On Wed, May 04, 2005 at 07:29:35AM -0700, Mark A. Biggar wrote:
> Except that xor or ^^ is only a binary operation, there is no
> "xor(p1,p2,...)", only "p1 xor p2 xor ..." which can really only be
> understood if you add () to disambiguate the order that the binary ops
> are performed. Fortunately, xor is associative so it doesn't matter how
> you add the (), you get the same answer. Try it out, you will discover
> that "p1 xor p2 xor ..." is true iff an odd number of the p's are true.
Be careful here, although C<xor> is indeed a binary op, that doesn't
make it a boolean one. In particular, C<xor> is NOT associative:
print ( ("a" xor "b") xor "c"); # outputs "c"
print ( "a" xor ("b" xor "c")); # outputs "a"
We might get the "select one value" interpretation of C<xor>
if xor is defined as a chained operator of some sort, but that's
really up to the perl6-language folks to decide (and any folloups
on that topic should go there).
Pm
