# [Python-ideas] Aid reiteration with new class: gfic

Mathias Panzenböck grosser.meister.morti at gmx.net
Sat Jun 20 21:23:54 CEST 2009

```Lie Ryan wrote:
> Steven D'Aprano wrote:
>> On Sat, 20 Jun 2009 01:55:42 pm John Graham wrote:
>>
>>> Hrm, that leads to the question, is it mathematically possible to
>>> iterate over an infinite list... twice? :)
>> Mathematically, yes. Practically, no.
>>
>> Mathematically, the trick is to ensure that the time it takes to iterate
>> over each item approaches zero sufficiently fast. E.g. if it takes 1
>> unit of time to process the first item, and 1/2 units of time for the
>> second, and 1/4 for the third, 1/8 for the fourth, etc, then you can
>> iterate over an infinite number of items in 2 units of time total. Then
>> you can do them all again :)
>
> It is also possible to do parallel iteration, but I'm not sure that
> mathematically parallel processing makes sense. I'm not even sure that
> mathematically there is such thing as iteration (that does not involve
> recursion).
>

Well there is something called "process algebra" (at least I think its called
that way, in german its: Prozess Algebra). This provides a (mathematical?) model
for such things.

```