Questions about R in production

I think this is as interesting point. It seems to me that even within R (i.e., without comparing R to other languages) there is a tension between performance vs clarity of the code. I'm not saying this is an either-or, but often it seems like one. My guess is that most R coders emphasize clarity because when you develop an analysis or a model, well, you want to make sure all the complicated steps you apply are as transparent as possible. Which makes sense.
On this point, I agree with Hadley Wickham's maxim that you should first write code for clarity, and then refactor parts for performance when you see you need it. I think it's a good approach.

But what would be the base R equivalent of something like purrr::map_df?