unofficial mirror of help-gnu-emacs@gnu.org
 help / color / mirror / Atom feed
From: David Kastrup <dak@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: Creating a list
Date: Thu, 19 Nov 2009 14:57:17 +0100	[thread overview]
Message-ID: <87y6m2ipmq.fsf@lola.goethe.zz> (raw)
In-Reply-To: 873a4afyi0.fsf@Traian.DecebalComp

Cecil Westerhof <Cecil@decebal.nl> writes:

> David Kastrup <dak@gnu.org> writes:
>
>>>>> At the moment I create a list with:
>>>>>       (setq ret-val (cons total-amount (cons current-amount ())))
>>>>> I thought about doing it with:
>>>>>       (setq ret-val (cons total-amount '(current-amount)))
>>>>>
>>>>> But then the second value is the string current-amount
>>>>
>>>> Wrong.  The _symbol_ current-amount.
>>>
>>> When evaluating I got:
>>>     (1570378.2570192777 current-amount)
>>> That is why I thought I got the string.
>>
>> A string would have quote marks around it.
>
> Off course.
>
> But I have a few questions on my mind.
> - Why is the first shown as value and the second as _symbol_?

Because you quoted the entire list containing the second value.

> - current-amount is a local variable. How is it possible that the symbol
>   is still defined?

I really recommend that you read a Lisp introduction.  Your questions
are very very basic.

A symbol, like a plain unquoted list, _is_ a valid expression all by
itself.  In the context of evaluation, a further interpretation tries
going from there (fetching a symbol's value, calling the first element
of a list as a function on the rest).  But whether or not you can
usefully call eval on it, either are printable and useful expressions.

-- 
David Kastrup


  parent reply	other threads:[~2009-11-19 13:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-19  7:38 Creating a list Cecil Westerhof
2009-11-19  8:35 ` David Kastrup
2009-11-19 10:59   ` Cecil Westerhof
2009-11-19 11:41     ` David Kastrup
2009-11-19 13:13       ` Cecil Westerhof
2009-11-19 13:47         ` Barry Margolin
2009-11-19 15:11           ` Cecil Westerhof
2009-11-19 19:26             ` Pascal J. Bourguignon
2009-11-19 13:57         ` David Kastrup [this message]
2009-11-19 15:14           ` Cecil Westerhof
2009-11-19 13:59         ` Pascal J. Bourguignon
2009-11-19 11:59   ` Gnus: Some new mails are automatically marked as 'O' Wang Lei

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87y6m2ipmq.fsf@lola.goethe.zz \
    --to=dak@gnu.org \
    --cc=help-gnu-emacs@gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).