在哈姆雷特捕捉渲染列表

Question

鉴于this我用来学习Haskell的小项目，我想将我的请求处理程序代码生成移动到Hamlet模板，但我不确定如何传递问题。

当取消注释行时，我的当前代码会生成以下错误，这是第一个阻止程序：

Couldn't match expected type `String -> String'
                with actual type `String'
    In the return type of a call of `renderHtml'
    Probable cause: `renderHtml' is applied to too many arguments
    In the expression: renderHtml ($ (shamletFile "fileList.hamlet"))
    In an equation for `myTemplate':
        myTemplate = renderHtml ($ (shamletFile "fileList.hamlet"))

代码：

site :: Snap ()
site =
    ifTop (writeBS "hello world") <|> 
    route [ ("foo", writeBS "ba"),
            ("view_root_json_files", listRootFilesHandler)
          ] <|> 
    dir "static" (serveDirectory ".")

--myTemplate :: String -> String
--myTemplate = renderHtml ( $(shamletFile "fileList.hamlet") )

toText :: [FilePath] -> Text
toText = foldMap (flip snoc '\n' . pack)

listRootFilesHandler :: Snap ()
listRootFilesHandler = do
    filenames <- liftIO $ getDirectoryContents "data"
    let filtered_filenames = filter (not . isPrefixOf ".") filenames
    writeText $ toText filtered_filenames

Answer 1

Ghc告诉你正确的类型签名。只需将String -> String替换为String。