LINQ Farm: Covariance and Contravariance in C# 4.0

This post is designed to help you begin to understand a new feature in the next version of Visual Studio that involves covariant and contravariant support for delegates and interfaces. Eric Lippert’s series of posts on this subject are definitely the definitive reference at this time. I’m writing this overview of the subject simply as an appendix to his explanation, and as quick reference for folks who want to get up to speed on this technology.