| Safe Haskell | Trustworthy |
|---|---|
| Language | Haskell2010 |
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 HandlerT 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.
Synopsis
- class Monad m => MonadLogger m where
- monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> m ()
- class (MonadLogger m, MonadIO m) => MonadLoggerIO m where
- data LogLevel
- type LogLine = (Loc, LogSource, LogLevel, LogStr)
- type LogSource = Text
- data LogStr
- class ToLogStr msg where
- fromLogStr :: LogStr -> ByteString
- newtype LoggingT m a = LoggingT {}
- runStderrLoggingT :: MonadIO m => LoggingT m a -> m a
- runStdoutLoggingT :: MonadIO m => LoggingT m a -> m a
- runChanLoggingT :: MonadIO m => Chan LogLine -> LoggingT m a -> m a
- runFileLoggingT :: MonadBaseControl IO m => FilePath -> LoggingT m a -> m a
- unChanLoggingT :: (MonadLogger m, MonadIO m) => Chan LogLine -> m void
- 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
- mapNoLoggingT :: (m a -> n b) -> NoLoggingT m a -> NoLoggingT n b
- newtype WriterLoggingT m a = WriterLoggingT {
- unWriterLoggingT :: m (a, DList LogLine)
- execWriterLoggingT :: Functor m => WriterLoggingT m a -> m [LogLine]
- runWriterLoggingT :: Functor m => WriterLoggingT m a -> m (a, [LogLine])
- mapLoggingT :: (m a -> n b) -> LoggingT m a -> LoggingT n b
- logDebug :: Q Exp
- logInfo :: Q Exp
- logWarn :: Q Exp
- logError :: Q Exp
- logOther :: Text -> Q Exp
- logDebugSH :: Q Exp
- logInfoSH :: Q Exp
- logWarnSH :: Q Exp
- logErrorSH :: Q Exp
- logOtherSH :: 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 ()
- logWithoutLoc :: (MonadLogger m, ToLogStr msg) => LogSource -> LogLevel -> msg -> m ()
- logDebugNS :: MonadLogger m => LogSource -> Text -> m ()
- logInfoNS :: MonadLogger m => LogSource -> Text -> m ()
- logWarnNS :: MonadLogger m => LogSource -> Text -> m ()
- logErrorNS :: MonadLogger m => LogSource -> Text -> m ()
- logOtherNS :: MonadLogger m => LogSource -> LogLevel -> Text -> m ()
- logDebugCS :: MonadLogger m => CallStack -> Text -> m ()
- logInfoCS :: MonadLogger m => CallStack -> Text -> m ()
- logWarnCS :: MonadLogger m => CallStack -> Text -> m ()
- logErrorCS :: MonadLogger m => CallStack -> Text -> m ()
- logOtherCS :: MonadLogger m => CallStack -> LogLevel -> Text -> m ()
- defaultLogStr :: Loc -> LogSource -> LogLevel -> LogStr -> LogStr
- data Loc = Loc {}
- defaultLoc :: Loc
- defaultOutput :: Handle -> Loc -> LogSource -> LogLevel -> LogStr -> IO ()
MonadLogger
class Monad m => MonadLogger m where Source #
A Monad which has the ability to log messages in some manner.
Minimal complete definition
Nothing
Methods
monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> m () Source #
default monadLoggerLog :: (MonadLogger m', MonadTrans t, MonadLogger (t m'), ToLogStr msg, m ~ t m') => Loc -> LogSource -> LogLevel -> msg -> m () Source #
Instances
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 transformer 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
default askLoggerIO :: (MonadTrans t, MonadLoggerIO n, m ~ t n) => m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) Source #
Instances
Constructors
| LevelDebug | |
| LevelInfo | |
| LevelWarn | |
| LevelError | |
| LevelOther Text |
Re-export from fast-logger
Log message builder. Use (<>) to append two LogStr in O(1).
Types that can be converted to a LogStr. Instances for
types from the text library use a UTF-8 encoding. Instances
for numerical types use a decimal encoding.
Instances
fromLogStr :: LogStr -> ByteString #
Converting LogStr to ByteString.
Helper transformers
Monad transformer that adds a new logging function.
Since: 0.2.2
Instances
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
runChanLoggingT :: MonadIO m => Chan LogLine -> LoggingT m a -> m a Source #
Run a block using a MonadLogger instance which writes tuples to an
unbounded channel.
The tuples can be extracted (ie. in another thread) with unChanLoggingT
or a custom extraction funtion, and written to a destination.
Since: 0.3.17
runFileLoggingT :: MonadBaseControl IO m => FilePath -> LoggingT m a -> m a Source #
Run a block using a MonadLogger instance which appends to the specified file.
Since: 0.3.22
unChanLoggingT :: (MonadLogger m, MonadIO m) => Chan LogLine -> m void Source #
Read logging tuples from an unbounded channel and log them into a
MonadLoggerIO monad, forever.
For use in a dedicated thread with a channel fed by runChanLoggingT.
Since: 0.3.17
Arguments
| :: (MonadBaseControl IO m, MonadIO m) | |
| => Int | Number of messages 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
mapNoLoggingT :: (m a -> n b) -> NoLoggingT m a -> NoLoggingT n b Source #
Map the unwrapped computation using the given function.
Since: 0.3.29
newtype WriterLoggingT m a Source #
Since: 0.3.28
Constructors
| WriterLoggingT | |
Fields
| |
Instances
execWriterLoggingT :: Functor m => WriterLoggingT m a -> m [LogLine] Source #
Run a block using a MonadLogger instance. Return logs in a list
| @since 0.3.28
runWriterLoggingT :: Functor m => WriterLoggingT m a -> m (a, [LogLine]) Source #
Run a block using a MonadLogger instance. Return a value and logs in a list
| @since 0.3.28
mapLoggingT :: (m a -> n b) -> LoggingT m a -> LoggingT n b Source #
Map the unwrapped computation using the given function.
Since: 0.3.29
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 of showable values
logDebugSH :: Q Exp Source #
Generates a function that takes a 'Show a => a' and logs a LevelDebug message. Usage:
$(logDebugSH) (Just "This is a debug log message")
Since: 0.3.18
logErrorSH :: Q Exp Source #
See logDebugSH
logOtherSH :: Text -> Q Exp Source #
Generates a function that takes a 'Show a => a' and logs a LevelOther message. Usage:
$(logOtherSH "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 #
Non-TH logging with source
logWithoutLoc :: (MonadLogger m, ToLogStr msg) => LogSource -> LogLevel -> msg -> m () Source #
Since: 0.3.23
logDebugNS :: MonadLogger m => LogSource -> Text -> m () Source #
logErrorNS :: MonadLogger m => LogSource -> Text -> m () Source #
logOtherNS :: MonadLogger m => LogSource -> LogLevel -> Text -> m () Source #
Callstack logging
logDebugCS :: MonadLogger m => CallStack -> Text -> m () Source #
logInfoCS :: MonadLogger m => CallStack -> Text -> m () Source #
See logDebugCS
Since: 0.3.19
logWarnCS :: MonadLogger m => CallStack -> Text -> m () Source #
See logDebugCS
Since: 0.3.19
logErrorCS :: MonadLogger m => CallStack -> Text -> m () Source #
See logDebugCS
Since: 0.3.19
logOtherCS :: MonadLogger m => CallStack -> LogLevel -> Text -> m () Source #
See logDebugCS
Since: 0.3.19
utilities for defining your own loggers
Loc
When monad-logger is compiled with the template_haskell flag set to true (the default), the Loc below is a re-export from the template-haskell package.
When the flag is false, the Loc below is a copy of that data structure defined in monad-logger itself.
If you are making a library that:
- Uses
monad-logger - Uses
Locin a type signature - But doesn't need to depend on
template-haskellfor other reasons
You can import Loc directly from this package, instead of adding an dependency on template-haskell and importing from there.
This allows users to compile your package in environments that don't support template-haskell.
Constructors
| Loc | |
Fields
| |
Instances
| Data Loc | |
Defined in Language.Haskell.TH.Syntax Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Loc -> c Loc # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Loc # dataTypeOf :: Loc -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Loc) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Loc) # gmapT :: (forall b. Data b => b -> b) -> Loc -> Loc # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Loc -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Loc -> r # gmapQ :: (forall d. Data d => d -> u) -> Loc -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Loc -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Loc -> m Loc # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Loc -> m Loc # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Loc -> m Loc # | |
| Generic Loc | |
| Show Loc | |
| Eq Loc | |
| Ord Loc | |
| type Rep Loc | |
Defined in Language.Haskell.TH.Syntax type Rep Loc = D1 ('MetaData "Loc" "Language.Haskell.TH.Syntax" "template-haskell" 'False) (C1 ('MetaCons "Loc" 'PrefixI 'True) ((S1 ('MetaSel ('Just "loc_filename") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String) :*: S1 ('MetaSel ('Just "loc_package") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String)) :*: (S1 ('MetaSel ('Just "loc_module") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String) :*: (S1 ('MetaSel ('Just "loc_start") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 CharPos) :*: S1 ('MetaSel ('Just "loc_end") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 CharPos))))) | |
defaultLoc :: Loc Source #
dummy location, used with logWithoutLoc
Since: 0.3.23
defaultOutput :: Handle -> Loc -> LogSource -> LogLevel -> LogStr -> IO () Source #
A default implementation of monadLoggerLog that accepts a file
handle as the first argument.
This is used in the definition of runStdoutLoggingT:
runStdoutLoggingT::MonadIOm =>LoggingTm a -> m arunStdoutLoggingTaction =runLoggingTaction (defaultOutputstdout)
Since: 0.3.36