Swift extension to add non mutating methods to Array

NonMutatingArray.swift

extension Array {
  func inserted(_ element: Element, at index: Int) -> Array<Element> {
    return updated({$0.insert(element, at: index)})
  }
  
  func appended(_ element: Element) -> Array<Element> {
    return updated({$0.append(element)})
  }
  
  func appended(contentsOf elements: Array<Element>) -> Array<Element> {
    return updated({$0.append(contentsOf: elements)})
  }
  
  // added for convenience
  func prepended(_ element: Element) -> Array<Element> {
    inserted(element, at: 0)
  }
  
  func removed(_ element: Element, at index: Int) -> Array<Element> {
    return updated({$0.remove(at: index)})
  }
  
  func lastRemoved(_ element: Element) -> Array<Element> {
    return updated({$0.removeLast()})
  }
  
  func updated(_ cb: (inout Array<Element>) -> Void) -> Array<Element> {
    var working = self
    cb(&working)
    return working
  }
}

Usage.swift

let array = [1,2,3]
let updatedArray = array.prepended(0).appended(4).appended(contentsOf: [5,6,7])
print(array, updatedArray)
// [1, 2, 3] [0, 1, 2, 3, 4, 5, 6, 7]

let updatedByCallback = array.updated { $0[0] = 3 }
print(array, updatedByCallback)
// [1, 2, 3] [3, 2, 3]

let updatedByBatchOfMutations = array.updated {
  $0.insert(10, at: 0)
  $0.append(20)
}
print(array, updatedByBatchOfMutations)
// [1, 2, 3] [10, 1, 2, 3, 20]