Anders Hejlsberg and Lars Bak: TypeScript, JavaScript, and Dart

I really like the idea of static type checking, but I'm not convinced about the usefulness of runtime checking. It will introduce a performance penalty and it will go against duck typing, which is one of the coolest features of languages like JS. It seems that this project is trying to build something in between of TypeScript and Dart: they want the optional runtime type checking of Dart vs the good interoperability with JS of TypeScript. In this interview [1] Anders Hejlsberg and Lars Bak (from TypeScript and Dart) discuss the idea of runtime type checking. They don't seem very convinced of the idea either. [1] [this video]

It was very unfortunate that the first time that most heard about Dart was through a leaked memo from Google predicting Dart would replace JavaScript [ [link] ]. It created an atmosphere of hostility towards Dart that I'm sure the developers didn't deserve. I now understand your objections and I'm sorry I lumped you in with the general hostility. My own doubts about Dart after using it for a commercial app, began after watching this video [ [this video] ] where Anders Hejlsberg and Lars Bak discuss Dart and TypeScript. I felt Anders made a better case for TypeScript and Lars was feeling a bit threatened, which confirmed for me that Anders was right. Considering where Dart and TypeScript are today, I made the right choice moving to TypeScript. The other problem that I felt wasn't being addressed was that the Dart2js output and JavaScript interop needed a lot of improvement. Since it became clear that the DartVM was not landing in other browsers, this should have been a top priority and it wasn't. Now it is a priority, but it's not clear to me how many resources Google is giving to it. I'm very glad that the path is much clearer these days and thank you for your efforts to sort these things out.

> trying to justify why something is still relevant or important in a company roadmap While I know what you mean, I didn't read the article that way at all. The author isn't a marketing type or someone high up in the company, but a programmer making a calculation about Dart and passing on his observation to his friends, who don't see that situation the way he does. Dart has received a lot of bad press because some Dart engineers made the mistake of saying it would replace JavaScript. I didn't get involved in defending JavaScript from Dart and wrote a bunch of Dart, and I noticed I was about twice as productive. I also learned along the way that Google was heavily invested in something called Google Web Toolkit, a Java based system for writing web apps. I figured Google was looking to replace that with Dart so it would always have a place, and it looks like I was right. The code that powers the engine that brings in 17 billion dollars a year is nothing to dismiss, like many do of Dart, if in fact they are converting GWT to Dart, and it sounds like they are. TypeScript is one way to add safety, Dart is another. The difference in the two approaches is discussed here by the two main authors Anders Hejlsberg and Lars Bak respectively [1]. What I found compelling about Dart was the elimination of "monkey patching" that Lars talks about. I was also drawn to try TypeScript and found it a great tool as well. So does Google as they are now using TypeScript in Angular 2.0. Microsoft and