FingerTreeTest.scala

"FingerTree" should {
  "apply effects in order" in {
    import std.string._
    import Id._
    type StringWriter[A] = Writer[String, A]
    val s: Writer[String, FingerTree[Int, Int]] = streamToTree(intStream.take(5)).traverseTree[StringWriter, Int, Int](x => Writer(x.toString, x))
    val (w, a) = s.runT
    (w, a.toStream) must be_===("12345", streamToTree(intStream.take(5)).toStream)
  }
}