From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Improving aesthetics & readability of backquote Date: Sun, 19 May 2019 23:38:38 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="25462"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon May 20 05:38:59 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hSZ8c-0006TS-SN for ged-emacs-devel@m.gmane.org; Mon, 20 May 2019 05:38:59 +0200 Original-Received: from localhost ([127.0.0.1]:57278 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hSZ8b-00078E-Tj for ged-emacs-devel@m.gmane.org; Sun, 19 May 2019 23:38:57 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:55684) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hSZ8W-000787-4m for emacs-devel@gnu.org; Sun, 19 May 2019 23:38:52 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hSZ8V-0005z9-9I for emacs-devel@gnu.org; Sun, 19 May 2019 23:38:52 -0400 Original-Received: from [195.159.176.226] (port=55324 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hSZ8V-0005xM-2Z for emacs-devel@gnu.org; Sun, 19 May 2019 23:38:51 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1hSZ8R-0006IE-6V for emacs-devel@gnu.org; Mon, 20 May 2019 05:38:47 +0200 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:QK6NS/DCQDuWIGwN/eO1cvS6bH0= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:236771 Archived-At: > Then it would be a case of augmenting the "unquote" ,VAR and "splice" ,@VAR > reader constructs: > > (quoteval (1 2 (unquote a) 5 (splice b) 8 )) > -> (1 2 (3 4) 5 6 7 8) You'd feel quite at home in Scheme where the reader's 'E => (quote E) is complemented by `E => (quasiquote E) ,E => (unquote E) ,@E => (unquote-splicing E) Elisp doesn't have that, mostly for historical reasons, I think. I haven't been able to confirm it, but I believe the road looked like: the Elisp reader originally only had the `quote` special element and since people don't like to write (backquote (foo bar (unquote baz))), they started writing (` (foo bar (, baz))) which was at least vaguely reminiscent of the "normal" backquote/unquote used in other Lisps. This is the "old-style" quotes. When the new-style quotes were added to the reader (those that look like regular Lisp) it was natural to map `E => (` E) so that the existing definition of the ` macro worked both with the new and with the old syntax. Stefan