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Re: The empty string and other empty strings


From: David Kastrup
Subject: Re: The empty string and other empty strings
Date: Fri, 13 Jan 2012 10:27:43 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.92 (gnu/linux)

address@hidden (Ludovic Courtès) writes:

> Hi Mark,
>
> Mark H Weaver <address@hidden> skribis:
>
>> What do other people think?
>
> As you said, R5RS makes it clear that there can be several (in the sense
> of eq?) empty strings, so I think what you did is the right thing.

Since it uses the same verbiage with regard to '(), could you please
point out _where_ R5RS states that "freshly allocated" means "not eq?"?
For me it means "does not contain any component in common with
previously allocated material".  The fixed constant '() or (list) (the
neutral element with regard to list concatenation) not containing any
allocated pairs meets that description, and the fixed constant "" or
(string) (the neutral element with regard to string concatenation) not
containing any allocated characters meets that description.

So why treat them differently?  What does it buy us except trouble?

-- 
David Kastrup




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