Lib.rs

Composable logging with monoids and contravariant functors.

If you want to use this library there are at least two ways to obtain it: you could depend on it with Cargo by adding contralog as a dependency in Cargo.toml, or you could copy the src/lib.rs file into your own project under a different name.

When developing this library please use Nix to ensure the build is reproducible:

nix run -ic cargo test

lib.rs:

Composable logging with monoids and contravariant functors.

A logger is a routine that takes input and has side-effects. Any routine that has the appropriate type will do. A logger can be seen as the opposite or dual of an infinite iterator.

The core trait of this crate is Logger. It has only a single method that must be implemented: log. To log something, pass it to this method. It is up to the logger to decide what to do with the value.

Loggers are composable: given two loggers with compatible types, a new logger can be created that forwards its input to both loggers.

Loggers can also be transformed using methods such as map and filter.