main :: IO ()
main = do
  pool <- newPool PoolConfig 
    { createResource = pure 0
    , freeResource = const (pure ())
    , poolCacheTTL = 60
    , poolMaxResources = 3
    }

  let takeAnd action = withResource pool (const action)

  putStrLn "-------------\n 1st\n-------------"
  takeAnd do
    print 1
    takeAnd do
      print 2
      takeAnd do 
        print 3
        putStrLn "here!"

  putStrLn "-------------\n 2nd\n-------------"
  takeAnd do
    print 1
    takeAnd do
      print 2
      takeAnd do 
        print 3
        takeAnd do 
          print 4
          putStrLn "here!"