Comment by thejameskyle

Flow tries to integrate with the existing ecosystem as much as possible. By taking advantage of Babel, ESLint, Atom, etc.

With Flow you don't even have to opt-in to a new syntax. You can just use comments:

    function foo(val /* : boolean */) /* : string */ {}

Using really powerful inference you can also write much fewer types. If you have well types libraries [you sometimes don't need types in your code at all](https://medium.com/@thejameskyle/flow-mapping-an-object-373d...).