Redux: Avoiding mutation on state change

app.js

const toggleObjectBoolean = object => {
  ...object,
  bool: !object.bool
}

const addToList = list => [
  ...list,
  'new item'
]

const removeFromList = (list, index) => [
  ...list.slice(0, index),
  ...list.slice(index + 1)
]

const incrementInList = (list, index) => [
  ...list.slice(0, index),
  list[index] + 1
  ...list.slice(index + 1)
]