import os, threadpool

proc spawnBackgroundJob[T](channel: ptr Channel[T], f: iterator (): T) =

  type Args = tuple[iter: iterator (): T, channel: ptr Channel[T]]

  proc threadFunc(args: Args) {.thread.} =
    echo "Thread is starting"
    let iter = args.iter
    var channel = args.channel # note: still a `ptr Channel`

    for i in iter():
      echo "Sending ", i
      channel[].send(i)

  channel[].open()

  var thread: Thread[Args]
  let args = (f, channel)
  createThread(thread, threadFunc, args)


# example use in some main thread:
iterator testJob(): int {.closure.} =
  yield 0
  sleep(500)
  yield 1
  sleep(500)
  yield 2


var channel: Channel[int]
spawnBackgroundJob(channel.addr, testJob)

for i in 1 .. 10:
  sleep(200)
  echo channel.peek()