Data.Bool

The Bool type and related functions.

Booleans

data Bool

Constructors

False

True

Instances

Bounded Bool

Since: 2.1

Defined in GHC.Enum

Methods

minBound :: Bool

maxBound :: Bool

Enum Bool

Since: 2.1

Defined in GHC.Enum

Methods

succ :: Bool -> Bool

pred :: Bool -> Bool

toEnum :: Int -> Bool

fromEnum :: Bool -> Int

enumFrom :: Bool -> [Bool]

enumFromThen :: Bool -> Bool -> [Bool]

enumFromTo :: Bool -> Bool -> [Bool]

enumFromThenTo :: Bool -> Bool -> Bool -> [Bool]

Eq Bool

Defined in GHC.Classes

Methods

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

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

Data Bool

Since: 4.0.0.0

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

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

toConstr :: Bool -> Constr

dataTypeOf :: Bool -> DataType

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

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

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

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

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

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

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

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

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

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

Ord Bool

Defined in GHC.Classes

Methods

compare :: Bool -> Bool -> Ordering

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

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

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

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

max :: Bool -> Bool -> Bool

min :: Bool -> Bool -> Bool

Read Bool

Since: 2.1

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS Bool

readList :: ReadS [Bool]

readPrec :: ReadPrec Bool

readListPrec :: ReadPrec [Bool]

Show Bool

Since: 2.1

Defined in GHC.Show

Methods

showsPrec :: Int -> Bool -> ShowS

show :: Bool -> String

showList :: [Bool] -> ShowS

Ix Bool

Since: 2.1

Defined in GHC.Ix

Methods

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

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

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

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

rangeSize :: (Bool, Bool) -> Int

unsafeRangeSize :: (Bool, Bool) -> Int

Generic Bool

Since: 4.6.0.0

Defined in GHC.Generics

Associated Types

type Rep Bool :: Type -> Type

Methods

from :: Bool -> Rep Bool x

to :: Rep Bool x -> Bool

FiniteBits Bool

Since: 4.7.0.0

Defined in Data.Bits

Methods

finiteBitSize :: Bool -> Int

countLeadingZeros :: Bool -> Int

countTrailingZeros :: Bool -> Int

Bits Bool

Interpret Bool as 1-bit bit-field

Since: 4.7.0.0

Defined in Data.Bits

Methods

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

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

xor :: Bool -> Bool -> Bool

complement :: Bool -> Bool

shift :: Bool -> Int -> Bool

rotate :: Bool -> Int -> Bool

zeroBits :: Bool

bit :: Int -> Bool

setBit :: Bool -> Int -> Bool

clearBit :: Bool -> Int -> Bool

complementBit :: Bool -> Int -> Bool

testBit :: Bool -> Int -> Bool

bitSizeMaybe :: Bool -> Maybe Int

bitSize :: Bool -> Int

isSigned :: Bool -> Bool

shiftL :: Bool -> Int -> Bool

unsafeShiftL :: Bool -> Int -> Bool

shiftR :: Bool -> Int -> Bool

unsafeShiftR :: Bool -> Int -> Bool

rotateL :: Bool -> Int -> Bool

rotateR :: Bool -> Int -> Bool

popCount :: Bool -> Int

Storable Bool

Since: 2.1

Defined in Foreign.Storable

Methods

sizeOf :: Bool -> Int

alignment :: Bool -> Int

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

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

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

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

peek :: Ptr Bool -> IO Bool

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

type Rep Bool

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

Boolean "and", lazy in the second argument

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

Boolean "or", lazy in the second argument

not :: Bool -> Bool

Boolean "not"

otherwise :: Bool

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

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

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: 4.7.0.0