;;; FILE: a.scm
(declare (uses b))
;; no (require-library b) 
;; no (require-extension b) 
;; no (use b) 

(define (a-hi) (print "hi from a"))

(a-hi)
(b-hi)

;;; FILE: b.scm
(declare (unit b))
(module b
  *
  (import scheme)
  (import chicken)
  
  (define (b-hi) (print "hi from b"))
  )

;;; COMMAND LINE
csc -c b.scm
csc -c a.scm
csc a.o b.o -o a

./a
Error: unbound variable: b-hi