missing 'xor' Boolean operator

Mark Dickinson dickinsm at gmail.com
Tue Jul 14 14:47:41 EDT 2009

On Jul 14, 7:25 pm, "Dr. Phillip M. Feldman" <pfeld... at verizon.net>
> Current Boolean operators are 'and', 'or', and 'not'.  It would be nice to
> have an 'xor' operator as well.

Hmm.  I don't think 'nice' is sufficient.  You'd need to make the case
that it's sufficiently useful to justify adding a new keyword 'xor' to
the language;  I suspect that would be an uphill struggle. :)

I'll just note that:

(1) It's easy to emulate xor:  'x xor y' <-> bool(x) != bool(y)

(2) 'and' and 'or' are special in that they have useful short-
circuiting behaviour; xor doesn't have this property (that is, you
always need to evaluate *both* operands to determine the result).

I'd also guess that 'xor' would be much less used than 'and' or 'or',
but maybe that's just a reflection of the sort of code that I tend to


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