I dived into prolog this year, and I really liked it. However, I didn't find a very active community to answer questions. The lack of energy in the community, and my wondering where I could use prolog for a practical application, tempered my enthousiasm, and I switched to learning something else (category theory).

What sources do you have to learn category theory?

The pdf generated from his blog is also interesting :

https://github.com/hmemcpy/milewski-ctfp-pdf

These are the best resources I found about the subject.