W3cubDocs

/Haskell 8

Data.Void

Copyright (C) 2008-2014 Edward Kmett
License BSD-style (see the file libraries/base/LICENSE)
Maintainer Edward Kmett <[email protected]>
Stability provisional
Portability portable
Safe Haskell Safe
Language Haskell2010

Description

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

Since: base-4.8.0.0

data Void Source

Uninhabited data type

Since: base-4.8.0.0

Instances
Instances details
Eq Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

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

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

Data Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

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

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

toConstr :: Void -> Constr Source

dataTypeOf :: Void -> DataType Source

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

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

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

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

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

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

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

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

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

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

Ord Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

compare :: Void -> Void -> Ordering Source

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

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

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

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

max :: Void -> Void -> Void Source

min :: Void -> Void -> Void Source

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
Instance details

Defined in Data.Void

Methods

readsPrec :: Int -> ReadS Void Source

readList :: ReadS [Void] Source

readPrec :: ReadPrec Void Source

readListPrec :: ReadPrec [Void] Source

Show Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

showsPrec :: Int -> Void -> ShowS Source

show :: Void -> String Source

showList :: [Void] -> ShowS Source

Ix Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

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

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

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

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

rangeSize :: (Void, Void) -> Int Source

unsafeRangeSize :: (Void, Void) -> Int Source

Generic Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Associated Types

type Rep Void :: Type -> Type Source

Methods

from :: Void -> Rep Void x Source

to :: Rep Void x -> Void Source

Semigroup Void

Since: base-4.9.0.0
Instance details

Defined in Data.Void

Methods

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

sconcat :: NonEmpty Void -> Void Source

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

Exception Void

Since: base-4.8.0.0
Instance details

Defined in Data.Void

Methods

toException :: Void -> SomeException Source

fromException :: SomeException -> Maybe Void Source

displayException :: Void -> String Source

type Rep Void
Instance details

Defined in Data.Void

type Rep Void = D1 ('MetaData "Void" "Data.Void" "base" 'False) (V1 :: Type -> Type)

absurd :: Void -> a Source

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 Source

If Void is uninhabited then any Functor that holds only values of type Void is holding no values.

Since: base-4.8.0.0

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.8.3/docs/html/libraries/base-4.13.0.0/Data-Void.html