MacRuby, an Objective-C based Ruby implementation is now available in version 0.4.
Among the new features is an embedding API ("Runtime Objective-C API") which allows to use MacRuby for scripting the host application. InfoQ previously reported on the API.
HotCocoa (added in MacRuby 0.3), makes it easy to integrate with Cocoa frameworks, eg. for building GUIs. A new feature now is HotCocoa::Graphics:
Inspiration for this project was derived from Processing and NodeBox. These excellent Java- and Python-based graphics programming environments are mature and full-featured, but HCG offers similar functionality using the elegant Ruby programming language and the power of native graphics processing on Mac hardware.
Processing is a Java-based langage for visualization. _why's Ruby Shoes also offers similar visualization capabilities.
The HotCocoa::Graphics blog provides a list of sample code (complete with graphical output).
For performance matters, MacRuby 0.4 now runs the GC on a separate thread, and also includes DTrace probes, which among other things can report on GC activity (DTrace sample scripts for MacRuby).
Among other changes, MacRuby 0.4 comes with Ruby 1.9.1 libraries, 64 bit support, as well as improved integration with XCode.
MacRuby is now available for download.