gistfile1.clj

(defn logging-seq
  "Seq that logs its counter every N items"
  ([title n s]
   (logging-seq title n s 0))
  ([title n s ix]
   (when-let [head (first s)]
     (when (= 0 (mod ix n))
       (timbre/info title ix))
     (cons head (lazy-seq (logging-seq title n (rest s) (inc ix)))))))