not
not Function
Syntax:
not x → boolean
Arguments and Values:
x—a generalized boolean (i.e., any object).
boolean—a boolean.
Description:
Returns t if x is false; otherwise, returns nil.
Examples:
(not nil) → T
(not ’()) → T
(not (integerp ’sss)) → T
(not (integerp 1)) → NIL
(not 3.7) → NIL
(not ’apple) → NIL
See Also:
nullNotes:
not is intended to be used to invert the ‘truth value’ of a boolean (or generalized boolean) whereas null is intended to be used to test for the empty list. Operationally, not and null compute the same result; which to use is a matter of style.
Expanded Reference: not
tip
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