From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: David Kastrup Newsgroups: gmane.lisp.guile.user Subject: Re: dynamic-wind Date: Wed, 05 Jul 2017 10:23:50 +0200 Organization: Organization?!? Message-ID: <87r2xvb8bt.fsf@fencepost.gnu.org> References: <20170702125831.192ddaec@bother.homenet> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1499243189 25349 195.159.176.226 (5 Jul 2017 08:26:29 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 5 Jul 2017 08:26:29 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Wed Jul 05 10:26:25 2017 Return-path: Envelope-to: guile-user@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dSfdg-0006Ko-7J for guile-user@m.gmane.org; Wed, 05 Jul 2017 10:26:24 +0200 Original-Received: from localhost ([::1]:44807 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSfdl-0001Pz-IF for guile-user@m.gmane.org; Wed, 05 Jul 2017 04:26:29 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:36943) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSfbW-0008U4-Br for guile-user@gnu.org; Wed, 05 Jul 2017 04:24:12 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dSfbT-0001Dy-7S for guile-user@gnu.org; Wed, 05 Jul 2017 04:24:10 -0400 Original-Received: from [195.159.176.226] (port=39128 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dSfbT-0001D1-0z for guile-user@gnu.org; Wed, 05 Jul 2017 04:24:07 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1dSfbG-0007SB-78 for guile-user@gnu.org; Wed, 05 Jul 2017 10:23:54 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 33 Original-X-Complaints-To: usenet@blaine.gmane.org X-Face: 2FEFf>]>q>2iw=B6, xrUubRI>pR&Ml9=ao@P@i)L:\urd*t9M~y1^:+Y]'C0~{mAl`oQuAl \!3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN; i"; /yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi$t^ Vc\LWP@J5p^rst0+('>Er0=^1{]M9!p?&:\z]|;&=NP3AhB!B_bi^]Pfkw Cancel-Lock: sha1:IObQ0IGeQhzGNVWctNeblNCfzKM= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-user-bounces+guile-user=m.gmane.org@gnu.org Original-Sender: "guile-user" Xref: news.gmane.org gmane.lisp.guile.user:13896 Archived-At: Catonano writes: > Chris, > > thank you for your remarks. > > Yo're right that I was being caught up by continuations AND that I was > probably missing the generality of the concept of dynamic wind > > And yet, I still want to clarify my point > > My point is not that the manual is incomplete or inaccurate > > My point is that the manual does not a good job of _introducing_ people to > the concept of dynamic wind > > Especially people wo have not clear in mind a complete map of the use cases > with relative possible solutions. > > The manual tends to be a very good reference for already educated people. > But it's not as good in educating people in the first place, in my view. Arguably the manual example is not done well because it does not cater for the case that other continuations might get invoked from a different cwd. So the cwd should get caught in the entry path of the dynamic-wind rather than outside, something which I find surprisingly hard to do. It's also not clear to me what the semantics of delimited continuations are: for those I don't see a formal reason that there couldn't be several active at the same time, making resource management via dynamic-wind even more tricky. -- David Kastrup