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kotlinlang

hi folks, I am relatively new to Kotlin and very new to functional programming... as a learning exercise I am trying to convert a scala parser library to Kotlin and I was wondering if there is anyway to do this with Kotlin/Arrow:

sealed trait FooBar[L &lt;: HList, T &lt;: HList, R &lt;: HList] {
  type Out &lt;: HList
}

object FooBar {
  implicit def foobar[L &lt;: HList, T &lt;: HList, R &lt;: HList, Out0 &lt;: HList]
  (implicit ts: Aux[L, L, T, T, R, HNil, Out0]): FooBar[L, T, R] { type Out = Out0 } = throw IllegalStateException("Compile-time only call")

I am having trouble with the "type" parameter which is reassigned with the function "foobar" (ie. fb.Out can be assigned a different type)...

<@U7L3827SM> we are still in the early stages of `arrow-generic` which eventually it will provide type class derivation for any type classes that already target a product type such as HList or Tuple* but it's not there yet. At the moment you can just derive the ones shown here <http://arrow-kt.io/docs/generic/product/>

Also Kotlin has no notion of abstract path dependent types like the `type Out` so that would look different once we have an strategy for it.

ok thanks Raul ... will keep checking back for new developments :slightly_smiling_face: