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Re: [RFC] bytecomp: simple source-level optimization

From: Stephen J. Turnbull
Subject: Re: [RFC] bytecomp: simple source-level optimization
Date: Wed, 25 Jun 2014 10:08:01 +0900

David Kastrup writes:

 > You cannot reliably compare integers with eq in Common Lisp, cf
 > <URL:http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node74.html>:
 >     However, numbers with the same value need not be eq [...]
 > The current Elisp implementation in Emacs (though possibly not in
 > XEmacs,

If bignums are enabled, "large" integers do not have an immediate
representation in XEmacs and SXEmacs (where bignums may be enabled by
default by now).  And of course floats and markers do not have an
immediate representation, but they can be = to integers in numerical
comparisons.  Finally, in XEmacs (and SXEmacs) characters and (small)
integers both have immediate representation and can compare equal
numerically, but their representations are different (they're
different types), so a character can never be eq to any integer.

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