Ruby the language is pretty gigantic, so there are a lot of hard-to-fix corner cases. IronRuby, IIRC, passes 85% or so and just hit 1.0 and can run Rails. So most Ruby you write will run on this, but it is possible to break it.
Re:MacRuby 0.6 Official Release
by knowtheory on Tuesday May 04, 2010 @12:09AM
(#1317029)
well... just because 85% of Ruby runs, doesn't mean that 85% of your usecases are covered. Unfortunately for me, a variety of rubygems that my apps and libs depend on break with 0.6, even things as lightweight as Addressable.
Still lookin' forward to more macruby though :)
"This release also passes about 85% of RubySpecs..."
Those two things seemed a little contradictory to me at first. But then I noticed the part about macruby apps being able to compile to machine code, so I guess what they mean is that if your app is stable in macruby, it will be stable when you ship it, even macruby isn't fully compatible with ruby yet.
Definitely looking forward to playing around with it.