Re: [Chicken-users] serialization of functions, closures, continuations

[felix winkelmann]

On 5/18/05, Michele Simionato <address@hidden> wrote:
> 
> So it seems possible but technically difficult.

Possible, yes. But the caveats still apply. How does one handle
pointer objects or ports, closed over by a pocedure?

> Are there  Scheme implementations that can serialize functions and closures?

SISC and the current Gambit beta can. And perhaps Kawa (?)

> 
> Yes, I was reading
> 
> http://www.double.co.nz/scheme/modal-web-server.html
> 
> which is interesting but stops at the point of serializing continuations,
> making the approach unpractical, I cannot keep everything in memory!
> BTW, do you know how people solve this? I think PLT has a modal
> server in its library (not sure, I should check).

There was an announcement of a Web-server based on SISC on c.l.s
recently, which uses serialization of continuations (built on top of Javas
serialization features). PLT used to have something similar, but scalability
was low, so they are researching a global CPS-transformation on the source
level (http://www.ccs.neu.edu/scheme/pubs/ase2001-gfkf.pdf). I don't know
which status this project has, though. What I remember is that the continuation-
serialization approach had some problems and that an explicit, "coarser"
CPS control-flow offers better scalability.

> 
> The modal web server seems to be the only usage of continuations
> I cannot emulate with other means (i.e. if my language has already
> generators and coroutines, why would I want continuations? there
> would be a real advantage if I could serialize continuations, but it
> seems difficult/unpractical).
> 

Hey, call/cc makes lexically scoped "goto" possible, don't forget that ;-)

> 
> P.S: BTW, I have added a recipe on the Chicken Wiki on how to implement
> Python generators for the Pythonistas in this list ;)

Thanks a lot. Additions to the wiki are always welcome.


cheers,
felix