[Flow]

http://cappuccino.org/ and some python on the backend for REST interaction.

Or GWT, just like GMail.

[atlbeer]

Not to be snarky but, GMail isn't written in GWT.

GWT though would be a step towards the OP's solution.

[fgd]

How sure are you in your claim? Any proof that GMail is not written in GWT?

[eneveu]

Here is proof:

http://news.ycombinator.com/item?id=56758

(Paul Buchheit was GMail's creator and lead developer)

Also, here is more proof:

http://news.ycombinator.com/item?id=190151

You could tell me: "OK, but it doesn't prove that current GMail is not in GWT. It may have been rewritten". I'd answer that:

- using firebug and looking at the js scripts loaded by GMail, there is no trace of GWT (things such as *.nocache.js scripts). They might have obfuscated to hide it, but why do that?

- if Google indeed rewrote GMail using GWT, they would have announced it, like they did for Wave / Adwords.

More discussion in this other thread: http://news.ycombinator.com/item?id=1470633

[gotouday]

Gmail was written using Closure library built by google itself. Google release it for open source community now.

[fgd]

That is not proof, just another statement that means nothing without supporting data.

Also, if GMail is such a successful use case for Closure library, one could wonder why did they build Google Wave client with GWT?

[atlbeer]

GMail predates GWT by at least 2 years.