| 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.
- class Monad m => MonadLogger m where
- data LogLevel
- = LevelDebug
- | LevelInfo
- | LevelWarn
- | LevelError
- | LevelOther Text
- type LogSource = Text
- newtype LoggingT m a = LoggingT {}
- runStderrLoggingT :: MonadIO m => LoggingT m a -> m a
- runStdoutLoggingT :: MonadIO m => LoggingT m a -> m a
- newtype NoLoggingT m a = NoLoggingT {
- runNoLoggingT :: m a
- logDebug :: Q Exp
- logInfo :: Q Exp
- logWarn :: Q Exp
- logError :: Q Exp
- logOther :: Text -> Q Exp
- logDebugS :: Q Exp
- logInfoS :: Q Exp
- logWarnS :: Q Exp
- logErrorS :: Q Exp
- logOtherS :: Q Exp
- liftLoc :: Loc -> Q Exp
MonadLogger
class Monad 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 | |
| LevelOther Text |
Helper transformer
Monad transformer that adds a new logging function.
Since 0.2.2
Instances
| MonadTrans LoggingT | |
| MonadTransControl LoggingT | |
| 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
newtype NoLoggingT m a Source
Monad transformer that disables logging.
Since 0.2.4
Constructors
| NoLoggingT | |
Fields
| |
Instances
| MonadTrans NoLoggingT | |
| MonadTransControl NoLoggingT | |
| 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 -> Q ExpSource
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"