ParallelContinuation

Given two ParallelContinuations, each of them modifies a var,

import com.thoughtworks.zerocost.parallel._
import com.thoughtworks.zerocost.continuation._
var count0 = 0
var count1 = 0
val pc0: ParallelContinuation[Unit] = Parallel(Continuation.delay {
  count0 += 1
})
val pc1: ParallelContinuation[Unit] = Parallel(Continuation.delay {
  count1 += 1
})

when map them together,

import cats.syntax.all._
val result: ParallelContinuation[Unit] = (pc0, pc1).mapN{ (u0: Unit, u1: Unit) => }

then the two vars have not been modified right now,

count0 should be(0)
count1 should be(0)

when the result ParallelContinuation get done, then two vars should be modified only once for each.

val Parallel(contResult) = result
contResult.map { _: Unit =>
  count0 should be(1)
  count1 should be(1)
}.toScalaFuture

Given two ParallelContinuations that contain immediate values,

import com.thoughtworks.zerocost.parallel._
import com.thoughtworks.zerocost.continuation._
val pc0: ParallelContinuation[Int] = Parallel(Continuation.pure[Unit, Int](40))
val pc1: ParallelContinuation[Int] = Parallel(Continuation.pure[Unit, Int](2))

when map them together,

import cats.syntax.all._
val result: ParallelContinuation[Int] = (pc0, pc1).mapN(_ + _)

then the result should be a ParallelContinuation as well, and it is able to convert to a normal Continuation

val Parallel(contResult) = result
contResult.map {
  _ should be(42)
}.toScalaFuture