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bit

bit Type

Supertypes:

bit, unsigned-byte, signed-byte, integer, rational, real, number, t

Description:

The type bit is equivalent to the type (integer 0 1) and (unsigned-byte 1).

Expanded Reference: bit​

Type Checking​

The type bit contains exactly two elements: the integers 0 and 1. It is equivalent to (integer 0 1) and is also equivalent to (unsigned-byte 1).

(typep 0 'bit)
=> T
(typep 1 'bit)
=> T
(typep 2 'bit)
=> NIL
(typep -1 'bit)
=> NIL
(typep 0.0 'bit)
=> NIL

Type Hierarchy​

The bit type is a subtype of several numeric types.

(subtypep 'bit 'unsigned-byte)
=> T
=> T
(subtypep 'bit 'fixnum)
=> T
=> T
(subtypep 'bit 'integer)
=> T
=> T
(subtypep 'bit '(integer 0 1))
=> T
=> T

Bit Arrays and Bit Vectors​

The bit type is primarily used as the element type for bit arrays and bit vectors, which provide compact storage and efficient bitwise operations.

;; Bit vectors
(make-array 8 :element-type 'bit :initial-element 0)
=> #*00000000

#*10110100
=> #*10110100

(typep #*1010 'bit-vector)
=> T
(array-element-type #*1010)
=> BIT

;; Bit arrays
(make-array '(2 3) :element-type 'bit :initial-element 1)
=> #2A((1 1 1) (1 1 1))

Bitwise Operations on Bit Vectors​

Bit vectors support efficient logical operations through specialized functions.

(bit-and #*1100 #*1010)
=> #*1000
(bit-ior #*1100 #*1010)
=> #*1110
(bit-xor #*1100 #*1010)
=> #*0110
(bit-not #*1100)
=> #*0011