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From: "Drew Adams" <drew.adams@oracle.com>
To: "'Thorsten Jolitz'" <tjolitz@gmail.com>, <help-gnu-emacs@gnu.org>
Subject: RE: 'length' function for lists and cons cells?
Date: Thu, 21 Mar 2013 15:05:16 -0700	[thread overview]
Message-ID: <4080986E7D894641B2B9A10FAF3FDCBC@us.oracle.com> (raw)
In-Reply-To: <871ub876us.fsf@gmail.com>

> actually I'm looking for a way to distinguish between cons cells and
> regular lists to avoid the errors when mapping an alist that contains
> both with functions that work only on one of them, using 'length' was
> just a hack. 

You distinguish them by the way they are distinguished ;-), i.e., by whether the
cdr of the last cons cell is non-nil.

A true list is either nil or a cons that has a true list as its cdr.  This
implies that it has nil as the cdr of its last cons.

See my previous message.




  reply	other threads:[~2013-03-21 22:05 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-21 18:21 'length' function for lists and cons cells? Thorsten Jolitz
2013-03-21 20:02 ` Stephen Berman
2013-03-21 21:58   ` Thorsten Jolitz
2013-03-21 22:05     ` Drew Adams [this message]
     [not found]   ` <mailman.22591.1363903134.855.help-gnu-emacs@gnu.org>
2013-03-23 11:24     ` Pascal J. Bourguignon
2013-03-21 20:10 ` Drew Adams
2013-03-21 22:09   ` Thorsten Jolitz
     [not found] ` <mailman.22588.1363896620.855.help-gnu-emacs@gnu.org>
2013-03-25 15:24   ` duthen.cnv
2013-03-25 20:02     ` Pascal J. Bourguignon
     [not found] <mailman.22586.1363890109.855.help-gnu-emacs@gnu.org>
2013-03-21 20:49 ` Pascal J. Bourguignon
2013-03-22  2:38   ` Thorsten Jolitz
2013-03-22  7:27     ` Mark Skilbeck
2013-03-22  9:57       ` Thorsten Jolitz
     [not found]       ` <mailman.22632.1363946271.855.help-gnu-emacs@gnu.org>
2013-03-23 12:19         ` Pascal J. Bourguignon
2013-03-23 15:35           ` Drew Adams
     [not found]           ` <mailman.22706.1364052941.855.help-gnu-emacs@gnu.org>
2013-03-23 15:52             ` Pascal J. Bourguignon
2013-03-24  5:20               ` Drew Adams
     [not found]   ` <mailman.22618.1363919920.855.help-gnu-emacs@gnu.org>
2013-03-22  7:45     ` Barry Margolin
2013-03-23 11:31     ` Pascal J. Bourguignon

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