From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Defining functions within functions? Date: Wed, 25 May 2016 04:36:16 -0400 Message-ID: References: <87k2ilbblk.fsf@mbork.pl> <87mvngsfiw.fsf@web.de> <874m9n6t3o.fsf@mbork.pl> <87vb2264mb.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1464165442 14514 80.91.229.3 (25 May 2016 08:37:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 25 May 2016 08:37:22 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed May 25 10:37:15 2016 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 1b5UJX-0005vm-DW for geh-help-gnu-emacs@m.gmane.org; Wed, 25 May 2016 10:37:15 +0200 Original-Received: from localhost ([::1]:58191 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5UJW-0001tm-My for geh-help-gnu-emacs@m.gmane.org; Wed, 25 May 2016 04:37:14 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:41184) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5UIn-0001ru-Aj for help-gnu-emacs@gnu.org; Wed, 25 May 2016 04:36:30 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b5UIk-0000gI-4X for help-gnu-emacs@gnu.org; Wed, 25 May 2016 04:36:29 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:34913) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5UIj-0000fx-TP for help-gnu-emacs@gnu.org; Wed, 25 May 2016 04:36:26 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1b5UIh-0005ce-Og for help-gnu-emacs@gnu.org; Wed, 25 May 2016 10:36:23 +0200 Original-Received: from 45.72.148.12 ([45.72.148.12]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 May 2016 10:36:23 +0200 Original-Received: from monnier by 45.72.148.12 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 May 2016 10:36:23 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 15 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 45.72.148.12 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) Cancel-Lock: sha1:YvCU5351VY78GLZysfJHgRKQsRU= 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: 2.1.21 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" Xref: news.gmane.org gmane.emacs.help:110104 Archived-At: > The reason is simple: I have this long, almost 60-lines function, with > three levels of lambdas nested. (I'm using request.el, and I have to > make two requests sequentially, so I have a callback inside a callback. > I could probably use deferred or something, this is one of the ideas.) > It's just pretty complicated, and changing anything in this code is > a headache. Also, edebugging is simpler with separate instrumentable > defuns. These kinds of callback codes are often described as "CPS-style code", and in some cases a couple of macros can go a long way to hiding this machinery and give the illusion of "plain old sequential code", reducing the nesting madness. Stefan