;;; hello.scm
(module hello (say-hello)
  (import chicken scheme)
  (define (say-hello)
    "hello"))

;;; goodbye.scm
(module goodbye *

(import chicken scheme)
(use ports hello)

(define (say-goodbye)
  "goodbye"))

;;; usage.scm
(eval '(use hello goodbye))
(print (eval '(string-append (say-hello) (say-goodbye))))