It seems John's email didn't get sent to the list, I'll quote it here:

 > I think it would be better to have write-fancy, so that a list or
vector (or array) would come out with all string elements printed raw,
recursively. Since the procedure can see the whole string, it can choose
the tag by itself. Indeed, a single character would almost always
suffice, as there are more than 150,000 graphical Unicode characters.
Alternatively, there are more than that many six-letter strings.