Second, as any code generation tool (and this is true of CoffeeScript as well), you’d better like the generated code. I didn’t, unfortunately. The code that I saw is not the code I would have written. What’s more, I didn’t always find the TypeScript code especially more expressive than what it gets compiled to.
I also have a few questions.
Is it possible to duck-type interfaces? For example, if I have an IPoint2D interface with x and y coordinates, can I pass any object that has x and y into a function that expects IPoint2D or do I need to necessarily create a class that implements that interface, and new up an instance that explicitly declares its contract? The appeal of dynamic languages is the ability to make objects as you go. This needs to be kept intact.
UPDATE: this works.
More technical: why are generated variables and functions prefixed with _ rather than the $ that the EcmaScript spec recommends for machine-generated variables?
You can play with TypeScript here: http://www.typescriptlang.org