Schnolgo is a musical composition system written in python (http://python.org).
Schnolgo was written to be the most flexible composition system it could be. Though far from fully realized, here is a brief rundown of Schnolgo's aims. For currently implemented features in more depth, please see the "features" section. Schnolgo aims to allow:

• Easy composition utilizing arbitrary rhythmic subdivisions and polyrhythms. For this, a new system of representing rhythmic structures has been fleshed out in the TimeUnit class.
  
  
• Easy composition in any musical scale, from the Western equal-tempered scale to experimental invented scales and temperaments.
  
  
• Theme-based composition, allowing variations on musical themes to be fleshed out without the explicit need to separately represent every note of every variation on a musical theme every time it comes up.
  
  
• Easy use of block-based and algorithmic arrangement.
  
  
• Easy use of any algorithmic composition methods generally.
  
  
• Song rendering in arbitrary formats.