Luhn in Clojure

luhn.clj

(defn- digits [n]
  (map read-string (re-seq #"[0-9]" (str n))))

(defn luhn? [n]
  (zero? (mod
    (reduce +
          (digits (reduce str
             (map * (cycle [1 2]) (reverse (digits n))))))
    10)))

(map luhn?
     [49927398716 49927398717 1234567812345678 1234567812345670])
;;=> (true false false true)

;; also: http://rosettacode.org/wiki/Luhn_test_of_credit_card_numbers#Clojure