Colog.Message

Message with Severity, and logging functions for them.

Basic message type

data Message

Consist of the message Severity level and the message itself.

Constructors

Message

Fields

• messageSeverity :: !Severity
• messageStack :: !CallStack
• messageText :: !Text

unMessageField :: forall fieldName m. MessageField m fieldName -> m (FieldType fieldName)

log :: WithLog env Message m => Severity -> Text -> m ()

Logs the message with given Severity.

logDebug :: WithLog env Message m => Text -> m ()

Logs the message with Debug severity.

logInfo :: WithLog env Message m => Text -> m ()

Logs the message with Info severity.

logWarning :: WithLog env Message m => Text -> m ()

Logs the message with Warning severity.

logError :: WithLog env Message m => Text -> m ()

Logs the message with Error severity.

logException :: forall e m env. (WithLog env Message m, Exception e) => e -> m ()

Logs Exception message.

fmtMessage :: Message -> Text

Prettifies Message type.

Externally extensible message type

type family FieldType (fieldName :: Symbol) :: Type

Open type family that maps some user defined tags (type names) to actual types. The type family is open so you can add new instances.

Instances

type FieldType "threadId"

Defined in Colog.Message

type FieldType "threadId" = ThreadId

type FieldType "utcTime"

Defined in Colog.Message

type FieldType "utcTime" = UTCTime

newtype MessageField (m :: Type -> Type) (fieldName :: Symbol) where

newtype wrapper. Stores monadic ability to extract value of FieldType.

Implementation detail: this exotic writing of MessageField is required in order to use it nicer with type applications. So users can write

MessageField @"threadId" myThreadId

instead of

MessageField _ "threadId" myThreadId

Simpler version of this newtype:

newtype MessageField m fieldName = MessageField
    { unMesssageField :: m (FieldType fieldName)
    }

Constructors

MessageField :: forall fieldName m. m (FieldType fieldName) -> MessageField m fieldName

Instances

(KnownSymbol fieldName, a ~ m (FieldType fieldName)) => IsLabel fieldName (a -> WrapTypeable (MessageField m))

Defined in Colog.Message

Methods

fromLabel :: a -> WrapTypeable (MessageField m)

type FieldMap (m :: Type -> Type) = TypeRepMap (MessageField m)

Depedent map from type level strings to the corresponding types. See FieldType for mapping between names and types.

defaultFieldMap :: MonadIO m => FieldMap m

Default message map that contains actions to extract ThreadId and UTCTime. Basically, the following mapping:

"threadId" -> myThreadId
"utcTime"  -> getCurrentTime

data RichMessage (m :: Type -> Type)

Contains additional data to Message to display more verbose information.

fmtRichMessageDefault :: MonadIO m => RichMessage m -> m Text

Formats RichMessage in the following way:

[Severity] [Time] [SourceLocation] [ThreadId] message

upgradeMessageAction :: forall m. FieldMap m -> LogAction m (RichMessage m) -> LogAction m Message

Allows to extend basic Message type with given dependent map of fields.