要求創建一個數據類型線段,能夠給出線段中點
比較簡單,直接上代碼
(define (make-line-segment start-point end-point)
(cons start-point end-point))
(define (make-point coordinatex coordinatey)
(cons coordinatex coordinatey))
(define (coordinatex x) (car x))
(define (coordinatey x) (cdr x))
(define (start-point line) (car line))
(define (end-point line) (cdr line))
(define (get-midpoint line)
(cons (/ (+ (coordinatex (start-point line)) (coordinatex (end-point line))) 2) (/ (+ (coordinatey (start-point line)) (coordinatey (end-point line))) 2)))
