When is a Function a Fold or an Unfold?

We give a necessary and sufficient condition for when a set-theoretic function can be written using the recursion operator fold, and a dual condition for the recursion operator unfold. The conditions are simple, practically useful, and generic in the underlying datatype.

Bibliographic Details
Main Authors: Gibbons, J, Hutton, G, Altenkirch, T
Format: Journal article
Published: 2001