Copyright | (c) The University of Glasgow 2001 |
---|---|

License | (c) The University of Glasgow 2001 |

Maintainer | libraries@haskell.org |

Stability | experimental |

Portability | portable |

Safe Haskell | Trustworthy |

- class Eq a => Bits a where
- (.&.) :: a -> a -> a
- (.|.) :: a -> a -> a
- xor :: a -> a -> a
- complement :: a -> a
- shift :: a -> Int -> a
- rotate :: a -> Int -> a
- bit :: Int -> a
- setBit :: a -> Int -> a
- clearBit :: a -> Int -> a
- complementBit :: a -> Int -> a
- testBit :: a -> Int -> Bool
- bitSizeMaybe :: a -> Maybe Int
- bitSize :: a -> Int
- isSigned :: a -> Bool
- shiftL :: a -> Int -> a
- unsafeShiftL :: a -> Int -> a
- shiftR :: a -> Int -> a
- unsafeShiftR :: a -> Int -> a
- rotateL :: a -> Int -> a
- rotateR :: a -> Int -> a
- popCount :: a -> Int

- class Bits b => FiniteBits b where
- finiteBitSize :: b -> Int

- bitDefault :: (Bits a, Num a) => Int -> a
- testBitDefault :: (Bits a, Num a) => a -> Int -> Bool
- popCountDefault :: (Bits a, Num a) => a -> Int

# Documentation

class Eq a => Bits a whereSource

The `Bits`

class defines bitwise operations over integral types.

- Bits are numbered from 0 with bit 0 being the least significant bit.

Minimal complete definition: `.&.`

, `.|.`

, `xor`

, `complement`

,
(`shift`

or (`shiftL`

and `shiftR`

)), (`rotate`

or (`rotateL`

and `rotateR`

)),
`bitSize`

, `isSigned`

, `testBit`

, `bit`

, and `popCount`

. The latter three can
be implemented using `testBitDefault`

, 'bitDefault, and `popCountDefault`

, if
`a`

is also an instance of `Num`

.

Bitwise "and"

Bitwise "or"

Bitwise "xor"

complement :: a -> aSource

Reverse all the bits in the argument

shifts `shift`

x i`x`

left by `i`

bits if `i`

is positive,
or right by `-i`

bits otherwise.
Right shifts perform sign extension on signed number types;
i.e. they fill the top bits with 1 if the `x`

is negative
and with 0 otherwise.

An instance can define either this unified `shift`

or `shiftL`

and
`shiftR`

, depending on which is more convenient for the type in
question.

rotates `rotate`

x i`x`

left by `i`

bits if `i`

is positive,
or right by `-i`

bits otherwise.

For unbounded types like `Integer`

, `rotate`

is equivalent to `shift`

.

An instance can define either this unified `rotate`

or `rotateL`

and
`rotateR`

, depending on which is more convenient for the type in
question.

`bit i`

is a value with the `i`

th bit set and all other bits clear

`x `setBit` i`

is the same as `x .|. bit i`

clearBit :: a -> Int -> aSource

`x `clearBit` i`

is the same as `x .&. complement (bit i)`

complementBit :: a -> Int -> aSource

`x `complementBit` i`

is the same as `x `xor` bit i`

testBit :: a -> Int -> BoolSource

Return `True`

if the `n`

th bit of the argument is 1

bitSizeMaybe :: a -> Maybe IntSource

Return the number of bits in the type of the argument. The actual
value of the argument is ignored. Returns Nothing
for types that do not have a fixed bitsize, like `Integer`

.

Deprecated: Use bitSizeMaybe or finiteBitSize instead

Return the number of bits in the type of the argument. The actual
value of the argument is ignored. The function `bitSize`

is
undefined for types that do not have a fixed bitsize, like `Integer`

.

Return `True`

if the argument is a signed type. The actual
value of the argument is ignored

Shift the argument left by the specified number of bits (which must be non-negative).

An instance can define either this and `shiftR`

or the unified
`shift`

, depending on which is more convenient for the type in
question.

unsafeShiftL :: a -> Int -> aSource

Shift the argument left by the specified number of bits. The
result is undefined for negative shift amounts and shift amounts
greater or equal to the `bitSize`

.

Defaults to `shiftL`

unless defined explicitly by an instance.

Shift the first argument right by the specified number of bits. The
result is undefined for negative shift amounts and shift amounts
greater or equal to the `bitSize`

.

Right shifts perform sign extension on signed number types;
i.e. they fill the top bits with 1 if the `x`

is negative
and with 0 otherwise.

An instance can define either this and `shiftL`

or the unified
`shift`

, depending on which is more convenient for the type in
question.

unsafeShiftR :: a -> Int -> aSource

Shift the first argument right by the specified number of bits, which must be non-negative an smaller than the number of bits in the type.

Right shifts perform sign extension on signed number types;
i.e. they fill the top bits with 1 if the `x`

is negative
and with 0 otherwise.

Defaults to `shiftR`

unless defined explicitly by an instance.

rotateL :: a -> Int -> aSource

Rotate the argument left by the specified number of bits (which must be non-negative).

An instance can define either this and `rotateR`

or the unified
`rotate`

, depending on which is more convenient for the type in
question.

rotateR :: a -> Int -> aSource

Rotate the argument right by the specified number of bits (which must be non-negative).

An instance can define either this and `rotateL`

or the unified
`rotate`

, depending on which is more convenient for the type in
question.

Return the number of set bits in the argument. This number is known as the population count or the Hamming weight.

class Bits b => FiniteBits b whereSource

finiteBitSize :: b -> IntSource

bitDefault :: (Bits a, Num a) => Int -> aSource