Copyright	(C) 2008-2014 Edward Kmett
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	provisional
Portability	portable
Safe Haskell	Safe
Language	Haskell2010

Data.Void

Description

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

Since: 4.8.0.0

Synopsis

dataVoid
absurd ::Void -> a
vacuous ::Functor f => fVoid -> f a

Documentation

dataVoid Source #

Uninhabited data type

Since: 4.8.0.0

Instances

Eq VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void Methods (==) ::Void ->Void ->Bool # (/=) ::Void ->Void ->Bool #
Data VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void Methods gfoldl :: (forall d b.Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) ->Void -> cVoid Source # gunfold :: (forall b r.Data b => c (b -> r) -> c r) -> (forall r. r -> c r) ->Constr -> cVoid Source # toConstr ::Void ->Constr Source # dataTypeOf ::Void ->DataType Source # dataCast1 ::Typeable t => (forall d.Data d => c (t d)) ->Maybe (cVoid)Source # dataCast2 ::Typeable t => (forall d e. (Data d,Data e) => c (t d e)) ->Maybe (cVoid)Source # gmapT :: (forall b.Data b => b -> b) ->Void ->Void Source # gmapQl :: (r -> r' -> r) -> r -> (forall d.Data d => d -> r') ->Void -> rSource # gmapQr :: (r' -> r -> r) -> r -> (forall d.Data d => d -> r') ->Void -> rSource # gmapQ :: (forall d.Data d => d -> u) ->Void -> [u]Source # gmapQi ::Int -> (forall d.Data d => d -> u) ->Void -> uSource # gmapM ::Monad m => (forall d.Data d => d -> m d) ->Void -> mVoid Source # gmapMp ::MonadPlus m => (forall d.Data d => d -> m d) ->Void -> mVoid Source # gmapMo ::MonadPlus m => (forall d.Data d => d -> m d) ->Void -> mVoid Source #
Ord VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void 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 #
Read VoidSource #	Reading a`Void` value is always a parse error, considering`Void` as a data type with no constructors. Since: 4.8.0.0
Instance details Defined inData.Void Methods readsPrec ::Int ->ReadS Void Source # readList ::ReadS [Void]Source # readPrec ::ReadPrec Void Source # readListPrec ::ReadPrec [Void]Source #
Show VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void Methods showsPrec ::Int ->Void ->ShowS Source # show ::Void ->String Source # showList :: [Void] ->ShowS Source #
Ix VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void Methods range :: (Void,Void) -> [Void]Source # index :: (Void,Void) ->Void ->Int Source # unsafeIndex :: (Void,Void) ->Void ->Int inRange :: (Void,Void) ->Void ->Bool Source # rangeSize :: (Void,Void) ->Int Source # unsafeRangeSize :: (Void,Void) ->Int
Generic VoidSource #
Instance details Defined inData.Void Associated Types typeRep Void ::Type ->Type Source # Methods from ::Void ->Rep Void xSource # to ::Rep Void x ->Void Source #
Semigroup VoidSource #	Since: 4.9.0.0
Instance details Defined inData.Void Methods (<>) ::Void ->Void ->Void Source # sconcat ::NonEmpty Void ->Void Source # stimes ::Integral b => b ->Void ->Void Source #
Exception VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void Methods toException ::Void ->SomeException Source # fromException ::SomeException ->Maybe Void Source # displayException ::Void ->String Source #
typeRep VoidSource #	Since: 4.8.0.0
Instance details Defined inData.Void typeRep Void =D1 (MetaData "Void" "Data.Void" "base"False) (V1 ::Type ->Type)

absurd ::Void -> aSource #

SinceVoid 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: 4.8.0.0

vacuous ::Functor f => fVoid -> f aSource #

IfVoid is uninhabited then anyFunctor that holds only values of typeVoid is holding no values.

Since: 4.8.0.0

Movatterモバイル変換

Documentation