RE: About self-referential object

[Drew Adams]

> (setq foo '(nil)) => (nil)
> (setcar foo foo)  => (#0)
> 
> It is an infinite recursion.  What does the `#0' mean here?  

The Elisp manual is your friend.  There are no doubt several ways to look this
up.  Start with `i' usually, which uses the indexes.

If you don't find what you want using `i' then try searching: `C-s #0' finds an
answer immediately in this case, in node `Output Function'.

If you can find what you want by means other than using the indexes (`i'),
consider reporting an Emacs bug to improve the index, explaining how you tried
to find it.