System.Log.Logger.TH

This module provides functions that generate hslogger functions using Template Haskell.

Notes:

• System.Log.Logger must be imported qualified, and the qualifier must match the qualifier given to deriveLoggers and/or deriveNamedLoggers.
• Don't forget to enable Template Haskell preprocessing: specify the pragma LANGUAGE TemplateHaskell at the top of your source file or extensions: TemplateHaskell in your cabal file.

Documentation

deriveLoggers

Arguments

:: String

Must match qualifier on import of System.Log.Logger.

-> [Priority]

List of priorities for which to generate logging functions.

-> Q [Dec]

Generate hslogger functions for a list of priorities.

Example usage:

 module Foo.Bar ( ... ) where

 import System.Log.Logger.TH (deriveLoggers)
 import qualified System.Log.Logger as HSL

 $(deriveLoggers "HSL" [HSL.DEBUG, HSL.INFO])

Used this way, deriveLoggers would generate the following functions:

 infoM :: MonadIO m => String -> m ()
 infoM s = liftIO (HSL.infoM "Foo.Bar" ((++) "Foo.Bar: " s))

 debugM :: MonadIO m => String -> m ()
 debugM s = liftIO (HSL.debugM "Foo.Bar" ((++) "Foo.Bar: " s))

The other hslogger priorities follow the same pattern.

So

 infoM "hi there"

would generate the INFO-level log event

 Foo.Bar: hi there

deriveNamedLoggers

Arguments

:: String

Message prefix, e.g., SomeProgram.

-> String

Must match qualifier on import of System.Log.Logger.

-> [Priority]

List of priorities for which to generate logging functions.

-> Q [Dec]

Like deriveLoggers, but allows you to specify a message prefix. This could be useful if the automatically determined module name (e.g., "Main") would not be informative enough.