Excel as a Turing-complete Functional Programming Environment

Abstract: Since the calculation engine of Excel was the subject of a major upgrade to accommodate Dynamic Arrays in 2018 there has been a series of seismic changes to the art of building spreadsheet solutions. This paper will show the ad-hoc end user practices of traditional spreadsheets can be replaced by radically different approaches that have far more in common with formal programming. It is too early to guess the extent to which the new functionality will be adopted by the business and engineering communities and the impact that may have upon risk. Nevertheless, some trends are emerging from pioneering work within the Excel community which we will discuss here.