A JS closure thing

js_closure_thing.js

const actionsFor = state => {
  const WITH = attrs => actionsFor(Object.assign({}, state, attrs))
  return {
    ADD_NAME: ({ name }) => WITH({names: [name, ...state.names] }),
    LOG_STATE: () => console.log(state) || actionsFor(state),
  }
}

// dispatcher
const buildDispatcher = actions => (action, options={}) =>
  actions = actions[action](options)

// user using the dispatcher to update their app state
const actions  = actionsFor({names: ['kris', 'chris']})
const dispatch = buildDispatcher(actions)

dispatch('ADD_NAME', { name: 'erica' })
dispatch('LOG_STATE')

dispatch('ADD_NAME', { name: 'eric' })
dispatch('LOG_STATE')

// original is not updated, only the dispatcher's are
actions.LOG_STATE()