As I said in the former thread, I have given some thoughts on this.
But I am not a guru and I would like many more opinions on this.
90% of the possible things are quite trivial or easy, like using
enumerator, defining methods like String#to_bytes or Integer#pred.
I do not really know where the main difficulties are, Fibers cannot be
done easily and I assume that a Thread based fiber implementation
might be ultra slow.