Here's a question. Does there exist a decent stand alone representation (BNF or otherwise) of the Ruby grammar? I see all this stuff that says Ruby-style, and it looks almost like straight up Ruby. Moreover, I Google around for a Ruby grammar and can't find much of anything substantial, but I haven't looked in awhile. I've tried cruising the Ruby YACC file, but that's kind of a disaster. Is there good one that exists as a reference for 3rd party Ruby implementations?
You might take a look at http://mirah.org, which is Charles Nutter's (creator of JRuby) forging of Ruby-like syntax with static typing that compiles to Java bytecode.