Processing.R is a mode for Processing that enables users to write Processing sketches using the R language. The mode can be installed in the Processing Development Environment (PDE). It can also run on the command line as a stand-alone jar.
Processing.R supports:
native R programming and syntax
most Processing built-in functions (draw(), rect(), box(), etc.)
Comments
It is also a most impressive (!!) Google Summer of Code 2017 project by @gaocegege -- originally proposed and discussed here.
See the PDE mode for a great collection of built-in demo sketches. Online reference documentation is available here: