title: High-level programming language for music composition
body: <p>I would like to write an interactive song. It would contain state and logic. A listener/user should be able to modify some state vars using a GUI or a MIDI interface. Listener accessible vars don't have to directly represent tempo, pitch or any other music property. They would rather represent values that logic would process in order to make changes to the song. </p>
  
  <p>Do I have to write such platform myself or something fitting my imagination already exists?</p>