hamlet模板中的$forall出现问题

Question

我和哈姆雷特有个奇怪的问题。我试图使用$forall来迭代一个列表，但是我总是得到一个“不在作用域”的错误。我在Win7上运行yesod 0.9.2.2。

抛开糟糕的设计不谈，有人知道我哪里错了吗？删除"db“的变量插值可以很好地执行。

相关的哈姆雷特：

 !!!
<h1> Database List
<hr>
<table>

  <tr>
       <td> Host
       <td> Status
  $forall db <- dbList
  <tr>
       <td> #{host db}

相关的处理程序代码：

data Database = Database {dbType :: DBType,
                        host :: String,
                        user :: String,
                        password :: String
                       }


dbList = [Database Oracle "cpalmerws" "system" "***",
          Database Oracle "bdblnx" "system" "***",
          Database Postgres "localhost" "postgres" "***"]

getDBStatusR :: Handler RepHtml
getDBStatusR = do
  mu <- maybeAuth
  defaultLayout $ do
    setTitle "DB Status Page"
    addWidget $(widgetFile "dbstatus")

我在运行yesod devel时遇到这个错误：

Handler\DBStatus.hs:47:17:
    Not in scope: `db'
    In the result of the splice:
      $(widgetFile "dbstatus")
    To see what the splice expanded to, use -ddump-splices
    In the first argument of `addWidget', namely
      `$(widgetFile "dbstatus")'
    In the expression: addWidget ($(widgetFile "dbstatus"))
Starting development server...

dist\devel.hs:3:1:
    Failed to load interface for `Application':
      it is not a module in the current program, or in any known package.
Exit code: ExitFailure 1

Answer 1

模板中的缩进级别错误：

$forall db <- dbList
    <tr>
        <td>#{host db}

在您的版本中，行超出了$forall的作用域。