what you’d like is something like a couple of MVar...

# arrow

[pakoito]

what you’d like is something like a couple of MVars that you update with the latest value, that you combine with Applicative.map into an Either or an Option

[Michael Marth]

Rx is working fine - but that's the only use case left I'd need it for. Will give MVars a try, thanks!

[pakoito]

to do multiple results you’ll need a recursive function

[pakoito]

so you do your operation, whether it succeeds or fails you then call yourself with the right parameters

[pakoito]

fun validate(ioA: IO<Int>, ioB: IO<String>): IO<Unit> =
  map(ioA, ioB) { a, b ->
    val vb = isValid(b)
    when(val va = isValid(a)) {
      true -> when (vb) {
        true -> nextStep(a + b)
        false -> validate(just(a), ioB) // wrong
      }
      false -> when (vb) {
        true -> validate(ioA, just(b)) // wrong
        false -> validate(ioA, ioB)
      }
    }
  }

[pakoito]

see if that makes sense to you

[pakoito]

if we had pattern matching we wouldn’t need nested when-s

[pakoito]

validate(mVarA.take(), mVarB.take()) to start it

[pakoito]

…actually

[pakoito]

hmmmm

[pakoito]

you may find a problem if there’s a new value that’s not valid anymore and we’re passing around that just

[pakoito]

we don’t have the equivalent of combineLatest , so what we’re doing here is reproducing it’s behavior

[pakoito]

fun Concurrent<ForIO>.pollNextTickOnTimeout(curr: A, next: IO<A>): IO<A> =
  IO.schedulers().default().raceN(
    Timer(this)
      .sleep(100.milliseconds)
      .flatMap { just(a) }, 
    next
  )

[pakoito]

with that

[pakoito]

fun Concurrent<ForIO>.validate(ioA: IO<Int>, ioB: IO<String>): IO<Unit> =
  map(ioA, ioB) { a, b ->
    val vb = isValid(b)
    when(val va = isValid(a)) {
      true -> when (vb) {
        true -> nextStep(a + b)
        false -> validate(pollNextTickOnTimeout(a, ioA), ioB)
      }
      false -> when (vb) {
        true -> validate(ioA, pollNextTickOnTimeout(b))
        false -> validate(ioA, ioB)
      }
    }
  }

[julian]

Is ^ missing an ioB?
validate(ioA, pollNextTickOnTimeout(b, ioB))

[Michael Marth]

Thanks, guys!
I simplified my approach to changing the contract between sender and receiver to deliver all textfield contents when one of them is updated - that's more a hack (that does not scale well), but still the most concise solution.
I really do not want to introduce a timer for that.