Re: [Haskell-beginners] hslogger question [Solved]

7 Aug 2011


      On Sat, 6 Aug 2011 21:43:17 +0200
Manfred Lotz  wrote:
...
Hi there,
Using hslogger I want to get
 - error messages and above to stdout and to logfile
 - debug messages and above to logfile only.
It seems the stderr handler must be redefined. 
Solved now by coding like this:


import System.IO
import System.Log.Logger
import System.Log.Handler.Simple
import System.Log.Handler (setFormatter)
import System.Log.Formatter


-- By default, all messages of level WARNING and above are sent to
stderr. -- Everything else is ignored.

main :: IO ()
main = do
  -- set global level to DEBUG 
  updateGlobalLogger rootLoggerName (setLevel DEBUG)

  -- want only ERROR and above to stderr
  s <- streamHandler stderr ERROR
  -- want all log messages to logfile
  h <- fileHandler "debug.log" DEBUG >>= \lh -> return $
                 setFormatter lh (simpleLogFormatter "[$time :
  $loggername : $prio] $msg")

  -- set handlers completely new
  updateGlobalLogger rootLoggerName (setHandlers [s,h])

  errorM "MyApp.Init" "This is a bad error"

  -- This message will go to logfile only. 
  debugM "MyApp.Main" "This buggy component is buggy"

  -- This message will go to logfile only. 
  warningM "MyApp.Finish" "Still Buggy"


-- 
Manfred