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Re: Elisp development news


From: Marius Vollmer
Subject: Re: Elisp development news
Date: 09 Jan 2002 22:25:32 +0100
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.1

Neil Jerram <address@hidden> writes:

> >>>>> "Marius" == Marius Vollmer <address@hidden> writes:
> 
>     Marius> Neil Jerram <address@hidden> writes:
>     >> I don't see why it's useful for the Elisp nil value to satisfy
>     >> Scheme's `symbol?'.
> 
>     Marius> What about 
> 
>     Marius>     (setq big-rivers '(amazonas nil ruhr))
> 
> What about it? :-)  This is Elisp code.

Yes, and I thought that Scheme might want to work with this list as
well... but

> Actually, the nil value can't be a Scheme symbol, at least not the one
> with name `nil'.  If it was, unsuspecting Scheme code could be tricked
> up by this:
> 
> (if 'nil #t #f)
> => #t              ; R5RS
> => #f              ; Guile, if 'nil evaluates to the Elisp nil value
> 
> IMO this would be an unacceptable violation of R5RS.

Right, damn.  I didn't think of this.  So nil can't be a Scheme
symbol, which makes it easier for us.



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