cat a.scm
(declare (unit a))
(define zooi 'a)

$ cat b.scm
(declare (uses a))
(print zooi)

$ csc -c a.scm b.scm ; csc -s a.o b.o -o c.so

$ csi
#;1> (load "c.so")  
; loading c.so ...
#;2> (print zooi)  
a
#;3> (exit)  
Warning: "exit" called while processing on-exit tasks
#;4>