From: Drew Adams <drew.adams@oracle.com>
To: Cecil Westerhof <Cecil@decebal.nl>, help-gnu-emacs@gnu.org
Subject: RE: Always using let*
Date: Sun, 14 Sep 2014 14:25:30 -0700 (PDT) [thread overview]
Message-ID: <93faab1c-96bd-4188-9686-3869fc027601@default> (raw)
In-Reply-To: <87fvfukmso.fsf@Equus.decebal.nl>
> Would it be OK to always use let*? I was just bitten by the fact
> that with let you can not previous variables from the let statement,
> as is possible with setq. So I am thinking about always using let*,
> so I do not have to think about it. Or are there good reasons to use
> let when you do not need let*?
The most common reason is when you want to use a variable value
in the cadr of a binding and you do *not* want to pick up the
variable's newly bound value. IOW, precisely the opposite use
case of what you wanted when you were bit.
(setq c 3)
(let ((c (+ c 4))
(b (* c 42))) ; Use original C value: 3
...)
(The other reason is that for some Lisps the bindings of `let'
can be done in parallel, which can be quicker.)
next prev parent reply other threads:[~2014-09-14 21:25 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 [this message]
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
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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