Asynchronous event loop brainstorm at FSF 30

[Christopher Allan Webber <cwebber@dustycloud.org>]

So David Thompson, Mark Weaver, Andrew Engelbrecht and I sat down to
talk over how we might go about an asynchronous event loop in Guile that
might be fairly extensible.  Here are some of what we discussed, in
bullet points:

 - General idea is to do something coroutine based.

 - This would be like asyncio or node.js, asynchronous but *not* OS
   thread based (it's too much work to make much of Guile fit around
   that for now)

 - If you really need to maximize your multiple cores, you can do
   multiple processes with message passing anyway

 - Initially, this would probably providing a general API for
   coroutines.  Mark thinks delimited continuations would not be as
   efficient as he'd like, but we think it's okay because we could
   provide a nice abstraction where maybe something nicer could be
   swapped out later, so delimited continuations could at least be a
   starting point.

 - So what we really need is a nice API for how to do coroutines, write
   asynchronous code, and work with some event loop with a scheduler

 - On top of this, "fancier" high level systems like an actor model or
   something like Sly's functional reactive programming system could be
   done.

 - Probably a good way to start on this would be to use libuv (or is it
   libev?) and prototype this.  It's not clear if that's a good long
   term approach (eg, I think it doesn't work on the HURD for those who
   care about that, and Guix certainly does)

 - Binary/custom ports could be a nice means of abstraction for this

So, that's our thoughts, maybe someone or one of us or maybe even *you*
will be inspired to start from here?

To invoke Ludo, WDYT?
 - Not Ludo