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Re: Is this use of nreverse a good practice?
From: |
Pascal J. Bourguignon |
Subject: |
Re: Is this use of nreverse a good practice? |
Date: |
Sun, 01 Feb 2015 14:02:02 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:
> Hi there,
>
> I'm writing a small function which should build a list and return it.
> What I'm doing is more or less this:
>
> (defun myfunc ()
> (let ((list-var))
> (while CONDITION
> (DO-SOMETHING)
> (push SOME-ELEMENT list-var))
> (nreverse list-var)))
>
> A more concrete example:
>
> (defun reverse-range (n)
> (let ((list-var))
> (while (> n 0)
> (push n list-var)
> (decf n))
> (nreverse list-var)))
>
> (reverse-range 5)
>
> ⇒ (5 4 3 2 1)
>
> Is this usage of `nreverse' correct? I guess it is, since list-var is
> only a temporary variable and destructing it doesn't bother me.
> However, I'm never sure I'm doing things right when using
> nconc/nreverse, so I though I'd better ask...
Yes, this is THE use case for nreverse.
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
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