But, it extends the syntax of JS, so the only thing one can do, is to create a compiler for it to compile into JS that is compatible with the target interpreter

But, it extends the syntax of JS, so the only thing one can do, is to create a compiler for it to compile into JS that is compatible with the target interpreter (most likely a web browser). In this case, I believe he outputs the "compiled" (more appropriately maybe, "transformed") code in Continuation Passing Style[1] where appropriate. [1]: http://en.wikipedia.org/wiki/Continuation-passing_style http://en.wikipedia.org/wiki/Continuation-passing_style