Composable Contravariant Comonadic Logging Library.

This package provides core types and functions to work with the LogAction data type which is both simple and powerful.

newtype LogAction m msg = LogAction
{ unLogAction :: msg -> m ()
}

The ideas behind this package are described in the following blog post:

• co-log: Composable Contravariant Combinatorial Comonadic Configurable Convenient Logging

See the following packages for different implementations based on co-log-core:

• co-log: taggless final implementations.

• co-log-polysemy: extensible effects implementation based on polysemy.

co-log-core

co-log-core is a lightweight package that provides core types and functions to work with the @LogAction@ data type which is both simple and powerful.

How to use

co-log-core is compatible with the following GHC versions - supported versions

In order to start using co-log-core in your project, you will need to set it up with these steps:

1. Add the dependency on co-log-core in your project's .cabal file. For this, you should modify the build-depends section according to the below section:

   build-depends: base ^>= LATEST_SUPPORTED_BASE
                , co-log-core ^>= LATEST_VERSION
   

2. To use this package, refer to the below example.

   module Main (main) where
   
   import Prelude hiding (log)
   
   import Colog.Core (LogAction, logStringStdout, (<&))
   
   
   app :: LogAction IO String -> IO ()
   app log = do
       log <& "Starting app..."
       log <& "Finishing app..."
   
   main :: IO ()
   main = app logStringStdout