Reimagining Literate Programming and Automated Report Generation

An FAQ about me when I travel

Where is your baggage?

Asked by border control officers, taxi drivers, and friends…

[…] A wealthy businessman who was passing through Radin and took advantage of the opportunity to visit the Rabbi (Chofetz Chaim). He was astounded by the lack of furniture in Rabbi’s home.

Unable to contain himself, he asked, “Where is your furniture?”

Rabbi responded by asking him where was his furniture.

The man, a bit surprised by the question, explained that he was only passing through.

Rabbi smiled and explained that in this world, he too, was only passing through.¹

Where is your Pandoc?

And jQuery?

Bootstrap?

Microsoft Office?

…?

The two richest men in Omaha, Nebraska

Warren Buffet
???

Minimalism: my new journey

litedown: https://github.com/yihui/litedown
litedown = min{
- knitr + evaluate +
- rmarkdown +
- bookdown + blogdown + pagedown + xaringan + tufte + distill
} – Pandoc – Bootstrap – jQuery

– GitBook – Hugo – paged.js – remark.js – tufte.css – distill.js/.css – …

+ super lightweight vanilla js/css

Re-implementing 12 years of work from scratch, with fewer features and dependencies²
- Easier to develop, install, and manage
- Also easier to be embedded in other applications (e.g., WebAssembly)
Choosing a stable foundation to develop software on top of
- e.g., base R, commonmark³
- Reproducibility would be hard without stability

Almost “feature-complete” in my eyes after a few months’ work (not because I’m smart but limited scope and a decade’s thinking)
Users will surely request for more features, but litedown is unlikely to gain major new features (time is up, pencils down!)

⚡ litedown ⚡

Make Markdown HTML Again

Do one thing, and do it well

In HTML I Trust

Quick tests for my audience today:

Italic tower HTML body End the war

How much fun you have missed without knowing HTML…

The impressive document converter

Pandoc, the swiss-army knife for converting documents from one format to another: https://pandoc.org (look at that impossible-to-read diagram on the homepage!)
A swiss-army knife?⁴ I think the Pandoc author is too modest!

One road to Rome

litedown re-implemented some Pandoc Markdown features on top of commonmark, but it doesn’t aim at becoming a swiss-army knife (perhaps a laser gun instead?)

Let me show you the “big picture” (pun intended)

['markdown_githubreader', 'htmlwriter', 'markdown_githubreader-&gt;htmlwriter'].forEach(title => {
  document.querySelectorAll('g > title').forEach(el => {
    if (el.innerHTML === title)
      el.nextElementSibling.setAttribute('fill', 'yellow');
  });
});

Yes, SVG is awesome, but…

discovering svg in powerpoint

Someday you will realize…

Word and PowerPoint are just awkward implementations of HTML, CSS, and web browsers.

<- web browsers | MS Office -> microsoft office

And you will also realize how awesome web browsers are…

(now cast the spell “go up”, “go down”, “dark mode”, “mirror my slides”, or “reset my slides”)

BTW, did you notice that this slide is actually editable?

Demos

# install from CRAN
install.packages('litedown')
# or install the dev version (recommended for now)
install.packages('litedown', repos = c('https://yihui.r-universe.dev', 'https://cloud.r-project.org'))

Core functions: litedown::mark() to convert plain Markdown documents; litedown::fuse() to compile R Markdown documents
The live previewer: litedown::roam()
Markdown syntax
Code chunks and inline code
Extra features via CSS/JS

Literate programming

Literate programming (Knuth, 1984) = documentation language + computing language

A 10-second introduction of R Markdown:

Write _narratives_ in Markdown, and _computer code_ in backticks:

```{r}
mean(rnorm(100))
```

Write **more** code chunks and narratives.

Custom execution order of code

I don’t have enough time showcase all possibilities of litedown, so let me highlight one tiny feature that I came up with when rethinking about literate programming.

---
title: A nice report
abstract: "In this report, we studied `{r, order = -1} nrow(x)` cars."
---

Filter cars with `mpg` above 20.

```{r, order = 1}
x = subset(mtcars, mpg > 20)
```

Thank you!

RIP, Fritz Leisch!
- One of my lifetime regrets…
Different people are just trying to make the world better in different ways, and we learn from each other, so thank you, Fritz, and authors of Pandoc, jQuery, Bootstrap, Quarto, …
- Perhaps I should be nice to myself, too—thank you, Yihui from 2013-2023 :)
Special thanks to the great ninja, Jeroen Ooms, for the commonmark package!
Of course, since I’m here, big thanks to Ross Ihaka & Robert Gentleman!

Contact:
- Github: https://github.com/yihui
- Personal website: https://yihui.org

source ↩
litedown only depends on xfun and commonmark. ↩
Much stabler than Pandoc. Maintaining compatibility with new Pandoc releases has not been easy in R Markdown. ↩
With 500 blades?! ↩