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 | Safe |
Language | Haskell2010 |
The Bool
type and related functions.
Booleans
Instances
Bits Bool | Interpret @since base-4.7.0.0 | ||||
Defined in GHC.Internal.Bits (.&.) :: 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 # 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 # | |||||
FiniteBits Bool | @since base-4.7.0.0 | ||||
Defined in GHC.Internal.Bits finiteBitSize :: Bool -> Int Source # countLeadingZeros :: Bool -> Int Source # countTrailingZeros :: Bool -> Int Source # | |||||
Data Bool | @since base-4.0.0.0 | ||||
Defined in GHC.Internal.Data.Data 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 # | |||||
Bounded Bool | @since base-2.01 | ||||
Enum Bool | @since base-2.01 | ||||
Storable Bool | @since base-2.01 | ||||
Defined in GHC.Internal.Foreign.Storable 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 # | |||||
Generic Bool | |||||
Defined in GHC.Internal.Generics | |||||
SingKind Bool | @since base-4.9.0.0 | ||||
Defined in GHC.Internal.Generics
| |||||
Ix Bool | @since base-2.01 | ||||
Read Bool | @since base-2.01 | ||||
Show Bool | @since base-2.01 | ||||
Eq Bool | |||||
Ord Bool | |||||
SingI 'False | @since base-4.9.0.0 | ||||
Defined in GHC.Internal.Generics | |||||
SingI 'True | @since base-4.9.0.0 | ||||
Defined in GHC.Internal.Generics | |||||
type DemoteRep Bool | |||||
Defined in GHC.Internal.Generics | |||||
type Rep Bool | @since base-4.6.0.0 | ||||
data Sing (a :: Bool) | |||||
Operations
bool :: a -> a -> Bool -> a Source #
Case analysis for the Bool
type.
evaluates to bool
f t pf
when p
is False
, and evaluates to t
when p
is True
.
This is equivalent to if p then t else f
; that is, one can
think of it as an if-then-else construct with its arguments
reordered.
@since base-4.7.0.0
Examples
Basic usage:
>>>
bool "foo" "bar" True
"bar">>>
bool "foo" "bar" False
"foo"
Confirm that
and bool
f t pif p then t else f
are
equivalent:
>>>
let p = True; f = "bar"; t = "foo"
>>>
bool f t p == if p then t else f
True>>>
let p = False
>>>
bool f t p == if p then t else f
True