calculate-area.clj

(def upper-left '(0,0))
(def lower-right '(5,5))

(defn calculate-area [ul, lr]
 (let [width (- (nth lr 0) (nth ul 0))
       height (- (nth lr 1) (nth ul 1))]
   (* width height)))


(calculate-area upper-left lower-right)
(calculate-area '(12 15) '(56 123))

;; etc