Adds 'sequence' for Map[A, ErrorOr[B]]

[cjllanwarne]

No description provided.

[mcovarr]

ToL could you implement traverse and have sequence be a special case that applies identity to the elements?

[mcovarr]

👍

[cjllanwarne]

@mcovarr is this what you intended?

[mcovarr]

[danbills]

You should get sequence and traverse for free (w/ the right import sauce) w/ cats

[cjllanwarne]

@danbills I wasn't able to get that to work, even with cats.implicits._, although that by no means rules it out as possible...

[danbills]

@cjllanwarne I wasn't either, but I was able to get it to work in Cats console... Investigating

cats:

scala> import cats.syntax.traverse._
import cats.syntax.traverse._

scala> import cats.instances.map._
import cats.instances.map._

scala> import cats.data.Validated._
import cats.data.Validated._

scala> validNel(1)
res0: cats.data.ValidatedNel[Nothing,Int] = Valid(1)

scala> Map("h" -> res0).sequence
res1: cats.data.ValidatedNel[Nothing,scala.collection.immutable.Map[String,Int]] = Valid(Map(h -> 1))

lenthall:

scala> import cats.syntax.traverse._
import cats.syntax.traverse._

scala> import cats.instances.map._
import cats.instances.map._

scala> import cats.data.Validated._
import cats.data.Validated._

scala> validNel(1)
res0: cats.data.ValidatedNel[Nothing,Int] = Valid(1)

scala> Map("h" -> res0).sequence
<console>:22: error: value sequence is not a member of scala.collection.immutable.Map[String,cats.data.ValidatedNel[Nothing,Int]]
       Map("h" -> res0).sequence