From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Rudolf Schlatte Newsgroups: gmane.emacs.help Subject: Re: Comparing lists Date: Tue, 12 Sep 2023 14:19:37 +0200 Message-ID: References: <87o7i7g8dq.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="7140"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:jSLRnHIhnUwKeQzAqo5UbctGfBQ= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Tue Sep 12 14:20:52 2023 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qg2Nw-0001ff-1X for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 12 Sep 2023 14:20:52 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qg2My-0000gN-5z; Tue, 12 Sep 2023 08:19:52 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qg2Mw-0000eI-19 for help-gnu-emacs@gnu.org; Tue, 12 Sep 2023 08:19:50 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qg2Mt-00084I-Lx for help-gnu-emacs@gnu.org; Tue, 12 Sep 2023 08:19:49 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1qg2Mq-00009A-Ec for help-gnu-emacs@gnu.org; Tue, 12 Sep 2023 14:19:44 +0200 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:145107 Archived-At: Emanuel Berg writes: > Petteri Hintsanen wrote: > >> I'm writing tests for Emms. There we have metadata >> structures like this: >> >> '((identification-header >> (opus-head . "OpusHead") >> (channel-count . 1) >> (opus-version . 1)) >> (comment-header >> (opus-tags . "OpusTags") >> (vendor-length . 13) >> (user-comments >> ((length . 38) (user-comment . "ENCODER=opusenc from opus-tools 0.1.10")) >> ((length . 7) (user-comment . "foo=bar")) >> ((length . 5) (user-comment . "Key=x"))) >> (vendor-string . "libopus 1.3.1") >> (user-comments-list-length . 3))) >> >> These come from bindat-unpack function. >> >> The problem is that sometimes the same data can be in >> a reversed or otherwise different order [...] > > So it is, basically, that data can be (1 2) or (2 1), and they > should be considered the same? > > The solution seems to be, either you write your own function > to check for equality (as you did), _or_ you normalize the > data and then use a standard function, in this case `equal'. > > So with normalization it could look like this: > > (require 'cl-lib) > > (cl-labels ((sort-list (lst) (sort lst #'<))) > (equal (sort-list '(1 2)) > (sort-list '(2 1)) )) ; t Mind the documentation of sort, especially the sentence "SEQ is modified by side effects.". So, the above code should rather be: (cl-labels ((sort-list (list) (sort (copy-list list) #'<))) (equal (sort-list '(1 2)) (sort-list '(2 1)) )) ; t