Question for TypeScript and specifically Angular 2: does Angular 2 being written in TypeScript mean that webapps based on Angular 2 that are also written in TypeScript, are basically 100% type-safe (e.g. all app-to-Angular library calls, or within-app view-to-model/etc. calls, are all type checked)?<p>I ask because after looking (admittedly very briefly) at writing an Ember app in TypeScript, it looked like because Ember assumes all of it's webapps will be JavaScript, there ends up being a lot of dynamic-/string-based idioms, e.g. model.set("property").<p>(There is a good SO post about turning this into a typed model.property.set(...) in TypeScript, but that solves just this one instance, and not the entire Ember experience.)<p>So, this left me with the feeling that for a TypeScript webapp to have a truly great/first-class/typed interaction with it's framework (Angular, Ember, whatever), that the framework itself would have to: a) be written in TypeScript, and b) have the founding assumption that most (all?) apps written for it would also be TypeScript.<p>So, per this post, Angular 2 is a), it's written in TypeScript. What about b)?