Google has announced an early preview of Dart, a new language for web applications. The news is not a surprise, especially if you have been keeping track of the developer conference GOTO Aarhus, whose organisers had pre-announced that Google would be announcing its new language there, as indeed it did.

Dart is a curly-brace language like JavaScript, Java, C, C++ and C#. In Dart, as in C# and Java, a class can implement multiple interfaces, but only inherit from a single class. Dart supports both static and dynamic typing. Google says it can be executed by a Dart VM, or converted to JavaScript:

Dart code can be executed in two different ways: either on a native virtual machine or on top of a JavaScript engine by using a compiler that translates Dart code to JavaScript. This means you can write a web application in Dart and have it compiled and run on any modern browser. The Dart VM is not currently integrated in Chrome but we plan to explore this option.

Google also says that you will be able to “execute Dart code directly in a VM on the server side”, so you can infer that Google has Dart in mind as an alternative PHP as well as to JavaScript. The company is using the phrase “structured web programming” to describe Dart, and this phrase appears in the announcement and as the subtitle on the Dart site. The implication is that JavaScript code tends to be poorly structured and that Dart will promote more maintainable code.

In the preview Dart only runs in Chrome, Safari 5 and Firefox 4+ – spot the missing browser vendors.

At first glance, Dart looks like a promising language, though I find myself asking what it is really for, when it bears a strong family resemblance to existing languages, and bearing in mind that the Google Web Toolkit, which compiles Java to JavaScript, already enables structured programming for web applications. The list of problems which Dart solves in the technical overview is not all that compelling.

Google states that:

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).

This is or was one of the attractions of Microsoft Silverlight, presuming you use C# on both server and client, but Silverlight is a plug-in that was never going to run on an iPad and from which Microsoft itself is now retreating; though it is worth noting that Dart is not unlike C#, especially the latest version of C# with dynamic features.

I guess that Dart is a consequence of the failure of ECMAScript 4.0, which was a cooperative effort to create a more modern and advanced JavaScript. Google is now going it alone; the key question is whether it can win support from others such as Apple and Microsoft, or whether this will be a Google language for Google on the server and Chrome on the client, or an interesting experiment that never really catches on.

Do we need Dart? I would value hearing from others what you think of Google’s proposal.