Part 4: Code

Code Embedding

Traditional code embedding can be done as in markdown or beamer listings. An interesting aspect is to have the code actually executed, and its output appended here.

One example of code in Python (not executed):

print("Hello World")

This is how it’s done:

\```{.python}
print("Hello World")
\```

Configuring highlighters

Command pandoc --list-highlight-styles (or just eval "$(pandoc --bash-completion)" to enable bash completion) will display options: pygments, tango, espresso, zenburn, kate, monochrome, breezedark, haddock

You can visually compare them here: https://www.garrickadenbuie.com/blog/pandoc-syntax-highlighting-examples

An interesting project for active code execution is codebraid for: Python 3.5+, Julia, Rust, R, Bash, JavaScript, and SageMath.

Fenced code blocks

fenced_code_blocks and backtick_code_blocks enable code highlight on pandoc.

fenced_code_attributes can add more attributes to them.

See Manual: https://pandoc.org/MANUAL.html#fenced-code-blocks

pandoc --list-highlight-languages will list languages (a lot!)

Active Code

To have code executed, you will need the plugin pandoc-source-exec from panflute pack (install as easy as python3 -m pip install pandoc-source-exec). On Pandoc, we can use .exec property (also hide=true and .hide). An specific command can be given, such as: cmd='codes/run_python2.sh'.

This approach is nice because it integrates nicely with markdown-preview-enhanced on Atom, where you can see results on real time.

Example of Active Code (Python3)

\```{.python .exec cmd='codes/run_python3.sh'}
...
\```

Expected output is:

Hello
World2

Real test

print("Hello")
x=2
if x > 1:
  print("World"+str(x))

Output:

Hello
World2

Example of Active Code hidden (Python2)

\```{.python .exec cmd='codes/run_python2.sh'
                        hide=true .hide output_label=''}
print 'Hello'
\```

Real test

Hello

Example of Active Code from file (Python3)

This is one of the most interesting approaches, just load script codes/example.py and execute it:

\```{.python .exec cmd='codes/run_python3.sh' args="codes/example.py"
                                      hide=true .hide output_label=''}
\```

File example.py contains:

print("Example Hello World")

Real test

Example Hello World

Example of C++ Active Code

This is where we wanted to arrive on codes/example.cpp:

\```{.cpp .exec cmd='codes/run_cpp.sh' args="codes/example.cpp"
                                  hide=true .hide output_label=''}
\```

File example.cpp contains:

#include<iostream>
int main() {
  std::cout << "Hello World C++" << std::endl;
  return 0;
}

Real test

Hello World C++

Pseudocode with LaTeX

LaTeX requires installation of pdf2svg for both markdown-preview-enhanced plugin and run_latex.sh.

\```{.latex .exec .hide hide=true cmd='codes/run_latex.sh'
          void=true  args="figs/pseudo1.svg" output_label=''}
\documentclass{standalone}
\usepackage[ruled,vlined,linesnumbered]{algorithm2e}
\begin{document}
\pagestyle{empty}
\begin{algorithm}[H]
\caption{Test Algo}
\end{algorithm}
\end{document}
\```

Complete test of algorithm

Ace Editor (on Atom)

For markdown-preview-enhanced, we can see Ace Editor (also on revealjs):