[Python-3000] Type Comparisons with Godel Numbers

[Aahz]

On Sat, Apr 22, 2006, Greg Ewing wrote:
> Guido van Rossum wrote:
>>
>> If I have some utterly dynamic code that comes up with a list of a
>> million ints, and then I pass that as an argument to a function that
>> requests the argument type is list[int],
>
> you wrap it in something that checks elements for intness as you
> access them. It'll still check a million ints if you access them all,
> but that would have to be done anyway if you were passing the list
> to fully dynamic code. And it spreads the cost of doing it out over
> whatever is being done with the ints, rather than doing it all up
> front. And it doesn't bother checking any ints that you don't use.

Guido alluded to this, but let's make a specific example for clarity:

    def foo(a -> list[int]):
        for x in a:
            blah blah
        for y in a:
            blah blah

How do we handle the cost of doing the typecheck in the second loop?
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"Argue for your limitations, and sure enough they're yours."  --Richard Bach