Google on Tuesday announced the release of Dart SDK Milestone 4 with a slew of improvements. You can download the fourth milestone now from dartlang.org/tools.

For those who don’t know, Dart is Google’s open-source Web programming language. Dart’s ultimate goal is to replace JavaScript – not exactly something that can happen overnight. In the meantime, Google seems content with offering better performance, scaling for large projects, and more security features.

Here’s the official changelog for Dark SDK v0.4.7 r21548:

  • Core, collection, and async libraries are now stable. There will be no more breaking changes to these libraries.
  • Performance improved in both the dart2js compiler and the Dart VM.
  • Dart Editor comes with an all-new analysis engine for faster real-time feedback.
  • Classes can be used as mixins.

The core libraries are thus now stable, but this first point has fine print worth noting. Google says the exception is the class Invoke, which will “change slightly to accommodate efficient minification.” The company didn’t elaborate further.

As for performance, Google says dart2js now generates more efficient code: compared to the previous M3 release, the benchmark DeltaBlue runs twice as fast and Richards runs 40 percent faster. Furthermore, the native Dart VM now runs Richards twice as fast as V8 while on DeltaBlue, the VM improved by 22 percent.

Screen Shot 2013 04 16 at 9.36.07 AM Google speeds up its JavaScript alternative Dart compiler and VM, says no more core library breaking changes

Meanwhile, the Dart Editor has received a new analysis engine for faster real-time feedback, code completion, refactoring, and so on. Google boasts that analyzing the content of a folder is now more than 50 percent faster. If you’re a Sublime user, you’ll be happy to know the Dart plugin has gained syntax highlighting, common Dart snippets, as well as dart2js and Pub integration.

Last but not least, the actual Dart language has gained a first implementation of mixins for sharing code between unrelated classes. We’ll keep you posted as Dart continues to evolve, as the language and tools become more and more important for Google.

Top Image Credit: Asif Akbar