A Gentle Introduction to Category Theory Lecture notes by Maarten M. Fokkinga introducing some important notions from category theory, in particular adjunctions. Proofs are given in a calculational style, and the (few) examples are taken from algorithmics. The text is a long PostScript file.
Structures Directory Email directory of logicians, algebraists, and programming linguists working primarily on structural problems in mathematics and computer science.
Toposes, Triples and Theories By Michael Barr and Charles Wells, 1983. A revised and corrected version is now available free for downloading. Formats: DVI, PDF, PostScript.
CT Category Theory Section of the e-print arXiv dealing with category theory, including such topics as: enriched categories, topoi, abelian categories, monoidal categories, homological algebra.
Computational Category Theory An implementation of concepts and constructions from category theory in the functional programming language Standard ML. Documentation and code.
