An improved file-seq reads a file to a lazy sequence of lines and closes the reader after

chuncked_line_seq.clj

(ns chunked-line-seq
  (:require [clojure.java.io :as io]))


(defn chunked-line-seq [file-name & {:keys [chunck-size] :or {chunck-size 1000}}]
    (let [rd (io/reader (io/input-stream (io/file file-name)))
          eof&?  (atom false)
          chunck-lines  (fn [ ]
                          (seq (loop [lines (transient  [] ) counter 0]
                                (if-let [line (.readLine rd)]
                                  (if (< counter chunck-size)
                                      (recur (conj! lines line) (inc counter))
                                      (persistent! lines))
                                  (do (swap! eof&? not)
                                      (persistent! lines))))))]
      (letfn [(chuncked-seq [] (if-not @eof&?
                                 (concat (chunck-lines)
                                         (lazy-seq  (chuncked-seq)))
                                 (.close ^java.io.BufferedReader rd)))]
              (chuncked-seq))))