optionHandlers :: [OptionChecker]
optionHandlers =
  [ (not . helpMode, printHelpMode)
  , (okayDir, printError "c_output and h_output options must accompany each other.")
  , (okayO, printError "Must have at most one compilation unit with --out option.")
  ]
optionHandlers :: [OptionChecker]
optionHandlers =
  [ (not . helpMode, printHelpMode)
  , (okayDir, printError "c_output and h_output options must accompany each other.")
  , (okayO, printError "Must have at most one compilation unit with --out option.")
  ]
optionHandlers =
  [ (not . helpMode, printHelpMode)
  , (okayDir, printError "c_output and h_output options must accompany each other.")
  , (okayO, printError "Must have at most one compilation unit with --out option.")
  ]