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Re: Always using let*
From: |
Cecil Westerhof |
Subject: |
Re: Always using let* |
Date: |
Mon, 15 Sep 2014 00:11:12 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
Op Sunday 14 Sep 2014 23:25 CEST schreef Drew Adams:
>> 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
> ...)
That makes my head spin. ;-)
> (The other reason is that for some Lisps the bindings of `let'
> can be done in parallel, which can be quicker.)
Nice to know, but in most cases the ‘let*’ will not be the bottleneck.
I think I am going to always use let*. Or maybe I should just engrave
the difference in my brain. After I was bitten, I remembered. Better
to remember before. :-)
--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof
- Re: Always using let*, (continued)
- Re: Always using let*, Emanuel Berg, 2014/09/18
- Message not available
- Re: Always using let*, sokobania . 01, 2014/09/16
- RE: Always using let*, Drew Adams, 2014/09/16
- Re: Always using let*, Stefan Monnier, 2014/09/16
- Re: Always using let*, Emanuel Berg, 2014/09/16
- Message not available
- Re: Always using let*, Emanuel Berg, 2014/09/16
- Re: Always using let*, Stefan Monnier, 2014/09/16
- Re: Always using let*, Emanuel Berg, 2014/09/16
Re: Always using let*, Joe Fineman, 2014/09/14
Message not available
Message not available
- Re: Always using let*,
Cecil Westerhof <=
Message not available
Message not availableRe: Always using let*, Stefan Monnier, 2014/09/14
Re: Always using let*, Pascal J. Bourguignon, 2014/09/14
Re: Always using let*, Stefan Monnier, 2014/09/15
RE: Always using let*, Drew Adams, 2014/09/15
Re: Always using let*, Stefan Monnier, 2014/09/15