Uh, I can't quite come up with a good name for this

RxDwifft.swift

//
//
//  Created by Robin Malhotra on 29/01/18.
//

// Special thanks to DaveDelong for suggesting this: https://github.com/davedelong/Syzygy/blob/master/SyzygyCore/Properties/Property%2BCollections.swift#L76
import RxSwift
import Dwifft


extension Observable where Element: Collection, Element.Element: Equatable {
  
  //implementation taken from https://github.com/RxSwiftCommunity/RxSwiftExt/blob/master/Source/RxSwift/nwise.swift
  public func nwise(_ n: Int) -> Observable<[E]> {
    assert(n > 1, "n must be greater than 1")
    return self
      .scan([]) { acc, item in Array((acc + [item]).suffix(n)) }
      .filter { $0.count == n }
  }
  
  //implementations taken from https://github.com/RxSwiftCommunity/RxSwiftExt/blob/master/Source/RxSwift/nwise.swift
  public func pairwise() -> Observable<(E, E)> {
    return self.nwise(2)
      .map { ($0[0], $0[1]) }
  }
  
  public func arrayfied() -> Observable<Array<Element.Element>> {
    return self.map({ (collection) in
      return Array(collection)
    })
  }
  
  func pairwiseDiffs() -> Observable<[DiffStep<Element.Element>]> {
    return self.arrayfied().pairwise().map { (oldArray, newArray) in
      return Dwifft.diff(oldArray, newArray)
    }
  }
 
  //TODO: Make a generic version that takes a closure (Array, Array) -> (IndexPaths to insert, IndexPaths to delete) that'll in theory work with any diffing library for true decoupling 😃
}