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From: Mickey Petersen <mickey@masteringemacs.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: casouri@gmail.com, 73404@debbugs.gnu.org
Subject: bug#73404: 30.0.50; [forward/kill/etc]-sexp commands do not behave as expected in tree-sitter modes
Date: Thu, 26 Sep 2024 13:13:53 +0100	[thread overview]
Message-ID: <87bk0a1u0o.fsf@masteringemacs.org> (raw)
In-Reply-To: <8634lmbs8t.fsf@gnu.org>


Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: 73404@debbugs.gnu.org
>> From: Mickey Petersen <mickey@masteringemacs.org>
>> Date: Thu, 26 Sep 2024 10:56:35 +0100
>>
>> In my opinion, that's not what `sexp' movement is.
>>
>> Sexp movement is movement by balanced expressions -- and a fallback to
>> word-like behaviour absent that -- and this is not that. It would be
>> better to relegate this sort of thing to its own set of keybindings.
>
> The term "balanced expression" is not well defined in languages other
> than Lisp and Lisp-like ones.  It is clear what expected when point is
> on a brace or a parenthesis, but entirely NOT clear when you start
> from something else.  For example:
>
>   int foo = bar + 2 * baz;
>
> Suppose you start with point at "foo": what would you expect
> forward-sexp to do? nothing?
>

I expect it to behave as it presently does: default to word-like
behaviour such as M-@ / M-f etc.

Balanced expression is not well defined, de jure, but it is in
practical terms, making it de facto rather well understood and
supported. It behaves reasonably consistently across languages, and I
use *-sexp commands thousands of times a day in a wide range of major modes and
contexts, both in code and also prose.

Most people who use *-sexp (or *-word commands for that matter) in
major modes come to recognise how they work and know what happens to
the text/point in their buffer before they run them.

I would challenge anyone, given even small samples of code, to do the
same with the current TS only implementation.

>> > We might need to add a user option so people can easily turn off
>> > tree-sitter sexp movement, since it isn’t a strict upgrade from the
>> > generic sexp movement—it’s more of a different flavored sexp movement.
>>
>> It should be opt-in, not opt-out.
>
> I disagree.  Moving by sub-trees is a natural generalization of sexp
> movement for languages where parentheses and braces are rare and far
> in-between.

Yes, if one can intuit the sub trees' structure, which is not so
simple; and if the selection of commands are sufficiently expressive
enough to let you navigate the tree. I am not sure they are.

The CSTs are deep, wide, and nodes' ranges frequently overlap; they
are multi-dimensional structures that map to a simple 2-dimensional
'grid' in your buffer. Making heads or tails of that is no easy feat.






  reply	other threads:[~2024-09-26 12:13 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-21  5:06 bug#73404: 30.0.50; [forward/kill/etc]-sexp commands do not behave as expected in tree-sitter modes Mickey Petersen
2024-09-26  7:42 ` Yuan Fu
2024-09-26  9:56   ` Mickey Petersen
2024-09-26 10:53     ` Eli Zaretskii
2024-09-26 12:13       ` Mickey Petersen [this message]
2024-09-26 13:46         ` Eli Zaretskii
2024-09-26 15:21           ` Mickey Petersen
2024-09-26 15:45             ` Eli Zaretskii
2024-09-27  5:43               ` Yuan Fu
2024-09-29 16:56                 ` Juri Linkov
2024-10-01  3:57                   ` Yuan Fu
2024-10-01 17:49                     ` Juri Linkov
2024-10-02  6:14                       ` Yuan Fu
2024-12-05 18:52                       ` Juri Linkov
2024-12-05 19:53                         ` Juri Linkov
2024-12-10 17:20                           ` Juri Linkov
2024-12-11  6:31                             ` Yuan Fu
2024-12-11 15:12                               ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-12-11 15:29                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-12-11 16:50                                 ` Mickey Petersen
2024-12-11 18:27                                 ` Yuan Fu
2024-12-12  7:17                                   ` Juri Linkov
2024-12-12  7:40                                     ` Eli Zaretskii
2024-12-12  7:58                                       ` Juri Linkov
2024-12-12  8:14                                         ` Juri Linkov
2024-12-12 16:31                                           ` Juri Linkov
2024-12-12 17:49                                             ` Juri Linkov
2024-12-12 19:13                                               ` Eli Zaretskii
2024-12-13  7:06                                                 ` Juri Linkov
2024-12-14 11:02                                                   ` Eli Zaretskii
2024-12-14 18:14                                                     ` Juri Linkov

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