Re: Back & Forth - Co-routines

There is indeed a restriction in standard §3.4:
"A program shall not attempt to nest compilation of definitions.
During the compilation of the current definition, a program
shall not execute any defining word, :NONAME, or any definition
that allocates dictionary data space."
However because local names are not compiled into dictionary data
space, but use their own transient dictionary entries, which
disappear after compilation, this restriction as of $3.4 does not
apply to embedded functions emulated by xt-locals, aka
defer-flavoured locals.