XLISP not

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# not

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

## Syntax

(not expr)
  expr - the expression to check
  return - T if the value is NIL , NIL otherwise

## Description

The 'not' predicate function checks to see if the 'expr' is false. T is returned if the expression is NIL , NIL is returned otherwise.

## Examples

    (not '())      ; returns T - empty list
    (not ())       ; returns T - still empty
    (setq a NIL)   ; set up a variable
    (not a)        ; returns T - value = empty list

    (not "a")      ; returns NIL - not a list
    (not 'a)       ; returns NIL - not a list

Note: The 'not' predicate is the same function as the null predicate.

See the not predicate function in the XLISP 2.0 manual.

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