Integration code between Scalaz and Scala standard concurrency libraries.

Task.scala

import scalaz.\/
import scalaz.concurrent.Task

import scala.concurrent.{ ExecutionContext, Future, Promise }
import scala.util.Try

class TaskCompat(private val T: Task.type) extends AnyVal {

  def fromScala[A](future: Future[A])(implicit ec: ExecutionContext): Task[A] =            
    Task async (handlerConversion andThen future.onComplete)

  def fromScalaDeferred[A](future: => Future[A])(implicit ec: ExecutionContext): Task[A] =
    Task delay fromScala(future)(ec) flatMap identity

  def unsafeToScala[A](task: Task[A]): Future[A] = {                           
    val p = Promise[A]
    task runAsync (_ fold (p failure _, p success _))
    p.future
  }

  private def handlerConversion[A]: ((Throwable \/ A) => Unit) => Try[A] => Unit =
    callback => (t: Try[A] => \/ fromTryCatch t.get) andThen callback
}