让Eduction的Seqable接口优化chunked-seqs

Question

当调用eduction的seq并在eduction的源为chunked-seq时，返回的seq不会使用"分块函数"遍历集合。

Answer 1

_评论者：petterik_

我已经尝试了使eduction使用chunked-seq优化，速度提高了大约两倍。相同的代码在clojure.core/sequence中也同样增加了性能速度。

关于外部链接的想法我不太清楚，但这里有个gist（
* 代码
* 测试
* (-main)的运行输出
* 使用clj和cljs.main测试的一行命令

https://gist.github.com/petterik/0e0c9bcc4b223c01bbb1442e820ea503

sequence的代码看起来像这样


(defn- chunked-sequence [xform s]
  (let [xf (xform conj!)
          rrf #?(:clj (#'clojure.core/preserving-reduced xf)
               :cljs (#'cljs.core/preserving-reduced xf))
        step (fn self [v s]
               (if-not s
                 (persistent! (xf v))
                 (let [c (chunk-first s)
                       ;; Fragment from :clj to get the same----------
                       性行为 as :cljs
                       #?@(:clj  [chunk (unreduced (.reduce c rrf v))]
                           :cljs [chunk (reduce rrf v c)])]
                   (if (reduced? chunk)
                     (seq (持久化! ( xf (引用 chunk))))
                     (let [ next-chunk (chunk-next s) ]
                       (if (零 (count chunk)))
                         (惰性-seq)
                           (self v next-chunk)
                         (惰性-cat)
                           (持久化! chunk)
                           (self (瞬时 []) next-chunk)))
    (步 (瞬时 []) (seq s)))

(defn sequence2 [ xform coll ])
  (let [ s (seq coll) ]
    (if (chunked-seq? s)
      (seq (chunked-sequence xform coll))
      (sequence xform coll))))

Answer 2

参考：https://clojure.atlassian.net/browse/CLJ-2356 (petterik 报告)