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