(defn distance [record1 record2]
  (let [R 6378.137
        dlat (Math/toRadians (- (latReturn record2) (latReturn record1)))
        dlon (Math/toRadians (- (longReturn record2) (longReturn record1)))
        lolnice (Math/toRadians (latReturn record1))
        dnice (Math/toRadians (latReturn record2))
        a (+ (* (Math/sin (/ dlat 2)) (Math/sin (/ dlat 2))) (* (Math/sin (/ dlon 2)) (Math/sin (/ 
dlon 2)) (Math/cos lolnice) (Math/cos dnice)))]
    (* R 2 (Math/asin (Math/sqrt a)))))

(distance (city "Toronto") (city "New York"))

record1和record2是来自城市及其属性的csv文件中的行。

函数latReturn和longReturn分别从这些行返回经纬度和经度。当我调用距离函数时，虽然出现nullpointerexception错误？我看过该函数，但似乎找不到导致它的原因？任何帮助都很好