On the expressiveness of programming languages (and other stuff)

Here's this interesting talk about which features add expressivity to given languages, and which don't.  It's an interesting way of looking at this problem.

The pdf (and ps which is extended). It goes in the same fashion of operational semantics I love so much on the lisp culture. The same as in Baker's MetaCircular article that mentions many CL special operators that can be written already with the rest of CL and macros.