[Stackless] interesting discussion on Scheme and continuations

Just van Rossum just at letterror.com
Wed Oct 18 09:17:48 CEST 2000


Thanks for those URL's! That sounds like an interesting thread with lots of
relevance for Python continuations. Before I dive in there, a couple of
comments.

At 7:08 AM +0200 18-10-2000, Jeremy Hylton wrote:
>There is an interesting discussion on continuations on the Scheme
>Request for Implementation mailing list (SRFIs as something like
>PEPs).  The thread index is here:
>http://srfi.schemers.org/srfi-18/mail-archive/threads.html#00003
>
>The thread seems particularly relevant given the current questions
>about how and whether the stackless changes should be incorporated
>into Python 2.1.
>
>Matthias Felleisen asked the reverse question about Scheme.
>http://srfi.schemers.org/srfi-18/mail-archive/msg00013.html
>
>>May I ask a heretical question (especially from me):
>>
>> How many of you use call/cc and continuation objects
>> (rather than mimicing continuations with lambda's)
>> in large programs? Do "we" really use it to implement
>> coroutines and backtracking and threads and whatever?
>>
>> Is call/cc necessary for Scheme?
>>
>>[Don't shoot. I wrote many papers on all aspects of call/cc
>>but now that we're building large systems we should revisit
>>these questions. I'd love to be wrong here.]
>>
>>-- Matthias

This seems to be about continuations. The questions need to be rephrased to
be of relevance for stackless Python:

1. Are continuations neccesary to implement co-routines & uthreads?
2. Are continuations neccesary for Python?

Answers:
1. No.
2. I honestly don't know...

However, if the question was:
3. Is a stackless version of Python neccesary to implement
   co-routines and uthreads?
..the answer would of course be "yes".

Just


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