Syntax:
null object => boolean
Arguments and Values:
object---an object.
boolean---a boolean.
Description:
Returns t if object is the empty list; otherwise, returns nil.
Examples:
(null '()) => T (null nil) => T (null t) => NIL (null 1) => NIL
Side Effects: None.
Affected By: None.
Exceptional Situations: None.
See Also:
Notes:
null is intended to be used to test for the empty list whereas not is intended to be used to invert a boolean (or generalized boolean). Operationally, null and not compute the same result; which to use is a matter of style.
(null object) == (typep object 'null) == (eq object '())The following X3J13 cleanup issue, not part of the specification, applies to this section:
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