XLISP symbolp

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# symbolp

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

## Syntax

(symbolp expr)
  expr - the expression to check
  returns - T if the expression is a symbol, NIL otherwise

## Description

The 'symbolp' predicate function checks if an 'expr' is a valid symbol. T is returned if 'expr' is a symbol, NIL is returned otherwise. An 'expr' that evaluates to an integer, function [subr or otherwise], and so on is not a symbol. However, the quoted [un-evaluated] name of these objects [like 'myarray] is a valid symbol.

## Examples

    (symbolp (make-symbol "a"))       ; returns T - symbol
    (symbolp 'a)                      ; returns T - symbol

    (symbolp #(1 2 3))                ; returns NIL - array
    (symbolp (lambda (x) (print x)))  ; returns NIL - closure
    (symbolp *standard-output*)       ; returns NIL - stream
    (symbolp 1.2)                     ; returns NIL - float
    (symbolp 2)                       ; returns NIL - integer
    (symbolp object)                  ; returns NIL - object
    (symbolp "hi")                    ; returns NIL - string

    (symbolp #'car)                   ; returns NIL - subr
    (symbolp 'car)                    ; returns T - it is a symbol now
    (symbolp '2)                      ; returns NIL - not a symbol

See the symbolp predicate function in the XLISP 2.0 manual.

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