[Python-Dev] Boolean transition

[Samuele Pedroni]

[Tim]
> I liked the APL approach best, simply because it was most useful.  Perhaps
> that's because my non-programming background is in discrete mathematics,
> where identifying 0/1 with false/true is of great practical value.  For
> example, see "Concrete Mathematics" (Knuth, Graham and Patashnik), where
> treating a true/false result as 1/0 is so common it's indicated merely by
> surrounding a predicate expression with plain square brackets.  This was a
> notational advance over the non-programming state of the art (most texts
> before CM, including Knuth's TAoCP, use a clumsy Kronecker delta notation).
> The programming state of the art would be advanced a little by Guido's PEP,
> in my view of the world.
> 

I agree with Tim, additivity for booleans means that you can
use predicates also as the indicator function of their corresponding
sets:

def count_visible(win_list):
  c = 0
  for win in win_list:
     c+=win.visible
  return c

Personally I find that very readable.

I can find also a senbible meaning for other mixed int/boolean
arithmetic operations. 

I can find also meaningless combinations but concretely
what kind of errors would the separation avoid?

regards.