Recoil lets you create a data-flow graph that flows from atoms (shared state) through selectors (pure functions) and down into your React components. Atoms are units of state that components can subscribe to. Selectors transform this state either synchronously or asynchronously.
And here's an awesome video from the library author explaining a bit more about Recoil from today's React Europe livestream.
The docs are incomplete yet, but this looks very promising and easy to use.