This talk describes how to write Lint for Ruby program.

Lint finds bugs from code automatically. So, if you can write Lint, you can reduce bugs from your code automatically.

This talk includes the following topics.

- Implementation of existing Lint such as [RuboCop](https://github.com/bbatsov/rubocop) and [Reek](https://github.com/troessner/reek).

- How to create new Lint or add a new rule to existing Lint yourself.