thats great. Though I would add in the flow vs TS debate the level of community suport / openness is (currently) hugely in typescripts favour, and for a tool that you are going to embed inot a lot of your files, so a reasonable effort to unwind, that matters. If you compare: https://github.com/Microsoft/TypeScript/milestones and https://github.com/Microsoft/TypeScript/wiki/Roadmap to the lack of information on progress from the flow team, especially on the win support issue https://github.com/facebook/flow/issues/6