String Diagrams for Modelling Functional Programming

It is currently impossible to model functional programs in the same way that UML is used to model object-oriented programs: no analogous graphical notation exists. Unlike object-oriented programs, however, functional programming is built on a solid mathematical basis and it may be possible to adapt graphical notation from the mathematical domain for such modelling. This work examines string diagrams as a way to model certain functional abstractions. A proposed notation is demonstrated in the contexts of equational reasoning and descriptive modelling, and is found to be suitable for both.