[plt-scheme] SXML Experience?

Hans Oesterholt-Dijkema wrote:
>   how can I insert or append new elements
>   to an sxml tree?

Oleg Kiselyov has previously mentioned the Zipper system:

http://okmij.org/ftp/Scheme/misc.html#zipper

...which is a "pure functional cursor into a data structure. It lets us 
replace an item deep in a data structure, e.g., a tree or a term, 
without any mutation. The result will share as much of its components 
with the old structure as possible."

Anton