I am really impressed by Scala, though I have not used it on any real projects yet. Apart from reflection, it seems to be much stronger than Java in all the kinds of features that are good for XML document processing: co-routines, pattern matching and so on. The built-in XML tree that documents can be parsed in to does not contain back pointers, so up-going axes require extra coding; Scala is obviously more congenial for OmniMark or XSLT programmers than Java.