Scalaz's Tasks can be composed easily

TaskCompositionDemo.sc

package com.github.before.examples

import scalaz.concurrent._

/**
 * Example how to compose Scalaz Tasks with a For-Comprehension
 */
object TaskCompositionDemo {

  // first task
  val t1 = Task.delay(List(1, 2, 3, 4, 5))        //> t1  : scalaz.concurrent.Task[List[Int]] = scalaz.concurrent.Task@5d3411d

  // second task
  val t2 = Task.delay(List(6, 7, 8, 9, 0))        //> t2  : scalaz.concurrent.Task[List[Int]] = scalaz.concurrent.Task@3bfdc050

  // sequence tasks
  val t3 = for {
    r1 <- t1
    r2 <- t2
  } yield r1 ++ r2                                //> t3  : scalaz.concurrent.Task[List[Int]] = scalaz.concurrent.Task@685cb137

  // run first and second task within `t3`
  t3.run                                          //> res0: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 0)

}