Status of callcc

[Charles Oliver Nutter]

While I'm waiting, hopefully, for someone to hold my hg-inexperienced 
hand, I was wondering about the status of copyStack/restoreStack at 
present. A few questions off the top of my head:

- What's the correct way to use Unsafe to test this out? All I can find 
online are the nasty reflection hacks that make a field visible.
- What's the performance like for copy/restore? I ask because I'm 
curious if it would be possible to implement a cooperative threading 
environment with the stack copying capabilities as they exist today.
- Is this mostly complete, waiting for discussions about a public API, 
or is it still under development?

- Charlie