TypeScript: Microsoft's Replacement For JavaScript

mikejuk writes "Everyone seems to have a replacement for JavaScript — Google even has two. Now Microsoft has revealed that Anders Hejlsberg, the father of C# among other languages, has been working on a replacement and it has released a preview of TypeScript. The good news is that it is compatible with JavaScript — you can simply load JavaScript code and run it. JavaScript programs are TypeScript programs. To improve on JavaScript, TypeScript lets you include annotations that allow the compiler to understand what objects and functions support. The annotations are removed by the compiler, making it a zero overhead facility. It also adds a full class construct to make it more like traditional object oriented languages. Not every JavaScript programmer will be pleased about the shift in emphasis, but the way it compiles to a JavaScript constructor is fairly transparent. At this early stage it is difficult to see the development as good. It isn't particularly good for JavaScript developers who already have alternatives, and it isn't good for C# developers who now have confirmation that Ander Hejlsberg is looking elsewhere for his future." Update: 10/01 20:34 GMT by U L : It's also freely available under under the Apache 2.0 license, and there's a language specification available. It looks pretty interesting: it even has ML-style type inference (including e.g. deducing the types of higher order functions).

Comments

Re:all these languages what am I to do?

[Anonymous Coward]

c? to write client-side code run by the browser?

are you high?

Re:Remember the old addage

[exomondo]

Once you start writing in TypeScript you are forever bound to Microsoft.

I see you're unfamiliar with the concept of open source: git clone https://git01.codeplex.com/typescript

Re:Full classes?

[chromatic]

Coming from you?

I know a little bit about compilers.

Every language has its ugly spots that make optimization difficult...

"Every number is a float" is one of them in JavaScript. "All objects are associative arrays" is another. "Object prototypes are mutable everywhere" is yet another.

... a large amount of the performance improvements that have come in recent years have nothing to do with the language syntax of javascript...

Some, yes, but many also come from tracing the flow of data as the program runs to figure out which pessimizations inherent to the semantics of JavaScript it's safe to undo. That's why modern JavaScript JITs work so hard to perform side exits with their guard clauses to produce code that runs in as straight a line as possible. Ask Jim Blandy about it sometime.

Perl would have to do similar optimizations. So would Python. So would Ruby. (It's instructive to talk to the people behind Rubinius and Unladen Swallow, if not people who've spent years optimizing Smalltalk implementations.)

Re:Remember the old addage

[thebjorn]

Python 3.3 didn't add a "yield" keyword, it added a "yield from" construct. Python has had "yield" since version 2.2. Python also has type annotations that "don't do anything": http://www.python.org/dev/peps/pep-3107/