Prime numbers

spoj02.clj

;; The input is:
;; first line: the number of test cases
;; next lines are the limits m n such as prime numbers are in [m;n]
;; Algorithm used: Sieve of Erasthotenes

(use '[clojure.set :only (difference)])

(defn mark
  ([all n limit] 
    (mark all n n limit))
  ([all n step limit]
    (let [current (+ n step)
          unmarked (disj all current)]
      (if (> n limit)
        all
        (recur unmarked current step limit)))))

(defn mark-all
  ([all limit]
    (mark-all all 2 limit))  
  ([all current limit]
	  (let [unmarked (mark all current limit)
	        marked (difference all unmarked)
          next-val (first (filter #(> % current) unmarked))]
     (if (> (* current current) limit)
       unmarked
	     (mark-all unmarked next-val limit)))))

(defn primes [start end]
  (let [all (apply sorted-set (range 2 (+ end 1)))]
    (filter #(>= % start) (mark-all all end))))

(let [times (Integer/parseInt (read-line))]
  (dotimes [_ times]
    (let [line (map #(Integer/parseInt %) (re-seq #"\w+" (read-line)))]
	    (println (reduce #(format "%s\n%d" %1 %2) (apply primes line)))
	    (printf "\n"))))