If you configure your Yesod site to log HTTP structures to Yesod, you will need instances of ToObject and LogItem for the structures you want to log.

By default, KatipContextSite will add the WAI request to the context - which is why its Yesod instance requires those classes on the Request type. This module contains simple implementations for those classes on Request, to help set up a quick and easy use of KatipContextSite.