Fibers/coroutines in SBCL

[orthecreedence]

You mentioned in a comp.lang.lisp thread that you implemented fiber support and were planning to implement unix's getcontext et al to make simple user-level threads portable to windows/unix.

Is this exposed anywhere in this branch? I'm currently developing a CL library for non-blocking IO and would love to build a layer on top of it that uses coroutines to simulate blocking IO.

Also, knowing very little (practically nothing) about the internals of most CL compilers, are coroutines something that are fairly easily implemented once threading is supported by an implementation? I think CL suffers by not having them and I'd love to get support for them in most thread-enabled implementations. Your thoughts/advice on this would be greatly appreciated.

Is there any documentation about the efforts to add green threads/coroutines/fibers to SBCL?

Also I found out about this through Nikodemus's blog.