Incremental cleanup of selector implementation and fix for multiple s…

…tores (#1568)

Summary:
Pull Request resolved: #1568

As a follow-on to D33737833 do some more incremental cleanup and simplification of the selector implementation.   Fix async selectors used from multiple stores which were not notifying other stores if they were no longer the latest evaluation in the first store to evaluate it.

Reviewed By: davidmccabe

Differential Revision: D33761732

fbshipit-source-id: 0872f5e243141af04624cb9028ebf7b07e62a226

CHANGELOG.md

@@ -32,6 +32,7 @@
   - Only clone the current snapshot for callbacks if the callback actually uses it. (#1501)
   - Cache the cloned snapshots from callbacks unless there was a state change. (#1533)
 - Fix transitive selector refresh for some cases (#1409)
+- Fix some corner cases with async selectors and multiple stores (#1568)
 - Atom Effects
   - Rename option from `effects_UNSTABLE` to just `effects` as the interface is mostly stabilizing (#1520)
   - Run atom effects when atoms are initialized from a set during a transaction from `useRecoilTransaction_UNSTABLE()` (#1466)

packages/recoil/adt/Recoil_Loadable.js

@@ -198,6 +198,10 @@ export type Loadable<+T> =
   | $ReadOnly<ErrorLoadable<T>>
   | $ReadOnly<LoadingLoadable<T>>;
 
+export type ValueLoadableType<+T> = $ReadOnly<ValueLoadable<T>>;
+export type ErrorLoadableType<+T> = $ReadOnly<ErrorLoadable<T>>;
+export type LoadingLoadableType<+T> = $ReadOnly<LoadingLoadable<T>>;
+
 function loadableWithValue<+T>(value: T): $ReadOnly<ValueLoadable<T>> {
   return Object.freeze(new ValueLoadable(value));
 }