"Clowns to the Left of me, Jokers to the Right"

Sam Gélineau will present Conor McBride's "Clowns to the Left of me, Jokers to the Right" (http://strictlypositive.org/CJ.pdf), in which a "dissection" operation is presented, as a generalization of the derivative of datatypes (http://strictlypositive.org/diff.pdf), out of which a bunch of interesting things can be derived, notably Huet's zipper (http://gallium.inria.fr/~huet/PUBLIC/zip.pdf) and Brzozowski's derivative of a regular expression (https://en.wikipedia.org/wiki/Brzozowski_derivative).

Everyone interested in powerful applications of type systems should enjoy this. I recommend reading the zipper pearl before attempting this month's paper, if one hasn't already.