Typescript: action type parameter for Store, Dispatch, etc.

[samfrances]

Looking at the Typescript typings for Redux, it looks like there is no built-in way to type check calls to dispatch, etc. This looks like something that could be improved. For example you could envisage a store definition that looks something like the following:

interface Store<S, A extends Action = Action> {
  dispatch: Dispatch<S, A>;
  getState(): S;
  subscribe(listener: () => void): Unsubscribe;
}

export interface Dispatch<S, A extends Action = Action> {
    (action: A): A;
}

Then, with appropriate modifications elsewhere, you could something like the following:

type MyAppActions =
  | CreateTodo
  | DeleteTodo
  | UpdateTodo;

const store = createStore<MyAppState, MyAppActions>(myReducer);

I would be interested to hear what you think of this as an idea. In particular, is this an idea that has already been considered and rejected in the past?

[samfrances]

Looks like this is already being worked on: #2563

Good to see.