io.popen() for a lua chunk?

[Mike <lua-l@...>]

Hello, everybody.

Is there a way to run a piece of code from the currently executing lua script
(I mean a lua chunk or a function) in a "subprocess" and establish a pipe
to/from its stdin/stdout something like io.popen() does?

This is somewhat different from the launching a subprocess for an external
program or for the lua script itself that may be done with io.popen()
as the launched chunk is to be able to access the current values of the
currently executing lua script global variables and/or upvalues
(at least their copies in the forked process's image).
More simply, I mean the feature like "process substitution" in bash,
for example:
-----
#! /bin/bash

greeting="Hello world!"

do-greeting()
{
  echo "$greeting"
}

cat < <(do-greeting)
-----

Thanks.

-- 
Mike