OWF12/PAUG Conf Days Dart a new html5 technology, nicolas geoffray, software engineer at google
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Dart is a programming language developed by Google to make web development easier. It aims to improve on JavaScript by providing better support for structuring large applications, faster startup performance, static typing for documentation and error prevention, and isolation-based concurrency. Dart code compiles to JavaScript, allowing it to run in any modern browser. It is open source and designed for programmer productivity and application performance.
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var x = 499;
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x + [];
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![No argument type checking
var x = 499;
x + null; // => 499
x + [];
x + undefined;
x - {};](https://image.slidesharecdn.com/dartanewhtml5technologynicolasgeoffraysoftwareengineeratgoogle-121026032649-phpapp01/85/OWF12-PAUG-Conf-Days-Dart-a-new-html5-technology-nicolas-geoffray-software-engineer-at-google-10-320.jpg)
![No argument type checking
var x = 499;
x + null; // => 499
x + []; // => "499"
x + undefined;
x - {};](https://image.slidesharecdn.com/dartanewhtml5technologynicolasgeoffraysoftwareengineeratgoogle-121026032649-phpapp01/85/OWF12-PAUG-Conf-Days-Dart-a-new-html5-technology-nicolas-geoffray-software-engineer-at-google-11-320.jpg)
![No argument type checking
var x = 499;
x + null; // => 499
x + []; // => "499"
x + undefined; // => NaN
x - {};](https://image.slidesharecdn.com/dartanewhtml5technologynicolasgeoffraysoftwareengineeratgoogle-121026032649-phpapp01/85/OWF12-PAUG-Conf-Days-Dart-a-new-html5-technology-nicolas-geoffray-software-engineer-at-google-12-320.jpg)
![No argument type checking
var x = 499;
x + null; // => 499
x + []; // => "499"
x + undefined; // => NaN
x - {}; // => NaN](https://image.slidesharecdn.com/dartanewhtml5technologynicolasgeoffraysoftwareengineeratgoogle-121026032649-phpapp01/85/OWF12-PAUG-Conf-Days-Dart-a-new-html5-technology-nicolas-geoffray-software-engineer-at-google-13-320.jpg)
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var array = new Array(32);
...
array[32];
array[-1];
array[.1];
array[null];
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var array = new Array(32);
...
array[32]; // => undefined
array[-1]; // => undefined
array[.1]; // => undefined
array[null]; // => undefined
array[array]; // => undefined](https://image.slidesharecdn.com/dartanewhtml5technologynicolasgeoffraysoftwareengineeratgoogle-121026032649-phpapp01/85/OWF12-PAUG-Conf-Days-Dart-a-new-html5-technology-nicolas-geoffray-software-engineer-at-google-15-320.jpg)
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array[.1]; // => void 0
array[null]; // => void 0
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![Flavour of generated JavaScript
class Point {
var x, y;
Point(this.x, this.y);
toString() => "($x,$y)";
}
Isolate.$defineClass("Point", "Object", ["x", "y"], {
toString$0: function() {
return '(' + $.toString(this.x) + ',' +
$.toString(this.y) + ')';
}
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OWF12/PAUG Conf Days Dart a new html5 technology, nicolas geoffray, software engineer at google
- 1. Dart: a modern web language Nicolas Geoffray Google
- 2. Who am I? Nicolas Geoffray, software engineer at Google Projects ● VVM - Highly dynamic runtime environment ● VMKit - Framework for writing VMs ● I-JVM - Better dependability in OSGi ● Dart - Structured programming for the web
- 3. Motivation Improve web development
- 4. The web is already pretty awesome ● It is easy to develop small applications ○ Code runs everywhere (phones, desktops) ○ No installation of applications ○ Deployment is almost trivial ● JavaScript is very flexible and supports incremental development
- 5. The rise of JavaScript Crankshaft Credit: http://iq12.com/blog/
- 6. Why is the web hard to program for? ● Writing large well-performing applications is hard ● Hard to reason about the program structure ● Startup performance is often really bad ● Difficult to document intent (lack of types) ● No support for modules, packages, or libraries
- 7. Make it easier ● We want to improve the web platform ○ Better support for programming in the large ○ Faster application startup (especially on mobile) ○ More predictable and better runtime performance ○ JavaScript is a powerful tool but it has sharp edges ● Keep up the innovation momentum ○ The web is evolving at a fantastic pace! ○ The developer tools have to keep up
- 8. JavaScript is full of ... surprises ● Lots and lots of implicit type conversions ● Most operations produce weird results when passed wrong or uninitialized values instead of failing in a recognizable way Keep on truckin'
- 9. No argument type checking var x = 499; x + null; x + []; x + undefined; x - {};
- 10. No argument type checking var x = 499; x + null; // => 499 x + []; x + undefined; x - {};
- 11. No argument type checking var x = 499; x + null; // => 499 x + []; // => "499" x + undefined; x - {};
- 12. No argument type checking var x = 499; x + null; // => 499 x + []; // => "499" x + undefined; // => NaN x - {};
- 13. No argument type checking var x = 499; x + null; // => 499 x + []; // => "499" x + undefined; // => NaN x - {}; // => NaN
- 14. No array bounds checking var array = new Array(32); ... array[32]; array[-1]; array[.1]; array[null]; array[array];
- 15. No array bounds checking var array = new Array(32); ... array[32]; // => undefined array[-1]; // => undefined array[.1]; // => undefined array[null]; // => undefined array[array]; // => undefined
- 16. No array bounds checking var array = new Array(32); ... array[32]; // => void 0 array[-1]; // => void 0 array[.1]; // => void 0 array[null]; // => void 0 array[array]; // => void 0
- 17. No spell checking? var request = new XMLHttpRequest(); ... request.onreadystatechange = function() { if (request.readystate == 4) { console.log('Request done!'); } };
- 18. No spell checking? var request = new XMLHttpRequest(); ... request.onreadystatechange = function() { if (request.readyState == 4) { console.log('Request done!'); } };
- 19. JavaScript has improved but ... ● JavaScript has fundamental issues at the language level that impact productivity ● Performance has improved but mostly for a pretty static subset of JavaScript ● It remains very time consuming to build and maintain large web apps
- 20. The story of Dart ● A few years ago Lars Bak and Kasper Lund prototyped Spot ○ A new simple programming language for the web ○ Based on their experiences from JavaScript/V8 ● Spot was the prelude for the Dart project
- 21. What is Dart? ● Unsurprising object-oriented programming language ● Class-based single inheritance with interfaces ● Familiar syntax with proper lexical scoping ● Single-threaded with isolate-based concurrency ● Optional static types
- 22. And more! Dart comes with a lot of developer tools: ● DartEditor: Eclipse based Dart editor ● Dartium: Chromium with embedded Dart VM ● dart2js: Dart-to-JavaScript compiler ● Libraries: io, crypto, i18n, ...
- 23. Deployment and execution Dart source Dart source Dart virtual Dart tools machine in browser or standalone Dart snapshot JavaScript runs in all modern browsers
- 24. Let's see it in action ● Let's write simple applications with the Eclipse-based Dart Editor
- 25. Conventional type checking ● Tries to prove that your program obeys the type system ● Considers it a fatal error if no proof can be constructed ● In Dart, you are innocent until proven guilty... List<Apple> apples = tree.pickApples(); printFruits(apples); void printFruits(List<Fruit> fruits) { for (Fruit each in fruits) print(each); }
- 26. Optional static types ● Static types convey the intent of the programmer ● Checkable documentation for code and interfaces ● Avoids awkward variable naming or comment schemes ● Type annotations have no effect on runtime semantics
- 27. Isolates Isolates are lightweight units of execution: ● Run in their own address space like processes ● Nothing is shared - nothing needs synchronization ● All communication takes place via messaging passing ● Supports concurrent execution
- 28. Communication ● ReceivePorts: ○ enqueues incoming messages ○ can not leave their isolate ○ can be created on demand ● SendPorts: ○ created by a ReceivePort ○ dispatches messages to its ReceivePort ○ can be transferred (across Isolate boundaries) ○ Unforgeable, transferable capability
- 29. Dart virtual machine ● Dart has been designed for performance ○ Simplicity gives more performance headroom ○ Enforced structure leads to better predictability ○ Virtual machine performs better than V8 at launch ● Works embedded in browser or standalone ○ Experimental Dart-enabled build of Chromium ○ SDK includes preliminary server-side libraries $ dart hello.dart
- 30. Dart-to-JavaScript ● Compiler is implemented in Dart ○ Generates JavaScript that runs in modern browsers ○ SSA based optimizations ○ Uses tree shaking to cut down on code size $ dart2js --out=hello.js hello.dart
- 31. Flavour of generated JavaScript class Point { var x, y; Point(this.x, this.y); toString() => "($x,$y)"; } Isolate.$defineClass("Point", "Object", ["x", "y"], { toString$0: function() { return '(' + $.toString(this.x) + ',' + $.toString(this.y) + ')'; } });
- 32. Performance
- 33. Open source ● Dart is available under a BSD license ● Developed in the open (code reviews, build bots, etc.) Online resources ● Primary site - http://www.dartlang.org/ ● Code - http://dart.googlecode.com/ ● Libraries - http://api.dartlang.org/ ● Specification - http://www.dartlang.org/docs/spec/
- 34. Summary ● Dart is an unsurprising, object-oriented language that is instantly familiar to most ● Dart allows you to write code that tools and programmers can reason about ● Dart applications runs in all modern browsers through translation to JavaScript
- 35. Dart allows rapid prototyping and structured development. Dart was designed with performance in mind. Thank you! Dart is open source and instantly familiar to lots of programmers. Dart runs everywhere JavaScript does.