From: Barry Margolin <barmar@alum.mit.edu>
To: help-gnu-emacs@gnu.org
Subject: Re: What does "lacks a prefix" mean?
Date: Fri, 10 Jul 2015 14:27:40 -0400 [thread overview]
Message-ID: <barmar-1C5C7B.14274010072015@88-209-239-213.giganet.hu> (raw)
In-Reply-To: mailman.6685.1436547891.904.help-gnu-emacs@gnu.org
In article <mailman.6685.1436547891.904.help-gnu-emacs@gnu.org>,
Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> >> let* says "I need variables which depend on each
> >> other" and if they're really not, that look strange.
>
> If let behaved like let* it wouldn't look strange to you. Many other
> functional languages dropped the "simultaneous let" and only kept the
> equivalent of let* (or even letrec).
It should be noted that the original LET macro in MacLisp was basically
a rearranged LAMBDA:
(let ((var1 val1) (var2 val2) ...) body...)
==>
((lambda (var1 var2 ...) body...) val1 val2 ...)
When written this way, you can see where the order of evaluation of the
values, and the parallel binding of the variables came from: arguments
to a function have to be evaluated before the function is called (except
in "lazy" languages).
Most other languages also have function call syntax, and if they have
anonymous functions they can express the same parallel binding. E.g. in
Javascript you can write an "IIFE":
(function(var1, var2, ...) {body...})(val1, val2, ...)
This is actually a common idiom (and whenever I see it, I cringe that
they somehow discovered the original Lisp syntax, yet didn't adopt the
LET-style rewrite that makes it easier to comprehend).
What they generally don't have is multiple ways to introduce local
variables in the same scope of a function.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
next prev parent reply other threads:[~2015-07-10 18:27 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 16:32 What does "lacks a prefix" mean? BobD
2015-07-08 16:45 ` Barry Margolin
2015-07-08 16:59 ` Vaidheeswaran C
2015-07-08 17:10 ` Vaidheeswaran C
2015-07-08 18:17 ` BobD
2015-07-08 18:21 ` Pascal J. Bourguignon
2015-07-08 18:45 ` BobD
2015-07-08 23:24 ` Emanuel Berg
2015-07-09 15:23 ` Filipp Gunbin
2015-07-09 22:32 ` Emanuel Berg
2015-07-10 17:04 ` Stefan Monnier
2015-07-11 22:42 ` Emanuel Berg
[not found] ` <mailman.6748.1436654668.904.help-gnu-emacs@gnu.org>
2015-07-11 23:58 ` Barry Margolin
2015-07-13 12:26 ` Filipp Gunbin
[not found] ` <mailman.6685.1436547891.904.help-gnu-emacs@gnu.org>
2015-07-10 18:27 ` Barry Margolin [this message]
[not found] ` <mailman.6612.1436455429.904.help-gnu-emacs@gnu.org>
2015-07-09 23:27 ` Barry Margolin
[not found] ` <mailman.6643.1436488423.904.help-gnu-emacs@gnu.org>
2015-07-10 0:49 ` Pascal J. Bourguignon
2015-07-10 5:04 ` Drew Adams
2015-07-10 14:42 ` Barry Margolin
[not found] ` <<barmar-2BC802.10421910072015@88-209-239-213.giganet.hu>
2015-07-10 14:53 ` Drew Adams
[not found] ` <<barmar-500871.19271109072015@88-209-239-213.giganet.hu>
2015-07-10 0:33 ` Drew Adams
[not found] ` <mailman.6590.1436397914.904.help-gnu-emacs@gnu.org>
2015-07-09 14:01 ` Barry Margolin
2015-07-09 14:10 ` Rusi
2015-07-09 22:27 ` Emanuel Berg
[not found] ` <mailman.6639.1436481016.904.help-gnu-emacs@gnu.org>
2015-07-10 3:10 ` Rusi
2015-07-10 16:00 ` Emanuel Berg
2015-07-09 22:19 ` Emanuel Berg
[not found] ` <<barmar-F23189.10014209072015@88-209-239-213.giganet.hu>
2015-07-09 15:33 ` Drew Adams
2015-07-12 1:47 ` Emanuel Berg
2015-07-12 16:59 ` Drew Adams
2015-07-13 0:46 ` Emanuel Berg
2015-07-13 7:26 ` Yuri Khan
2015-07-13 23:47 ` Emanuel Berg
2015-07-14 6:23 ` Yuri Khan
2015-07-14 21:58 ` Emanuel Berg
2015-07-19 0:59 ` Robert Thorpe
2015-07-28 0:24 ` Emanuel Berg
2015-07-30 1:40 ` Robert Thorpe
[not found] ` <mailman.7638.1438220428.904.help-gnu-emacs@gnu.org>
2015-07-30 2:49 ` Rusi
2015-07-30 2:53 ` Rusi
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