Python
lejaren is built in Python to be written in Python - including all the major features.
MusicXML
lejaren outputs a MusicXML file, a standard interchange format for music notation.
MEI
Support for MEI (Music Encoding Initiative) coming soon.
Object-Oriented
Use the built-in notation objects, and build your own objects in Python.
Open Source
lejaren is free (as in beer) and open-source. You're welcome to submit pull requests.
Multi-use
Use for composition, or notation-based sonification of data available in Python.