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Re: Are symbols garbage collected?

From: Christopher Allan Webber
Subject: Re: Are symbols garbage collected?
Date: Mon, 23 Oct 2017 14:30:53 -0500
User-agent: mu4e 0.9.18; emacs 25.3.1

David Kastrup writes:

> Christopher Allan Webber <address@hidden> writes:
>> I thought they weren't but now I'm not really sure where I got that
>> idea from.  Does anyone know for sure?
> They are garbage-collected.  This is not overly relevant outside of
> C/C++ code since as long as any code references a symbol, it will stay
> around.  It's only when you look at things like its address independent
> of the symbol that you'd notice.
> scheme@(guile-user)> (object-address 'blablaaaaaa)
> $4 = 94515697299616
> scheme@(guile-user)> (gc)
> scheme@(guile-user)> (object-address 'blablaaaaaa)
> $5 = 94515696660320
> scheme@(guile-user)> 
> Similar for hashq: without the symbol being stored somewhere, it will
> likely deliver different values each time round.
> If you put this into code rather than retyping it on the command line,
> the address will be the same each time.  You'd need to use something
> like
> (string->symbol "blablaaaaaa")
> in order to get different addresses: a literal symbol in the code would
> be protected.

Thanks for the reply!  That's helpful.  Dave Thompson also did a little
demo for me, and I'm totally convinced that symbols are GC'ed now. :)

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