Haskell 获得；没有YesodDispatch的实例”；使用“扭曲”时出错

沙洛姆！我使用YesSOD编写了以下程序：

main = warp 2060 $
  onStatic "home" (dispatchTo $ return $ h1 $ toHtml "Sheepfold")

但是当我运行它时，我得到以下错误：

No instance for (YesodDispatch
                   (Control.Monad.Trans.Writer.Lazy.Writer LiteApp ()))
  arising from a use of `warp'
Possible fix:
  add an instance declaration for
  (YesodDispatch (Control.Monad.Trans.Writer.Lazy.Writer LiteApp ()))
In the expression: warp 2060
In the expression:
  warp 2060
  $ onStatic "home" (dispatchTo $ return $ h1 $ toHtml "Sheepfold")
In an equation for `main':
    main
      = warp 2060
        $ onStatic "home" (dispatchTo $ return $ h1 $ toHtml "Sheepfold")

---

有人能帮忙吗？

你需要打电话到

liteApp

。看