[jcoglan]

The rationale is that I wanted to learn how to write an interpreter, particularly some of the more challenging parts like tail recursion, macros, continuations and laziness. It's in Ruby because that's what I know best; it's not intended for production use as a replacement for Ruby, though I have used it myself to do a little code transformation and testing in Ruby apps.

So basically it's a toy, but one that I hope others can learn something from.