From: "Štěpán Němec" <stepnem@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: "Mattias Engdegård" <mattiase@acm.org>, emacs-devel@gnu.org
Subject: Re: Regexp bytecode disassembler
Date: Sat, 21 Mar 2020 21:16:02 +0100 [thread overview]
Message-ID: <875zex79bx.fsf@gmail.com> (raw)
In-Reply-To: <834kuhecsr.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 21 Mar 2020 21:19:16 +0200")
On Sat, 21 Mar 2020 21:19:16 +0200
Eli Zaretskii wrote:
>> >> + (pcase opcode
>> >> + (0 (cons 'no-op 1))
>> >> + (1 (cons 'succeed 1))
>> >
>> > Is pcase really needed here? It looks like a simple cond will do.
>>
>> Well, pcase is a lot more readable here, don't you think?
>
> No, I don't, not in this case. You are just selecting from a list of
> fixed values.
Please forgive my intrusion, but, while I tend to agree with most of
your other comments, I find this one very surprising.
Do you mean you would prefer to use `cond' and rewrite all those clauses
to something like the following?
(cond
((eql opcode 0) (cons 'no-op 1))
((eql opcode 1) (cons 'succeed 1))
...
Maybe readability is much more subjective than I thought, but I find the
latter very suboptimal, to say the least.
Also, isn't "just selecting from a list of fixed values" precisely the
reason to use some sort of case/switch instead of the general `cond'?
Certainly `pcase' can also be useful in more complicated use cases, but
it will expand to the cond form anyway, so I also don't see any
performance concerns.
--
Štěpán
next prev parent reply other threads:[~2020-03-21 20:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 12:27 Regexp bytecode disassembler Mattias Engdegård
2020-03-20 12:58 ` Andreas Schwab
2020-03-20 14:34 ` Eli Zaretskii
2020-03-21 16:52 ` Mattias Engdegård
2020-03-21 19:19 ` Eli Zaretskii
2020-03-21 20:16 ` Štěpán Němec [this message]
2020-03-21 20:30 ` Eli Zaretskii
2020-03-21 20:40 ` Mattias Engdegård
2020-03-21 20:44 ` Štěpán Němec
2020-03-22 14:12 ` Eli Zaretskii
2020-03-22 14:43 ` Štěpán Němec
2020-03-22 16:55 ` Eli Zaretskii
2020-03-22 17:16 ` Štěpán Němec
2020-03-22 17:30 ` Eli Zaretskii
2020-03-22 18:34 ` Paul Eggert
2020-03-22 18:36 ` Dmitry Gutov
2020-03-21 20:50 ` Dmitry Gutov
2020-03-21 23:58 ` Drew Adams
2020-03-22 0:02 ` Drew Adams
2020-03-21 20:37 ` Mattias Engdegård
2020-03-22 3:28 ` Eli Zaretskii
2020-03-22 9:23 ` Mattias Engdegård
2020-03-22 10:37 ` Eli Zaretskii
2020-03-22 15:24 ` Mattias Engdegård
2020-03-22 17:06 ` Eli Zaretskii
2020-03-22 19:39 ` Mattias Engdegård
2020-03-22 20:12 ` Eli Zaretskii
2020-03-22 20:22 ` Corwin Brust
2020-03-20 15:39 ` Pip Cet
2020-03-21 16:56 ` Mattias Engdegård
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