I'll make this a short one.
I was just having a conversation with a friend, a Rubyist whose opinion I respect, who clued me in that he really hates when JRuby users use Java libraries with little or no Ruby syntactic sugar. He hates that there's a better chance every day that Java-related technologies will enter his world. That he's going to have to fix someone's Java-like Ruby. He lamented the lack of decent wrapper libraries that hide "the Java insanity", that are just bare-metal shims over the Java classes they call. He expressed his frustration that JRuby being successful will mean he's going to have to deal with Java. He doesn't want to *ever* have to do that.
And he said it's our fault.
I've heard variations of this from other key Rubyists too. There's a lot of hate and angst in the Ruby community. Many of them are Java escapees, who long ago decided they couldn't tolerate Java as a language or were fed up dealing with some of the many failed libraries and development patterns it has spawned. Some of them are C escapees who've never quite been able to let go of C, be it for performance reasons or because of specific libraries they need. Some of them have been Rubyists longer than anything else (or maybe just longer than anyone else), and see themselves as the purists, the elite, the Ivory Tower, keepers of all that's good in the Ruby world and judge, jury, and executioner for all that's bad. In the end, however, there's one thing these folks share in common.
They think JRuby is a terrible idea.
Of course it's not everyone. I think the general Ruby populace still looks at JRuby as an interesting project...for Java developers. Or maybe just as a gateway to bring people into the community. A growing minority of folks, however, have managed to move beyond prejudices against Java to make new tools, applications, and libraries using JRuby that might not otherwise have been possible. And some folks are simply ecstatic about JRuby's potential.
Why is JRuby such a polarizing issue?
I don't see this in the Python community, for example, which might surprise some Rubyists. Pythonistas seem to have positively embraced both IronPython and Jython. There's no side-chatter at the conferences about the evils of anything with a J in it. There's no mocking slides, no jokes at Jython or IronPython developers' expense. No "Python elite" cliques actively working to shut Jython or IronPython out, or to discourage others from considering them. The community as a whole--Guido included--seems to be genuinely thankful for implementation diversity. Even if one of them does have a J in it.
What's different about these two communities? Why?
I work on JRuby. For the past 3-4 years, it has been my passion. There's been pain and there's been triumph: compatibility hassles; performance numbers steadily increasing; rewriting subsystems I swore I'd never touch like IO and Java integration. Over the past two years, I've put in four years' worth of work, writing compilers, rewriting JRuby's runtime, rewriting whole subsystems, speaking at conferences, staying up late nights (frequently ALL night) helping users on the JRuby IRC channel or mailing lists, and hacking, hacking, hacking almost all day, every day. For what? Because I want to infect the JRuby community with a new and more virulent strain of Java? Because I don't know any better?
I work on JRuby because I love Ruby and I honestly believe JRuby is one of the best things ever to happen to Ruby. JRuby takes a decade of Java dogma and turns it on its head. JRuby isn't about Java, it's about taking the best of the Java platform and using it to improve Ruby. It's about me and others working relentlessly, writing Java so you don't have to. It's about giving Ruby access to one of the best VMs around, to one of the largest collections of libraries in the world, to a pool of talented engineers who've written this stuff a dozen times over. Sure there's crap in the Java world. Sure the Java elite took power in the late 90s and started to jam a bunch of nonsense down our throats. Sure the language has aged a bit. That's all peripheral. JRuby makes it possible to filter out and take advantage of the good parts of the Java world without writing a single line of Java.
Tell me that's not a good idea.
I sympathize with my friend...I really do. I've not only seen a lot of really bad Ruby code come out of JRubyists, I've created some of it. Writing good code is hard in any language, but writing Ruby code that meets the Ivory Tower's standards is like trying to decipher J2EE specifications. If I have to listen to some speaker meditate on what "beautiful code" means one more time I think I'm going to kill someone. Yes, beauty is important. I have my idea of beautiful code and you have yours, and there may be a nexus where the two meet. But tearing into people who are trying to learn Ruby, trying to move away from Java, doing the best they can to meet the Ivory Tower's standards of "beauty"...well that's just mean. And it doesn't have to be that way. "Beauty" doesn't have to be Ruby's "Enterprise".
JRuby doesn't mean Java any more than MRI means C, Ironruby means C#, or Rubinius means C++ and LLVM. JRuby, like the other implementations, is a tool, an enabler, an alternative. JRuby does many things extremely well and others poorly, just like the other implementations. It's bringing new people into Ruby, and for that we should be thankful. It's pushing the boundaries of what you can do with Ruby, and for that we should be thankful. It's not about Java...it's about learning from the successes and mistakes of the past and using that knowlege to push Ruby forward.
So what do we do about JRuby users that start writing Java code in Ruby? We teach them. We help them. We don't slap a scarlet J on their chest and run them out of town. What do we do about shim layers over Java libraries? We build a layer on top of that shim that better exercises Ruby's potential, or we help build a new wrapper to replace the old. That's what Nick Sieger did with Warbler. That's what the Happy Campers are doing with Monkeybars and Jeremy Ashkenas did with Ruby-Processing. More and more people are recognizing that JRuby isn't a threat, doesn't represent the old world, doesn't mean Java...it means empowerment, it means standing on the shoulders of giants, and never having to leave Ruby.
I guess what it really comes down to is this:
The next time someone tries to cut down JRuby, tries to convince you it's a bad idea, to avoid it, to stay away from the evils of Java; the next time someone tears into a library author who hasn't learned the best way to utilize Ruby; the next time someone complains about a library that doesn't lend itself to reimplementation on the C-based implementations, doesn't hide the fact that it's wrapping Java code; the next time someone tries to convince you that JRuby is going to hurt the Ruby community...you tell them to remember this:
JRuby is not going away. More people try JRuby every day. As long as Rubyists who know "the way", who have learned how to create beautiful APIs and DSLs, who serve as the stars, the leaders of the Ruby community, setting standards for others to follow...as long as those people try to marginalize JRuby, treat it like a pariah, or convince others to do the same...
...it will only get worse.