App.js

import { StoreProvider, useStore } from './store'

const Counter = () => {
  // Use the store
  const [state, setState] = useStore();

  const increment = () =>
    setState(old => ({
      ...old,
      count: old.count + 1
    }));

  const decrement = () =>
    setState(old => ({
      ...old,
      count: old.count - 1
    }));

  return (
    <div>
      <button onClick={decrement}>-</button>
      {state.count}
      <button onClick={increment}>+</button>
    </div>
  );
};

const App = () => {
  return (
    // Provide the store to the app
    <StoreProvider initialValue={{ count: 0 }}>
      <Counter />
    </StoreProvider>
  );
};