Project Euler 26 by Clojure

euler26.clj

(defn remainders
  [n m]
  (let [r (rem n m)]
    (lazy-seq (cons r (remainders (* r 10) m)))))

(defn distance-of-same-value-elements
  [xs]
  (loop [i 0, dict {}, xs xs]
    (let [x (first xs)]
      (if-let [j (get dict x)]
        (- i j)
        (recur (inc i) (assoc dict x i) (rest xs))))))

(def recurring-length
  (comp distance-of-same-value-elements
        (partial remainders 1)))

(defn euler26
  [n]
  (loop [d n, d-max 0, len-max 0]
    (if (>= len-max d)
      d-max
      (let [len (recurring-length d)]
        (if (> len len-max)
          (recur (dec d) d len)
          (recur (dec d) d-max len-max))))))

(println (euler26 999))