From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Jean Louis Newsgroups: gmane.emacs.help Subject: Re: Adding String to Beginning of Lines Date: Wed, 11 Nov 2020 00:22:24 +0300 Message-ID: References: <20201110111024.GA15992@tuxteam.de> <87zh3pctr1.fsf@web.de> <87o8k5csqj.fsf@web.de> <87tutxb7yz.fsf@web.de> <87y2j9f186.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19816"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mutt/2.0 (3d08634) (2020-11-07) Cc: help-gnu-emacs@gnu.org To: Michael Heerdegen Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Tue Nov 10 22:47:10 2020 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 1kcbTq-000538-09 for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 10 Nov 2020 22:47:10 +0100 Original-Received: from localhost ([::1]:53978 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kcbTp-0005sv-1r for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 10 Nov 2020 16:47:09 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:59898) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kcbT3-0005sh-7z for help-gnu-emacs@gnu.org; Tue, 10 Nov 2020 16:46:21 -0500 Original-Received: from static.rcdrun.com ([95.85.24.50]:39663) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kcbT0-0001U9-Vb for help-gnu-emacs@gnu.org; Tue, 10 Nov 2020 16:46:20 -0500 Original-Received: from localhost ([::ffff:197.157.34.177]) (AUTH: PLAIN admin, TLS: TLS1.2,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by static.rcdrun.com with ESMTPSA id 00000000002C0005.000000005FAB0A28.00002256; Tue, 10 Nov 2020 21:46:16 +0000 Content-Disposition: inline In-Reply-To: <87y2j9f186.fsf@web.de> Received-SPF: pass client-ip=95.85.24.50; envelope-from=bugs@gnu.support; helo=static.rcdrun.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/10 14:03:25 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.help:125214 Archived-At: * Michael Heerdegen [2020-11-10 22:42]: > If you look at the definition: > > (defsubst string-empty-p (string) > "Check whether STRING is empty." > (string= string "")) I looked as my thing collided and I did not know what is happening that suddenly everything is breaks. I cannot even see how that helps, it just gives better meaning maybe: (string-empty-p string) (string= st "") -- shorter and does same > and check the doc of `string=' you'll see that for symbols (like `nil') > their name is used as string. This is surely not useful for > `string-empty-p', but thus a symbol which has the empty string as name > (the interned one has a reader syntax "##") fulfills the predicate: > > (string-empty-p '##) ==> t > > No, that's not useful, just a side effect of the implementation. > > | (defun rcd-string-empty-p (s) > | "Returns T if string is empty or NIL" > | (let ((s (if (null s) "" s))) > | (if (stringp s) > | (if (zerop (length s)) t nil)))) > > That's more or less the same as > > (defun rcd-string-empty-p (s) > (or (null s) (and (stringp s) (zerop (length s))))) Alright. > But why handling an empty list specially, and not other empty sequences, > like the empty vector? That's what `seq-empty-p' in seq.el does, > btw. If I understand well I can simply remove my function and instead use seq-empty-p? It looks that it does what we discussed here.