Worlds

Via Lambda the Ultimate I found "Worlds: Controlling the scope of side-effects". With Alan Kay as one of the authors you can assume it's worth reading. And what is really worth visiting is the environment the prototype implementation is built on.

It has really reminded me of Software Transactional Memory and there are several comments in the same line. I've read some of the work by Simon Peyton Jones on the subject, mainly related to Haskell, and I consider it an interesting approach that could simplify many tasks contributing to an increase in quality in many types of applications. 

And as this paper shows,  you don't need a pure functional programming language to play with this kind of concepts, but I really think a type system that, at least, make the existance (or not) of side-effects explicit is really helpful.