[Python-Dev] Can Python implementations reject semantically invalid expressions?

[Stefan Behnel]

Glyph Lefkowitz, 02.07.2010 06:43:
> On Jul 2, 2010, at 12:28 AM, Steven D'Aprano wrote:
>
>> This question was inspired by something asked on #python today. Consider
>> it a hypothetical, not a serious proposal.
>>
>> We know that many semantic errors in Python lead to runtime errors, e.g.
>> 1 + "1". If an implementation rejected them at compile time, would it
>> still be Python? E.g. if the keyhole optimizer raised SyntaxError (or
>> some other exception) on seeing this:
>>
>> def f():
>>     return 1 + "1"
>>
>> instead of compiling something which can't fail to raise an exception,
>> would that still be a legal Python implementation?
>
> I'd say "no".  Python has defined semantics in this situation: a TypeError is raised.

So, would it still be Python if it folded

     1 + "1"

into

     raise TypeError()

at compile time?

Stefan