conj 在通过 recur 调用时不添加到向量的末尾

Question

为什么这老是问杰克要不要喝杯茶，而不是其他爸爸。

(defn tea-anyone
  "Ask 'fathers' if they would like some tea"
  [fathers]
  (loop [asks 0 to-ask fathers]
    (let [[father & others] to-ask]
      (println (str "Cup of tea " father "? "))
        (if (> asks 6)
          (println (str father ": All right then!"))
          (recur (inc asks) (conj others father))))))

(tea-anyone ["Jack" "Ted" "Dougle"])

Answer 1

因为 others 不是向量。自己看看：

(let [[f & o :as a] [1 2 3 4]]
    (println f)
    (println o)
    (println a)
    (println (type f))
    (println (type o))
    (println (type a))
    (println (type (conj o 5)))
    (println (type (conj a 5))))

为了达到你想要的效果，你可以使用cycle。

Answer 2

试试这个： (recur (inc asks) (conj (vec others) father))

conj 在通过 recur 调用时不添加到向量的末尾

conj not adding to end of vector when called via recur

clojure