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From: <tomas@tuxteam.de>
To: help-gnu-emacs@gnu.org
Subject: Re: [el-search] How to search string excluding docstring?
Date: Mon, 25 Dec 2017 20:14:20 +0100	[thread overview]
Message-ID: <20171225191420.GB3245@tuxteam.de> (raw)
In-Reply-To: <86d132n0e0.fsf@zoho.com>

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On Mon, Dec 25, 2017 at 07:11:19PM +0100, Emanuel Berg wrote:
> t wrote:
> 
> >> Pattern match, like they have for arguments
> >> in Erlang and SML?
> >
> > Pattern match like pcase, I guess.
> 
> Isn't that the same?

No. Regexps are built to match regular languages. Pcase is
built to match S-expressions, which are beyond regular.
Well-nested parentheses are more than a regular language.

Start with the Chomsky hierarchy[1], and delve as deep as
you like :-)

> AFAIK there isn't any
> native pattern matching i Lisp, but one can do
> it with macros...

whatever you understand by "native pattern matching".

> I don't like it personally because it makes
> writing code neurotic keeping track of all
> those cases, rather than just examine what the
> value is and act accordingly...

It's not a psychological question, but rather a mathematical
one: there are things you can't do with regexps.

> Whenever I use `pcase' it isn't really pattern
> matching in my eyes, i.e. in the Erlang/SML
> sense, more like a way of doing case with
> strings.

There lies your error: you are matching S-expressions, not
strings. The "case" part isn't the exciting one :-)

> I guess it could be used in other ways
> as well. Even tho technically it is the
> same thing.

Hmmm.

Cheers
[1] https://en.wikipedia.org/wiki/Chomsky_hierarchy

- -- tomás
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  reply	other threads:[~2017-12-25 19:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <mailman.6328.1514197667.27995.help-gnu-emacs@gnu.org>
2017-12-25 12:00 ` [el-search] How to search string excluding docstring? Emanuel Berg
2017-12-25 13:57   ` Chunyang Xu
2017-12-25 14:34     ` Michael Heerdegen
     [not found]   ` <mailman.6334.1514210258.27995.help-gnu-emacs@gnu.org>
2017-12-25 14:08     ` Emanuel Berg
2017-12-25 17:55       ` tomas
     [not found]       ` <mailman.6358.1514224565.27995.help-gnu-emacs@gnu.org>
2017-12-25 18:11         ` Emanuel Berg
2017-12-25 19:14           ` tomas [this message]
     [not found]           ` <mailman.6366.1514229270.27995.help-gnu-emacs@gnu.org>
2017-12-25 19:36             ` Emanuel Berg
2017-12-25 21:20               ` tomas
     [not found]               ` <mailman.6371.1514236843.27995.help-gnu-emacs@gnu.org>
2017-12-25 21:56                 ` Emanuel Berg
2017-12-26  2:44                   ` Emanuel Berg
2017-12-26 13:34                   ` Emanuel Berg
2017-12-26 13:48                     ` Jean-Christophe Helary
     [not found]                     ` <mailman.6381.1514296097.27995.help-gnu-emacs@gnu.org>
2017-12-26 15:19                       ` Emanuel Berg
2017-12-27  5:38                     ` Chunyang Xu
2017-12-27 13:58                       ` Michael Heerdegen
     [not found]                     ` <mailman.6406.1514353148.27995.help-gnu-emacs@gnu.org>
2017-12-27  6:58                       ` Emanuel Berg
2017-12-25 19:39             ` Emanuel Berg
2017-12-25 10:27 Chunyang Xu
2017-12-25 10:40 ` Jean-Christophe Helary
2017-12-25 12:00 ` Skip Montanaro
2017-12-25 18:04   ` Michael Heerdegen
2017-12-25 14:56 ` Michael Heerdegen
2017-12-25 16:58   ` Chunyang Xu
2017-12-25 17:51     ` Michael Heerdegen
     [not found] ` <mailman.6340.1514213787.27995.help-gnu-emacs@gnu.org>
2017-12-25 15:50   ` Emanuel Berg
2017-12-25 16:59     ` Michael Heerdegen
     [not found]     ` <mailman.6351.1514221174.27995.help-gnu-emacs@gnu.org>
2017-12-25 18:04       ` Emanuel Berg

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