I've started writing a 'book': Functional programming and unit testing for data munging with R

I have started writing a ‘book’ using the awesome bookdown package. In the book I explain and show why using functional programming and putting your functions in your own packages is the way to go when you want to clean, prepare and transform large data sets. It makes testing and documenting your code easier. You don’t need to think about managing paths either. The book is far from complete, but I plan on working on it steadily. For now, you can read an intro to functional programming, unit testing and creating your own packages that will hold your code. I also show you can write documentation for your functions. I am also looking for feedback; so if you have any suggestions, do not hesitate to shoot me an email or a tweet! You can read the book by clicking here.