Install Atom (debian/mint/ubuntu)###

Probably ignore distro version download latest version (at least 1.8.0) and:-

sudo dpkg --install atom-amd64.deb

Tough luck if you want the 32 bit version

You must provide a link to the processing-java script, I would use:-

sudo update-alternatives --install /usr/local/bin/processing-java processing-java /home/tux/processing-3.2.1/processing-java 50

Install Packages

From the atom editor install the processing and processing-language packages.

What`s it look like?:-

ctrl+alt+b to run the sketch (as with vanilla processing sketch must live in an eponymous folder nuts or what?)

For the adventurous

You could write your own package to k9 --run JRubyArt sketches, emacs wrapped sketches can run as ruby scripts, so only need the script package to run them.

PS: there is probably bit of performance hit cf running from jEdit or the processing ide (but the look and feel is much better). With JRubyArt you could create an outline sketch from a regular console ideally in empty folder:-

k9 --create fred 200 200

Set it running in watch mode

k9 --watch fred.rb

Then edit the sketch from atom, to see the effect of your changes you only need to save the sketch (best of all worlds, a clean modern editor that should not compromise performance).