Task

A Task can be created from for-comprehension, where keywords.Each and keywords.Fork can be used together to asynchronously iterate collections. For example, the above concatenateRemoteData downloads and concatenates data from multiple URLs.

import com.thoughtworks.dsl.comprehension._
import com.thoughtworks.dsl.keywords._
import com.thoughtworks.dsl.keywords.Shift._
import com.thoughtworks.dsl.domains.task.Task
import java.net.URL
def concatenateRemoteData(urls: List[URL], downloader: URL => Task[Vector[Byte]]): Task[Vector[Byte]] = {
  for {
    url <- Fork(urls)
    data <- downloader(url)
    byte <- Each(data)
  } yield byte
}.as[Task[Vector[Byte]]]

A Task can be also created from Task.apply

def mockDownloader(url: URL) = Task {
  "mock data\n".getBytes.toVector
}

A Task can be then converted to scala.concurrent.Future via Task.toFuture, in order to integrate into other frameworks. In this example, it's a Future[Assertion] required by org.scalatest.freespec.AsyncFreeSpec.

val mockUrls = List(new URL("http://example.com/file1"), new URL("http://example.com/file2"))
import org.scalatest.Assertion
def assertion: Task[Assertion] = Task {
  !concatenateRemoteData(mockUrls, mockDownloader) should be("mock data\nmock data\n".getBytes.toVector)
}
Task.toFuture(assertion)