When we say “R Markdown”, we usually refer to the rmarkdown package, which is based on Pandoc and knitr. Prior to the rmarkdown package, there actually existed an older version of R Markdown, which was based on the markdown package instead of Pandoc. Later we called this version “R Markdown v1”.
R Markdown v1 was more or less an experiment, although many people liked it (perhaps because they had suffered for too long from LaTeX). It did not take long before we started developing v2, i.e., rmarkdown. V1 was much less powerful than v2. For example, it only supported HTML output but not LaTeX or any other output format. The now widespread CommonMark specs did not exist at that time, so v1’s Markdown syntax was chaos just like pretty much any other Markdown conversion tools (each having its own homemade or wild-caught specs) except Pandoc.
After R Markdown v2 became mature, v1 did not seem to be of much value any more. Perhaps it would just quietly fade out and eventually die. But…
But Jeroen Ooms, the great ninja, created the R package commonmark later. That changed the destiny of the markdown package. Previously, markdown was based on a C library, which had been deprecated for a long time. Last year, I removed the C library from markdown, and rewrote the package based on commonmark.
Although I’m a minimalist, commonmark’s Markdown features are too limited in my eyes. On the other hand, Pandoc’s Markdown is too rich to me. What I did in the markdown package was a compromise. You can read the introduction vignette to learn which features are supported in this package.
If you prefer reading slides over documentation, I have given a talk in May, which was not recorded but you will not miss anything by only reading the slides.
This post is not meant to encourage people to use R Markdown v1. On the contrary, I think v2 and Quarto are better choices for most people. I just want to mention the revived markdown package, and there is a small chance that it actually meets some people’s need.
Declaring “feature complete” is hard, and it is definitely not a firm rejection to all future feature requests. It only means that “being feature-rich” is not the goal of this package. In particular, new features that require substantial work are unlikely to be added. Please feel free to request new features without a high expectation that they would be implemented.