| Safe Haskell | None |
|---|---|
| Language | Haskell98 |
Control.Monad.Logger
Contents
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
- monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> m ()
- class (MonadLogger m, MonadIO m) => MonadLoggerIO m where
- data LogLevel
- = LevelDebug
- | LevelInfo
- | LevelWarn
- | LevelError
- | LevelOther Text
- type LogSource = Text
- data LogStr :: *
- class ToLogStr msg where
- newtype LoggingT m a = LoggingT {}
- runStderrLoggingT :: MonadIO m => LoggingT m a -> m a
- runStdoutLoggingT :: MonadIO m => LoggingT m a -> m a
- withChannelLogger :: (MonadBaseControl IO m, MonadIO m) => Int -> LoggingT m a -> LoggingT m a
- filterLogger :: (LogSource -> LogLevel -> Bool) -> LoggingT m a -> LoggingT 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
- logDebugN :: MonadLogger m => Text -> m ()
- logInfoN :: MonadLogger m => Text -> m ()
- logWarnN :: MonadLogger m => Text -> m ()
- logErrorN :: MonadLogger m => Text -> m ()
- logOtherN :: MonadLogger m => LogLevel -> Text -> m ()
- logDebugNS :: MonadLogger m => Text -> Text -> m ()
- logInfoNS :: MonadLogger m => Text -> Text -> m ()
- logWarnNS :: MonadLogger m => Text -> Text -> m ()
- logErrorNS :: MonadLogger m => Text -> Text -> m ()
- logOtherNS :: MonadLogger m => Text -> LogLevel -> Text -> m ()
- defaultLogStr :: Loc -> LogSource -> LogLevel -> LogStr -> LogStr
- data Loc :: *
MonadLogger
class Monad m => MonadLogger m where Source
A Monad which has the ability to log messages in some manner.
Instances
| MonadLogger m => MonadLogger (MaybeT m) | |
| MonadLogger m => MonadLogger (ListT m) | |
| MonadLogger m => MonadLogger (IdentityT m) | |
| MonadLogger m => MonadLogger (ResourceT m) | |
| MonadIO m => MonadLogger (LoggingT m) | |
| Monad m => MonadLogger (NoLoggingT m) | |
| (MonadLogger m, Monoid w) => MonadLogger (WriterT w m) | |
| (MonadLogger m, Monoid w) => MonadLogger (WriterT w m) | |
| MonadLogger m => MonadLogger (StateT s m) | |
| MonadLogger m => MonadLogger (StateT s m) | |
| MonadLogger m => MonadLogger (ReaderT r m) | |
| (MonadLogger m, Error e) => MonadLogger (ErrorT e m) | |
| MonadLogger m => MonadLogger (ContT r m) | |
| MonadLogger m => MonadLogger (ExceptT e 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) |
class (MonadLogger m, MonadIO m) => MonadLoggerIO m where Source
An extension of MonadLogger for the common case where the logging action
is a simple IO action. The advantage of using this typeclass is that the
logging function itself can be extracted as a first-class value, which can
make it easier to manipulate monad transfomrer stacks, as an example.
Since 0.3.10
Minimal complete definition
Nothing
Methods
askLoggerIO :: m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) Source
Request the logging function itself.
Since 0.3.10
Instances
| MonadLoggerIO m => MonadLoggerIO (MaybeT m) | |
| MonadLoggerIO m => MonadLoggerIO (ListT m) | |
| MonadLoggerIO m => MonadLoggerIO (IdentityT m) | |
| MonadLoggerIO m => MonadLoggerIO (ResourceT m) | |
| MonadIO m => MonadLoggerIO (LoggingT m) | |
| MonadIO m => MonadLoggerIO (NoLoggingT m) | |
| (MonadLoggerIO m, Monoid w) => MonadLoggerIO (WriterT w m) | |
| (MonadLoggerIO m, Monoid w) => MonadLoggerIO (WriterT w m) | |
| MonadLoggerIO m => MonadLoggerIO (StateT s m) | |
| MonadLoggerIO m => MonadLoggerIO (StateT s m) | |
| MonadLoggerIO m => MonadLoggerIO (ReaderT r m) | |
| (MonadLoggerIO m, Error e) => MonadLoggerIO (ErrorT e m) | |
| MonadLoggerIO m => MonadLoggerIO (ContT r m) | |
| MonadLoggerIO m => MonadLoggerIO (ExceptT e m) | |
| MonadLoggerIO m => MonadLoggerIO (ConduitM i o m) | |
| (MonadLoggerIO m, Monoid w) => MonadLoggerIO (RWST r w s m) | |
| (MonadLoggerIO m, Monoid w) => MonadLoggerIO (RWST r w s m) | |
| MonadLoggerIO m => MonadLoggerIO (Pipe l i o u m) |
Constructors
| LevelDebug | |
| LevelInfo | |
| LevelWarn | |
| LevelError | |
| LevelOther Text |
Re-export from fast-logger
class ToLogStr msg where
Instances
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) | |
| MonadWriter w m => MonadWriter w (LoggingT m) | |
| MonadState s m => MonadState s (LoggingT m) | |
| MonadReader r m => MonadReader r (LoggingT m) | |
| Monad m => Monad (LoggingT m) | |
| Monad m => Functor (LoggingT m) | |
| Monad m => Applicative (LoggingT m) | |
| MonadIO m => MonadIO (LoggingT m) | |
| MonadResource m => MonadResource (LoggingT m) | |
| MonadThrow m => MonadThrow (LoggingT m) | |
| MonadMask m => MonadMask (LoggingT m) | |
| MonadCatch m => MonadCatch (LoggingT m) | |
| MonadCont m => MonadCont (LoggingT m) | |
| MonadActive m => MonadActive (LoggingT m) | |
| MonadIO m => MonadLoggerIO (LoggingT m) | |
| MonadIO m => MonadLogger (LoggingT m) | |
data StT LoggingT = StReader {
| |
| data StM (LoggingT m) = StMT (StM m a) |
runStderrLoggingT :: MonadIO m => LoggingT m a -> m a Source
Run a block using a MonadLogger instance which prints to stderr.
Since 0.2.2
runStdoutLoggingT :: MonadIO m => LoggingT m a -> m a Source
Run a block using a MonadLogger instance which prints to stdout.
Since 0.2.2
Arguments
| :: (MonadBaseControl IO m, MonadIO m) | |
| => Int | Number of mesasges to keep |
| -> LoggingT m a | |
| -> LoggingT m a |
Within the LoggingT monad, capture all log messages to a bounded
channel of the indicated size, and only actually log them if there is an
exception.
Since 0.3.2
filterLogger :: (LogSource -> LogLevel -> Bool) -> LoggingT m a -> LoggingT m a Source
Only log messages passing the given predicate function.
This can be a convenient way, for example, to ignore debug level messages.
Since 0.3.13
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) | |
| MonadError e m => MonadError e (NoLoggingT m) | |
| MonadWriter w m => MonadWriter w (NoLoggingT m) | |
| MonadState s m => MonadState s (NoLoggingT m) | |
| Monad m => Monad (NoLoggingT m) | |
| Monad m => Functor (NoLoggingT m) | |
| Monad m => Applicative (NoLoggingT m) | |
| MonadIO m => MonadIO (NoLoggingT m) | |
| MonadResource m => MonadResource (NoLoggingT m) | |
| MonadThrow m => MonadThrow (NoLoggingT m) | |
| MonadMask m => MonadMask (NoLoggingT m) | |
| MonadCatch m => MonadCatch (NoLoggingT m) | |
| MonadActive m => MonadActive (NoLoggingT m) | |
| MonadIO m => MonadLoggerIO (NoLoggingT m) | |
| Monad m => MonadLogger (NoLoggingT m) | |
data StT NoLoggingT = StIdent {
| |
| data StM (NoLoggingT m) = StMT' (StM m a) |
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 Exp Source
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:
$logDebugS "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:
$logOtherS "SomeSource" "My new level" "This is a log message"
TH util
Non-TH logging
logDebugN :: MonadLogger m => Text -> m () Source
logInfoN :: MonadLogger m => Text -> m () Source
logWarnN :: MonadLogger m => Text -> m () Source
logErrorN :: MonadLogger m => Text -> m () Source
logOtherN :: MonadLogger m => LogLevel -> Text -> m () Source
Non-TH logging with source
logDebugNS :: MonadLogger m => Text -> Text -> m () Source
logInfoNS :: MonadLogger m => Text -> Text -> m () Source
logWarnNS :: MonadLogger m => Text -> Text -> m () Source
logErrorNS :: MonadLogger m => Text -> Text -> m () Source
logOtherNS :: MonadLogger m => Text -> LogLevel -> Text -> m () Source
utilities for defining your own loggers
data Loc :: *