[Python-Dev] PEP239 (Rational Numbers) Reference Implementation and new issues

[Eric S. Raymond]

Andrew Koenig <ark@research.att.com>:
> Eric> APL faced this problem twenty-five years ago.  I like its
> Eric> solution; a `fuzz' variable defining the
> Eric> close-enough-for-equality range.
> 
> I used to like APL's approach, but I've changed my mind.
> 
> Part of the reason is that there are some places where unfuzzed
> comparison is essential, such as sorting.  Another part is that
> fuzzy comparison destroys substitutability:  If a==b, it is
> not always true that f(a)==f(b).
> 
> Much as I like APL, I'd rather use Scheme's numeric model.

Good points...but the fuzz variable could default to zero.  It didn't in APL,
which I always thought a mistake.
-- 
		<a href="http://www.tuxedo.org/~esr/">Eric S. Raymond</a>