

The theory behind covariance and contravariance in C# 4 (2012) - kevinskii
http://tomasp.net/blog/variance-explained.aspx/

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acjohnson55
This is a really great article. I've read simpler explanations of covariance
and contravariance, but this is one of the most accessible illustrations of
category theoretical concepts I've read. I'd love to see the author expand
upon it to show how the concept of functors leads to map operation and how the
monads and flatmap can be conceptualized within the category theoretical
framework.

