parallel jobs simplest demo

jobs.scala

//>using lib "org.typelevel::cats-effect:3.5.1"
import cats.effect.*
import cats.implicits.*

object HowToRunJobsInParallel extends IOApp.Simple:
  def jobConstructor(r: Ref[IO, Long])(jobId: Any) = r
    .modify(n => (n + 1, n))
    .flatMap(v => IO.println(s"Job $jobId processed task $v"))
  def run                               =
    for
      ref     <- Ref[IO].of(0l)
      mkJob = jobConstructor(ref)
      jobs = (1 to 10000).map(mkJob).toList
      _ <- jobs.parSequence_
    yield ()