hi guys, I want to get a variable bidden from outside environment, such as
the code below:

-----------------------correct code------------------------
(define fp (open-output-file "/tmp/aaa"))
(eval-string "(write 123 fp)" (current-module))
-------------------------end----------------------------------

This code can run successfully.

But I want to use this trick in a procedure:
-----------------------wrong code------------------------------
(define (func)
   (let ((fp (open-output-file "/tmp/aaa")))
       (eval-string "(write 123 fp)" (current-module))
    ))
-----------------------end code------------------------------------

Guile will throw :
========================================
scheme@(guile-user)> (func)
ERROR: In procedure memoize-variable-access!:
ERROR: Unbound variable: fp0
========================================

Is this a bug? Or I missed something?