Created
April 7, 2017 17:08
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Tasks to Task of ValidationNel
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import scalaz._, Scalaz._ | |
import scalaz.concurrent.Task | |
object flip { | |
def flip: String = { | |
val rnd = new java.util.Random() | |
if (rnd.nextInt(2) == 1) { | |
"Heads" | |
} else { | |
throw new RuntimeException("Tails") | |
} | |
} | |
val flips = List(Task.delay(flip), Task.delay(flip), Task.delay(flip), Task.delay(flip), Task.delay(flip)) | |
val flipLists = flips.map(_.map(List(_))) // Turn Heads/Tails into List (Monoid) | |
val attempts = flipLists.map(_.attempt) // List[Task[Throwable \/ List[String]]] | |
val validations = attempts.map(_.map(_.validation)) // List[Task[Validation[Throwable, List[String]]]] | |
val vNels = validations.map(_.map(_.toValidationNel)) // List[Task[ValidationNel[Throwable, List[String]]]] | |
val task = Nondeterminism[Task].aggregate(vNels) // Task[ValidationNel[Throwable, List[String]]] | |
/* | |
scala> task.unsafePerformSync | |
res1: scalaz.ValidationNel[Throwable,List[String]] = Failure(NonEmpty[java.lang.RuntimeException: Tails,java.lang.RuntimeException: Tails,java.lang.RuntimeException: Tails]) | |
*/ | |
} |
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