[plt-scheme] eval-string namespace

Hi all,

Check the following:
(module test mzscheme
  
  (require (lib "string.ss"))
  
  (define (foo)
    (eval-string (read-line)))
  
  (define (bar)
    (display "Done"))
  
  (provide foo))

If I run this, require test.scm and enter bar for read-line I get that
bar is undefined. But it'll work alright if I provide bar. Why? 
I don't understand this behaviour, it's definitely not what I expected.
In the manual there is no mention to this situation, which is I might
say strange and boring since I have in the module 20 functions that can
be called through eval-string that I don't want to provide.

Any suggestions?

Best regards,

Paulo J. Matos