Re: pcall() and coroutine.yield()

[Mark Hamburg <mhamburg@...>]

I think a reasonable goal might be:

* All pure Lua code written using the standard distribution libraries is
yield friendly -- e.g., pcall and foreach need to support yielding.

* On systems where there is a straightforward way to make yielding work for
arbitrary C code, that too is supported.

The second is nice to have but might open up more problems than it's really
worth. For example, would OS libraries get confused?

Furthermore, I think the second needs to be subject to the constraint that
it not slow the behavior of pure Lua coroutines.

Mark