A projectional editor for G-Sharp, a superset of Guido music notation, implemented in MPS
To use, download and install Jetbrains MPS and import this repo as a project. Information on how to use MPS can be found on Jetbrains's website.
G-Sharp is intended to add a number of abstractions not present in Guido music notation, including the ability to add chords based off root note and chord quality.