exam10.1.2

;; mht created on Nov 15, 2011

;; hours->wages : list-of-numbers -> list-of-numbers
;; to create a list of weekly wages from a list of weekly hours (alon)
(define (hours->wages alon)
  (cond
    [(empty? alon) empty]
    [else (cons (wage (first alon)) (hours->wages (rest alon)))]))

;; wage : number -> number
;; to compute the total wage (at $12 per hour)
;; of someone who worked for h hours
(define (wage h)
  (cond
    [(> h 100)
     (error "too many hours")]
    [else  (* 14 h)]))

;; hours->wages
(hours->wages (cons 40 (cons 80 empty)))