steve+comp.lang.python at pearwood.info
Mon Jul 2 02:41:32 CEST 2012
On Sun, 01 Jul 2012 05:18:09 -0400, Devin Jeanpierre wrote:
> Also, you claimed earlier that the notion of associative "<" is not
> founded in mathematical notation. It really depends on whose
> mathematical notation you use -- there's more than one, you know. For
> example, it's reasonable to expect < to be left- or right-associative in
> a system like Rick Hehner's Unified Algebra:
> http://www.cs.toronto.edu/~hehner/UA.pdf (although, he himself doesn't
> specify it as being one or the other, so by default one would assume 'a
> < b < c' to be nonsensical.)
Sheesh guys. Don't go hunting through the most obscure corners of
mathematics for examples of computer scientists who have invented their
own maths notation. (Which, by your own admission, is under-specified and
therefore incomplete.) Who uses Hehner's "Unified Algebra" notation?
Apart from Hehner, if he even uses it himself.
Pick up any standard maths book and you will see chained comparisons used
with exactly the meaning that Python gives them.
For example, Wolfram MathWorld uses it:
Chained comparisons in the Python sense may be rare in computer
languages, but it is the standard in mathematics and hardly needs to be
explained to anyone over the age of twelve. That is a terrible indictment
on the state of programming language design.
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