useReducer + context

SomethingUsefulProvider.js

import React, { useReducer, useContext, createContext } from 'react'
import PropTypes from 'prop-types'

const SomethingUsefulContext = createContext()

export const reducer = ( state, action ) => {
  switch(action.type) {
    default:
      throw new Error(`Unrecognised action type: ${action.type} `)
  }
}

export const SomethingUsefulProvider = ({ children }) => (
  <SomethingUsefulContext.Provider value={useReducer(reducer, initialState)}>
    {children}
  </SomethingUsefulContext.Provider>
)

SomethingUseful.propTypes = {
  children: PropTypes.oneOfType([PropTypes.arrayOf(PropTypes.node), PropTypes.node]).isRequired
}

export const useSomethingUseful = () => useContext(SomethingUsefulContext)