A definition of closures - A good article where they talk about what closures are and if they should add them to Java.

I recently learned about closures through Ruby, and have gotten really into them, trying to really get a good grasp on them. I've started to read the Lambda the Ultimate... series of papers. So cool to read about the history of programming, wow, there is so much excellent research from the past that we need to incorporate into our current programming practices, and with faster computers, we should really start looking back to things that were abandoned because computers were too slow back then.

A great example of a language that reaches back to give us great stuff is Ruby. Ruby is just a beautiful language, so powerful, expressive and elegant.