为什么这个Clojure代码会导致NPE？

Question

以下Clojure代码会导致NPE。从堆栈跟踪看来，这是在调用>=时引起的。我似乎无法弄清楚为什么会这样。

(def service-thresholds
  [{:service "cpu idle" :invert true :warning 50 :critital 10}
   {:service "cpu user" :invert false :warning 80 :critical 90}])

(defn threshold-check
  [thresholds]
  (fn [e]
    (or (first (for [threshold thresholds
                     :when (= (:service threshold) (:service e))]
                 (assoc e :state
                        (if (not (:invert threshold))
                          (condp <= (:metric e)
                            (:critical threshold) "critical"
                            (:warning threshold) "warning"
                            "ok")
                          (condp >= (:metric e)
                            (:critical threshold) "critical"
                            (:warning threshold) "warning"
                            "ok")))))
        e)))

(println ((threshold-check service-thresholds) {:service "cpu idle" :metric 20 :state nil}))

Answer 1

:critital拼写不正确:critical。