From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: "The starting list count" ????? Date: Mon, 03 Jan 2022 13:05:23 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="20110"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: Alan Mackenzie Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Jan 03 19:08:13 2022 Return-path: Envelope-to: ged-emacs-devel@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 1n4Rki-0004yO-Am for ged-emacs-devel@m.gmane-mx.org; Mon, 03 Jan 2022 19:08:12 +0100 Original-Received: from localhost ([::1]:57276 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n4Rkh-0006rq-36 for ged-emacs-devel@m.gmane-mx.org; Mon, 03 Jan 2022 13:08:11 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:48880) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n4RiA-0002vM-It for emacs-devel@gnu.org; Mon, 03 Jan 2022 13:05:37 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:33980) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n4Ri6-00048E-Kr for emacs-devel@gnu.org; Mon, 03 Jan 2022 13:05:33 -0500 Original-Received: from pmg1.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id A22081001C2; Mon, 3 Jan 2022 13:05:25 -0500 (EST) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 6B0FE10000B; Mon, 3 Jan 2022 13:05:24 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1641233124; bh=PskhQLQ3x+d2bLOcFhJNKS4Me7zn5ybhx9NRT1P4fnM=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=NbnjR/5NK1oWAz4tgIm35DX81lmA6AAR8+da9hRVsWNTRUZHHIzelTeUTEBgg6f9x zRNf1RN8wlphdO9112s/SHGwE/mGKpraamzJuapvNH1u5X+tru9GwvpXGOVY1oj/nE hbMw/c2v5B0vm4wu5GrD81IHg3KWu3wEgEmm8HT2fLPOy/e7b7qDhjhC9OjedB19oi 2FX1o3ViJ9ounVAiDYA1NGeZx+xrmsyuSjxHy6+cmWgOf4CDLLpRK++l1yl2Tv2Ar1 SNush5WbExqDeAMJAZEuAdBUiNOgy/XCFs7/t3EDgWBGPTehORVWItnpNEX+0hLS/F nPxAUCm78YrxA== Original-Received: from ceviche (unknown [216.154.30.173]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 384101203DF; Mon, 3 Jan 2022 13:05:24 -0500 (EST) In-Reply-To: (Alan Mackenzie's message of "Mon, 3 Jan 2022 17:49:40 +0000") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:284081 Archived-At: > .. What does this mean, please? What does "is the starting list count" > mean? There is only one "list", so what is the "list count"? I'm not sure how to define it in general, but: (let ((x (list 1 2 3 4 5 6 7))) (setf (nthcdr 5 x) (nthcdr N x)) x) returns a list with a #N inside of it (well, for N sufficiently small to make sense here, obviously). AFAIK this is only used to avoid inf-looping, but if/when you actually care about that you should use `print-circle` which additionally preserves sharing and gives an output that's more explicit about what's going on, and hence easier to understand (tho not necessarily easier to read). Stefan