在Snap中冲洗部分响应

Question

我想要这样的东西

{-# LANGUAGE OverloadedStrings #-}
import           Control.Concurrent     (threadDelay)
import           Control.Monad.IO.Class
import           Snap.Core
import           Snap.Http.Server

main :: IO ()
main = quickHttpServe site

site :: Snap ()
site = do
        writeBS "testing\n"
        liftIO $ threadDelay (1000 * 1000 * 5)
        writeBS "one two three"

除了我想在写testing\n后立即刷新回复。应该很简单，但我的谷歌搜索技能让我失望。