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

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

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Since it appears there's no performance degradation, can we merge this?

If others would like to do some testing, that'd be great.

On Mon, Apr 9, 2018 at 8:33 AM, Tianxiang Xiong <tianxiang.xiong@gmail.com>
wrote:

> 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
>>>
>>
>>
>

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