Dart是一种基于类的可选类型化编程语言，设计用于创建Web应用程序。 Google称，Dart的设计目标是为Web编程创造结构化但又富有灵活性的语言；编程方法一目了然，符合程序员的自然习惯，易于学习；能在所有浏览器 和不同环境中实现高性能。
Dart 发布了首个 Beta 版本，包含性能和产品方面的提升，主要包括：
dart2js
Added support for dart:typed_data
Improved type inferrer by using union types and keeping track of side effects
Implemented sharing of code mixed into multiple classes
More coverage for handling of generic type
Performance improvements
20% faster on Richards, 10% faster on DeltaBlue, 8% faster on Tracer
Significant progress on mirrors support (work in progress)
Dart VM
DeltaBlue: 40% faster than M4
Tracer: 33% faster than M4
Full SIMD acceleration
Reduced initial snapshot size
improves startup time for new isolates
Improved stability of debugging experience
Editor
A new 20% faster Analyzer in Editor and SDK.
Remove old analyzer.
More quick fixes and refactorings in Editor.
Code Folding has returned with the new ability to collapse classes and local functions.
Mark Occurrences is back.
New Pub Deploy command.
Many Code Completion enhancements
Proposal filtering now accepts camelCase input (e.g., type 'i' then 'E' to filter out everything except isEmpty).
Unused optional parameters are deleted automatically after template editing is done.
Requesting completion in an empty argument list will include an option to insert the argument template.
The seed is now case-insensitive (e.g., map.isemp+Ctrl-Space -> map.isEmpty).
Greatly improved WebGL performance in Dartium because of move to dart:typed_data library for typed arrays.
Libraries
dart:async
Stream bugfixing (one breaking change: disallow re-subscribing to cancelled stream)
dart:core
Allow Pattern (like String and RegExp) in more places.
dart:uri
Functionality moved to dart:core, API improved, stable.
dart:crypto
Not essential to have as a dart: library at this point. Moved to a pub package.
dart:io
Added IPv6 support
Improved speed and stability of HTTP and Web Sockets. HTTP handing is now more than 50% faster
Better support for processing HTTP bodies
Improved HTTP authentication and proxy support
pub:
New backtracking version solver, SDK version constraints
Add offline mode
Initial version of pub deploy
html:
New dart:mdv_observe library
Typed_data
dartium: devtools improvements
Repl-style behavior including creating new Dart objects from the console
Mouse over of Dart fields and getters now displays their values
Fewer crashes
Web UI
New polymer branch, implementing Web UI with Polymer polyfills (work in progress)
下载地址：http://www.dartlang.org/tools/
来自:开源中国社区
