extension Collection where Element: Hashable, Index == Int {

    func changes(comparedTo other: Self) -> [CollectionChange] {
        var oldDict = Dictionary(uniqueKeysWithValues: zip(other, other.startIndex..<other.endIndex))
        var changes = enumerated().map { (newValue, element) -> CollectionChange in
            if let oldValue = oldDict.removeValue(forKey: element) {
                return .move(from: oldValue, to: newValue)
            } else {
                return .insert(at: newValue)
            }
        }
        changes += oldDict.map { .remove(at: $0.value) }
        return changes
    }
}

enum CollectionChange {
    case insert(at: Int)
    case remove(at: Int)
    case move(from: Int, to: Int)
}