To create and run processing sketches on the raspberryPI using ruby and the geanyIDE, you only need to install the picrate gem (and its dependencies ie jruby).
This is super easy using the provided Rakefile:-
Which installs jruby, configures gem home and geany, and installs picrate gem
Simple clone or download this repo
cd install-picrate
rake # rake --tasks to see TasksSome lines in script require sudo authority (eg to write to /opt folder), so you will be asked for password.
Installs latest jruby etc....