This comes up every so often and people argue over the merits of learning category theory or not or how useful or abstract it is. The answer is it is very abstract and you shouldn't learn it expecting great dividends in your day to day work. Like with most mathematics you should learn it because it will change the way you think and solve problems. I definitely don't use calculus in my day to day work but the idea of infinitesimal quantities, continuity, and linear approximations have more than once helped me come up with an approximation to a problem that has made the solution tractable.
If you are expecting to apply something immediately to your work then combinatorics and probability theory are way more relevant and practical for day to day programming work.
If you are expecting to apply something immediately to your work then combinatorics and probability theory are way more relevant and practical for day to day programming work.