交换协议中没有单一方法错误！请来Clojure

导致错误：

线程“main”java.lang.IllegalArgumentException中的异常：没有单一方法：接口损坏：协议\记录\u learning.core.Hit\为函数找到的点数：协议损坏：命中点数（core.clj:34）

有人能解释一下这个错误，是什么导致的，以及如何正确地改变原子吗？

这应该行得通

(ns protocols-records-learning.core)

(defprotocol Hit-points
  "Able to be harmed by environment interaction."
  (hit? [creature hit-roll] "Checks to see if hit.")
  (damage [creature damage-roll] "Damages target by damage-roll, negated by per-implementation factors.")
  (heal [creature heal-roll] "Heals creature by specified amount."))

(defrecord Human [ac, health, max-health]
  Hit-points
  (hit? [creature hit-roll] (>= hit-roll ac))
  (damage [creature damage-roll] (if (pos? damage-roll) (Human. ac (- health damage-roll) max-health)))
  (heal [creature heal-roll] (if (pos? heal-roll)
                    (if (>= max-health (+ heal-roll health))
                      (Human. ac max-health max-health)
                      (Human. ac (+ heal-roll health) max-health)))))

(def ryan (atom (Human. 10 4 4)))

(defn hurt-ryan
  "Damage Ryan by two points."
  [ryan]
  (swap! ryan (damage 2)))

注意，拆下的一对左右翼子板损坏。错误消息是一个笨拙的尝试，告诉您Clojure没有找到算术为1的损坏版本。损害的当事人试图做到这一点：用一个参数（2）调用损害

改进错误消息是一项正在进行的任务，目前尚未达成协议

(defn hurt-ryan
  "Damage Ryan by two points."
  [ryan]
  (swap! ryan damage 2))