CL-XML is a collection of Common LISP modules for data stream parsing and serialization according to the "Extensible Markup Language" and anscilliary standards. The modules perform parsing and serialization between XML, XML Query, and XML Path expressions and DOM-compatible CLOS instances.
HAXL takes a different approach. It is designed to manipulate existing XML documents. Broadly speaking, HAXL operates as follows:
1. Read in an existing XML document.
2. Retrieve, modify, and manipulate content in the XML document.
3. Write out the resultant XML document.