I just had a nice side discussion with Eli that has allayed many of my fears
at the prospect of merging this branch.

What we're talking about here is not the kind of concurrency that leads to
nightmares involving corruption of global state, but cooperative concurrency.
Think of it as "timers, done right", if that helps. It would make a library
like emacs-deferred trivial to write, for example, which today is tortuously
implemented on top of the hackish timers we have now.

Tom, if I can find some volunteers to help, would you be willing to see the
work of merging this into master through to completion?

-- 
John Wiegley                  GPG fingerprint = 4710 CF98 AF9B 327B B80F
http://newartisans.com                          60E1 46C4 BD1A 7AC1 4BA2