Possible to flow-annotate a point-free function?

Question

Given these types:

type Bar = number;
type Foo = {
  bar: Bar,
};

And this point-free conversion function fooToBar:

import { prop } from 'ramda';
const fooToBar = prop('bar');

Is it possible to annotate fooToBar's signature of Foo -> Bar?

Answer 1

The function type annotation docs are pretty detailed. It looks like the following should work for you

/* @flow */

type Bar = number;
type Foo = {
  bar: Bar,
};

const prop = y => x => x[y];

const fooToBar : Foo => Bar = prop('bar');

Flow says

No errors!