Question

我刚刚进入Clojure并且希望做一些简单的功能让我的脚湿透，并试图摆脱我的Imperative编程背景。

下面简单地在字符串中搜索重复元素，但是循环似乎将其旋转失控;我做错了什么？是的，这可能看起来势在必行;我仍然试图围绕功能编程和非状态变化。是的，html没有经过验证，我只是以它为例。

(def src "
  <html>
  <head>
  <title>Astronomy
  </title>
  <title>Science
  </title>
  </head>
  </html>
")


(defn findit [ele body i]
  (let [n (.indexOf body (clojure.string/join ["<" ele ">"]) i)]
    (if (> n -1)
      (let [n2 (.indexOf body (clojure.string/join ["</" ele ">"]) (+ n 1))] ;if we found opening element, then find closing element
        (if (> n2 -1) ;found both open and close of element?
          [(subs body (+ n (.length ele) 2) n2) (+ n2 1)]))))
  )

; (let [[r i] (findit "title" src 69)] (println i) (if r (println r,i)))

(defn findthem [ele body]
  (loop [x 0]
    (let [[r i] (findit ele body 0)]
      (println r,i)
      (if i
        (recur i)))
    )
  )

(findthem "title" src)

Answer 1

在循环的每次迭代中发生的let语句中，调用findit时索引为0，而不是x（或i }）。

(defn findthem [ele body]
  (loop [i 0]
    (let [[r i] (findit ele body i)]
      (println r i)
      (when i
        (recur i)))))

在Clojure中，如何正确终止此循环

1 个答案: