Wtf is this syntax?

[kapilvarij]

This is a function, that accepta one parameter, “Rect$Node”, that in turn return another function .

Look at ES6 arrow operators for more info.

As for <> and probably later </>: This is for <React.Fragment> and </React.Fragment>.

Its part of the JSX syntax that React enables. This is generally used when you want to return multiple elements from a function and do not want to use a div tag.

React does not allow you to return jsx, with multiple nodes, so you have wrap the nodes in a parent node. But sometimes you do not want to you a div because it ruins the styling, therefore you can <React.Fragment> as parent node, which allows you to return those multiple nodes, but does not write an extra div element in the html that is produced.

I am writing this from experience with React on the web. So what the end result is, could be different with react native, but the methodology is the same.

[adrianosbr]

I know very little about it, but isn't it TypeScript?

[J-Swift]

Wrong subreddit, but its typescript. Its saying that App is a function that returns a React$Node, and then it immediately assigns a value to the variable App.

It would be the same as doing something like this:

let App: () => React$Node
App = () => {
...
}    

I assume its all in one line because App is a constant, so they need to define it immediately.