wagjo

(require '[clojure.java.io :as jio])

(deftype Slurp [filename]
  clojure.core.protocols/CollReduce
  (coll-reduce [this f1]
    (clojure.core.protocols/coll-reduce this f1 (f1)))
  (coll-reduce [_ f1 init]
    (with-open [#^java.io.Reader r
                (apply jio/reader filename nil)]
      (loop [ret init

wagjo

// original

int CheckExtension (char *filename, char *ext)
{
  char *s;
  if (!filename) return(0);
  if (strlen(filename) == 0) return(0);
  s = strrchr(filename,'.');
  if (!s) return(0);
  if (!strcmp(s,ext)) return(1);

wagjo

  ;; machine: amd64 Linux 2.6.32-48-server 16 cpu(s)
  ;;          Java HotSpot(TM) 64-Bit Server VM 23.25-b01
  ;;
  ;; == without lazy seq realization
  ;; regex split: 258.567183 ms
  ;; parallelized regex split: 65.053176 ms - lazy seqs are not realized!
  ;; correct reduce: 623.541446 ms
  ;; correct fold: 252.817020 ms
  ;;
  ;; == lazy seq realization with (into [] %)

wagjo

  (defn lazy-seq* [reducible]
    (let [c (chan)
          NIL (Object.)
          encode-nil #(if (nil? %) NIL %)
          decode-nil #(if (identical? NIL %) nil %)
          reduce-fn (fn [r v] (>!! c (encode-nil v)))]
      (thread
       (reduce reduce-fn nil reducible)
       (close! c))
      (->> #(<!! c)