[pypy-dev] Scheme front end - Google Summer of Code

Armin Rigo arigo at tunes.org
Thu Mar 22 15:40:36 CET 2007


Hi Michael,

On Sun, Mar 18, 2007 at 04:43:37PM +0000, Michael Hudson wrote:
> There's also the mildly interesting theoretical question of whether
> you can use the stackless primitive "yield_current_frame_to_caller" to
> implement call-with-current-continuation (I suspect not, but would be
> interesting to see how close you can get).

No, by itself it only gives one-shot continuations.  But then there is
the frightening topic of the cloning operation of our GC, which can be
used to clone whatever objects including such frame chains.  This gives
full continuations.  (For the records, in a stackless and framework-gc
build of pypy-c, you get "clonable coroutines" usable from the
application-level Python, which I think are a rather nicer way than
low-level continuations to express how much of the world you want to
copy and how much you want to share.)


A bientot,

Armin.



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