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ANSI Common Lisp  5 Data and Control Flow 5.3 Dictionary of Data and Control Flow
- 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:
-
null
- Notes:
-
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.
- Allegro CL Implementation Details:
-
None.
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