Welcome to the fourth (and final!) post in the “Teaching the Tidyverse in 2020” series. So far we have covered getting started, data visualisation, and data wrangling and tidying. Today the focus will be on when to introduce the purrr package, or more widely, the notion of iteration and functional programming. In a nutshell, purrr enhances R’s functional programming toolkit by providing a complete and consistent set of tools for working with functions and vectors.