Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	stable
Portability	portable
Safe Haskell	Trustworthy
Language	Haskell2010

Data.Bool

Contents

Booleans
- Operations

Description

The Bool type and related functions.

Synopsis

data Bool
- = False
- | True
(&&) :: Bool -> Bool -> Bool
(||) :: Bool -> Bool -> Bool
not :: Bool -> Bool
otherwise :: Bool
bool :: a -> a -> Bool -> a

Booleans

data Bool Source #

Constructors

False
True

Instances

Instances details

Data Bool Source #

Since: base-4.0.0.0

Instance details

Defined in Data.Data

Methods

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

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

toConstr :: Bool -> Constr Source #

dataTypeOf :: Bool -> DataType Source #

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

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

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

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

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

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

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

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

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

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

Storable Bool Source #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Methods

sizeOf :: Bool -> Int Source #

alignment :: Bool -> Int Source #

peekElemOff :: Ptr Bool -> Int -> IO Bool Source #

pokeElemOff :: Ptr Bool -> Int -> Bool -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO Bool Source #

pokeByteOff :: Ptr b -> Int -> Bool -> IO () Source #

peek :: Ptr Bool -> IO Bool Source #

poke :: Ptr Bool -> Bool -> IO () Source #

Bits Bool Source #

Interpret Bool as 1-bit bit-field

Since: base-4.7.0.0

Instance details

Defined in GHC.Bits

Methods

(.&.) :: Bool -> Bool -> Bool Source #

(.|.) :: Bool -> Bool -> Bool Source #

xor :: Bool -> Bool -> Bool Source #

complement :: Bool -> Bool Source #

shift :: Bool -> Int -> Bool Source #

rotate :: Bool -> Int -> Bool Source #

zeroBits :: Bool Source #

bit :: Int -> Bool Source #

setBit :: Bool -> Int -> Bool Source #

clearBit :: Bool -> Int -> Bool Source #

complementBit :: Bool -> Int -> Bool Source #

testBit :: Bool -> Int -> Bool Source #

bitSizeMaybe :: Bool -> Maybe Int Source #

bitSize :: Bool -> Int Source #

isSigned :: Bool -> Bool Source #

shiftL :: Bool -> Int -> Bool Source #

unsafeShiftL :: Bool -> Int -> Bool Source #

shiftR :: Bool -> Int -> Bool Source #

unsafeShiftR :: Bool -> Int -> Bool Source #

rotateL :: Bool -> Int -> Bool Source #

rotateR :: Bool -> Int -> Bool Source #

popCount :: Bool -> Int Source #

FiniteBits Bool Source #

Since: base-4.7.0.0

Instance details

Defined in GHC.Bits

Methods

finiteBitSize :: Bool -> Int Source #

countLeadingZeros :: Bool -> Int Source #

countTrailingZeros :: Bool -> Int Source #

Bounded Bool Source #

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

minBound :: Bool Source #

maxBound :: Bool Source #

Enum Bool Source #

Since: base-2.1

Instance details

Defined in GHC.Enum

Methods

succ :: Bool -> Bool Source #

pred :: Bool -> Bool Source #

toEnum :: Int -> Bool Source #

fromEnum :: Bool -> Int Source #

enumFrom :: Bool -> [Bool] Source #

enumFromThen :: Bool -> Bool -> [Bool] Source #

enumFromTo :: Bool -> Bool -> [Bool] Source #

enumFromThenTo :: Bool -> Bool -> Bool -> [Bool] Source #

Generic Bool Source #

Instance details

Defined in GHC.Generics

Associated Types

type Rep Bool	Since: base-4.6.0.0
Instance details Defined in GHC.Generics type Rep Bool = D1 ('MetaData "Bool" "GHC.Types" "ghc-prim" 'False) (C1 ('MetaCons "False" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "True" 'PrefixI 'False) (U1 :: Type -> Type))

Methods

from :: Bool -> Rep Bool x Source #

to :: Rep Bool x -> Bool Source #

Ix Bool Source #

Since: base-2.1

Instance details

Defined in GHC.Ix

Methods

range :: (Bool, Bool) -> [Bool] Source #

index :: (Bool, Bool) -> Bool -> Int Source #

unsafeIndex :: (Bool, Bool) -> Bool -> Int Source #

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

rangeSize :: (Bool, Bool) -> Int Source #

unsafeRangeSize :: (Bool, Bool) -> Int Source #

Read Bool Source #

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS Bool Source #

readList :: ReadS [Bool] Source #

readPrec :: ReadPrec Bool Source #

readListPrec :: ReadPrec [Bool] Source #

Show Bool Source #

Since: base-2.1

Instance details

Defined in GHC.Show

Methods

showsPrec :: Int -> Bool -> ShowS Source #

show :: Bool -> String Source #

showList :: [Bool] -> ShowS Source #

Eq Bool

Instance details

Defined in GHC.Classes

Methods

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

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

Ord Bool

Instance details

Defined in GHC.Classes

Methods

compare :: Bool -> Bool -> Ordering Source #

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

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

(>) :: Bool -> Bool -> Bool Source #

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

max :: Bool -> Bool -> Bool Source #

min :: Bool -> Bool -> Bool Source #

type Rep Bool Source #

Since: base-4.6.0.0

Instance details

Defined in GHC.Generics

type Rep Bool = D1 ('MetaData "Bool" "GHC.Types" "ghc-prim" 'False) (C1 ('MetaCons "False" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "True" 'PrefixI 'False) (U1 :: Type -> Type))

Operations

(&&) :: Bool -> Bool -> Bool infixr 3 Source #

Boolean "and", lazy in the second argument

(||) :: Bool -> Bool -> Bool infixr 2 Source #

Boolean "or", lazy in the second argument

not :: Bool -> Bool Source #

Boolean "not"

otherwise :: Bool Source #

otherwise is defined as the value True. It helps to make guards more readable. eg.

 f x | x < 0     = ...
     | otherwise = ...

bool :: a -> a -> Bool -> a Source #

Case analysis for the Bool type. bool x y p evaluates to x when p is False, and evaluates to y when p is True.

This is equivalent to if p then y else x; that is, one can think of it as an if-then-else construct with its arguments reordered.

Examples

Expand

Basic usage:

>>> bool "foo" "bar" True
"bar"
>>> bool "foo" "bar" False
"foo"

Confirm that bool x y p and if p then y else x are equivalent:

>>> let p = True; x = "bar"; y = "foo"
>>> bool x y p == if p then y else x
True
>>> let p = False
>>> bool x y p == if p then y else x
True

Since: base-4.7.0.0