anchor.diff:  [source, haskell]
   ----
   {-# LANGUAGE OverloadedStrings #-}
  -import Network.Wai
  -import Network.Wai.Handler.Warp
  -import Network.HTTP.Types
  +import           Network.HTTP.Types       (status200)
  +import           Network.Wai              (Application, responseLBS)
  +import           Network.Wai.Handler.Warp (run)
   
   main :: IO ()
   main = run 3000 app
   
   app :: Application
  -app req = return $ responseLBS
  +app _req = return $ responseLBS
       status200
       [("Content-Type", "text/plain")]
       "Hello Warp!"
  
positive.code: [source, haskell]
  ----
  {-# LANGUAGE OverloadedStrings #-}
  import Network.Wai
  import Network.Wai.Handler.Warp
  import Network.HTTP.Types
  import Text.Blaze.Html5
  import qualified Text.Blaze.Html5 as H
  import Text.Blaze.Html.Renderer.Utf8
  
  main :: IO ()
  main = run 3000 app
  
  app :: Application
  app req = return $ responseBuilder
      status200
      [("Content-Type", "text/html")] -- yay!
      (renderHtmlBuilder myPage)
  
negative.code: [source, haskell]
  ----
  {-# LANGUAGE OverloadedStrings #-}
  import           Network.HTTP.Types       (status200)
  import           Network.Wai              (Application, pathInfo, responseLBS)
  import           Network.Wai.Handler.Warp (run)
  
  main :: IO ()
  main = run 3000 app
  