Stream a Json array

build.sbt

{ 
  val akkaStream = "com.typesafe.akka" %% "akka-stream" % "2.4.17"
  val akkaStreamJson = "de.knutwalker" %% "akka-stream-json" % "3.2.0"
  val jawn = "org.spire-math" %% "jawn-parser" % "0.10.4"
}

JsonStreaming.scala

import akka.NotUsed
import akka.stream.scaladsl.Flow
import akka.util.ByteString
import jto.validation._
import play.api.libs.json._

object JsonStreaming {

  implicit val facade: jawn.Facade[JsValue] =
    new jawn.SimpleFacade[JsValue] {
      def jnull() = JsNull
      def jfalse() = JsBoolean(false)
      def jtrue() = JsBoolean(true)
      def jnum(s: String) = JsNumber(BigDecimal(s))
      def jint(s: String) = JsNumber(BigDecimal(s))
      def jstring(s: String) = JsString(s)
      def jarray(vs: List[JsValue]) = JsArray(vs)
      def jobject(vs: Map[String, JsValue]) = JsObject(vs.toSeq)
    }

  def flow[A](implicit r: RuleLike[JsValue, A]): Flow[ByteString, VA[A], NotUsed] = {
    de.knutwalker.akka.stream.JsonStreamParser.flow(jawn.AsyncParser.UnwrapArray).map(r.validate)
  }
}