surajsau

fun add(a: Int, b: Int, c: Int) = a + b + c

fun wrap(f: (Int, Int, Int) -> Int) = { x: Int -> { y: Int -> { z: Int -> f(x, y, z) }}}

val result = Functor.Something(1).map(wrap(::add)) // Something({ y -> { z -> add(1, y, z) }})
                                .apply(Functor.Something(2)) // Something({z -> add(1, 2, z) })
                                .apply(Functor.Something(3)) // Something(6)

surajsau

fun add3() = { a: Int -> a + 3 }

val wrappedFunction = Functor.Something(add3()) //Something({it -> it + 3})
val wrappedValue = Functor.Something(2) //Something(2)

/*
  apply() = Functor.Something(2).map({it -> it + 3})
*/
val result = wrappedValue.apply() //Something(5)

surajsau

//Extension function for type context wrapped function of type: (T) -> S
fun<T, S> Functor<(T) -> S>.apply(f: Functor<T>): Functor<S> = when(this) {
    is Nothing -> this
    is Something -> f.map(this.value) //this.value is the unwrapped function itself
}

surajsau

fun add3(x: Int) = x + 3 //our normal function

val something = Functor.Something(3)
val altered = something.map { add3(it) }.map { add3(it) } //returns Something(9)

val nothing = Functor.Nothing
val alteredNothing = nothing.map { add3(it) } //returns Nothing

surajsau

sealed class Functor<out T> {

    object Nothing: Functor<kotlin.Nothing>()

    data class Something<out T>(val value: T): Functor<T>()

    inline fun<S> map(f: (T) -> S): Functor<S> = when(this) {
        is Nothing -> this
        is Something -> Something(f(this.value))
    }

surajsau

struct APIService {
  
  @GET(url: "https://swapi.co/api/films")
  static var getFilms: Observer<Films>
  
}
    
APIService.getFilms { (response) in
   //response is the same received in Alamofire's completionHandler
   ..

surajsau

@propertyWrapper
struct GET<T: Decodable> {
  private var url: URL
  
  init(url: String) {
    self.url = URL(string: url)!
  }
  
  var wrappedValue: Observer<T> {
    get {

surajsau

typealias Observer<T: Decodable> = (_ completionhandler: @escaping (DataResponse<T, AFError>) -> Void) -> ()

surajsau

struct APIService {
  
  @GET(url: "https://swapi.co/api/films")
  static var getFilms: Service<Films>
  
}

surajsau

func fetchFilms() {
    AF.request("https://swapi.co/api/films")	    
      .validate()	
      .responseDecodable(of: Films.self) { (response) in
        ..
      }
}


func searchStarships(for name: String) {