Clojure loop reads one extra.

Question

When length is 4 following loop executes 5 times. Reading 5 characters from the stream.

(loop [i (.read stream)  result ""  counter length]
    (let [c (char i)]
      (println "=>" c)
      (if (zero? counter)
        result
        (recur (.read stream) (str result c) (dec counter)))))

Answer 1

I don't know clojure, but it looks to me like you're reading the stream again in "result" form, is this like final in CL ?

Answer 2

You should test for zero? before you do the read. Note that your version will call read once even if length == 0 to begin with.

(loop [result "" counter length]
  (if (zero? counter)
    result
    (let [c (char (.read stream))]
      (println "=>" c )
      (recur (str result c) (dec counter)))))

Another way which avoids an explicit loop:

(apply str 
       (take length 
             (repeatedly #(let [c (char (.read stream))]
                            (println "=>" c) c)))))