Re: Performance issue w/ `cl-loop`s `collect...into`

[Tianxiang Xiong <tianxiang.xiong@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 2069 bytes --]

I also figured out what the `(progn ... t)` pattern does. Here's a
macroexpansion w/ it:

(macroexpand-1 '(cl-loop for i in '(1 2 3) collect i))

(cl-block nil
  (let*
      ((--cl-var--
        '(1 2 3))
       (i nil)
       (--cl-var-- nil))
    (while
        (consp --cl-var--)
      (setq i
            (car --cl-var--))
      (push i --cl-var--)
      (setq --cl-var--
            (cdr --cl-var--)))
    (nreverse --cl-var--)))

And one w/out it:

(macroexpand-1 '(cl-loop for i in '(1 2 3) collect i))

(cl-block nil
  (let*
      ((--cl-var--
        '(1 2 3))
       (i nil)
       (--cl-var-- nil))
    (while
        (and
         (consp --cl-var--)
         (progn
           (setq i
                 (car --cl-var--))
           (push i --cl-var--)))
      (setq --cl-var--
            (cdr --cl-var--)))
    (nreverse --cl-var--)))

Apparently `cl--loop-build-ands` uses this pattern
<http://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/emacs-lisp/cl-macs.el?h=emacs-26#n1723>
to determine whether clauses go into an `and` or not 🤷. Of course 🙄!


On Mon, Apr 9, 2018 at 8:28 AM, Tianxiang Xiong <tianxiang.xiong@gmail.com>
wrote:

> Here's the result of `benchmark-run` on the new code:
>
> (benchmark-run 10 (cl-loop for i in (number-sequence 1 1E6)
>                      collect i))
>
> ;; => (10.488984668 6 3.555157208999999)
>
> and old code:
>
> (benchmark-run 10 (cl-loop for i in (number-sequence 1 1E6)
>                      collect i))
>
> ;; => (14.876455789000001 25 2.328459104999999)
>
> So there actually seems to be an improvement due to less GC.
>
> On Mon, Apr 9, 2018 at 5:22 AM, Basil L. Contovounesios <contovob@tcd.ie>
> wrote:
>
>> Tianxiang Xiong <tianxiang.xiong@gmail.com> writes:
>>
>> > Is there a function to easily time operations in Emacs Lisp? Something
>> > like Clojure's `core/time`?
>>
>> There are the macros benchmark-run and benchmark-run-compiled, as
>> mentioned under (info "(elisp) Profiling").
>>
>> --
>> Basil
>>
>
>

[-- Attachment #2: Type: text/html, Size: 7640 bytes --]