Updated tech overview

src/site/docs/technical-overview/index.html

 ---
 layout: default
 title: "Technical Overview"
 ---
 <h1>Technical Overview </h1>
 
 <section>
   <p>
-  Dart is a new class-based programming language
-  for creating structured web applications.
-  Developed with the goals of simplicity, efficiency, and scalability,
-  the Dart language combines powerful new language features
+  Dart helps developers productively build
+  high-performance apps for the modern web.
+  Targeting modern desktop and mobile browsers,
+  Dart apps can run natively in a Dart virtual machine (VM)
+  or be compiled to JavaScript.
+  </p>
+
+  <p>
+  Developed with the goals of <b>simplicity</b>,
+  <b>efficiency</b>, and <b>scalability</b>,
+  the Dart language combines powerful new features
   with familiar language constructs into a clear, readable syntax.
+  But Dart's not just a language.
+  The Dart open-source project also includes <b>libraries</b>,
+  a <b>package manager</b>,
+  and <b>tools</b> such as a full-featured <b>editor</b>.
   </p>
 
+<p>
+Additional open-source projects and the Pub package manager

[sethladd, 2012/12/16 22:23:03]

this confused me briefly. What about "Additional /dart/ open-source projects" or
"Additional libraries and tools from the Dart project"

Or...

A rich collection of Dart libraries can be found in Pub, a package manager for
Dart.

[Kathy Walrath, 2012/12/18 00:21:56]

Done.

+help developers be even more productive.
+For example, developers can use Pub to get packages for
+<b>JavaScript interoperability</b>,
+a <b>web UI</b> framework,
+a <b>unit testing</b> library,
+libraries for <b>game development</b>,
+and much more.
+</p>
+
 <aside>
   <div class="alert alert-info">
     <strong>Note:</strong>
-    This document is part of an early preview of
-    the Dart language and programming environment.
-    Some elements are missing from the current release,
-    and the details are subject to change based on the feedback we receive.
+    Although the Dart language will continue to change,

[sethladd, 2012/12/16 22:23:03]

You say this, but then in the next paragraph, you say "the language has
stabilized"  Seems to contradict. Also, I don't think this needs to be a note.

[Kathy Walrath, 2012/12/18 00:21:56]

Done.

+    we expect the changes to be backward compatible.
+    The Dart libraries, on the other hand,
+    are not yet stable.
   </div>
 </aside>
 
+<p>
+Now that the language has stabilized,
+the Dart team is working on <b>performance</b>.
+The Dart VM is already much faster than Chrome’s JavaScript engine, V8,
+on two important benchmarks.
+See the <a href="/performance/">performance page</a>
+for the latest measurements of Dart and JavaScript code.
+</p>
+
+</section>
+
+
   <h4> Contents </h4>
 
   <ol class="toc">
-    <li> <a href="#key">Key features</a> </li>
     <li> <a href="#goals">Design goals</a> </li>
-    <li> <a href="#code">Show me the code </a>
+    <li> <a href="#key">Language features</a>
       <ol>
-      <li> <a href="#classes">Classes and interfaces </a> </li>
-      <li> <a href="#optional-types">Optional types </a> </li>
+      <li> <a href="#lang-classes">Classes </a></li>
+      <li> <a href="#lang-optional-types">Optional types</a> </li>
+      <li> <a href="#lang-lexical-scope">Lexical scoping</a> </li>
+      <li> <a href="#lang-libraries">Libraries</a> </li>
+      <li> <a href="#lang-isolates">Isolates</a> </li>
+      <li> <a href="#lang-tooling">Toolability</a> </li>
+      </ol> </li>
+    <li> <a href="#code">Examples of Dart code</a>
+      <ol>
+      <li> <a href="#classes">Using classes </a></li>
+      <li> <a href="#optional-types">Adding types</a> </li>
+      <li> <a href="#browser">Writing web apps</a> </li>
       </ol>
     </li>
-    <li> <a href="#howtouse">How can I use Dart? </a>
+    <li> <a href="#tools">Tools</a>
       <ol>
+      <li> <a href="#running">Dart code execution</a> </li>
       <li> <a href="#editor">Dart Editor</a> </li>
-      <li> <a href="#mimetype">New MIME type </a> </li>
-      </ol>
-    </li>
-    <li> <a href="#tools">Tools </a> </li>
-    <li> <a href="#libraries">Libraries </a> </li>
-    <li> <a href="#involved">Get involved </a> </li>
+      <li> <a href="#pub">The Pub package manager</a> </li>
+      </ol></li>
+    <li> <a href="#libraries">Libraries</a> </li>
+    <li> <a href="#get-started">Get started with Dart</a> </li>
+    <li> <a href="#involved">More information</a> </li>
   </ol>
 </section>
 
-
-<section id="key">
-  <h2> Key features </h2>
-
-  <p>
-  Key features of the Dart language include:
-  </p>
-
-
-  <h3>Classes</h3>
-  <p>
-  Classes and interfaces provide a well understood mechanism
-  for efficiently defining APIs.
-  These constructs enable encapsulation and reuse of methods and data.
-  </p>
-
-  <h3>Optional types</h3>
-  <p>
-  Dart programmers can optionally add static types to their code.
-  Depending on programmer preference and stage of application development,
-  the code can migrate from a simple, untyped experimental prototype
-  to a complex, modular application with typing.
-  Because types state programmer intent,
-  less documentation is required to explain what is happening in the code,
-  and type-checking tools can be used for debugging.
-  </p>
-
-  <h3>Libraries</h3>
-  <p>
-  Developers can create and use libraries
-  that are guaranteed not to change during runtime.
-  Independently developed pieces of code can therefore
-  rely on shared libraries.
-  </p>
-
-  <h3>Tooling</h3>
-  <p>
-  Dart will include a rich set of
-  execution environments, libraries, and development tools
-  built to support the language.
-  These tools will enable productive and dynamic development,
-  including edit-and-continue debugging and beyond&mdash;up
-  to a style where you program an application outline, run it,
-  and fill in the blanks as you run.
-  </p>
-</section>
-
-
 <section id="goals">
   <h2> Design goals </h2>
 
   <p>
-  The Dart programming language is presented here in its early stages.
-  The following design goals will guide
-  the continued evolution and refinement of this open source project:
+  The following design goals guide
+  the continued evolution and refinement of this project:
   </p>
 
   <ul>
     <li>Create a <b>structured yet flexible</b>
       programming language for the web.</li>
     <li>Make Dart feel <b>familiar and natural</b> to programmers
       and thus easy to learn.</li>
     <li>Ensure that all Dart language constructs allow
       <b>high performance</b> and
       <b>fast application startup</b>.</li>
     <li>Make Dart appropriate for the
       <b>full range of devices on the web</b>&mdash;including
       phones, tablets, laptops, and servers.</li>
-    <li>Provide tools that make Dart run fast
-      <b>across all major modern browsers</b>. </li>
+    <li>Provide tools that make Dart run fast across
+      <b>all major modern browsers</b>. </li>
   </ul>
 
   <p>
   These design goals address the following problems
   currently facing web developers:
   </p>
 
   <ul>
     <li>Small scripts often evolve into
       large web applications with no apparent structure&mdash;they&rsquo;re
       hard to debug and difficult to maintain.
       In addition, these monolithic apps can&rsquo;t be split up
       so that different teams can work on them independently.
       It&rsquo;s difficult to be productive
       when a web application gets large.</li>
-    <li>Scripting languages are popular
-      because their lightweight nature makes it easy to write code quickly.
-      Generally, the contracts with other parts of an application
-      are conveyed in comments rather than in the language structure itself.
-      As a result, it&rsquo;s difficult for someone other than the author
+    <li>
+      In scripting languages, the contracts with other parts of an application
+      are usually conveyed in comments rather than in the language structure itself.
+      As a result, it can be difficult for someone other than the author
       to read and maintain a particular piece of code.</li>
-    <li>With existing languages,
-      the developer is forced to make a choice between
+    <li>Before Dart,
+      the developer was forced to make a choice between
       static and dynamic languages.
       Traditional static languages require heavyweight toolchains
       and a coding style that can feel inflexible and overly constrained.</li>
     <li>Developers have not been able to create homogeneous systems
       that encompass both client and server,
       except for a few cases such as Node.js and Google Web Toolkit (GWT).
       </li>
     <li>Different languages and formats entail context switches
       that are cumbersome and add complexity to the coding process.</li>
   </ul>
+
+</section>
+
+
+
+<section id="key">
+  <h2> Language features </h2>
+
+  <p>
+  Key features of the Dart language include
+  classes, optional types, lexical scoping, libraries, isolates, and toolability.
+  </p>
+
+  <p>
+  Although Dart is designed to be familiar,
+  we took the opportunity to fix
+  some problematic features of common languages.
+  We also introduced a few good features from lesser known languages.
+  Some Dart features you might not expect include
+  top-level functions,
+  optional parameters,
+  string interpolation,
+  multi-line strings,
+  dynamic method handling (<code>noSuchMethod</code>),
+  a cascade operator (<code>..</code>), and
+  a function shorthand syntax (<code>=></code>). 
+  Details are in the
+  <a href="/docs/dart-up-and-running/ch02.html">language tour</a>.
+  </p>
+
+
+  <h3 id="lang-classes">Classes</h3>
+  <p>
+  Classes provide a well understood mechanism
+  for efficiently defining APIs.
+  Each class implicitly defines an interface.
+  Together, classes and interfaces
+  enable encapsulation and reuse of methods and data.
+  </p>
+
+  <h3 id="lang-optional-types">Optional types</h3>
+  <p>
+  Optional types can help a Dart program scale from a quick prototype
+  into a complex, modular application.
+  While a small program or prototype might not have type annotations,
+  you always have the option of adding them.
+  Types make the code's intent clearer,
+  which helps developers to understand the code.
+  Types also enable more powerful tools 
+  for writing and debugging code.
+  </p>
+
+  <h3 id="lang-lexical-scope">Lexical scoping</h3>
+  <p>
+  Scoping rules in Dart make sense.
+  Each identifier is scoped to the block it's declared in,
+  which means that you can tell a variable's scope
+  by looking at the braces in your code <code>{...}</code>.
+  Even in a closure within a loop,
+  the value of a variable is what you intuitively expect.
+  </p>
+
+
+  <h3 id="lang-libraries">Libraries</h3>
+  <p>
+  Developers can create and use libraries
+  that are guaranteed not to change during runtime.
+  Independently developed pieces of code can therefore
+  rely on shared libraries.
+  </p>
+
+  <h3 id="lang-isolates">Isolates</h3>
+  <p>
+  Modern web browsers, even on mobile platforms,
+  run on multi-core CPUs.
+  To take advantage of all those cores,
+  developers traditionally use shared-memory threads running concurrently.
+  However, shared-state concurrency is error prone
+  and can lead to complicated code.
+  Instead of threads, all Dart code runs inside of isolates.
+  Each isolate has its own memory heap,
+  ensuring that no isolate’s state is accessible from any other isolate.
+  </p>
+
+  <h3 id="lang-tooling">Toolability</h3>
+  <p>
+  Dart is designed to work well with tools.
+  A rich set of execution environments, libraries, and development tools
+  have already been built to support the language.
+  Dart's toolability enables productive and dynamic development,
+  including edit-and-continue debugging and beyond&mdash;up
+  to a style where you program an application outline, run it,
+  and fill in the blanks as you run.
+  </p>
 </section>
 
 
 <section id="code">
-<h2>Show me the code</h2>
+<h2>Examples of Dart code</h2>
 
 <p>
-Here are several code snippets
+Here are some code snippets
 to give you a feel for what Dart code looks like.
 </p>
 
 <section id="classes">
-<h3>Classes and interfaces</h3>
+<h3>Using classes</h3>
 
 <p>
-Dart&rsquo;s interfaces and classes provide you with
+Dart&rsquo;s classes provide
 a set of reusable and extensible building blocks.
-An <em>interface</em> defines a basic set of methods and constants,
-sometimes by inheriting from other interfaces.
-A <em>class</em> can implement multiple interfaces,
-but it only inherits from a single superclass.
+A <em>class</em> defines methods and data
+and can provide method implementations.
+Every <em>object</em> is an instance of a class.
 </p>
 
 <p>
-The following example defines an interface,
-along with a class and subclass that implement it:
+Each class implicitly defines an <em>interface</em>.
+A class can implement multiple interfaces,
+but it only <em>extends</em>—inherits implementation from—a
+single superclass.
+</p>
+
+<p>
+The following example shows the code for three classes.
+The first class, Shape, is an <em>abstract class</em>&mdash;a
+class that can't be instantiated.
+The second class, Rectangle,
+implements the interface defined by Shape.
+The third class, Square, is a subclass of Rectangle.
 </p>
 
 {% highlight dart %}
-interface Shape {
+abstract class Shape {
   num perimeter();
 }
 
 class Rectangle implements Shape {
   final num height, width; 
-  Rectangle(num this.height, num this.width);  // Compact constructor syntax.
-  num perimeter() => 2*height + 2*width;       // Short function syntax.
+  Rectangle(this.height, this.width);    // Compact constructor syntax.
+  num perimeter() => 2*height + 2*width; // Function shorthand syntax.
 }
 
 class Square extends Rectangle {
   Square(num size) : super(size, size);
 }
 {% endhighlight %}
 
 </section> <!-- classes -->
 
 
 <section id="optional-types">
-<h3>Optional types</h3>
+<h3>Adding types</h3>
 
 <p>
 Dart provides, at the programmer&rsquo;s option,
 a mixture of static and dynamic checking.
 When experimenting,
 the programmer can write untyped code for simple prototyping.
 As the application becomes larger and more stable,
-types can be added to aid debugging and impose structure where desired.
+types can be added to aid debugging and impose structure.
 </p>
 
 <p>
 For example, here is a sample of untyped code in Dart

[sethladd, 2012/12/16 22:23:03]

Thoughts on a more compelling, or simple, example here?

What about:

function recalculate(origin, offset, estimate) {
  ...
}



num recalculate(Point origin, num offset, {bool estimate:false}) {
  ...
}

This sample makes it painfully obvious why type annotations are awesome.

[Kathy Walrath, 2012/12/18 00:21:56]

You wouldn't really have 'function' here, would you?
You could do the optional argument without types, although it makes sense to
progress that way, so I'll try to explain that.

[sethladd, 2012/12/18 00:31:45]

Right, sorry, the first is JavaScript.

-that creates a new Point class that has parameters
-<code>x</code> and <code>y</code>
-and two methods:
-<code>scale()</code> and <code>distance()</code>.
+that creates a new Point class that has two instance variables
+(<code>x</code> and <code>y</code>)
+and two methods
+(<code>scale()</code> and <code>distance()</code>).
 </p>
 
 {% highlight dart %}
 import 'dart:math';
 
 class Point {
   var x, y;
   Point(this.x, this.y);
   scale(factor) => new Point(x*factor, y*factor);
   distance() => sqrt(x*x + y*y);
 }
 
 main() {
   var a = new Point(2,3).scale(10);
   print(a.distance());
 }
 {% endhighlight %}
 
 <p>
-Here is what this code looks like with types added
-that ensure that
-<code>x</code>, <code>y</code>, and <code>factor</code>
-are of type <code>num</code>,
-and that a <code>Point</code> contains two values
-of type <code>num</code>:
+Here is what this code looks like with a few types added
+to make the API of Point clearer.
+For example, this code specifies that
+<code>x</code> and <code>y</code>
+are of type <code>num</code>.
 </p>
 
 {% highlight dart %}
 import 'dart:math';
 
 class Point {
   num x, y;
-  Point(num this.x, num this.y);
+  Point(this.x, this.y);
   Point scale(num factor) => new Point(x*factor, y*factor);
   num distance() => sqrt(x*x + y*y);
 }
 
-void main() {
-  Point a = new Point(2,3).scale(10);
+main() {
+  var a = new Point(2,3).scale(10);
   print(a.distance());
 }
 {% endhighlight %}
 
 </section> <!-- optional types -->
-</section> <!-- code -->
 
-<section id="howtouse">
-<h2>How can I use Dart?</h2>
+<section id="browser">
+<h3>Writing web apps</h3>
 
 <p>
-You can run Dart code in several ways:
-</p>
-
-<ul>
-  <li>
-    <p>
-    Compile Dart code to JavaScript that can run in any modern browser:<br />
-    Chrome, Safari 5+, and Firefox 4+ (more browser support coming shortly)
-    </p>
-  </li>
-  <li>
-    <p>
-    Execute Dart code directly in a VM on your computer
-    </p>
-  </li>
-  <li>
-    <p>
-    With a <a href="#mimetype">new MIME type</a>,
-    use Dart in a browser
-    without first compiling to JavaScript
-    </p>
-  </li>
-</ul>
-
-<section id="editor">
-<h3>Dart Editor</h3>
-
-<p>
-Dart Editor is a tool for
-creating, modifying, and launching Dart web apps.
-With one click, you can compile a Dart web app to JavaScript
-and launch the app in a browser.
-Taking advantage of Dart&rsquo;s structured nature,
-Dart Editor supports method name completion and refactoring.
-</p>
-
-<p>
-For information about downloading and using Dart Editor, see the
-<a href="/docs/editor/getting-started/">Dart Editor tutorial</a>.
-</p>
-</section>
-
-<section id="mimetype">
-<h3>New MIME type</h3>
-
-<p>
-You will be able to link to a Dart program directly from an HTML page.
-Here is the proposed new MIME type,
-&ldquo;application/dart&rdquo;:
+Dart code can be compiled to JavaScript
+that runs in any modern browser.
+Dart code can also run directly in browsers that have a Dart VM,
+including Dartium and eventually Chrome.
+Here's an example of an HTML file that loads Dart code:
 </p>
 
 {% highlight html %}
 <!DOCTYPE html>
+<html>
+  <head> <title>Simple Dart Web App</title> </head>
+  <body>
+    <h1>Simple Dart Web App</h1> 
+    <button id="button-text"></button>
+    <output id="msg"></output>
 
-<html>
-  <head>
-    <title>Simple Dart Web App</title>
-  </head>
-  <body>
-    <h1>Simple Dart Web App</h1>
-    <h2 id="status">dart is starting up...</h2>
-    <script type="application/dart" src="SimpleDartWebApp.dart"></script>
-    <script src="http://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js"></script>
+    <script type="application/dart" src="app.dart"></script>
+    <script src="https://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js"></script>
+
   </body>
 </html>
 {% endhighlight %}
 
 <p>
-The dart.js file above will swap out the <code>application/dart</code>
-tag with a <code>text/javascript</code> tag if the browser does not
-have an embedded Dart virtual machine.
+  The first &lt;script> tag in this example
+  loads the code from app.dart.
+  If the browser has an embedded Dart VM,
+  then the browser loads Dart code,
+  which has the MIME type <code>application/dart</code>.
+  Otherwise, the browser loads the code's JavaScript equivalent,
+  thanks to the <code>dart.js</code> script
+  in the second &lt;script> tag.
 </p>
 
 <p>
-The following is the Dart code for the page above:
+Here is the code in app.dart:
 </p>
 
 {% highlight dart %}
 import 'dart:html';
 
-class SimpleDartWebApp {
-  void run() {
-    write("Hello World!");
-  }
-
-  void write(String message) {
-    // the HTML library defines a global "document" variable
-    document.query('#status').innerHTML = message;
-  }
+main() {
+  query('#button-text')
+    ..text = "Click me!"
+    ..on.click.add(respond);
 }
 
-void main() {
-  new SimpleDartWebApp().run();
+respond(event) {
+  query("#msg").text = "You clicked the button!";
 }
 {% endhighlight %}
-</section> <!-- howtouse -->
-</section> <!-- mimetype -->
+
+<p>
+  The main() function's call to query()
+  returns the HTML element that has the ID "button-text".
+  The code then uses the cascade operator (<code>..</code>)
+  to perform multiple operations on that element.
+  The first operation initializes
+  the element's <code>text</code> property,
+  and the second adds an event handler to the element.
+</p>
+
+<p>
+  Libraries and frameworks will
+  ease the task of developing sophisticated web apps.
+  For example, the libraries and tools in the
+  <a href="http://www.dartlang.org/articles/dart-web-components/">Web UI</a>
+  package provide web components, templates, data binding,
+  and encapsulation.
+  Just to give you a taste of the Web UI package,
+  here's an example of one-way data binding in an HTML file:
+</p>
+
+{% highlight html %}

[sethladd, 2012/12/16 22:23:03]

for reference, there is a way to wrap this in {{ raw }} I think to avoid the
double escapes

[Kathy Walrath, 2012/12/18 00:21:56]

Done.

+<!-- HTML code... -->
+<div>
+  The current time is: {{'{{'}}currentTime}}

[sethladd, 2012/12/16 22:23:03]

This would be more compelling if you rewrote the above example with Web UI

[Kathy Walrath, 2012/12/18 00:21:56]

I couldn't see a way of using Web UI at this point without writing a bunch of
code that obscured the point I was trying to make.

+</div>
+<!-- more HTML code... -->
+{% endhighlight %}
+
+<p>
+In the rendered page,
+<code>{{'{{'}}currentTime}}</code> is replaced by
+the value of the top-level <code>currentTime</code> variable
+from the following Dart code:
+</p>
+
+{% highlight dart %}
+String currentTime;
+
+void main() {
+  Date today = new Date.now();
+  currentTime = formatTime(today.hour, today.minute, today.second);
+}
+
+// ...The formatTime() function and any other code goes here...
+{% endhighlight %}
+
+</section> <!-- browser -->
+
+</section> <!-- code -->
 
 
 <section id="tools">
 <h2>Tools</h2>
 
 <p>
 The Dart language is accompanied by a set of tools
 to aid rapid prototyping, coding, and debugging
 for the entire development cycle.
 Offerings include:
 </p>
 
 <ul>
-  <li>The Dart Editor</li>
-  <li>The dart2js compiler</li>
-  <li>The Dart VM</li>
-  <li>Dartium: Chromium with an embedded Dart VM</li>
+  <li><b>Dart Editor:</b> A Dart-savvy editor that supports creating, modifying, running, and debugging Dart apps</li>
+  <li><b>Pub:</b> A package manager that features libraries published on <a href="http://pub.dartlang.org/">pub.dartlang.org</a></li>
+  <li><b>dart2js:</b> The Dart-to-JavaScript compiler</li>
+  <li><b>dart:</b> The Dart VM</li>
+  <li><b>Dartium:</b> Chromium with an embedded Dart VM</li>
 </ul>
 
+<section id="running">
+<h3>Dart code execution</h3>
+
 <p>
 On the client side, you can deploy Dart apps in two ways.
 For browsers without an embedded Dart VM,
 you can compile the Dart code to JavaScript,
-using the dart2js compiler. This compiler generates ECMAScript5-compatible
-JavaScript from the Dart code. Dart code can run
-directly in browsers that have a Dart VM,
-including Dartium (a special build of Chromium)
-and eventually Chrome.
+using the <b>dart2js</b> compiler.
+This compiler generates ECMAScript5-compatible
+JavaScript from the Dart code.
+This JavaScript code works in the latest versions of
+Chrome, Safari, and Firefox,
+plus IE9+, mobile Safari, and Chrome for Android.
+Dart code can run directly in browsers
+that have a Dart VM,
+including Dartium and eventually Chrome.
 </p>
 
 <p>
 On the server side, the Dart code runs directly on the command line,
+using the <b>dart</b> tool,
 for fast iteration and for cloud-based tasks.
 </p>
 
+<p>
 <img src="images/source-flow.png"
-     alt="Dart source -> Dart Editor; Dart Editor -> either [Dart VM] or [JavaScript source -> Browser (JavaScript Engine)]"
-     width="266" height="417" >
+     alt="Dart source -> either [Dart VM] or [dart2js -> JavaScript source -> Browser (JavaScript Engine)]">
+</p>
+
+</section>
+
+<section id="editor">
+<h3>Dart Editor</h3>
+
+<p>
+Dart Editor is based on Eclipse components,
+but it has a simplified user interface.
+</p>
+
+<aside>
+  <div class="alert alert-info">
+    <strong>Note:</strong>
+    You aren't limited to using Dart Editor.
+    If you prefer Eclipse, IntelliJ, or WebStorm,
+    you can download Dart plugins for those IDEs.
+    Dart configurations also exist for popular text editors
+    such as Vim, Emacs, TextMate, and Sublime.
+  </div>
+</aside>
+
+<p>
+Features of Dart Editor include:
+</p>
+
+<ul>
+  <li> Easy launching of both web apps and command-line apps </li>
+  <li> Interactive debugging of both web apps (with Dartium)
+       and command-line apps </li>
+  <li> Static analysis to catch errors and potential problems </li>
+  <li> Code completion </li>
+  <li> Code navigation </li>
+  <li> Refactoring </li>
+  <li> Auto-update of the editor, SDK, and Dartium </li>
+  <li> Code update help for breaking changes
+       to the language and core libraries </li>
+</ul>
+
+<p>
+The following screenshot shows
+Dart Editor being used to debug a web app.
+</p>
+
+<p>
+<img src="images/DartEditor-debugger.png"
+     alt="screenshot of Dart Editor debugging a web app">
+</p>
+
+<p>
+To get the tools and find more information, go to the
+<a href="/downloads.html">downloads page</a>.</p>
+
+</section>
+
+<section id="pub">
+<h3>The Pub package manager</h3>
+
+<p>
+  Pub is a package mananger for Dart.
+  It helps developers reuse existing Dart code
+  and bundle Dart apps and libraries
+  for reuse and sharing with other people.
+  Pub handles versioning and dependency management.
+</p>
+
+<p>
+  You can use Pub either at the command line
+  or through Dart Editor.
+  Because Pub is part of the SDK,
+  it's updated whenever Dart Editor or the SDK is updated.
+</p>
+
+<p>
+  For more information, go to
+  <a href="http://pub.dartlang.org/">pub.dartlang.org</a>.
+</p>
+
+</section>
 </section>
 
 
 <section id="libraries">
 <h2>Libraries</h2>
 
 <p>
-Dart provides the following libraries
-to support web and web server development:
+Dart provides several libraries
+to support web and web server development.
+The
+<a href="/docs/dart-up-and-running/ch03.html">library tour</a>
+and the
+<a href="http://api.dartlang.org">API reference</a>
+have details on all the bundled Dart libraries.
+Bundled libraries include the following (and more):
 </p>
 
 <dl>
-  <dt> <a href="http://api.dartlang.org/dart_core.html">Core Library</a> </dt>
-  <dd> Contains interfaces to support
-    common data structures and operations.
+  <dt> <a href="http://api.dartlang.org/dart_core.html">Core library</a> </dt>
+  <dd> Common data structures and operations.
     </dd>
-  <dt> <a href="http://api.dartlang.org/html.html">HTML Library</a> </dt>
-  <dd> Contains interfaces to the HTML5 DOM,
+  <dt> <a href="http://api.dartlang.org/dart_html.html">HTML library</a> </dt>
+  <dd> The interface to the HTML5 DOM,
     loosely based on the proposed HTML5 standard
     as specified by the W3C/WHATWG.
-    These interfaces will evolve in parallel with
+    This library is evolving in parallel with
     the HTML5 standards.</dd>
 
-  <dt> <a href="http://api.dartlang.org/io.html">I/O Library</a> </dt>
-  <dd> Contains interfaces to read and write files, open directories,
-    open network sockets, and run HTTP servers. This library is for
-    command-line Dart programs.
+  <dt> <a href="http://api.dartlang.org/dart_io.html">I/O library</a> </dt>
+  <dd> Server-side support for I/O:
+    read and write files, open directories,
+    open network sockets, and run HTTP servers.
   </dd>
 
-  <dt> <a href="http://api.dartlang.org/dart_isolate.html">Isolate Library</a> </dt>
+  <dt> <a href="http://api.dartlang.org/dart_isolate.html">Isolate library</a> </dt>
   <dd>
-    Contains interfaces for spawning and communicating with isolates,
+    Support for spawning and communicating with isolates,
     the mechanism for concurrency and security in a Dart program.
   </dd>
 
-  <dt> <a href="http://api.dartlang.org/crypto.html">Crypto Library</a> </dt>
+  <dt> <a href="http://api.dartlang.org/dart_json.html">JSON library</a> </dt>
   <dd>
-    Contains interfaces for creating one-way hashes (SHA1, MD5, SHA256)
-    and HMAC support.
+    Support for parsing and producing JSON-encoded text.
   </dd>
 
-  <dt> <a href="http://api.dartlang.org/json.html">JSON Library</a> </dt>
+  <dt> <a href="http://api.dartlang.org/dart_math.html">Math library</a> </dt>
   <dd>
-    Contains the ability to parse and produce JSON-encoded text.
-  </dd>
-
-  <dt> <a href="http://api.dartlang.org/unittest.html">Unit Test Library</a> </dt>
-  <dd>
-    Contains functions and classes for writing unit tests in Dart.
+    Common functionality such as sine and cosine,
+    maximum and minimum,
+    and constants such as <em>pi</em> and <em>e</em>.
   </dd>
 </dl>
 
 <p>
-  See the
-  <a href="/docs/dart-up-and-running/ch03.html">library tour</a>
-  and the
-  <a href="http://api.dartlang.org">API reference</a> docs for
-  details on all the bundled
-  Dart libraries.
+  The <a href="http://pub.dartlang.org">pub.dartlang.org</a> site
+  has many additional libraries and tools.
+  Here are just a few:
 </p>
 
+<dl>
+  <dt> <a href="http://pub.dartlang.org/packages/js">JavaScript Interop</a>
+    </dt>
+  <dd> Use JavaScript from Dart code. </dd>
+
+  <dt> <a href="http://pub.dartlang.org/packages/unittest">Unit test</a> </dt>
+  <dd> Write unit tests for Dart code. </dd>
+
+  <dt> <a href="http://pub.dartlang.org/packages/web_ui">Web UI</a> </dt>
+  <dd> Build web apps using an API based on Web Components,
+       with additional features inspired by model-driven views. </dd>
+
+  <dt> <a href="http://pub.dartlang.org/packages/meta">Meta</a> </dt>
+  <dd> Use annotations to give tools
+    additional semantic information about your program. </dd>
+</dl>
+
 </section> <!-- libraries -->
 
 
-<section id="involved">
-<h2>Get involved</h2>
+<section id="get-started">
+<h2>Get started with Dart</h2>
 
 <p>
-This project is open source
-and will evolve with feedback and participation from the community.
-We have released the draft language specification at an early stage
-to gather responses from the developers
-who will be using this new language and infrastructure for web programming.
-Here are some additional links for learning more about Dart
-and providing your feedback:
+You can get started with Dart in two easy steps:
+</p>
+
+<ol>
+  <li> <a href="/docs/editor/">Download Dart Editor</a> </li>
+  <li> <a href="/docs/tutorials/">Follow the tutorials</a> </li>
+</ol>
+
+<p>
+Then join the community,
+so you can get help, meet other Dart developers,
+and find out the latest news:
 </p>
 
 <ul>
   <li>
-    Other pages in the Dart website,
-    such as the <a href="/docs/dart-up-and-running/ch02.html">language tour</a>,
+    <a href="https://plus.google.com/+dartlang">Dart page on Google+</a>
+    </li>
+  <li>
+    <a href="https://plus.sandbox.google.com/communities/114566943291919232850">Dartisans community on Google+</a> </li>
+  <li>
+    <a href="http://stackoverflow.com/questions/tagged/dart">Dart on Stack Overflow</a> </li>
+</ul>
+
+</section> <!-- get-started -->
+
+
+<section id="involved">
+<h2>More info</h2>
+
+<p>
+Here are some additional resources for learning about Dart
+and providing feedback:
+</p>
+
+<ul>
+  <li>
+    This website,
+    especially the
+    <a href="/docs/dart-up-and-running/ch02.html">language tour</a>,
     <a href="/docs/dart-up-and-running/ch03.html">library tour</a>,
-    tutorials, and <a href="/docs/spec/">language specification</a>.
+    <a href="/articles/">articles</a>,
+    and <a href="/docs/dart-up-and-running/ch05.html">Dart Chat walkthrough</a>
   </li>
   <li>
-    <a href="https://code.google.com/p/dart/">Dart project</a>
-    with issue tracker and source code </li>
+    The <a href="https://groups.google.com/a/dartlang.org/group/misc/">Dart 
+    discussion group</a> (misc at dartlang.org)
+  </li>
   <li>
-    <a href="https://groups.google.com/a/dartlang.org/group/misc/">Dart 
-    discussion group</a> (misc at dartlang.org) </li>
+    The Dart open-source project at
+    <a href="https://code.google.com/p/dart">code.google.com/p/dart</a>
+  </li>
   <li>
-    <a href="https://plus.google.com/109866369054280216564/">+Dart</a> on Google+ </li>
+    Additional open-source projects from the Dart team at
+    <a href="https://github.com/dart-lang">github.com/dart-lang</a>
+  </li>
 </ul>
 
 </section> <!-- involved -->
 
-