scalaz-streamsのTask.startは、既存のTaskの実行Threadも変更できそう

scalaz-streams-Task-es.scala

import streams._
import util._
implicit val s = Strategy.fromExecutionContext(scala.concurrent.ExecutionContext.Implicits.global)
val t = Task(println(Thread.currentThread.getName))

// Exiting paste mode, now interpreting.

import streams._
import util._
s: streams.util.Strategy = streams.util.Strategy$$anon$1@60d8175
t: streams.Task[Unit] = streams.Task@60ae2b6d

scala> for{
     |  t1 <- t
     |  t2 <- Task.start(t)(Strategy.sequential)
     |  t3 <- t2
     | } yield {Unit}
res0: streams.Task[Unit.type] = streams.Task@4bb621c

scala> res0.run
ForkJoinPool-1-worker-13
ForkJoinPool-1-worker-11
res1: Unit.type = object scala.Unit

scala> Task(println(Thread.currentThread.getName))(Strategy.sequential).run
run-main-0

scalaz-streams-Task.scala

scala> import streams._
import streams._

scala> import util._
import util._

scala> implicit val s = Strategy.fromExecutionContext(scala.concurrent.ExecutionContext.Implicits.global)
s: streams.util.Strategy = streams.util.Strategy$$anon$1@785eb11

scala> val t = Task(println(Thread.currentThread.getName))
t: streams.Task[Unit] = streams.Task@77de626

scala> t.run
ForkJoinPool-1-worker-13

scala> for{
     |   t1 <- t
     |   t2 <- Task.start(t)
     |   t3 <- t2
     | } yield {(t1,t3)}
res1: streams.Task[(Unit, Unit)] = streams.Task@5509b26b

scala> res1.run
ForkJoinPool-1-worker-13
ForkJoinPool-1-worker-11
res2: (Unit, Unit) = ((),())