sieve.clj

;; Helper function for marking multiples of a number as 0
(def mark (fn [[x & xs] k m]
                 (if (= k m) 
                   (cons 0 (lazy-seq (mark xs 1       m)))
                   (cons x (lazy-seq (mark xs (inc k) m)))
                   )))

;; Sieve of Eratosthenes
(defn sieve
  [x & xs]
  (if (= x 0)
    (lazy-seq (sieve xs))
    (cons x (lazy-seq (sieve (mark xs 1 x))))
    ))

(take 10 (sieve (iterate inc 2)))