PEP 285: Adding a bool type

[Martin v. Loewis]

Pearu Peterson <pearu at cens.ioc.ee> writes:

> Just a random thought ...
> 
> Theorem:
> ========
> Assume specification of PEP 285. The following statements hold truth:
> 
>   True is One
> 
> and
> 
>   False is Zero,
> 
> where One and Zero represent integers 1 and 0, respectively.

It depends on what the meaning of 'is' is. Did you mean 'is' in the
Python sense of checking identity? Then this theorem can't possibly
true: type(One) is int and type(True) is bool implies One is not True.

> 
> Proof:
> ------
> According to PEP, True and False are instances of bool that is a subclass
> of int. Therefore True and False can be considered as integers and it
> makes sense to compare them with integers. If n is an integer then the
> following statements hold
> 
>   True == n   only if n is 1
> 
> and
> 
>   False == n  only if n is 0.

That is correct. However, a==b does not imply a is b.

Regards,
Martin