I like everything you propose here. Dart is earlier in development than I think most people realize, and I really hope we can get to something like what you're listing. Definitely self-hosting and a self-hosted IDE would be on my love-to-have list. As a testing nerd, integrating testing would definitely be on it too.

A good development environment is something where you could really differentiate yourselves, and I guess you could very easily integrate introspection and analysis features into chrome to help with it.

I've been thinking for years that if I ever were to develop a new language, I would start from developer usability first - I think there is much more to innovate there than in the core language features, nowadays. Developer usability is tightly coupled with the development tools the developer can use, not just with abstract language features. And especially for web development, you can't think only about top of class developers.

As I'm at it, I'll write here my dream feature of any language and IDE - not knowing if it is really feasible, but it doesn't look really impossible to me. Use case:

- You run your unit tests

- An assertion fails/there is an error

- A debugger brings you to where the problem is

- You can step back from where you are, make changes on the fly to your code and the tests, and step forward to the assertion/error again.

I guess that with a VM, and excluding some operations that depend from external status and which are destructive, this could be possible, and it could allow an incredible speedup in development...

Certainly feasible: Smalltalk debuggers do this. And Smalltalkers (allegedly) use a workflow just like you describe.

Yup. I often do something like this:

  - write a test for a method that isn't there yet
  - run it, get a red bar, as expected
  - run it in debug mode, and get a debugger
  - write the method implementation in the debugger
  - possibly write other methods that the new method calls, also in the debugger
  - resume the program, get a green bar

Writing code in the debugger is great, because you've got all the runtime state right in front of you, and you can step through the code you're working on. I'd love, love, love to see this in Dart.

But, is it possible to step backwards from the current state of the VM, to execute a changed code?

I read about this, and even tried downloading squeak once, but didn't find it very compelling. I admit that I might not have given it the time it needed, though...

A few weeks ago I whipped up this 3-minute video showcasing a Smalltalk class browser, method finder, and debugger: http://vimeo.com/27850933

You raise a good point. I'd like to see more about testing Dart.

We have a rudimentary unit test framework [1] that we've been using for the samples, though we're still playing with different styles. Personally, I'm fond of the Jasmine-inspired stuff I tried to slap together here [2]. This is of course different from the testing infrastructure for the language itself, which is its own thing.

    [1] https://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/#dart%2Fclient%2Ftesting%2Funittest
    [2] https://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/client/tests/client/view/ViewTests.dart

Thanks! I will take a look at these.