Update stderr and the bar on receiving exception

3 files changed, 20 insertions, 4 deletions

diff --git a/src/Xmobar/Plugins/StdinReader.hs b/src/Xmobar/Plugins/StdinReader.hs
index 18958be..ad7291e 100644
--- a/src/Xmobar/Plugins/StdinReader.hs
+++ b/src/Xmobar/Plugins/StdinReader.hs
@@ -22,16 +22,21 @@ import Prelude
 import System.Posix.Process
 import System.Exit
 import System.IO
-import Control.Exception (SomeException(..), handle)
 import Xmobar.Run.Exec
 import Xmobar.X11.Actions (stripActions)
+import Xmobar.System.Utils (onSomeException)
 
 data StdinReader = StdinReader | UnsafeStdinReader
   deriving (Read, Show)
 
 instance Exec StdinReader where
   start stdinReader cb = do
-    s <- getLine
+    s <-
+      getLine `onSomeException`
+      (\e -> do
+         let errorMessage = "xmobar: Received exception " <> show e
+         hPrint stderr errorMessage
+         cb errorMessage)
     cb $ escape stdinReader s
     eof <- isEOF
     if eof
diff --git a/src/Xmobar/Run/Exec.hs b/src/Xmobar/Run/Exec.hs
index d8cf81a..e1b6709 100644
--- a/src/Xmobar/Run/Exec.hs
+++ b/src/Xmobar/Run/Exec.hs
@@ -10,7 +10,7 @@
 --
 -- The 'Exec' class and the 'Command' data type.
 --
--- The 'Exec' class rappresents the executable types, whose constructors may
+-- The 'Exec' class represents the executable types, whose constructors may
 -- appear in the 'Config.commands' field of the 'Config.Config' data type.
 --
 -- The 'Command' data type is for OS commands to be run by xmobar
diff --git a/src/Xmobar/System/Utils.hs b/src/Xmobar/System/Utils.hs
index 636436b..59c485c 100644
--- a/src/Xmobar/System/Utils.hs
+++ b/src/Xmobar/System/Utils.hs
@@ -17,7 +17,7 @@
 ------------------------------------------------------------------------------
 
 
-module Xmobar.System.Utils (expandHome, changeLoop)
+module Xmobar.System.Utils (expandHome, changeLoop, onSomeException)
 where
 
 import Control.Monad
@@ -25,6 +25,7 @@ import Control.Concurrent.STM
 
 import System.Environment
 import System.FilePath
+import Control.Exception
 
 expandHome :: FilePath -> IO FilePath
 expandHome ('~':'/':path) = fmap (</> path) (getEnv "HOME")
@@ -39,3 +40,13 @@ changeLoop s f = atomically s >>= go
             new <- s
             guard (new /= old)
             return new)
+
+-- | Like 'finally', but only performs the final action if there was an
+-- exception raised by the computation.
+--
+-- Note that this implementation is a slight modification of
+-- onException function.
+onSomeException :: IO a -> (SomeException -> IO b) -> IO a
+onSomeException io what = io `catch` \e -> do _ <- what e
+                                              throwIO (e :: SomeException)
+