| Safe Haskell | None |
|---|
Control.Monad.Logger
Description
This module provides the facilities needed for a decoupled logging system.
The MonadLogger class is implemented by monads that give access to a logging facility. If you're defining a custom monad, then you may define an instance of MonadLogger that routes the log messages to the appropriate place (e.g., that's what yesod-core's GHandler does). Otherwise, you may use the LoggingT monad included in this module (see runStderrLoggingT). To simply discard log message, use NoLoggingT.
As a user of the logging facility, we provide you some convenient Template Haskell splices that use the MonadLogger class. They will record their source file and position, which is very helpful when debugging. See logDebug for more information.
- classMonad m => MonadLogger m where
- monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> m ()
- dataLogLevel
- typeLogSource = Text
- newtypeLoggingT m a = LoggingT {}
- runStderrLoggingT :: MonadIO m => LoggingT m a -> m a
- runStdoutLoggingT :: MonadIO m => LoggingT m a -> m a
- newtypeNoLoggingT m a = NoLoggingT {
- runNoLoggingT :: m a
- logDebug :: QExp
- logInfo :: QExp
- logWarn :: QExp
- logError :: QExp
- logOther :: Text -> QExp
- logDebugS :: QExp
- logInfoS :: QExp
- logWarnS :: QExp
- logErrorS :: QExp
- logOtherS :: QExp
- liftLoc :: Loc -> QExp
MonadLogger
classMonad m => MonadLogger m whereSource
Instances
| MonadLogger m => MonadLogger (ResourceT m) | |
| MonadLogger m => MonadLogger (ListT m) | |
| MonadLogger m => MonadLogger (MaybeT m) | |
| MonadLogger m => MonadLogger (IdentityT m) | |
| MonadIO m => MonadLogger (LoggingT m) | |
| MonadIO m => MonadLogger (NoLoggingT m) | |
| MonadLogger m => MonadLogger (ContT r m) | |
| (MonadLogger m, Error e) => MonadLogger (ErrorT e m) | |
| MonadLogger m => MonadLogger (ReaderT r m) | |
| MonadLogger m => MonadLogger (StateT s m) | |
| MonadLogger m => MonadLogger (StateT s m) | |
| (MonadLogger m, Monoid w) => MonadLogger (WriterT w m) | |
| (MonadLogger m, Monoid w) => MonadLogger (WriterT w m) | |
| MonadLogger m => MonadLogger (ConduitM i o m) | |
| (MonadLogger m, Monoid w) => MonadLogger (RWST r w s m) | |
| (MonadLogger m, Monoid w) => MonadLogger (RWST r w s m) | |
| MonadLogger m => MonadLogger (Pipe l i o u m) |
Constructors
| LevelDebug | |
| LevelInfo | |
| LevelWarn | |
| LevelError | |
| LevelOtherText |
Helper transformer
Monad transformer that adds a new logging function.
Since 0.2.2
Instances
| MonadTransLoggingT | |
| MonadTransControlLoggingT | |
| MonadRWS r w s m => MonadRWS r w s (LoggingT m) | |
| MonadBaseControl b m => MonadBaseControl b (LoggingT m) | |
| MonadBase b m => MonadBase b (LoggingT m) | |
| MonadError e m => MonadError e (LoggingT m) | |
| MonadReader r m => MonadReader r (LoggingT m) | |
| MonadState s m => MonadState s (LoggingT m) | |
| MonadWriter w m => MonadWriter w (LoggingT m) | |
| Monad m => Monad (LoggingT m) | |
| Monad m => Functor (LoggingT m) | |
| Monad m => Applicative (LoggingT m) | |
| MonadThrow m => MonadThrow (LoggingT m) | |
| MonadResource m => MonadResource (LoggingT m) | |
| MonadIO m => MonadIO (LoggingT m) | |
| MonadCont m => MonadCont (LoggingT m) | |
| MonadIO m => MonadLogger (LoggingT m) |
runStderrLoggingT :: MonadIO m => LoggingT m a -> m aSource
Run a block using a MonadLogger instance which prints to stderr.
Since 0.2.2
runStdoutLoggingT :: MonadIO m => LoggingT m a -> m aSource
Run a block using a MonadLogger instance which prints to stdout.
Since 0.2.2
newtypeNoLoggingT m a Source
Monad transformer that disables logging.
Since 0.2.4
Constructors
| NoLoggingT | |
Fields
| |
Instances
| MonadTransNoLoggingT | |
| MonadTransControlNoLoggingT | |
| MonadBaseControl b m => MonadBaseControl b (NoLoggingT m) | |
| MonadBase b m => MonadBase b (NoLoggingT m) | |
| Monad m => Monad (NoLoggingT m) | |
| Monad m => Functor (NoLoggingT m) | |
| Monad m => Applicative (NoLoggingT m) | |
| MonadThrow m => MonadThrow (NoLoggingT m) | |
| MonadResource m => MonadResource (NoLoggingT m) | |
| MonadIO m => MonadIO (NoLoggingT m) | |
| MonadIO m => MonadLogger (NoLoggingT m) |
TH logging
Generates a function that takes a Text and logs a LevelDebug message. Usage:
$(logDebug) "This is a debug log message"
logOther :: Text -> QExpSource
Generates a function that takes a Text and logs a LevelOther message. Usage:
$(logOther "My new level") "This is a log message"
TH logging with source
Generates a function that takes a LogSource and Text and logs a LevelDebug message. Usage:
$logDebug "SomeSource" "This is a debug log message"
Generates a function that takes a LogSource, a level name and a Text and logs a LevelOther message. Usage:
$logOther "SomeSource" "My new level" "This is a log message"
