From: Philip Kaludercic <philipk@posteo.net>
To: Lynn Winebarger <owinebar@gmail.com>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
Matthew Trzcinski <matt@excalamus.com>,
emacs-devel <emacs-devel@gnu.org>
Subject: Re: [elpa] externals/org 26ef5e3e5b: org-src: Use `sh-mode' for all the shells it can handle
Date: Mon, 17 Apr 2023 16:27:46 +0000 [thread overview]
Message-ID: <87bkjmh3st.fsf@posteo.net> (raw)
In-Reply-To: <CAM=F=bCww+bpZyjz7hJfBvnDHO1n1tHOaX7XR7C248KrXc4R_w@mail.gmail.com> (Lynn Winebarger's message of "Mon, 17 Apr 2023 12:16:36 -0400")
Lynn Winebarger <owinebar@gmail.com> writes:
> On Mon, Apr 17, 2023, 12:10 PM Stefan Monnier <monnier@iro.umontreal.ca>
> wrote:
>
>> > (defcustom org-src-lang-modes
>> > - '(("C" . c)
>> > + `(("C" . c)
>> > ("C++" . c++)
>> > ("asymptote" . asy)
>> > - ("bash" . sh)
>> > ("beamer" . latex)
>> > ("calc" . fundamental)
>> > ("cpp" . c++)
>> > @@ -208,9 +215,10 @@ but which mess up the display of a snippet in Org
>> exported files.")
>> > ("elisp" . emacs-lisp)
>> > ("ocaml" . tuareg)
>> > ("screen" . shell-script)
>> > - ("shell" . sh)
>> > ("sqlite" . sql)
>> > - ("toml" . conf-toml))
>> > + ("toml" . conf-toml)
>> > + ("shell" . sh)
>> > + ,@(org-src--get-known-shells))
>> > "Alist mapping languages to their major mode.
>>
>> Side note: while it really doesn't matter here for such trivial
>> top-level code, I prefer to put such ,@ at the beginning rather than the
>> end of lists, when it's an option. Basically because it's more
>> efficient to add to the beginning rather than to the end of a list:
>>
>> ELISP> (macroexpand '`(,@(list 1 2) a b c d))
>> (append (list 1 2) '(a b c d))
>> ELISP> (macroexpand '`(a b c d ,@(list 1 2)))
>> (cons 'a (cons 'b (cons 'c (cons 'd (list 1 2)))))
>> ELISP>
Is this just an implementation detail, or is there a reason that this
could not expand to
(append '(a b c d) (list 1 2))
> Why is the former more efficient than the latter? It looks like the former
> would have to construct the '(1 2) list twice, and the latter only once.
> And the '(a b c d) cons cells are only allocated once either way.
(I believe) It is more efficient, since there are fewer function calls.
I have had issues in the past with ,@ expanding to code that would have
exceeded the maximal evaluation depth, until I split it up and manually
used `append' that has the advantage of being implemented in C.
> Lynn
next prev parent reply other threads:[~2023-04-17 16:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <168174708495.14139.12756054653439048176@vcs2.savannah.gnu.org>
[not found] ` <20230417155805.3E200C1391A@vcs2.savannah.gnu.org>
2023-04-17 16:08 ` [elpa] externals/org 26ef5e3e5b: org-src: Use `sh-mode' for all the shells it can handle Stefan Monnier
2023-04-17 16:16 ` Lynn Winebarger
2023-04-17 16:27 ` Philip Kaludercic [this message]
2023-04-17 16:37 ` Andreas Schwab
2023-04-17 16:42 ` Philip Kaludercic
2023-04-17 16:39 ` Mattias Engdegård
2023-04-17 16:47 ` Mattias Engdegård
2023-04-17 17:37 ` Stefan Monnier
2023-04-17 18:33 ` Mattias Engdegård
2023-04-17 20:08 ` Stefan Monnier
2023-04-18 9:50 ` Mattias Engdegård
2023-04-17 17:11 ` Stefan Monnier
2023-04-17 17:24 ` Lynn Winebarger
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