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RE: 'length' function for lists and cons cells?
From: |
Drew Adams |
Subject: |
RE: 'length' function for lists and cons cells? |
Date: |
Sat, 23 Mar 2013 08:35:24 -0700 |
> > So if both, true lists and cons cells, are processed in a...
>
> proper-lists, not true lists.
> They all are true lists, ie. cons cells or nil.
Maybe for some people. For others, "true list" and "proper list" mean the same
thing. FWIW, Emacs itself calls such a beast a "true list".
>From (elisp) `Cons Cells':
Also by convention, the CDR of the last cons cell in a
list is `nil'. We call such a `nil'-terminated structure
a "true list". In Emacs Lisp, the symbol `nil' is both
a symbol and a list with no elements. For convenience,
the symbol `nil' is considered to have `nil' as its CDR
(and also as its CAR).
Hence, the CDR of a true list is always a true list.
The CDR of a nonempty true list is a true list containing
all the elements except the first.
If the CDR of a list's last cons cell is some value
other than `nil', we call the structure a "dotted list"...
In any case, it is the description/meaning that is most important, not the name,
and there we agree.
- Re: 'length' function for lists and cons cells?, (continued)
RE: 'length' function for lists and cons cells?, Drew Adams, 2013/03/21
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Re: 'length' function for lists and cons cells?, Pascal J. Bourguignon, 2013/03/21
- Re: 'length' function for lists and cons cells?, Thorsten Jolitz, 2013/03/21
- Re: 'length' function for lists and cons cells?, Mark Skilbeck, 2013/03/22
- Re: 'length' function for lists and cons cells?, Thorsten Jolitz, 2013/03/22
- Message not available
- Re: 'length' function for lists and cons cells?, Pascal J. Bourguignon, 2013/03/23
- RE: 'length' function for lists and cons cells?,
Drew Adams <=
- Message not available
- Re: 'length' function for lists and cons cells?, Pascal J. Bourguignon, 2013/03/23
- RE: 'length' function for lists and cons cells?, Drew Adams, 2013/03/24
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