From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Random832 Newsgroups: gmane.emacs.help Subject: Re: why are there [v e c t o r s] in Lisp? Date: Sat, 17 Oct 2015 00:40:08 -0400 Message-ID: <87lhb2w1jr.fsf@fastmail.com> References: <87mvvjeg29.fsf@kuiper.lan.informatimago.com> <87eggvebfs.fsf@kuiper.lan.informatimago.com> <87pp0eckss.fsf@kuiper.lan.informatimago.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1445056889 28434 80.91.229.3 (17 Oct 2015 04:41:29 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 17 Oct 2015 04:41:29 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sat Oct 17 06:41:21 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZnJJ3-0002hH-DA for geh-help-gnu-emacs@m.gmane.org; Sat, 17 Oct 2015 06:41:21 +0200 Original-Received: from localhost ([::1]:56971 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnJJ2-000431-DB for geh-help-gnu-emacs@m.gmane.org; Sat, 17 Oct 2015 00:41:20 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:48067) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnJIW-00040z-4i for help-gnu-emacs@gnu.org; Sat, 17 Oct 2015 00:40:49 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZnJIS-0006lQ-0q for help-gnu-emacs@gnu.org; Sat, 17 Oct 2015 00:40:48 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:42426) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnJIR-0006lM-RD for help-gnu-emacs@gnu.org; Sat, 17 Oct 2015 00:40:43 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZnJIM-0001yH-Oo for help-gnu-emacs@gnu.org; Sat, 17 Oct 2015 06:40:38 +0200 Original-Received: from c-68-39-146-59.hsd1.in.comcast.net ([68.39.146.59]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 17 Oct 2015 06:40:38 +0200 Original-Received: from random832 by c-68-39-146-59.hsd1.in.comcast.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 17 Oct 2015 06:40:38 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 38 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: c-68-39-146-59.hsd1.in.comcast.net User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Cancel-Lock: sha1:zgtYwWkt1tS7CSI5uhmEJSNBLRY= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:107692 Archived-At: "Pascal J. Bourguignon" writes: > Emanuel Berg writes: >> Why the syntax is there at all is to provide fast >> (faster) access to the vector data type which has >> other time and space properties than do lists. > > ABSOLUTELY NOT. > > For example, in C++ you have vectors and lists, > but you don't have any literal syntax for them. > > You can have fast and slow data structures without having any literal > syntax for it. > > > Why do you keep confusing the two concepts? There are certainly situations where having a literal syntax can make the language fast*er*. For example, in Python, the lack of a literal syntax for the frozendict and frozenset type means it has to do a runtime lookup on the name to make sure it hasn't been overridden, and it means they, despite being immutable objects, can't participate in a constants pool. C++ doesn't have any such mechanism to have uncertainty about what type a class name refers to, but a compiler would have to be very clever indeed to do the kind of optimized construction for arbitrary classes that it can do for types such as arrays and POD-structs for which literals do exist. Basically, a literal syntax doesn't make a type faster in general, but for many languages and many real-world implementations it can certainly make the specific action of constructing an object faster. Having a literal syntax means that the object can be completely pre-built at compile time, and for an immutable object it simply copies a pointer, and for a mutable object (in some cases) it can simply copy a block of memory. Whereas suppose make-vector were reassigned or advised.