Print an error before usage if we can't parse the page.

diff --git a/src/Main.hs b/src/Main.hs
index 3ce1eef324283e94ac6ae1cb1850d35edca79619..1f6d7c5f436a583d5143b05c1cf55aaf4126995e 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -7,8 +7,11 @@ import System.Directory (doesFileExist)
 import System.IO (
   Handle,
   IOMode (WriteMode),
+  hPutStrLn,
   openBinaryFile,
-  stdout)
+  stderr,
+  stdout
+  )
 
 import CommandLine (show_help)
 import Configuration (Cfg(..), get_cfg)
@@ -40,12 +43,14 @@ main = do
   cfg  <- case aif of
            False -> get_login_cookie cfg'
            True  -> return cfg'
+
   page <- page_from_url cfg (article cfg)
   case page of
     Just p -> do
       output_handle <- get_output_handle (output cfg)
       epublish p output_handle
     Nothing -> do
+      hPutStrLn stderr "ERROR: could not parse an LWN page from the given URL."
       _ <- show_help
       return ()