[Python-ideas] `numbers.Natural`

[David Mertz]

On Fri, Sep 26, 2014 at 1:27 PM, Ian Cordasco <graffatcolmingov at gmail.com>
wrote:

>
> The only motivations I can think of for making this a type (not that
> they're good ones) is you could do something like:
>
> if isinstance(x, (Natural, Complex, Real)):
>    #
> elif isinstance(x, Rational):
>    #
> else:
>    raise ValueError
>

This code seems a bit broken, given:

>>> issubclass(numbers.Rational, numbers.Real)
Out[3]: True


> def isNatural(x):
>     return isinstance(x, int) and x > 0
>

I think the original desired behavior is this different one-liner:

    isNatural = lambda x: int(x)==x and x>0


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