Policy that determines how the case of a congested logging pipeline is addressed.

The Internal log message type.

The type parameter a is expected to provide intances of Show, Typeable, and NFData.

If we need to support different backends, we may consider including the backend here...

This is given to logger when it is created. It formats and delivers individual log messages synchronously.

The type parameter a is expected to provide instances for Show Typeable, and NFData.

The Left values of the argument allows the generation of log messages that are independent of the parameter a. The motivation for this is reporting issues in Logging system itself, like a full logger queue or providing statistics about the fill level of the queue. There may be other uses of this, too.

TODO there may be scenarios where chunked processing is beneficial. While this can be done in a closure of this function a more direct support might be desirable.

This function is provided by the logger.

Abstraction of a logger context that can be used without dependening on a specific monadic context.

The loggerFunIO incorporates a LoggerBackend. An instance of a LoggerCtx is free to use a hard coded LoggerBackend or to be usable with different LoggerBackend functions. The latter is recommended but not required.

You don't have to provide an instance of this for your logger. Instead you may just provide an instance of MonadLog directly.

If this doesn't fit your needs you may use a newtype wrapper and define your own instances.

Instances of MonadLog that allow to obtain a LogFunctionIO as plain value. This is helpful when dealing with frameworks that take a logging function in IO as parameter.

An instance of this class should apply the LogLevel, LogScope, and LogPolicy at the time when logFunIO is called and not when the returned action is excecuted. If the returned action is excecuted after the logger got released or otherwise invalidated the behavior should match the behavior on a congested logging pipeling accorrding to the log-policy that was in scope when logFunIO was called.

Even though it can be very convenient, instances of this class must be used with care. The action may contain in its closure a reference to some internal state of the MonadLog instance. Beside of being a source of potential memory leaks, there also is nothing that prevents a programer to call this action outside of the valid scope of the MonadLog instance. In case that the context of the MonadLog instance depends on some state that gets explicitely deallocated this action may have unexectped behavior.