rb8-trepanning

https://github.com/rocky/rb8-trepanning

A modular, testable, Ruby debugger using some of the best ideas from ruby-debug, other debuggers, and Ruby Rails. Some of the core debugger concepts have been rethought. As a result, some of this may be experimental. This version works only with MRI 1.8 and 1.9' See rbx-trepanning for a version that works with Rubinius, and trepanning and for something that works with a patched YARV 1.9.2.