On Mon, Jun 22, 2009 at 4:12 PM, Minimiscience<minimiscie...@gmail.com> wrote:
> On Jun 22, 2009, at 5:51 PM, Damian Conway wrote:
>> Perl 6's approach to xor is consistent with the linguistic sense of
>> 'xor' ("You may have a soup (x)or a salad (x)or a cocktail"), and also
>> with the IEEE 91 standard for logic gates.
> I don't think natural language -- especially the abomination that is English
> -- is the best guide for understanding logical operations (why, yes, I *do*
> speak Lojban; how did you know?).  As for consistency, Perl 6's bitwise
> exclusive-or operators follow the mathematical meaning of XOR, so using the
> "exactly one true value" definition for ^^ and xor would make Perl 6
> inconsistent with itself.

You're aware that Perl was designed by a linguist, with an eye toward
incorporating natural language concepts, right?

As for the bitwise xor: I consider the "inconsistency" between it and
the logical xor to be a feature, not a bug.  Mind you, it's a feature
that needs to be made apparent; but it's a feature nonetheless.
Specifically, it gives you a simple way of choosing which semantics
you wish to use: '^' gives you the natural language semantics, while
'?^' gives you the mathematical semantics.  This gives the programmer
an easy way of choosing which semantics he wants to use.

> I was going to say more in support of adding a separate operator for
> "exactly one true value," but Darren Duncan beat me to it.

Well, we already have "one" to mean "exactly one true value".

Jonathan "Dataweaver" Lang

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