What about this?
(define-macro (bound? x) `(with-exception-handler (lambda (e) #f) (lambda () (and ,x #t))))
(pp (bound? x)) (let ((y 3)) (pp (bound? y)))
Cheers,
P!
2011/5/9 William James w_a_x_man@yahoo.com:
How do you check to see if a symbol is already bound? To be used in this fashion:
(if (bound? x) (set! x 22) (define x 22)) _______________________________________________ Gambit-list mailing list Gambit-list@iro.umontreal.ca https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list