Compiles without warnings

examples/fact.lhs

@@ -1,4 +1,9 @@
+I in general recommend type signatures for everything. However, I wanted
+to show in this example how it is possible to get away without the
+signatures.
+
 \begin{code}
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
 {-# LANGUAGE QuasiQuotes #-}
 
 import Yesod
@@ -18,11 +23,15 @@ instance Yesod Fact where
 index = return $ StaticFile TypeHtml "examples/fact.html"
 fact i = return $ toHtmlObject 
             [ ("input", show i)
-            , ("result", show $ product [1..fromIntegral i])
+            , ("result", show $ product [1..fromIntegral i :: Integer])
             ]
 factRedirect = do
     i <- getParam "num"
     redirect $ "../" ++ i ++ "/"
+\end{code}
+In particular, the following line would be unnecesary if we had a type
+signature here.
+\begin{code}
     return ()
 
 main :: IO ()