Nice ignatz! I was merely shooting for a minimalist example in my OP, but this is a great demo of a more realistic application of the idea. I like the encapsulation of the core routine and the use of static Comparators to facilitate ease of use. And of course since public sort method can take any Comparator, using it in custom applications would be a breeze. The one part that concerns me is that the map that does the initial setup isn't always going to be the same (string => length), so there needs to be some way of conveying dynamic behavior for that aspect through the public sort method. Writing a general wrapper in Perl for the ST you'd probably pass a subroutine reference; in Java you'd probably have to pass an object or break the rules and pass a java.lang.reflect.Method. Hmmm, actually, that latter option probably would work:

sort(Comparator c, Method prepare) ....
....
// The second map would then look something like this
map(new Block() {
    protected Object process(Object elem) {
        ArrayList temp = new ArrayList();
        temp.add(elem);
        try {
          temp.add(prepare.invoke(elem, null)); // or possibly with ar
+gs;
        } catch (Exception e) {
          // for real we'd catch finer grained exceptions and 
          // do something smart
        }
}, in);
[download]

This does work, I just passed in the result of String.class.getMethod("length", null) and it ran as expected :^) Of course one limitation is the assumption that the transformation to be run on the element exists as an instance method. Probably this measure could be omitted for the first map as in basically all cases you just want to pull out the first element.

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"The dead do not recognize context" -- Kai, Lexx

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