In this episode, we implement a minimal subset of Markdown in Elixir by chaining together regex replace functions into a processing pipeline. If you've ever written a static page on Github or a comment on Reddit, then you've used Markdown. Here's a quick overview in case you're not familiar with it.
Markdown is a terse, human-readable document format that is easily converted to HTML. Anything that appears between a pair of asterisks is *italicized*, while text between a pair of asterisks is **bolded**. A line starting with # creates an H1 tag while starting with ## creates an H2 tag, etc, etc. Markdown is pretty handy when you just want to write a document quickly.
The plan
- Create a new module with a
to_html function that converts Markdown to HTML by calling a pipeline of other functions
- Create an
italics function that will take a text input and use Regex.replace to globally replace *text* with <em>text</em> and return the new text.
- Create a similar
bold function that will globally replace **text** with <strong>text</strong>
- Create a
p function that wraps lines of text with <p> tags
- Create a test string that uses various features and lets us easily test our module as we add to it.
- Try writing an output.html file from a simple markdown file.
This module isn't that complex, but it's a great way to show off the power of Elixir's function pipelines! We'll go into a more standard way of doing unit tests once we start working with mix in a few lessons.
Challenge 5
Add two more HTML tags to markdown—"big" and "small". Decide for yourself what the syntax should be to generate them.
(solution here)
