typealias Curr = String

typealias CurrT = Tuple2<Curr, Curr>

fun main(parameters: String) {
  val validated: List<ValidatedNel<CurrT>> = parameters.split(" ").map { 
    when (val split = it.split(":")) {
      split.length == 2 && (isCurrency(split[0]) && isCurrency(split[1])) -> 
	    Validated.validNel(split[0] toT split[1])
      else -> 
	    Validated.invalidNel(NotInPairFormat(it))
    }
  }

  val validatedParameters: ValidatedNel<List<CurrT>> =
    validated.sequence(Validated.applicative()).fix()

  val program: IO<Unit> = validatedParameters.fold({ err: Nel<NotInPairFormat> ->
    IO.raiseError<Unit>(err)
  }, { tuples: List<CurrT> ->

    // Create call to network
    val request: IO<List<FixerResponse>> = tuples.map { (orig: Curr, dest: Curr) ->
      IO { requestToFixer(orig, dest) }
    }.sequence(IO.applicative()).fix()

    fx {
	  // Call with retry 
      val responses: IO<List<FixerResponse>> = !request
        .handleErrorWith { withRetry(it, request, 3) }

      continueOn(UI)
	  // Display on screen in the UI thread
      /* Unit */ !displayList(responses)
    }/* IO<Unit> */
  })

  // Start
  program.unsafeRunAsync {}
}


fun withRetry(err: Throwable, request: IO<List<FixerResponse>>, retries: Int) =
  if (retries == 0) IO.raiseError(err)
  else request.handleErrorWith { withRetry(it, request, retries - 1) }