can't seem to run two loops together in a coroutine

[git-oykko]

my code probably looks bad but uh i cant get my coroutine running here's the code so uh when i like try to run these two loops together only the second one runs and im losing braincells why

local caller = coroutine.create(function()
    print("test")
    while true do
        print("caller")
        local event, side, channel, replyChannel, message, distance

        repeat
            event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
        until channel == ch

        print(replyChannel)

        if replyChannel == 15 then
            local selected_floor = message
            local current_floor = getCurrentFloor()

            gotoFloor(selected_floor, current_floor)
        end
    end
end)

coroutine.resume(caller)

while true do
    os.pullEvent("redstone")

    local selected_floor
    local current_floor

    local is_selected

    is_selected = getIsSelected()

    if is_selected then
        selected_floor = getSelectedFloor()
        current_floor = getCurrentFloor()

        if selected_floor ~= current_floor then
            gotoFloor(selected_floor, current_floor)
        end
    end
end

[SquidDev]

The main thing to note about coroutines, is that they're not "true" preemptive threads, like you might see in other languages. You can't actually have multiple coroutines at once - instead you switch between coroutines using coroutine.resume (which resumes a coroutine) or coroutine.yield (which stops running this coroutine and returns to whichever one ran coroutine.resume).

This means when you call coroutine.resume(caller), you run your coroutine until the first os.pullEvent("modem_message"), but after that it's never run again - hence the loop no longer running!

The trick here is to put both loops inside their own coroutines, and then have a loop which pulls events and feeds them into both coroutines. In your case, you can actually get away with using the parallel API to do this for you:

parallel.waitForAll(function()
  print("test")
  while true do
    print("caller")
    local event, side, channel, replyChannel, message, distance

    -- etc...
  end
end, function()
  while true do
    os.pullEvent("redstone")

    local selected_floor
    local current_floor

    -- etc...
  end
end)

[git-oykko]

tysm!!! your explanation was great