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boundp

boundp

type: predicate function (subr)
location: built-in
source file: xlbfun.c
Common LISP compatible: yes
supported on: all machines

SYNTAX

(boundp <symbol> )
        <symbol>        -       the symbol expression to check for a value

DESCRIPTION

The BOUNDP predicate checks to see if <symbol> is a symbol with a value bound to it. T is returned if <symbol> has a value, NIL is returned otherwise. Note that <symbol> is a symbol expression - it is evaluated and the resulting expression is the one that is checked.

EXAMPLES

(setq a 1)                              ; set up A with value 1
(boundp 'a)                             ; returns T - value is 1
(defun foo (x) (print x))               ; set up function FOO
(boundp 'foo)                           ; returns NIL - value is closure
(boundp 'defvar)                        ; returns NIL - value is closure
(boundp 'car)                           ; returns NIL - value is closure
(print myvar)                           ; error: unbound variable
(BOUNDP 'myvar)                         ; returns NIL 
(setq myvar 'abc)                       ; set up MYVAR with a value
(BOUNDP 'myvar)                         ; returns T - because of SETQ
(setq myvar 'qq)                        ; set up MYVAR to have value QQ
(BOUNDP myvar)                          ; returns NIL - because QQ has
                                        ;               no value yet
(setq qq 'new-value)                    ; set QQ to have value NEW-VALUE
(BOUNDP myvar)                          ; returns T


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