Try the free online textbook Category Theory for Computing Science by Michael Barr and Charles Wells [1]. It's a true textbook with exercises and lots of conten

Try the free online textbook Category Theory for Computing Science by Michael Barr and Charles Wells [1]. It's a true textbook with exercises and lots of content. [1]: http://www.math.mcgill.ca/triples/Barr-Wells-ctcs.pdf http://www.math.mcgill.ca/triples/Barr-Wells-ctcs.pdf