From: Eric Abrahamsen <eric@ericabrahamsen.net>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>, emacs-devel@gnu.org
Subject: Re: Help with recursive destructive function
Date: Sun, 06 May 2018 10:29:39 -0700 [thread overview]
Message-ID: <87sh743d6k.fsf@ericabrahamsen.net> (raw)
In-Reply-To: <87zi1e9kju.fsf@web.de> (Michael Heerdegen's message of "Sat, 05 May 2018 17:41:41 +0200")
Michael Heerdegen <michael_heerdegen@web.de> writes:
> I wrote:
>
>> I guess I would use an iterator: the definition would still looks
>> recursive, but the execution isn't problematic any more if done right.
Thanks to both of you! This was some good food for thought. I made
Stefan's suggested change to my original function and it works fine. It
still looks ugly to me because I'm doing the same test-and-set in three
different places, but with sufficient poking I can probably get it all
inside the same loop.
All else being equal I prefer this more "basic" version, simply because
I understand everything that's happening in it. I haven't used `cl-loop'
before, but I assume it's not doing anything that
(while (consp thing)
...
(setq thing (cdr thing))
Isn't doing? Oh, but then you wouldn't be able to use cl-callf directly
on thing.
Recursion is an issue, but the original version recurses on car, not
cdr, which I think (?) is much less of a problem. It went through your
huge-list with no trouble (and faster than the iterative version). I
suppose someone might have accumulated 801 levels of nested quotes in
their Gnus registry (god, I hope not), but otherwise I'm not sure it's a
worry.
On the third hand, if "bulletproof" is the goal, maybe it's best not to
risk it...
> #+begin_src emacs-lisp
> (iter-defun iter-tree-example (tree)
> (cl-loop for thing in-ref tree by #'cdr do
> (if (consp thing)
> (iter-yield-from (iter-tree-example thing))
> (iter-yield
> (ignore
> (when (stringp thing)
> (cl-callf upcase thing)))))))
> Yield values don't have any purpose but I guess without yielding you
> would get no CPS rewrite but a standard recursive function that would be
> problematic with the HUGE-LIST.
I guess this works because the calls to `iter-yield' and
`iter-yield-from' fully return from the function? Also, what does "CPS
rewrite" mean?
Thanks again,
Eric
next prev parent reply other threads:[~2018-05-06 17:29 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-05 1:04 Help with recursive destructive function Eric Abrahamsen
2018-05-05 1:18 ` Stefan Monnier
2018-05-05 1:37 ` Michael Heerdegen
2018-05-05 15:41 ` Michael Heerdegen
2018-05-06 17:29 ` Eric Abrahamsen [this message]
2018-05-06 19:29 ` Michael Heerdegen
2018-05-06 19:34 ` Eric Abrahamsen
2018-05-06 18:27 ` Eric Abrahamsen
2018-05-07 2:01 ` Michael Heerdegen
2018-05-07 3:01 ` Eric Abrahamsen
2018-05-07 4:16 ` Clément Pit-Claudel
2018-05-07 14:14 ` Michael Heerdegen
2018-05-07 16:26 ` Stefan Monnier
2018-05-07 16:52 ` Eric Abrahamsen
2018-05-08 13:15 ` Michael Heerdegen
2018-05-08 18:42 ` Eric Abrahamsen
2018-05-08 19:03 ` Clément Pit-Claudel
2018-05-08 19:41 ` Eric Abrahamsen
2018-05-10 1:52 ` Michael Heerdegen
2018-05-10 17:08 ` Michael Heerdegen
2018-05-11 2:12 ` Eric Abrahamsen
2018-05-14 14:27 ` Michael Heerdegen
2018-05-14 16:57 ` Eric Abrahamsen
2018-05-14 23:16 ` Michael Heerdegen
2018-05-15 0:28 ` Eric Abrahamsen
2018-07-28 20:52 ` Eric Abrahamsen
2018-07-28 23:46 ` Michael Heerdegen
2018-07-28 23:59 ` Eric Abrahamsen
2018-07-29 0:09 ` Michael Heerdegen
2018-06-04 22:28 ` Eric Abrahamsen
2018-06-05 0:23 ` Michael Heerdegen
2018-06-06 21:04 ` Eric Abrahamsen
2018-06-06 21:58 ` Michael Heerdegen
2018-06-06 22:10 ` Eric Abrahamsen
2018-06-06 23:10 ` Eric Abrahamsen
2018-06-06 23:30 ` Michael Heerdegen
2018-06-07 0:49 ` Eric Abrahamsen
2018-06-07 1:13 ` Michael Heerdegen
2018-06-06 23:18 ` Michael Heerdegen
2018-06-07 13:59 ` Stefan Monnier
2018-06-07 16:51 ` Eric Abrahamsen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87sh743d6k.fsf@ericabrahamsen.net \
--to=eric@ericabrahamsen.net \
--cc=emacs-devel@gnu.org \
--cc=michael_heerdegen@web.de \
--cc=monnier@iro.umontreal.ca \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.