Example.Rmd showing executable Elixir code in Tufte Handout RMarkdown format

gistfile1.txt

---
title: "Executable Elixir in Tufte Handout"
author: "Wendy Smoak"
date: "September 1, 2015"
output: rmarkdown::tufte_handout
---
```{r setup, echo=FALSE}

  # Adapted from http://datadrivensecurity.info/blog/posts/2015/Jun/running-other-languages-in-r-markdown-files/
  # Licensed CC-BY-SA http://creativecommons.org/licenses/by-sa/4.0/
  # As required by http://datadrivensecurity.info/blog/pages/license.html
  
library(knitr)

eng_elixir <- function(options) {

  # create a temporary file

  f <- basename(tempfile("temp", '.', paste('.', "exs", sep = '')))
  on.exit(unlink(f)) # cleanup temp file on function exit
  writeLines(options$code, f)

  out <- ''

  # if eval != FALSE compile/run the code, preserving output

  if (options$eval) {
    out <- system(sprintf('elixir %s', paste(f, options$engine.opts)), intern=TRUE)
  }

  # spit back stuff to the user

  engine_output(options, options$code, out)
}

knitr::knit_engines$set(elixir=eng_elixir)

```

# Introduction

This is an example document in Tufte Handout Format.  It is edited in RStudio in RMarkdown format and transformed into a PDF with File -> Knit from the menu, or Cmd-Shift-K.

# Tufte Handout

> Tufte Handouts[^tufte-handout] are documents formatted[^tufte-latex] in the style that Edward Tufte uses in his books and handouts. Tufte’s style is known for its extensive use of sidenotes, tight integration of graphics with text, and well-set typography:

The format has the usual `#` and `##` headings. Also margin figures (see the equation --> over there, with a caption even,) as well as full-width and main-column figures. 

\begin{marginfigure}
$$ x^2 + y^2 = 1 $$
\caption{An equation}
\end{marginfigure}


# Elixir Code

Here is some Elixir code *and the output*, which was produced by executing the code at the time the PDF was created:

\marginnote{This is a margin note.}

```{elixir}
defmodule Math do
  def sum(a, b) do
    a + b
  end
end

IO.puts "The answer is #{ Math.sum(4,3) }"    
```

In the source[^source] of this document, you will find the code that makes this possible, adapted from an article on running Go snippets in RMarkdown files[^go-rmd].

[^tufte-handout]: http://rmarkdown.rstudio.com/tufte_handout_format.html
[^tufte-latex]: https://tufte-latex.github.io/tufte-latex/
[^go-rmd]: http://datadrivensecurity.info/blog/posts/2015/Jun/running-other-languages-in-r-markdown-files/
[^source]: https://gist.github.com/wsmoak/f5fd090df809e87a13fb