From: Jim Porter <jporterbugs@gmail.com>
To: rms@gnu.org, emacs-devel@gnu.org
Subject: Re: Instead of pcase
Date: Thu, 16 Nov 2023 10:22:12 -0800 [thread overview]
Message-ID: <ab500e97-7fc5-b733-9d41-ec08f92935cd@gmail.com> (raw)
In-Reply-To: <E1r3SgH-0007Rb-BU@fencepost.gnu.org>
On 11/15/2023 7:04 PM, Richard Stallman wrote:
> Those of you who are fans of `pcase' may not recognize the cost it
> imposes on the Emacs Lisp language. You paid that cost already,
> perhaps a few years ago, and perhaps you enjoy each new language
> construct you learn. Perhaps, for you, the more complexity of
> features to be learned, the better.
I'd like to offer a slightly different perspective here, as someone who
only fairly recently became comfortable with Lisp (of any variety). I've
used Emacs for a long time, but I found Lisp completely incomprehensible
until just a couple of years ago. While getting started with Lisp isn't
terribly complex, it's still quite a bit to learn, and it took a period
where I was between jobs before I could dedicate the time I needed to
get comfortable with writing Lisp.
I encountered a lot of hurdles with Lisp along the way. The first one
was extremely basic: I needed to get used to the style of indentation
and develop an intuition for *reading* Lisp code, rather than slowly and
laboriously translating it into a form I could understand more easily.
The next hurdle was quoting. I still remember that one of my first
patches to Emacs needed someone else to fix it in a followup because I
messed up the quoting. The issues of quoting came up repeatedly for me
as I encountered progressively more complex examples of quoting.
This is where we get to 'pcase'. I'll agree that the upper limit on
complex quoted forms in 'pcase' is very high. I've used 'pcase-defmacro'
in one nontrivial case, and I found it very difficult to get right.
*However*, 99% of the 'pcase' instances I've written or encountered are
pretty simple for me to understand. Once I learned about 'pred' matcher
and how to destructure via backquote patterns, it was mostly smooth
sailing for me.
Now, while I'd certainly say that I enjoy learning overall (or else I
likely wouldn't have learned Lisp in the first place), I don't consider
the complexity of a feature to be a positive. Instead, I prefer features
that give me more power or better expressiveness. Often, that
expressiveness comes at the cost of complexity under the hood (e.g.
'pcase-defmacro'), but that's not a positive to me in and of itself.
Overall, 'pcase' is one of the parts of Elisp that I appreciate the
most. Learning the basics of its mini-language took just a bit of
reading. In addition to the docs, seeing examples helped: the first few
times were a bit tricky to read, but I could usually understand what was
happening, even if I couldn't (at the time) write my own 'pcase' code
that worked. However, once I got the basics down, I quickly saw the
benefits: I could combine a handful of basic tools to do bigger things,
meaning I only need to know a small set of facts before I can tackle a
complex task. This, to me, is the mark of a good language feature: I can
compose it in ways that *multiply* the power of each (small, easy) bit.
At a higher level, I'd say it's worth considering the audience we want
to focus on. For veteran (Emacs) Lisp programmers, new additions like
'pcase' can increase the difficulty of reading new Elisp code: your
prior mastery of the language isn't any good when you hit that "(pcase".
However, many programmers today don't know Lisp, of any variety. For
people like that, learning to contribute to Emacs means learning from
the very beginning. Having gone through this, most of 'pcase' was very
easy for me to pick up, and other parts of Elisp were much more
challenging (it took me a long time to get comfortable with writing
macros, which is also probably one of the reasons I found
'pcase-defmacro' to be so tricky).
That said, it's true that every feature we add to Elisp increases the
overall complexity because now there are more things to learn. However,
in my opinion, the expressiveness of 'pcase' far outweighs this cost.
next prev parent reply other threads:[~2023-11-16 18:22 UTC|newest]
Thread overview: 342+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 3:04 Instead of pcase Richard Stallman
2023-11-16 7:37 ` Philip Kaludercic
2023-11-16 17:18 ` T.V Raman
2023-11-16 17:44 ` Michael Heerdegen
2023-11-16 18:16 ` Philip Kaludercic
2023-11-17 8:54 ` Complex SPEC for variables/customization like font-lock-keywords/org-capture-templates/etc (was: Instead of pcase) Ihor Radchenko
2023-11-25 4:03 ` Complex SPEC for variables/customization like font-lock-keywords/org-capture-templates/etc Stefan Monnier
2023-11-16 19:19 ` Instead of pcase Eli Zaretskii
2023-11-17 8:02 ` Michael Heerdegen
2023-11-16 18:21 ` Dmitry Gutov
2023-11-16 18:39 ` T.V Raman
2023-11-16 18:47 ` Philip Kaludercic
2023-11-16 18:51 ` T.V Raman
2023-11-18 3:04 ` Richard Stallman
2023-11-19 12:23 ` Michael Heerdegen
2023-11-19 16:02 ` Barry Fishman
2023-11-19 17:59 ` Dmitry Gutov
2023-11-19 19:31 ` Eric Abrahamsen
2023-11-25 4:23 ` Stefan Monnier via Emacs development discussions.
2023-11-27 3:12 ` Richard Stallman
2023-11-19 21:15 ` Barry Fishman
2023-11-20 1:15 ` Dmitry Gutov
2023-11-20 15:32 ` Michael Heerdegen
2023-11-23 2:57 ` Richard Stallman
2023-11-24 17:14 ` Dmitry Gutov
2023-11-27 3:09 ` Richard Stallman
2023-11-27 12:21 ` Dmitry Gutov
2023-11-29 3:42 ` Richard Stallman
2023-11-29 12:56 ` Dmitry Gutov
2023-12-01 3:17 ` Richard Stallman
2023-11-28 2:44 ` Richard Stallman
2023-11-28 12:39 ` Dmitry Gutov
2023-11-30 3:37 ` Richard Stallman
2023-12-01 0:18 ` Dmitry Gutov
2023-12-01 5:51 ` Emanuel Berg
2023-12-10 8:34 ` Alfred M. Szmidt
2023-12-10 9:35 ` Eli Zaretskii
2023-12-10 9:53 ` Alfred M. Szmidt
2023-12-10 10:35 ` Eli Zaretskii
2023-12-10 11:05 ` Alfred M. Szmidt
2023-12-01 7:21 ` Eli Zaretskii
2023-12-01 8:03 ` Manuel Giraud via Emacs development discussions.
2023-12-02 3:21 ` Richard Stallman
2023-11-24 18:14 ` Michael Heerdegen
2023-11-24 18:35 ` Dmitry Gutov
2023-11-27 3:14 ` Richard Stallman
2023-11-28 2:46 ` Richard Stallman
2023-11-28 6:35 ` Nikita Domnitskii
2023-11-30 3:37 ` Richard Stallman
2023-12-02 21:37 ` Lynn Winebarger
2023-12-10 15:14 ` Richard Stallman
2023-12-10 16:27 ` Lynn Winebarger
2023-12-10 20:28 ` Michael Heerdegen via Emacs development discussions.
2023-12-10 21:13 ` Lynn Winebarger
2023-12-12 3:43 ` Richard Stallman
2023-12-12 6:46 ` Tomas Hlavaty
2023-12-12 15:18 ` [External] : " Drew Adams
2023-12-14 3:24 ` Richard Stallman
2023-12-14 16:52 ` Drew Adams
2023-12-16 4:24 ` Richard Stallman
2023-12-16 5:04 ` Drew Adams
2023-12-16 18:30 ` Bob Rogers
2023-12-18 4:13 ` Richard Stallman
2023-12-12 19:24 ` Tomas Hlavaty
2023-12-12 21:36 ` [External] : " Drew Adams
2023-12-12 22:25 ` Michael Heerdegen via Emacs development discussions.
2023-12-13 1:32 ` Adam Porter
2023-12-14 3:23 ` Richard Stallman
2023-12-16 4:23 ` Richard Stallman
2023-12-18 4:09 ` cond* Richard Stallman
2023-12-18 10:08 ` cond* João Távora
2023-12-21 4:20 ` cond* Richard Stallman
2023-12-21 9:50 ` cond* João Távora
2023-12-21 16:01 ` [External] : cond* Drew Adams
2023-12-21 16:20 ` João Távora
2023-12-24 3:56 ` Richard Stallman
2023-12-24 3:57 ` cond* Richard Stallman
2023-12-21 14:10 ` cond* Ihor Radchenko
2023-12-24 3:57 ` cond* Richard Stallman
2023-12-25 14:14 ` cond* Ihor Radchenko
2023-12-19 3:49 ` cond* Richard Stallman
2023-12-19 12:13 ` cond* João Távora
2023-12-22 3:14 ` cond* Richard Stallman
2023-12-22 7:27 ` cond* Philip Kaludercic
2023-12-25 3:41 ` cond* Richard Stallman
2023-12-25 12:32 ` cond* Philip Kaludercic
2023-12-27 4:54 ` cond* Richard Stallman
2023-12-27 14:34 ` cond* Philip Kaludercic
2023-12-29 3:52 ` cond* Richard Stallman
2024-01-01 14:49 ` cond* Ihor Radchenko
2024-01-03 4:13 ` cond* Richard Stallman
2024-01-03 15:57 ` cond* Ihor Radchenko
2024-01-05 4:23 ` cond* Richard Stallman
2024-01-06 14:33 ` cond* Ihor Radchenko
2024-01-06 22:25 ` [External] : cond* Drew Adams
2024-01-08 3:45 ` Richard Stallman
2024-01-08 15:20 ` Drew Adams
2024-01-09 2:53 ` map seq and radix-tree-leaf, in pcase Richard Stallman
2024-01-08 3:47 ` cond* Richard Stallman
2024-01-10 13:03 ` cond* Ihor Radchenko
2024-01-13 3:50 ` cond* Richard Stallman
2024-01-13 6:32 ` cond* Adam Porter
2024-01-16 3:31 ` cond* Richard Stallman
2024-01-13 19:47 ` cond* Ihor Radchenko
2024-01-15 3:13 ` cond* Richard Stallman
2024-01-08 3:47 ` cond* Richard Stallman
2024-01-08 15:13 ` cond* Ihor Radchenko
2024-01-27 3:37 ` cond* Richard Stallman
2024-02-01 16:26 ` cond* Ihor Radchenko
2024-02-03 3:36 ` cond* Richard Stallman
2024-02-03 16:52 ` cond* Ihor Radchenko
2024-01-03 4:13 ` cond* Richard Stallman
2024-01-03 15:48 ` cond* Ihor Radchenko
2024-01-06 4:31 ` cond* Richard Stallman
2024-01-06 13:09 ` cond* Ihor Radchenko
2024-01-08 3:47 ` cond* Richard Stallman
2024-01-08 15:26 ` cond* Ihor Radchenko
2024-01-27 3:37 ` cond* Richard Stallman
2024-01-03 4:13 ` cond* Richard Stallman
2024-01-03 15:50 ` cond* Ihor Radchenko
2024-01-06 4:31 ` cond* Richard Stallman
2024-01-06 13:13 ` cond* Ihor Radchenko
2024-01-08 3:47 ` cond* Richard Stallman
2024-01-08 15:35 ` cond* Ihor Radchenko
2023-12-19 15:53 ` [External] : cond* Drew Adams
2023-12-21 4:22 ` Richard Stallman
2023-12-21 4:22 ` Richard Stallman
2023-12-18 4:09 ` cond* Richard Stallman
2023-12-18 5:41 ` cond* Adam Porter
2023-12-21 4:20 ` cond* Richard Stallman
2023-12-16 4:23 ` Instead of pcase Richard Stallman
2023-12-16 4:23 ` Richard Stallman
2023-12-16 6:57 ` Adam Porter
2023-12-20 3:28 ` Richard Stallman
2023-12-20 10:52 ` Adam Porter
2023-12-23 2:53 ` Richard Stallman
2023-12-23 2:53 ` Richard Stallman
2023-12-25 14:26 ` Ihor Radchenko
2023-12-27 4:54 ` Richard Stallman
2023-12-28 13:05 ` Ihor Radchenko
2023-12-30 3:20 ` Richard Stallman
2024-01-01 14:33 ` Ihor Radchenko
2024-01-03 4:13 ` Richard Stallman
2024-01-03 4:13 ` Richard Stallman
2024-01-03 16:08 ` Ihor Radchenko
2024-01-05 4:23 ` Richard Stallman
2024-01-06 13:04 ` Ihor Radchenko
2024-01-08 3:47 ` Richard Stallman
2024-01-08 15:42 ` Ihor Radchenko
2024-01-27 3:37 ` Richard Stallman
2023-12-13 4:58 ` Richard Stallman
2023-12-11 3:31 ` Richard Stallman
2023-11-19 13:49 ` Dmitry Gutov
2023-11-21 2:42 ` Richard Stallman
2023-11-21 5:14 ` Jim Porter
2023-11-21 5:34 ` Yuri Khan
2023-11-21 11:11 ` Dmitry Gutov
2023-11-21 15:38 ` Michael Heerdegen
2023-11-23 3:00 ` Richard Stallman
2023-11-24 3:34 ` Richard Stallman
2023-11-24 4:30 ` Jim Porter
2023-11-24 7:45 ` Eli Zaretskii
2023-11-25 3:08 ` Emanuel Berg
2023-11-24 17:01 ` Dmitry Gutov
2023-11-24 17:29 ` Lynn Winebarger
2023-11-28 2:44 ` Richard Stallman
2023-11-30 19:14 ` Lynn Winebarger
2023-11-30 19:26 ` Eli Zaretskii
2023-11-30 20:30 ` Michael Heerdegen via Emacs development discussions.
2023-12-01 6:24 ` Eli Zaretskii
2023-12-01 15:47 ` Michael Heerdegen via Emacs development discussions.
2023-12-01 16:07 ` Eli Zaretskii
2023-12-01 20:27 ` Alan Mackenzie
2023-12-02 13:24 ` Michael Heerdegen via Emacs development discussions.
2023-12-02 13:51 ` Emanuel Berg
2023-12-04 3:11 ` Richard Stallman
2023-12-03 3:28 ` Richard Stallman
2023-11-30 20:47 ` João Távora
2023-12-01 6:31 ` Eli Zaretskii
2023-12-01 7:07 ` Yuri Khan
2023-12-01 8:10 ` Eli Zaretskii
2023-12-01 9:04 ` Andreas Schwab
2023-12-04 3:08 ` Richard Stallman
2023-12-04 11:58 ` Eli Zaretskii
2023-12-04 12:35 ` Lynn Winebarger
2023-12-04 13:20 ` Eli Zaretskii
2023-12-04 17:46 ` Andreas Schwab
2023-12-07 2:48 ` Richard Stallman
2023-12-07 17:42 ` Andreas Schwab
2023-12-09 4:02 ` Richard Stallman
2023-12-04 18:17 ` Lynn Winebarger
2023-12-04 12:37 ` Dmitry Gutov
2023-12-08 3:54 ` Richard Stallman
2023-12-01 10:13 ` João Távora
2023-12-01 8:35 ` Andreas Schwab
2023-12-01 10:02 ` João Távora
2023-12-01 11:52 ` Eli Zaretskii
2023-12-01 12:48 ` Dmitry Gutov
2023-12-01 14:44 ` Eli Zaretskii
2023-12-01 18:28 ` Dmitry Gutov
2023-12-01 18:40 ` Eli Zaretskii
2023-12-01 18:45 ` João Távora
2024-01-09 5:36 ` Stefan Kangas
2023-12-01 13:28 ` João Távora
2023-12-01 16:25 ` Andreas Schwab
2024-01-09 5:33 ` Stefan Kangas
2024-01-09 10:43 ` João Távora
2023-12-01 16:04 ` Michael Heerdegen via Emacs development discussions.
2023-12-01 16:33 ` Eli Zaretskii
2023-12-02 3:20 ` Richard Stallman
2023-12-02 8:41 ` Andreas Schwab
2023-12-02 9:02 ` Philip Kaludercic
2023-12-02 10:14 ` Emanuel Berg
2023-12-02 17:02 ` Barry Fishman
2023-12-02 20:25 ` Michael Heerdegen via Emacs development discussions.
2023-12-03 4:30 ` Emanuel Berg
2023-12-05 2:58 ` Richard Stallman
2023-12-05 3:36 ` chad
2023-12-08 3:53 ` Richard Stallman
2023-12-02 14:33 ` Michael Heerdegen via Emacs development discussions.
2023-12-04 3:11 ` Richard Stallman
2023-12-02 18:01 ` Lynn Winebarger
2023-12-04 3:11 ` Richard Stallman
2023-12-04 12:27 ` Lynn Winebarger
2023-12-03 3:27 ` Richard Stallman
2023-11-25 4:15 ` Stefan Monnier
2023-11-27 3:12 ` Richard Stallman
2023-11-30 18:06 ` Michael Heerdegen
2023-11-16 18:49 ` Dmitry Gutov
2023-11-16 23:41 ` Emanuel Berg
2023-11-17 7:34 ` Eli Zaretskii
2023-11-26 3:17 ` Richard Stallman
2023-11-16 15:06 ` Michael Heerdegen
2023-11-16 17:31 ` T.V Raman
2023-11-16 18:26 ` Jim Porter
2023-11-16 18:40 ` T.V Raman
2023-11-16 19:13 ` Jim Porter
2023-11-20 3:06 ` Richard Stallman
2023-11-20 14:35 ` Michael Heerdegen
2023-11-23 2:57 ` Richard Stallman
2023-11-16 15:20 ` Spencer Baugh
2023-11-16 20:16 ` Tomas Hlavaty
2023-11-16 21:37 ` [External] : " Drew Adams
2023-11-25 4:34 ` Stefan Monnier via Emacs development discussions.
2023-11-25 8:53 ` Eli Zaretskii
2023-11-18 3:03 ` combining cond and let, to replace pcase Richard Stallman
2023-11-19 11:20 ` Michael Heerdegen
2023-11-19 11:43 ` Eli Zaretskii
2023-11-19 12:16 ` Gerd Möllmann
2023-11-19 13:21 ` Eli Zaretskii
2023-11-19 13:32 ` Gerd Möllmann
2023-11-19 14:41 ` Eli Zaretskii
2023-11-19 15:27 ` Gerd Möllmann
2023-11-19 15:29 ` Eli Zaretskii
2023-11-19 16:03 ` Joost Kremers
2023-11-19 16:59 ` Eli Zaretskii
2023-11-19 18:29 ` Joost Kremers
2023-11-19 18:35 ` Eli Zaretskii
2023-11-19 12:50 ` Michael Heerdegen
2023-11-19 13:08 ` Eli Zaretskii
2023-11-19 13:52 ` Michael Heerdegen
2023-11-19 14:45 ` Eli Zaretskii
2023-11-20 15:35 ` Michael Heerdegen
2023-11-20 16:37 ` Eli Zaretskii
2023-11-21 8:33 ` Michael Heerdegen
2023-11-21 8:39 ` Michael Heerdegen
2023-11-19 13:59 ` Dmitry Gutov
2023-11-19 14:49 ` Eli Zaretskii
2023-11-19 14:53 ` Dmitry Gutov
2023-11-19 12:04 ` Gerd Möllmann
2023-11-19 18:10 ` Tomas Hlavaty
2023-11-25 4:45 ` Stefan Monnier via Emacs development discussions.
2023-11-28 15:31 ` João Távora
2023-11-28 15:55 ` Stefan Monnier
2023-11-19 21:36 ` Alan Mackenzie
2023-11-21 16:14 ` Michael Heerdegen
2023-11-19 16:08 ` Axel Forsman
2023-11-21 15:53 ` Michael Heerdegen
2023-11-23 2:58 ` Richard Stallman
2023-11-23 7:02 ` Tomas Hlavaty
2023-11-26 3:14 ` Richard Stallman
2023-11-27 17:07 ` Tomas Hlavaty
2023-11-27 17:59 ` Yuri Khan
2023-11-28 14:25 ` Tomas Hlavaty
2023-11-23 8:58 ` Manuel Giraud via Emacs development discussions.
2023-11-26 3:14 ` Richard Stallman
2023-11-24 3:08 ` Daniel Semyonov
2023-11-24 3:26 ` Daniel Semyonov
2023-11-25 2:59 ` Richard Stallman
2023-11-25 5:11 ` Stefan Monnier via Emacs development discussions.
2023-11-27 3:11 ` Richard Stallman
2023-11-27 18:13 ` Manuel Giraud via Emacs development discussions.
2023-11-27 18:49 ` Yuri Khan
2023-11-27 23:12 ` Stefan Monnier
2023-11-29 3:41 ` Richard Stallman
2023-11-29 3:40 ` Richard Stallman
2023-11-27 3:11 ` Richard Stallman
2023-11-16 18:11 ` Instead of pcase Emanuel Berg
2023-11-16 19:26 ` Eli Zaretskii
2023-11-16 22:16 ` Emanuel Berg
2023-11-17 7:30 ` Eli Zaretskii
2023-11-17 8:09 ` Emanuel Berg
2023-11-17 12:16 ` Eli Zaretskii
2023-11-18 6:26 ` Emanuel Berg
2023-11-18 7:21 ` Po Lu
2023-11-18 7:41 ` Eli Zaretskii
2023-11-16 18:22 ` Jim Porter [this message]
2023-11-16 22:55 ` Emanuel Berg
2023-11-17 5:36 ` Po Lu
2023-11-19 11:48 ` Michael Heerdegen
2023-11-19 12:50 ` Eli Zaretskii
2023-11-19 14:05 ` Dmitry Gutov
2023-11-19 14:41 ` Po Lu
2023-11-19 14:44 ` Dmitry Gutov
2023-11-19 14:52 ` Eli Zaretskii
2023-11-19 14:58 ` Dmitry Gutov
2023-11-19 15:14 ` Eli Zaretskii
2023-11-19 18:04 ` Dmitry Gutov
2023-11-19 18:30 ` Eli Zaretskii
2023-11-19 18:51 ` Dmitry Gutov
2023-11-19 19:49 ` Eli Zaretskii
2023-11-21 2:43 ` Richard Stallman
2023-11-19 14:14 ` Michael Heerdegen
2023-11-19 15:09 ` Eli Zaretskii
2023-11-20 14:52 ` Michael Heerdegen
2023-11-19 14:29 ` Po Lu
2023-11-20 15:20 ` Michael Heerdegen
2023-11-20 15:29 ` Dmitry Gutov
2023-11-20 23:43 ` Po Lu
2023-11-21 1:09 ` Dmitry Gutov
2023-11-21 1:49 ` Po Lu
2023-11-21 1:59 ` Dmitry Gutov
2023-11-21 4:04 ` Po Lu
2023-11-21 11:27 ` Dmitry Gutov
2023-11-21 11:49 ` Po Lu
2023-11-20 23:45 ` Jose E. Marchesi
2023-11-20 23:54 ` Emanuel Berg
2023-11-21 2:01 ` Dmitry Gutov
2023-11-22 2:59 ` Richard Stallman
2023-11-22 3:29 ` Emanuel Berg
2023-11-22 11:58 ` Dmitry Gutov
2023-11-24 3:38 ` Richard Stallman
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