xmd

XMD: RMarkdown and other language variants

"XMarkdown" is our name for RMarkdown-like formats, that is, RMarkdown but extended to language X, where X includes Python, Javascript, etc. See https://bookdown.org/yihui/rmarkdown/language-engines.html

In RMarkdown, R code is embedded in "code chunks". There are two types of code chunks: inline and block.

Inline code chunks

An inline code chunk is equivalent to Stencila's CodeExpr. They are declared using Markdown code spans prefixed by the language label e.g.

The answer is `r x * y`

Inline code chunks are parsed to a CodeExpr with programmingLanguage and text properties set e.g.

{
  "type": "CodeExpr",
  "programmingLanguage": "r",
  "text": "x * y"
}

Block code chunks

A block code chunks is equivalent to Stencila's CodeChunk. They are declared using Markdown fenced code blocks with attributes starting with the language label and, optionally, a chunk label and other chunk options e.g.

```{r myplot, fig.width=6, fig.height=7}
plot(x,y)
```

Here myplot is the chunk label and fig.width=6, fig.height=7 are chunk options. A list of chunk options, recognized by the RMarkdown rendering engine, Knitr, is available at http://yihui.name/knitr/options/.

Block code chunks are decoded to a CodeChunk with programmingLanguage and text properties set. The chunk label, if defined is used for the name property and other options go into the meta property e.g.

{
  "type": "CodeChunk",
  "programmingLanguage": "r",
  "name": "myplot",
  "meta": {
    "fig.width": "6",
    "fig.width": "7"
  },
  "text": "plot(x,y)"
}