gistfile1.scm

(define-struct time (hours minutes seconds))

(define (time-point hours minutes seconds)
  (make-time hours minutes seconds))

(define (time-diff t1 t2)
  (cond
    [(> (seconds t1) (seconds t2)) ((- one-day (seconds t1)) + (seconds t2))]
    [else (- (seconds t2) (seconds t1))])) 

(define (seconds time)
  (+
   (* (time-hours time) 3600)
   (* (time-minutes time) 60)
   (time-seconds time)))

(define one-day (* 24 3600))

  (test-equal? "time-diff" (time-diff (time-point 1 2 3) (time-point 4 5 6)) 10983)