A a very simple immer alternative

CopyState

let state = {
  lists: [1, 2, 3, 4],
  items: ['a', 'b', 'c'],
}

const cloneMyState = (f) => {
  let copy = {
    items: [...state.items],
    lists: [...state.lists]
  }  
  return f(copy)
}

let update = cloneMyState(draft=>{
  draft.items.push('d')
  draft.lists.splice(1,1)
  return draft
})

console.log(update, update.items == state.items,update.lists == state.lists)