Question

我正在为我的Clojure程序编写一个函数，用于从键盘读取用户输入。如果用户输入无效输入，则会警告用户，然后再次提示。在像Python这样的语言中使用过程样式时，我会这样做：

while 1:
    value = input("What is your decision?")
    if validated(value):
        break
    else:
        print "That is not valid."

我能在Clojure中提出的最好的是：

(loop [value (do
               (println "What is your decision?")
               (read-line))]
  (if (validated value)
    value
    (recur (do
             (println "That is not valid.")
             (println "What is your decision?")
             (read-line)))))

这是有效的，但它是多余的，似乎很冗长。是否有更多的Lispy / Clojurey方法来做到这一点？

Answer 1

(defn input []
   (println "What is your decision?")
   (if-let [v (valid? (read-line))]
      v
      (do
         (println "That is not valid")
         (recur)))

Answer 2

将println / read-line组合分解为get-line函数：

(defn get-input [prompt]
  (println prompt)
  (read-line))

(defn get-validated-input []
  (loop [input (get-input "What is your decision?")]
    (if (valid? input)
      value
      (recur (get-input "That is not valid.\nWhat is your decision?")))))

这基本上就是你的Python版本所做的;区别在于get-input是内置的Python。

Lispy在Clojure中从键盘读取用户输入的方法？

2 个答案: