[David Christiansen] Zippers: pure functional cursors into datatypes

Room: 2A12

Gérard Huet's zippers are a means of transforming a datatype into a version with a hole in it, allowing pure local modifications without demanding a complete traversal from the root each time. I'll present the notion of zipper, a few example zippers and applications for them, and a discussion of how to derive the zipper for a custom datatype, exemplified through a connection that Conor McBride noticed between zippers and calculating derivatives.