.Internal.Base" "ghc-internal" 'False) (V1 :: Type -> Type)

Methods

from :: Void -> Rep Void x

to :: Rep Void x -> Void

Ix Void

Since: base-4.8.0.0

Defined in GHC.Internal.Ix

Methods

range :: (Void, Void) -> [Void]

index :: (Void, Void) -> Void -> Int

unsafeIndex :: (Void, Void) -> Void -> Int

inRange :: (Void, Void) -> Void -> Bool

rangeSize :: (Void, Void) -> Int

unsafeRangeSize :: (Void, Void) -> Int

Read Void

Reading a Void value is always a parse error, considering Void as a data type with no constructors.

Since: base-4.8.0.0

Defined in GHC.Internal.Read

Methods

readsPrec :: Int -> ReadS Void

readList :: ReadS [Void]

readPrec :: ReadPrec Void

readListPrec :: ReadPrec [Void]

Show Void

Since: base-4.8.0.0

Defined in GHC.Internal.Show

Methods

showsPrec :: Int -> Void -> ShowS

show :: Void -> String

showList :: [Void] -> ShowS

Eq Void

Since: base-4.8.0.0

Defined in GHC.Internal.Base

Methods

(==) :: Void -> Void -> Bool

(/=) :: Void -> Void -> Bool

Ord Void

Since: base-4.8.0.0

Defined in GHC.Internal.Base

Methods

compare :: Void -> Void -> Ordering

(<) :: Void -> Void -> Bool

(<=) :: Void -> Void -> Bool

(>) :: Void -> Void -> Bool

(>=) :: Void -> Void -> Bool

max :: Void -> Void -> Void

min :: Void -> Void -> Void

type Rep Void

Since: base-4.8.0.0

Defined in GHC.Internal.Generics

type Rep Void = D1 ('MetaData "Void" "GHC.Internal.Base" "ghc-internal" 'False) (V1 :: Type -> Type)

absurd :: Void -> a

Since Void values logically don't exist, this witnesses the logical reasoning tool of "ex falso quodlibet".

>>> let x :: Either Void Int; x = Right 5
>>> :{
case x of
    Right r -> r
    Left l  -> absurd l
:}
5

Since: base-4.8.0.0

vacuous :: Functor f => f Void -> f a

If Void is uninhabited then any Functor that holds only values of type Void is holding no values. It is implemented in terms of fmap absurd.

Since: base-4.8.0.0