 let full_path = bp </> fp

        exists <- doesFileExist full_path
        return $ if exists
                   then Just full_path
                   else Nothing


mkDelayedCachedYamlLoader :: ( F
runDelayedYamlLoaderExc :: (MonadIO m) =>
    FilePath    -- ^ 消息文件存放目录
    -> DelayedYamlLoader a
    -> m a
runDelayedYamlLoaderExc base_dir = runDelayedYamlLoaderExcL (base_dir :| [])
runDelayedYamlLoaderExc base_dir = runDelayedYamlLoaderExcL (base_dir :| [])