base-4.18.1.0: Basic libraries

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 :: Type -> Type Source # 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