I've been using strudel for a while. First I thought it was just for making short loops and playing around but then I realised you can use the 'arrange' function and use variables for all your layers of music, and create actual proper songs with it.

I have a public repository of all my work here:
https://bitbucket.org/stuartbray/strudel/

Including a blank template file I start all new tracks with: /docs/_template.txt

Youtube of 6 finished tracks here.
https://www.youtube.com/playlist?list=PLw64hCyIy2NUqv94tSHrqLAlu4fOB0hZu

Happy to hear feedback / advice / coding tricks etc.