It turns out that `Validated` is probably a better...

# arrow

[xenomachina]

It turns out that Validated is probably a better fit where I was using Either, and it looks like Validated uses Nothing in the two subclasses:

data class Valid<out A>(val a: A) : Validated<Nothing, A>()
  data class Invalid<out E>(val e: E) : Validated<E, Nothing>()