Convert List[ValidationNEL[String, Unit]] to ValidationNEL[String, Unit]

Question

Is there a standard way to flatten the left sides into a single list?

thanks!

Answer 1

I'm not exactly sure what you're trying to do, but the Monoid instance should do the trick:

scala> List(
     |   println("test").successNel[String],
     |   "a".failNel[Unit],
     |   "b".failNel[Unit]
     | ).suml == Failure(NonEmptyList("a", "b"))
test
res0: Boolean = true

Where suml is a method that's pimped onto any collection full of something with a Monoid instance.