run-lua

Executes any Lua command in a lua XML processing instruction and includes the result in the document.

Example:

The number <?lua return 1 + 2 + 3 + 4 + 5?> is the fifth triangular number.

This yields

The number 15 is the fifth triangular number.

The value that’s returned by the Lua code is spliced back into the document. The = character can be used as a shorthand for return when placed at the beginning of an expression.

1 + 2 = <?lua =1 + 2 ?>

Result:

1 + 2 = 3

The filter tries to detect when the return has been omitted and inserts it automatically in that case. Therefore, the above can be shortened to

1 + 2 = <?lua 1 + 2 ?>

1 + 2 = 3

Raw attributes syntax with format run-lua or runlua can be used as an alternative to the processing-instructions-based syntax.

For example,

𝜋 ≈ `math.pi`{=run-lua}

𝜏 ≈ `2 * math.pi`{=runlua}

yields

𝜋 ≈ 3.1415926535898

𝜏 ≈ 6.2831853071796

Note that pandoc isn’t an XML processor, and the processing instruction is terminated by a single >. Use the “raw attribute” syntax if your code contains that character:

```{=runlua}
return 1 > 0 and 'all is well'
```

Usage

The filter modifies the internal document representation; it can be used with many publishing systems that are based on pandoc.

Plain pandoc

Pass the filter to pandoc via the --lua-filter (or -L) command line option.

pandoc --lua-filter run-lua.lua ...

Quarto

Users of Quarto can install this filter as an extension with

quarto install extension pandoc-ext/run-lua

and use it by adding run-lua to the filters entry in their YAML header.

---
filters:
  - run-lua
---

R Markdown

Use pandoc_args to invoke the filter. See the R Markdown Cookbook for details.

---
output:
  word_document:
    pandoc_args: ['--lua-filter=run-lua.lua']
---

License

This pandoc Lua filter is published under the MIT license, see file LICENSE for details.