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Re:Categories for the Practicing Physicist (2009) [pdf] by adolgert on Sunday September 28, 2014 @10:33PM (#8381476)
And for the practicing computer scientist, category theory provides a single structure suitable for expressing linear control theory, automata, and more: Arbib, Michael A., and Ernest G. Manes. "Machines in a category: An expository introduction." SIAM review 16.2 (1974): 163-192.

"Category theory, not always a total waste of time." (TM)