Are the critiques in "All the things I hate about Python" valid?

[Steven D'Aprano]

On Mon, 19 Feb 2018 09:40:09 +0100, Alain Ketterlin wrote:

> Tim Delaney <timothy.c.delaney at gmail.com> writes:
> 
> [...]
>> As others have said, typing is about how the underlying memory is
>> treated.
> 
> No. It is much more than that. Typing is about everything you can say
> about a given statement.

"Everything"? Truly *everything*?

Given:

    # engage the type system somehow...
    # declare a, b, c: non-negative integers
    a = abs(int(input("Give me an integer")))
    b = a*a
    c = (a+1)*(a+1)

can you give me an example of a type-system which is capable of telling 
me that:

    if (c - b) % 2 == 1:
        print("hello world")
    else:
        fire_missiles()

will never fire the missiles?

I'd be impressed enough with a type system that knew that a%2 was always 
0 or 1, although I suppose there could be some that already know that.

Hell, I'd even be impressed if it could tell that c was not zero...



-- 
Steve