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Re: (0 <= i && i < N) is not "backwards"

From: Paul Eggert
Subject: Re: (0 <= i && i < N) is not "backwards"
Date: Mon, 25 Mar 2013 09:49:28 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4

On 03/25/13 07:53, Eli Zaretskii wrote:
> the problem with relying on 0 < foo is that most people won't even
> consider the subtle difference between that and !(foo >= 0)

There must be dozens of places in the Emacs source code that
use floating-point comparisons and rely on NaNs behaving the
way that they do.  It'd be unnecessary clutter to add comments
and/or isnan() calls to them all.  Sure, we could modify our
compilers (and this would include the Emacs Lisp compiler)
to recognize and optimize-away the isnan calls, but that would
be even more make-work.  Programmers who deal with
floating-point should be cognizant of NaNs; that's just
life in the floating-point big city these days.

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