APN 20130628 - finally figured the way to understand coroutine based programming was (as always) to sit and actually write some real code. The result is the fiber package. From its introduction:
This package provides an implementation of "fibers" for Tcl.
Fibers, as the term is used in this package, are threads
of execution that are co-operatively multitasked and use
message passing as their primary means of communication,
including channel based I/O.
Fibers are implemented using Tcl coroutines and are compatible
with any Tcl application model provided it runs the Tcl event
loop.
Erlang programmers may find some similarity to that language's
process model. That is not just happenstance.Documentation is at [L1 ]. The project page is at [L2 ]