call-with-dynamic-root and fluids

[Mikael Djurfeldt <mdj at mdj dot nada dot kth dot se>]

Michael Livshin and I are thinking about reimplementing fluids using
the thread local data abstraction (getspecific/setspecific) directly,
i.e. letting fluids, as now, be smobs, but store the key returned from
key_create directly in the CDR.

But then we stumble on the fact that each dynamic root currently has
its own set of fluid values.  Currently, fluids are not per thread,
but per dynamic root.

I think this should change.  I think dynamic roots should be much less
ambitious, if we need them at all.

It seems to me that the only reason of existence for the current
`call-with-dynamic-root' is to be able to prevent other dynamic roots
to call continuations produced by the current root.

Do we really need this ability?

Is anyone familiar with any other implementation which supports this?

Is anyone using `call-with-dynamic-root'?