Mutating XML in Clojure

You can use the xml-zip library to "mutate" XML just like you would any other of Clojure's immutable structures. It has a full set of "mutating" functions: (api)

They all return an entire "modified" zipper. You can then go to the top of that zipper, and user xml/emit to print the XML.

Update: Actually, for emitting XML, it's best to use clojure.contrib.lazy-xml/emit, because clojure.xml/emit is currently likely to break things! See my comment below.

(Leaving this answer here for now as a warning.)

If I understand correctly, the main thrust of the question has to do with turning the (possibly mutated) XML representation back into XML text?

If so, have a look at clojure.xml/emit and clojure.xml/emit-element:

user> (with-out-str (xml/emit {:tag :foo :attrs {:bar "quux"}}))"<?xml version='1.0' encoding='UTF-8'?>\n<foo bar='quux'/>\n"

(with-out-str captures printed output and wraps it up as a string; for some reason xml/emit prints the xml, so it comes in handy here. You'll want to use emit-element if <?xml version='1.0' encoding='UTF-8'?> is not what you want.)