For anyone that may want a deeper look into Category Theory from the perspective of a programmer I highly recommend - https://bartoszmilewski.com/2014/10/28/category-theory-for-p...
He also covers it all in few youtube series - https://www.youtube.com/user/DrBartosz/playlists
I also heartily recommend this. I’ve been watching the videos whilst ploughing through the PDF book version [1] on my Kindle. He really is a very good teacher.