Observations

Categories for Scala Programmers

Pretty primitive, but well, the target audience... just to dispel some myths and clear the people's conscience.

http://mathoverflow.net/questions/171809/building-a-product-of-two-categories

But not ashamed of it (takes some guts)

Also, for internal categories in a topos, I can build all that crap in an instant.

An update: reasked. https://math.stackexchange.com/questions/2818595/products-and-coproducts-in-the-category-of-all-categories