MDEx

Fast and Extensible Markdown for Elixir.

Features

Fast
Compliant with the CommonMark spec
Plugins
Formats:
- Markdown (CommonMark)
- HTML
- JSON
- XML
Floki-like Document AST
Req-like Pipeline API
GitHub Flavored Markdown
Discord and GitLab Flavored-ish Markdown
Wiki-style links
Emoji shortcodes
Built-in Syntax Highlighting for code blocks
Code Block Decorators
HTML sanitization
~MD Sigil for Markdown, HTML, JSON, and XML

Examples

Livebook examples are available at Pages / Examples

Installation

Add :mdex dependency:

def deps do
  [
    {:mdex, "~> 0.8"}
  ]
end

Or use Igniter:

mix igniter.install mdex

Usage

iex> MDEx.to_html!("# Hello :smile:", extension: [shortcodes: true])
"<h1>Hello 😄</h1>"

iex> import MDEx.Sigil
iex> ~MD[
...> # Hello :smile:
...> ]HTML
"<h1>Hello 😄</h1>"

iex> import MDEx.Sigil
iex> ~MD[
...> # Hello :smile:
...> ]
%MDEx.Document{nodes: [%MDEx.Heading{nodes: [%MDEx.Text{literal: "Hello "}, %MDEx.ShortCode{code: "smile", emoji: "😄"}], level: 1, setext: false}]}

Foundation

The library is built on top of:

comrak - a fast Rust port of GitHub's CommonMark parser
ammonia for HTML Sanitization
autumnus for Syntax Highlighting

Used By

Are you using MDEx and want to list your project here? Please send a PR!

Motivation

MDEx was born out of the necessity of parsing CommonMark files, to parse hundreds of files quickly, and to be easily extensible by consumers of the library.

earmark is extensible but can't parse all kinds of documents and is slow to convert hundreds of markdowns.
md is very extensible but the doc says "If one needs to perfectly parse the common markdown, Md is probably not the correct choice" and CommonMark was a requirement to parse many existing files.
markdown is not precompiled and has not received updates in a while.
cmark is a fast CommonMark parser but it requires compiling the C library, is hard to extend, and was archived on Apr 2024.

Comparison

Feature	MDEx	Earmark	md	cmark
Active	✅	✅	✅	❌
Pure Elixir	❌	✅	✅	❌
Extensible	✅	✅	✅	❌
Syntax Highlighting	✅	❌	❌	❌
Code Block Decorators	✅	❌	❌	❌
AST	✅	✅	✅	❌
AST to Markdown	✅	⚠️²	❌	❌
To HTML	✅	✅	✅	✅
To JSON	✅	❌	❌	❌
To XML	✅	❌	❌	✅
To Manpage	❌	❌	❌	✅
To LaTeX	❌	❌	❌	✅
Emoji	✅	❌	❌	❌
GFM³	✅	✅	❌	❌
GitLab⁴	⚠️¹	❌	❌	❌
Discord⁵	⚠️¹	❌	❌	❌

Partial support
Possible with earmark_reversal
GitHub Flavored Markdown
GitLab Flavored Markdown
Discord Flavored Markdown

Benchmark

A simple script is available to compare existing libs:

Name              ips        average  deviation         median         99th %
cmark          7.17 K       0.139 ms     ±4.20%       0.138 ms       0.165 ms
mdex           2.71 K        0.37 ms     ±7.95%        0.36 ms        0.45 ms
md            0.196 K        5.11 ms     ±2.51%        5.08 ms        5.55 ms
earmark      0.0372 K       26.91 ms     ±2.09%       26.77 ms       30.25 ms

Comparison:
cmark          7.17 K
mdex           2.71 K - 2.65x slower +0.23 ms
md            0.196 K - 36.69x slower +4.98 ms
earmark      0.0372 K - 193.04x slower +26.77 ms

The most performance gain is using the ~MD sigil to compile the Markdown instead of parsing it at runtime, prefer using it when possible:

Comparison:
mdex_sigil_MD    176948.46 K
cmark                31.47 K - 5622.76x slower +31.77 μs
mdex_to_html/1        7.32 K - 24184.36x slower +136.67 μs
md                    2.05 K - 86176.93x slower +487.01 μs
earmark               0.21 K - 855844.67x slower +4836.68 μs

To finish, a friendly reminder that all libs have their own strengths and trade-offs so use the one that better suits your needs.

Acknowledgements

comrak crate for all the heavy work on parsing Markdown and rendering HTML
Floki for the AST
Req for the pipeline API
Logo based on markdown-mark