使用递归在Clojure中构建字符串

Question

I need to generate a random char and build a string and only stop when my string contains the newly generated char.

(defn rand-char [len]
  (apply str (take len (repeatedly #(char (+ (rand 26) 65))))))

(def random-string
  (loop [x (rand-char 1)
         result []]
    (if (some #(= x %) result)
      (apply str (conj result x))
      (recur (conj result x) (x (rand-char 1))))))

I am getting

java.lang.String cannot be cast to clojure.lang.IFn

Answer 1

rand-char returns a string but in (x (rand-char 1)) you're attempting to call x as a function, hence the error. You only need to call rand-char to generate the next random string to try. The arguments to recur should be in the same order as those declared in the loop so yours are in the wrong order:

(recur (rand-char 1) (conj result x))

Answer 2

something like this does it serve you?

(defn random-string []
  (loop [x (rand-char 1)
         result []]
    (if (.contains result x)
      (apply str result)
      (recur (rand-char 1) (conj result x)))))