async-dispatch-thunk.tsx

type ThunkAction<T> = (dispatch: Dispatch<T>) => T
type AsyncDispatch<T> = Dispatch<T | ThunkAction<T>>

function wrapAsync<T>(dispatch: Dispatch<T>): AsyncDispatch<T> {
  return function(action: T | ThunkAction) {
    if (action instanceof Function) {
      return action(dispatch)
    }
    return dispatch(action)
  }
}