[web-devel] [ Yesod ][ Newbie ][ Widgets ] Ways of adding app manu

Kamil Ciemniewski ciemniewski.kamil at gmail.com
Fri Jul 1 15:43:21 CEST 2011

Hi all,

I'm trying to add to my "admin layout" main menu in Yesod.

Normally - doing it in Rails - I would create a partial
or helper and then use it in my layout file.

But here in Yesod - the concept of widgets seems
somewhat fereign to me. I don't quite get them.

In my Handler.Admin module I define:

adminLayout :: GWidget MyApp MyApp () -> GHandler MyApp MyApp RepHtml
adminLayout widget = do
        mmsg <- getMessage
    mroute <- getCurrentRoute
    pc <- widgetToPageContent $ do
    hamletToRepHtml $(hamletFile "admin/admin-layout")

then I define my widget ( all in the same file ):

mainMenu :: Widget ()
mainMenu =
  addWidget $(widgetFile "admin/_menu")

And finally in "admin/admin-layout.hamlet" I'm trying to render my menu:


All without a luck.. Compiler yells at me strange ( to me ) things:

    Couldn't match expected type `GGWidget
                                    MyApp (GHandler MyApp MyApp) ()'
                with actual type `(url0 -> [(T.Text, T.Text)] -> T.Text)
    Expected type: Widget ()
      Actual type: hamlet-0.8.1:Text.Hamlet.Quasi.Hamlet url0
    In the return type of a call of `pageBody'
    In the first argument of
`hamlet-0.8.1:Text.Hamlet.Quasi.fromHamletValue', namely
      `pageBody pc'

Which doesn't occur when I'm not trying to render "mainMenu" widget.

What am I doing wrong? And are there any informations about using widgets
( because I haven't found many.. )?

Best regards
Kamil Ciemniewski
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