An Invitation to Applied Category Theory: Seven Sketches in Compositionality

This book has a very nice gradual progression building from basic ideas. The tone and pace are quite pleasant, which is a blessing since its so easy to make the presentation of definitions dull and dry. I've found it very straight forward to follow the explanations and at the end of them I feel like I truly understand the concepts. I'm half way through it and don't feel overwhelmed or lost. A proof of its good pedagogy is that I have been able to successfully complete all of the exercises. It was a great decision by the authors to intersperse the exercises with the content instead of adding them at the end of the chapters. It's the first Maths book in which I'm doing absolutely all of the exercises. The authors do a good job in linking the concepts with actual useful stuff, like relating Monoids to concurrency and Categories, Functors and Natural transformations to databases. Even though there are quite a few of this kind of examples, I think the work would benefit from even more of them. In the Haskell community there is a lot of talk about Category Theory, but every time I tried to learn a concept it would be explained in terms of other category-theoretical concepts in a definition loop. This book is filling an important void and I am finally being able to understand the relation between these ideas and their implementation in Haskell.

The authors did a great job but the publishers didn't. A lot of the pages are going over the edge.

This has lots of explanation and nice exercises. Just did 5 questions in the first chapter. 3/5. After that the notation became very dense.

A huge improvement over all the other category theory books where all the examples are from 20th century pure math and all the morphisms are functions. Especially the last chapter.

Livro muito bem escrito, claro, intuitivo e correto

The book is wonderful but, why do even pages have the margin on the left making the lines in those pages to almost get into the spine?

The book itself is made with attention to many small details that make it a pleasure to read. To mention a few: there is a margin broad enough for my own annotations, the references to other resouces go back and forth (showing you where it was cited), there are lots of cross-references in the book itself, the paper is of good quality and allows me to use text-markers the way I like it, there are plenty of illustrations and so on. The topics are chosen to give am impression of the wide applicability of category theory, thus connecting many other mathematical and practical applications with categories. The tone varies from casual notes that explain quite clearly the ideas and intentions behind certain constructions and rigid mathematical definitions and proofs. For me this is much easier to digest then a bare definition-proposition-proof style. There are many examples and exercises (inlcuding solutions) in the book and one is well adviced to put in the work to use ones own brain. Many examples and exercises come up again in later chapters. All chapters start easy and then slowly pick up speed until some become quite demanding. If you are looking for a book that is not only about category theory, but shows the ramifications into other sciences, is well written and takes you by the hand through different interesting topics, this is the book I would recommend!