拆分导管链

我有一个管道表达式,它有效:

main1 = runResourceT
       $ CB.sourceHandle stdin
      $$ CB.lines
      =$ Cl.concatMap matches
      =$ Cl.mapMaybe readDouble
      =$ Cl.map fst
      =$ Cl.map bucket
      =$ Cl.map (BS.pack . show)
      =$ Cl.map (\x -> x <> BS.pack "\n")
      =$ CB.sinkHandle stdout

我很难把它分成两部分,比如:

source = CB.sourceHandle stdin
  $$ CB.lines
  =$ Cl.concatMap matches
  =$ Cl.mapMaybe readDouble
  =$ Cl.map fst
  =$ Cl.map bucket

sink = Cl.map (BS.pack . show)
  =$ Cl.map (\x -> x <> BS.pack "\n")
  =$ CB.sinkHandle stdout

以便我可以使用:

runResourceT $ source =$ sink

或者其他什么。。。我从类型检查器中得到的错误消息有些不可思议。