This is a great question, and to clarify for anyone not following along closely:
Some of us using TypeScript dream of a day when TypeScript emits JavaScript already annotated with type meditations which express as much of the typescript type system as possible in a way that Closure can understand, thereby making it possible for Closure to perform maximally efficient tree shaking and other magic with code that started as TypeScript. Such a thing as necessary and helpful because the addition of this detailed type data makes it possible for Closure to do a much better job that it can do with "just" untyped JavaScript.
It's already used within Google to effectively optimize TypeScript apps. However, someone still needs to write the integrations between tsickle and the multitude of public JS build systems and there's not a lot of pressure on me to do it (I have lots of other work to do).
Oh yes, I've been following this, at least the bits of information that emerge publicly.
But my dream is that this work could make it back into typescript itself - that a future version could possibly be persuaded to emit Closure type limitations without the help of a parallel/postprocessing pass by a tool.
I wonder if that would that change your workflow in any way?
Usually people use typescript compiler to compile TS into JS and usually it's being executed by some runner (grunt, gulp, bazel...).
Adding tsickle + closure compiler to the process should be essentially just adding couple of lines in the build process. I agree that it may be slower and have bugs - is that the worry?
Both Closure and TypeScript support (some of) the JSDoc type annotations and syntax (http://usejsdoc.org/). AFAICT, TypeScript supports a subset of what Closure does - so anything here should be portable between the two:
I commented elsewhere in this thread, but: tsickle is mostly the work of one person (me) who also has other responsibilities. I'd love some help on it, particularly in integrating it into the world of webpack etc.
I just tested moving my Typescript/React template to Google Closure using a webpack plugin. It came in at 148KB with UglifyJS, and 102KB with Google Closure running after Typescript did the ES5 conversion.
This may not be the "integration" some are seeking but it's sure a step ahead.
TypeScript understands some of the comment syntax, but the type systems are different, the module systems are different, and a ton of other stuff is different. Look through the test cases in https://github.com/angular/tsickle/tree/master/test_files to see the difference between TypeScript-annotated code and Closure-annotated code.
That's a pretty awesome project. Didn't realize something like that existed.
In this case, I think closure should start to understand typescript syntax. Or typescript needs to borrow ideas from closure on minifying and dead code removal.
