How this compares to TypeScript? At the quick glance I noted:

- more powerful type system (union types, hurray)

- support for JSX

- no windows binaries

- supports more of ES6 stuff

- ...but has no support for modules yet

- no generics (??)

How about performance? and workflow? Didn't yet find this: does it use a normal "write then compile" model like TS or has something like Hack (if I'm not mistaken it has a daemon running in the background, checking the code as you write it).

Wonder why FB decided to roll this on instead of using TS.