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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: help-gnu-emacs@gnu.org
Subject: Re: Always using let*
Date: Mon, 15 Sep 2014 08:31:35 -0400	[thread overview]
Message-ID: <jwvegvdgje8.fsf-monnier+gmane.emacs.help@gnu.org> (raw)
In-Reply-To: 87mwa1lhb1.fsf@kuiper.lan.informatimago.com

> But if you have side-effect free expressions, (or at least, provably
> independent ones), then they could be evaluated in parallel despite the
> left-to-right rule.

Same holds for let* or pretty much anything else for that matter: if
some analysis can prove that it can be done in parallel, well, then
unsurprisingly it can be performed in parallel.  But it's not the
"parallel binding" semantics of `let' that lets you do that.

While some details of language semantics can make analysis of code
easier for that (e.g. the non-aliasing constraints on arguments in
Fortran), I've never heard of anyone being able to use the
parallel-binding of "let" for that.

So, I stand by my claim: it's an Urban Legend.


        Stefan




  reply	other threads:[~2014-09-15 12:31 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-14 19:46 Always using let* Cecil Westerhof
2014-09-14 21:25 ` Drew Adams
2014-09-15 16:15   ` Drew Adams
     [not found]   ` <mailman.8924.1410797740.1147.help-gnu-emacs@gnu.org>
2014-09-15 18:01     ` Cecil Westerhof
2014-09-15 22:20       ` Emanuel Berg
2014-09-16 12:05         ` Cecil Westerhof
2014-09-16 22:40           ` Emanuel Berg
2014-09-18 17:02             ` Cecil Westerhof
2014-09-18 21:05               ` Emanuel Berg
2014-09-16 14:23     ` sokobania.01
2014-09-16 16:41       ` Drew Adams
2014-09-16 20:49       ` Stefan Monnier
2014-09-16 22:45       ` Emanuel Berg
     [not found]       ` <mailman.8998.1410901776.1147.help-gnu-emacs@gnu.org>
2014-09-16 22:48         ` Emanuel Berg
2014-09-17  1:09           ` Stefan Monnier
2014-09-17  1:18             ` Emanuel Berg
2014-09-14 21:40 ` Joe Fineman
     [not found] ` <mailman.8868.1410729956.1147.help-gnu-emacs@gnu.org>
2014-09-14 21:41   ` Emanuel Berg
2014-09-14 22:11   ` Cecil Westerhof
2014-09-14 22:56     ` Drew Adams
2014-09-14 22:41   ` Stefan Monnier
2014-09-14 23:06     ` Drew Adams
     [not found]     ` <mailman.8871.1410736002.1147.help-gnu-emacs@gnu.org>
2014-09-15  0:47       ` Emanuel Berg
2014-09-15  2:12         ` Pascal J. Bourguignon
2014-09-15  2:22       ` Stefan Monnier
2014-09-15  2:59         ` Pascal J. Bourguignon
2014-09-15 12:31           ` Stefan Monnier [this message]
2014-09-15 16:15             ` Drew Adams
2014-09-15 19:05               ` Stefan Monnier
     [not found]               ` <mailman.8930.1410808006.1147.help-gnu-emacs@gnu.org>
2014-09-15 22:28                 ` Emanuel Berg
2014-09-16  0:38                   ` Pascal J. Bourguignon
2014-09-15 13:14           ` Barry Margolin

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