Fukuda-san has made some progress towards a ruby mode for processing

NB: Post updated 5 July 2014, so the first two comments below refer to a non-working linux and windows version.

Ruby mode for Processing ちょっと動いたー pic.twitter.com/x3ltoiIL8U

— tyfkda (@tyfkda) June 2, 2014

Working, on linux (for me) and windows (Fukuda-san) as well as original Mac version (for which Makefile is written) see below for ruby in ide on my linux box

The sketch is saved to /tmp on linux as an *.rb file prior to running (similar to processing). To get the ide to look right you need a theme, here I stole fjenetts coffee-script theme, blue diamonds would look nice for ruby. You can get the Fukuda-san repo here. For a modified Makefile for linux (not archlinux) see this gist. Possibly it may tempt some processing users (especially Windows users) to dabble with ruby, but I have never been very happy with the editor in the processing ide (and there are other limitations) neverthless kudos to Fukuda-san. I expect to report more experiments soon.