[grayrest]

> I remember Mike Pall saying something similar in an LTU thread some time ago.

He did and the mozilla guys pointed out how this wasn't the case. The languages are very similar but JS has some weird semantics due to how things are scoped. (ref. the Chakra optimization brouhaha a month ago)

[jules]

Going the other way: what small changes in languages can we make to make them much more optimize-able while at the same time keeping (most of) the expressiveness?

[grayrest]

It's a tradeoff between compatibility with existing JS versus perf/capability enhancements. The ECMAScript committee goes back and forth on this topic. The biggest stride in that direction was strict mode, which is intended to catch most of the low hanging fruit. I know Brendan Eich has mentioned a number of things that could change to get the language faster. I don't, however, know if I read it all in one place or I'm combining nultiple one-off examples.

I'm not confident enough in my memory to write out a probably incorrect list of things I remember. Here's a list of the various things I've read from Brendan in case you're interested in tracking it down:

http://lambda-the-ultimate.org/node/3851#comment-57671

This is the LtU thread my previous comment referred to. It's a large (and fantastic!) thread, but I believe that comment and children are the most direct comments back and forth between Mike and Brendan. Andreas Gal is also on the thread and from Mozilla.

http://www.aminutewithbrendan.com/

Brendan's weekly JS podcast. They're relatively accessible and generally cover a lot of area. A good way to get in the language zeitgeist.

http://brendaneich.com/

Brendan's blog, mostly focuses on ES Harmony stuff and Mozilla specific topics.