XLISP atom

Nyquist / XLISP 2.0 - Contents | Tutorials | Examples | Reference

# atom

Type: | - | predicate function (subr)
Source: | - | xlbfun.c

## Syntax

(atom expr)
  expr - an arbitrary Lisp expression
  returns - T if the value is an atom, NIL otherwise

## Description

The 'atom' predicate function tests if the 'expr' is an atom. T is returned if 'expr' is an atom, NIL is returned otherwise.

## Examples

    (atom 'a)                      => T   ; symbol
    (atom #'atom)                  => T   ; subr - function
    (atom "string")                => T   ; string
    (atom 4)                       => T   ; integer
    (atom 4.5)                     => T   ; float
    (atom object)                  => T   ; object
    (atom #(1 2 3))                => T   ; array
    (atom #'quote)                 => T   ; fsubr
    (atom *standard-output*)       => T   ; stream
    (atom '())                     => T   ; NIL is an atom
    (atom (lambda (x) (print x)))  => T   ; closure
    (atom '(a b c))                => NIL ; list
    (setq a '(a b))                => (A B)
    (atom a)                       => NIL ; value of A is not an atom

Note: NIL or '() is used in many places as a list or atom expression. Both 'atom' and listp, when applied to NIL, return T .

See also:

- Contents → Predicate Functions

Back to Top

XLISP > XLISP 2.0 - Contents - Reference