"So... Go's interfaces actually look an awful lot like message passing."
That's a bit of a tautology. ^_^ If I'm not mistaken, you took the term "message-passing" from its object-oriented "foo.bar( baz )" context to begin with.
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"Yeah, I've probably been a bit too excitable about this... ^^;"
Well, I (rocketnia) can't blame you for that, and I can't blame you for not having runnable examples either. I tend to be guilty of both those things a lot, and this discussion is a great example. >.>