ConcatinateAsyncFuncs

ConAsyncFunc.swift

infix operator --> :AdditionPrecedence

func --><InputA, CompA, CompB>(first: @escaping ( InputA, @escaping (CompA?) -> () ) -> (),
                               second: @escaping ( CompA, @escaping (CompB?) -> () ) -> ()) -> (InputA, @escaping (CompB?) -> ()) -> () {
  
  return { (input: InputA, compB: @escaping (CompB?) -> () ) in
    
    first(input, { compA in
      
      guard let validCompaA = compA else { compB(nil); return }
      second(validCompaA, compB)
    })
  }
}

func a(a: Int, completion: @escaping (Int?) -> ()) {
  
    completion(a + 1)
}

func b(b: Int, completion: @escaping (String?) -> ()) {
  
    completion("ahmad")
}

func c(c: String, completion: @escaping (Int?) -> ()) {
  
    completion(66)
}


let result = a --> b --> c


result(4, { result in

  if result == nil {
    print("fail")
  } else {
    print("success")
  }
})