Scheme + opendir question

[Piotr K. Isajew]

Hi,

I would like to make a Scheme script, that displays all files in
specified directory. I tried something like:

(define (script-fu-main a_arg)
  (let* 
      (
       (dir (opendir a_arg))
       (dirent ())
       )
    (while set! dirent (readdir dir)
       (print dirent)
          )
    (closedir dir)
    ) 
  )

but this fails with:
ERROR: unbound variable (errobj opendir)


What should I do to correct this problem.

Thanks in advance

Piotr.