gistfile1

-- | Fetch the contents of a uri, which must be an ascii string.
-- Redirects, authentication, https: and file: uris are supported.
readUri :: Manager -> String -> Opts -> IO String
readUri manager s opts =
    case parseURI' s of
      Just URI{uriScheme="file:",uriPath=f} -> readFeedFile f
      Just _ -> do
        r <- parseUrl s
        let cachecontrol = cache_control opts
            r' | null cachecontrol = r
               | otherwise = r{requestHeaders=(hCacheControl, B8.pack cachecontrol):requestHeaders r}
        rsp <- httpLbs r' manager
        return $ LB8.unpack $ responseBody rsp --  $$+- return ()  ? https://github.com/snoyberg/http-conduit/issues/97#issuecomment-12876868
      Nothing -> opterror $ "could not parse URI: " ++ s