Hi, I have a file : "data.ss" where we can found just this (one constant) : (Contact 25) In beginning of my program, I read "data.ss" to load my  constant like this : _________________________________ (define NBCONTACT      (when (file-exists? "data.ss" )     (call-with-input-file  "data.ss"  (...) _________________________________ No problems with this. (equal? NBCONTACT 25) --> #t But I want to add a new contact: I try this : (define (reload a)   (when (file-exists? "data.ss" )     (call-with-output-file  "data.ss"       (lambda (p-out)         (fprintf p-out "(Contact ~a)\n" a)) 'replace))) reload = replace new value in  data.ss. I do (reload 98): And now if I open "data.ss",  I can see new values for Contact, I see (Contact 99) but if i tell NBCONTACT  I have the old values !!!!! 25 My question is :  How to make a method who refresh or reload  the data.ss file (without recompil my main ) Because I want create an executable when my program  will be finish !! Thanks