Fantastic Morphisms and Where to Find Them

Talk by Nicolas Wu, Imperial College London

Structured recursion schemes have been widely used in constructing, optimising, and reasoning about programs over inductive and coinductive datatypes. Their plain forms, catamorphisms and anamorphisms, are restricted in expressiveness. Thus many generalisations have been proposed, which further lead to several unifying frameworks of structured recursion schemes. However, the existing work on unifying frameworks typically focuses on the categorical foundation, and thus is perhaps inaccessible to practitioners who are willing to apply recursion schemes in practice but are not versed in category theory. We will be introducing structured recursion schemes from a practical point of view and explore the basic ideas of category theory involved.

These lectures will be based on: Fantastic Morphisms and Where to Find Them – A Guide to Recursion Schemes.

Zhixuan Yang, Nicolas Wu: MPC 2022: 222-267

Dr Nicolas Wu is a Reader at the Department of Computing, Imperial College London, where he leads the Functional Programming Research Group. His research interests are centred around programming languages, where he has made advances in applications of category theory for giving the semantics of programs and algorithms. In particular, his recent work has been focused on showing the connections between domain specific languages, algebraic effect handlers, and structured recursion schemes.