Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
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 :: *

Constructors

False

True

Instances

Bounded Bool Source

Methods

minBound :: Bool Source

maxBound :: Bool Source

Enum Bool Source

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

Eq Bool

Methods

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

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

Data Bool Source

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 :: (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

Ord Bool

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 Source

Methods

readsPrec :: Int -> ReadS Bool Source

readList :: ReadS [Bool] Source

readPrec :: ReadPrec Bool Source

readListPrec :: ReadPrec [Bool] Source

Show Bool Source

Methods

showsPrec :: Int -> Bool -> ShowS Source

show :: Bool -> String Source

showList :: [Bool] -> ShowS Source

Ix Bool Source

Methods

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

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

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

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

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

unsafeRangeSize :: (Bool, Bool) -> Int

Generic Bool Source

Associated Types

type Rep Bool :: * -> * Source

Methods

from :: Bool -> Rep Bool x Source

to :: Rep Bool x -> Bool Source

FiniteBits Bool Source

Methods

finiteBitSize :: Bool -> Int Source

countLeadingZeros :: Bool -> Int Source

countTrailingZeros :: Bool -> Int Source

Bits Bool Source

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

Storable Bool Source

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

type Rep Bool

type (==) Bool a b Source

Operations

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

Boolean "and"

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

Boolean "or"

not :: Bool -> Bool

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

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