gistfile1.hs

module Views where

import Control.Monad
import Happstack.Server (ServerPart, Response, ok, toResponse, dir)
import Text.Blaze ((!))
import qualified Text.Blaze.Html5 as H
import qualified Text.Blaze.Html5.Attributes as A

routes = msum [ dir "smth" $ notok
	      , index
	      ]

mainTpl :: H.Html
mainTpl = 
  H.docTypeHtml $ do
    H.head $ do
      H.title "A"
    H.body $ do
      H.p "OK!"

index :: ServerPart Response
index = ok $ toResponse $ mainTpl

notok :: ServerPart Response
notok = ok $ toResponse "NOT OK!"

gistfile2.txt

Views.hs:26:14:
    No instance for (Happstack.Server.Response.ToMessage H.Html)
      arising from a use of `toResponse'
    Possible fix:
      add an instance declaration for
      (Happstack.Server.Response.ToMessage H.Html)
    In the expression: toResponse
    In the second argument of `($)', namely `toResponse $ mainTpl'
    In the expression: ok $ toResponse $ mainTpl