This is a set of macros that are a front end to xy-pic that make it (relatively) easy to use it to set the kind of diagrams that are especially interesting to category theorists. There are two modes of macros: the first kind uses shapes such as squares and various triangles that fit together like Lego blocks; the second sets the nodes on an xy-grid and labels them and then sets arrows between the nodes. All the arrow types of xy are allowed in either mode. For the latest upgrade (if any) look at http://www.math.mcgill.ca/barr/papers/.