This package provide a mtl style MonadLog class and a concrete monad transformer LogT , the main difference between this package and monad-logger are:

Base monad has to be an instance of MonadIO .

Parametrized logging environment for extensibility.

Basic logging environment type( Label , Loc , NameSpace , ThreadId ) are included, and you can easily make your own.

JSON logging built-in.

default to fast-logger backend, with good stdout and file support.

If you are an application author, you can use LogT transformer, it's just a specialized reader monad to inject `Logger env`.

If you are a library author, you should do following two things: