[HARLEQUIN][Common Lisp HyperSpec (TM)] [Previous][Up][Next]

Function NULL


null object => boolean

Arguments and Values:

object---an object.

boolean---a boolean.


Returns t if object is the empty list; otherwise, returns nil.


 (null '()) =>  T
 (null nil) =>  T
 (null t) =>  NIL
 (null 1) =>  NIL

Side Effects: None.

Affected By: None.

Exceptional Situations: None.

See Also:



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:

[Starting Points][Contents][Index][Symbols][Glossary][Issues]
Copyright 1996, The Harlequin Group Limited. All Rights Reserved.