Wrote small Common Lisp library for accessing the echonest music analysis API. All the other APIs are jealous.
Writing this was fun because I got to use Relax NG for the first time in actual code. By inspecting the XML that comes back from echonest I guessed at what the schema was and wrote it up in the compact form of RNG (see here). Isn’t that easy to read!

Inserting the library cxml-rng for validating your XML given a Relax NG schema and inserted it into the SAX pipeline took less than a half dozen tokens (see here). My reward: is that the handler that loads the XML into a useful data structure doesn’t need to be as paranoid. How relaxing!