Syntax Extensions#

MyST-Parser is highly configurable, utilising the inherent “plugability” of the markdown-it-py parser. The following syntaxes are optional (disabled by default) and can be enabled via the sphinx conf.py (see also Configuration). Their goal is generally to add more Markdown friendly syntaxes; often enabling and rendering markdown-it-py plugins that extend the CommonMark specification.

To enable all the syntaxes explained below:

myst_enable_extensions = [
    "amsmath",
    "colon_fence",
    "deflist",
    "dollarmath",
    "fieldlist",
    "html_admonition",
    "html_image",
    "linkify",
    "replacements",
    "smartquotes",
    "strikethrough",
    "substitution",
    "tasklist",
]

Important

myst_enable_extensions replaces previous configuration options: admonition_enable, figure_enable, dmath_enable, amsmath_enable, deflist_enable, html_img_enable

Typography#

Adding "smartquotes" to myst_enable_extensions (in the sphinx conf.py configuration file) will automatically convert standard quotations to their opening/closing variants:

  • 'single quotes': ‘single quotes’

  • "double quotes": “double quotes”

Adding "replacements" to myst_enable_extensions (in the sphinx conf.py configuration file) will automatically convert some common typographic texts

text

converted

(c), (C)

©

(tm), (TM)

(r), (R)

®

(p), (P)

§

+-

±

...

?....

?..

!....

!..

????????

???

!!!!!

!!!

,,,

,

--

---

Strikethrough#

New in version 0.17.0.

The strikethrough extension allows text within ~~ delimiters to have a strikethrough (horizontal line) placed over it. For example, ~~strikethrough with *emphasis*~~ renders as: strikethrough with emphasis.

Warning

This extension is currently only supported for HTML output, and you will need to suppress the myst.strikethrough warning (see Suppress warnings)

Math shortcuts#

Math is parsed by adding to the myst_enable_extensions list option, in the sphinx conf.py configuration file one or both of:

These options enable their respective Markdown parser plugins, as detailed in the markdown-it plugin guide.

Important

myst_dmath_enable=True and myst_amsmath_enable=True are deprecated, and replaced by myst_enable_extensions = ["dollarmath", "amsmath"]

Dollar delimited math#

Enabling dollarmath will parse the following syntax:

  • Inline math: $...$

  • Display (block) math: $$...$$

Additionally if myst_dmath_allow_labels=True is set (the default):

  • Display (block) math with equation label: $$...$$ (1)

For example, $x_{hey}=it+is^{math}$ renders as \(x_{hey}=it+is^{math}\). This is equivalent to writing:

{math}`x_{hey}=it+is^{math}`

Escaping Dollars

Math can be escaped (negated) by adding a \ before the first symbol, e.g. \$a$ renders as $a$. Escaping can also be used inside math, e.g. $a=\$3$ renders as \(a=\$3\).

Conversely \\ will negate the escaping, so \\$a$ renders as \\(a\).

Block-level math can be specified with $$ signs that wrap the math block you’d like to parse. For example:

$$
   \begin{eqnarray}
      y    & = & ax^2 + bx + c \\
      f(x) & = & x^2 + 2xy + y^2
   \end{eqnarray}
$$

becomes

\[\begin{split} \begin{eqnarray} y & = & ax^2 + bx + c \\ f(x) & = & x^2 + 2xy + y^2 \end{eqnarray} \end{split}\]

This is equivalent to the following directive:

```{math}
   \begin{eqnarray}
      y    & = & ax^2 + bx + c \\
      f(x) & = & x^2 + 2xy + y^2
   \end{eqnarray}
```

You can also add labels to block equations:

$$
e = mc^2
$$ (eqn:best)

This is the best equation {eq}`eqn:best`
(1)#\[ e = mc^2 \]

This is the best equation (1)

There are a few other options available to control dollar math parsing:

myst_dmath_allow_space=False, will cause inline math to only be parsed if there are no initial / final spaces, e.g. $a$ but not $ a$ or $a $.

myst_dmath_allow_digits=False, will cause inline math to only be parsed if there are no initial / final digits, e.g. $a$ but not 1$a$ or $a$2.

These options can both be useful if you also wish to use $ as a unit of currency.

New in version 0.14.0: myst_dmath_double_inline option

To allow display math (i.e. $$) within an inline context, set myst_dmath_double_inline = True (False by default). This allows for example:

Hence, for $\alpha \in (0, 1)$,
$$
  \mathbb P (\alpha \bar{X} \ge \mu) \le \alpha;
$$
i.e., $[\alpha \bar{X}, \infty)$ is a lower 1-sided $1-\alpha$ confidence bound for $\mu$.

Hence, for \(\alpha \in (0, 1)\),

\[ \mathbb P (\alpha \bar{X} \ge \mu) \le \alpha; \]
i.e., \([\alpha \bar{X}, \infty)\) is a lower 1-sided \(1-\alpha\) confidence bound for \(\mu\).

Math in other block elements#

Math will also work when nested in other block elements, like lists or quotes:

- A list
- $$ a = 1 $$

> A block quote
> $$ a = 1 $$
  • A list

  • \[ a = 1 \]

A block quote

\[ a = 1 \]

Direct LaTeX Math#

Want to use amsmath LaTeX directly, with no dollars? See the extended syntax option.

Mathjax and math parsing#

When building HTML using the sphinx.ext.mathjax extension (enabled by default), If dollarmath is enabled, Myst-Parser injects the tex2jax_ignore (MathJax v2) and mathjax_ignore (MathJax v3) classes in to the top-level section of each MyST document, and adds the following default MathJax configuration:

MathJax version 2 (see the tex2jax preprocessor:

MathJax.Hub.Config({"tex2jax": {"processClass": "tex2jax_process|mathjax_process|math|output_area"}})

MathJax version 3 (see the document options):

window.MathJax = {"options": {"processHtmlClass": "tex2jax_process|mathjax_process|math|output_area"}}

This ensurea that MathJax processes only math, identified by the dollarmath and amsmath extensions, or specified in math directives.

To change this behaviour, set a custom regex, for identifying HTML classes to process, like myst_mathjax_classes="math|myclass", or set myst_update_mathjax=False to inhibit this override and process all HTML elements.

Linkify#

Adding "linkify" to myst_enable_extensions (in the sphinx conf.py configuration file) will automatically identify “bare” web URLs and add hyperlinks:

www.example.com -> www.example.com

To only match URLs that start with schema, such as http://example.com, set myst_linkify_fuzzy_links=False.

Important

This extension requires that linkify-it-py is installed. Either directly; pip install linkify-it-py or via pip install myst-parser[linkify].

Substitutions (with Jinja2)#

Adding "substitution" to myst_enable_extensions (in the sphinx conf.py configuration file) will allow you to add substitutions, added in either the conf.py using myst_substitutions:

myst_substitutions = {
  "key1": "I'm a **substitution**"
}

or at the top of the file, in the front-matter section (see this section):

---
myst:
  substitutions:
    key1: "I'm a **substitution**"
    key2: |
      ```{note}
      {{ key1 }}
      ```
    key3: |
      ```{image} img/fun-fish.png
      :alt: fishy
      :width: 200px
      ```
    key4: example
---

Important

Keys in the front-matter will override ones in the conf.py.

You can use these substitutions inline or as blocks, and you can even nest substitutions in other substitutions (but circular references are prohibited):

Inline: {{ key1 }}

Block level:

{{ key2 }}

| col1     | col2     |
| -------- | -------- |
| {{key2}} | {{key3}} |

Inline: I’m a substitution

Block level:

Note

I’m a substitution

col1

col2

Note

I’m a substitution

fishy

Important

Substitutions will only be assessed where you would normally use Markdown, e.g. not in code blocks:

```
{{ key1 }}
```
{{ key1 }}

One should also be wary of using unsuitable directives for inline substitutions. This may lead to unexpected outcomes.

Substitution references are assessed as Jinja2 expressions which can use filters, and also contains the Sphinx Environment in the context (as env). Therefore you can do things like:

- version: {{ env.config.version }}
- docname: {{ env.docname | upper }}
- {{ "a" + "b" }}
  • version: 0.17.2

  • docname: SYNTAX/OPTIONAL

  • ab

You can also change the delimiter if necessary, for example setting in the conf.py:

myst_sub_delimiters = ["|", "|"]

Will parse: || "a" + "b" ||. This should be changed with care though, so as not to affect other syntaxes.

The exact logic for handling substitutions is:

  1. Combine global substitutions (specified in conf.py) with front-matter substitutions, to create a variable context (front-matter takes priority)

  2. Add the sphinx env to the variable context

  3. Create the string content to render using Jinja2 (passing it the variable context)

  4. If the substitution is inline and not a directive, render ignoring block syntaxes (like lists or block-quotes), otherwise render with all syntax rules.

Substitutions and URLs#

Substitutions cannot be directly used in URLs, such as [a link](https://{{key4}}.com) or <https://{{key4}}.com>. However, since Jinja2 substitutions allow for Python methods to be used, you can use string formatting or replacements:

{{ '[a link](https://{}.com)'.format(key4) }}

{{ '<https://myst-parser.readthedocs.io/en/latest/REPLACE.html>'.replace('REPLACE', env.docname) }}

a link

https://myst-parser.readthedocs.io/en/latest/syntax/optional.html

Code fences using colons#

By adding "colon_fence" to myst_enable_extensions (in the sphinx conf.py configuration file), you can also use ::: delimiters to denote code fences, instead of ```.

Using colons instead of back-ticks has the benefit of allowing the content to be rendered correctly, when you are working in any standard Markdown editor. It is ideal for admonition type directives (as documented in Directives) or tables with titles, for example:

:::{note}
This text is **standard** _Markdown_
:::

:::{table} This is a **standard** _Markdown_ title
:align: center
:widths: grid

abc | mnp | xyz
--- | --- | ---
123 | 456 | 789
:::

Note

This text is standard Markdown

This is a standard Markdown title#

abc

mnp

xyz

123

456

789

Similar to normal directives, these directives can also be nested:

::::{important}
:::{note}
This text is **standard** _Markdown_
:::
::::

Important

Note

This text is standard Markdown

and also parameter options can be used:

:::{admonition} This *is* also **Markdown**
:class: warning

This text is **standard** _Markdown_
:::

This is also Markdown

This text is standard Markdown

Admonition directives#

Important

myst_admonition_enable is deprecated and replaced by myst_enable_extensions = ["colon_fence"] (see above). Also, classes should now be set with the :class: myclass option.

Also see HTML Admonitions.

Auto-generated header anchors#

The MyST Parser can automatically generate label “slugs” for header anchors so that you can reference them from markdown links. For example, you can use header bookmark links, locally; [](#header-anchor), or cross-file [](path/to/file.md#header-anchor). To achieve this, use the myst_heading_anchors = DEPTH configuration option, where DEPTH is the depth of header levels for which you wish to generate links.

For example, the following configuration in conf.py tells the myst_parser to generate labels for heading anchors for h1, h2, and h3 level headings (corresponding to #, ##, and ### in markdown).

myst_heading_anchors = 3

You can then insert markdown links directly to anchors that are generated from your header titles in your documentation. For example [](#auto-generated-header-anchors): Auto-generated header anchors.

The paths to other files should be relative to the current file, for example [**link text**](./syntax.md#core-syntax): link text.

Anchor slug structure#

The anchor “slugs” created aim to follow the GitHub implementation:

  • lower-case text

  • remove punctuation

  • replace spaces with -

  • enforce uniqueness via suffix enumeration -1

To change the slug generation function, set myst_heading_slug_func in your conf.py to a function that accepts a string and returns a string.

Definition Lists#

By adding "deflist" to myst_enable_extensions (in the sphinx conf.py configuration file), you will be able to utilise definition lists. Definition lists utilise the markdown-it-py deflist plugin, which itself is based on the Pandoc definition list specification.

This syntax can be useful, for example, as an alternative to nested bullet-lists:

  • Term 1

    • Definition

  • Term 2

    • Definition

Using instead:

Term 1
: Definition

Term 2
: Definition
Term 1

Definition

Term 2

Definition

From the Pandoc documentation:

Each term must fit on one line, which may optionally be followed by a blank line, and must be followed by one or more definitions. A definition begins with a colon or tilde, which may be indented one or two spaces.

A term may have multiple definitions, and each definition may consist of one or more block elements (paragraph, code block, list, etc.)

Here is a more complex example, demonstrating some of these features:

Term with Markdown

Definition with reference

A second paragraph

A second definition

Term 2

Definition 2a

Definition 2b

Term 3
A code block

A quote

A final definition, that can even include images:

fishy

This was created from:

Term *with Markdown*
: Definition [with reference](syntax/definition-lists)

  A second paragraph
: A second definition

Term 2
  ~ Definition 2a
  ~ Definition 2b

Term 3
:     A code block

: > A quote

: A final definition, that can even include images:

  <img src="img/fun-fish.png" alt="fishy" width="200px">

Task Lists#

By adding "tasklist" to myst_enable_extensions (in the sphinx conf.py configuration file), you will be able to utilise task lists. Task lists utilise the markdown-it-py tasklists plugin, and are applied to markdown list items starting with [ ] or [x]:

- [ ] An item that needs doing
- [x] An item that is complete
  • An item that needs doing

  • An item that is complete

Field Lists#

New in version 0.16.0.

Field lists are mappings from field names to field bodies, based on the reStructureText syntax.

:name only:
:name: body
:*Nested syntax*: Both name and body may contain **nested syntax**.
:Paragraphs: Since the field marker may be quite long, the second
   and subsequent lines of a paragraph do not have to line up
   with the first line.
:Alignment 1: If the field body starts on the first line...

              Then the entire field body must be indented the same.
:Alignment 2:
  If the field body starts on a subsequent line...

  Then the indentation is always two spaces.
:Blocks:

  As well as paragraphs, any block syntaxes may be used in a field body:

  - Me
  - Myself
  - I

  ```python
  print("Hello, world!")
  ```
name only

name

body

Nested syntax

Both name and body may contain nested syntax.

Paragraphs

Since the field marker may be quite long, the second and subsequent lines of a paragraph do not have to line up with the first line.

Alignment 1

If the field body starts on the first line…

Then the entire field body must be indented the same.

Alignment 2

If the field body starts on a subsequent line…

Then the indentation is always two spaces.

Blocks

As well as paragraphs, any block syntaxes may be used in a field body:

  • Me

  • Myself

  • I

print("Hello, world!")

A prominent use case of field lists is for use in API docstrings, as used in Sphinx’s docstring renderers:

```{py:function} send_message(sender, priority)

Send a message to a recipient

:param str sender: The person sending the message
:param priority: The priority of the message, can be a number 1-5
:type priority: int
:return: the message id
:rtype: int
:raises ValueError: if the message_body exceeds 160 characters
```
send_message(sender, priority)#

Send a message to a recipient

Parameters
  • sender (str) – The person sending the message

  • priority (int) – The priority of the message, can be a number 1-5

Returns

the message id

Return type

int

Raises

ValueError – if the message_body exceeds 160 characters

Note

Currently sphinx.ext.autodoc does not support MyST, see Use sphinx.ext.autodoc in Markdown files.

Images#

MyST provides a few different syntaxes for including images in your documentation, as explained below.

The first is the standard Markdown syntax:

![fishy](img/fun-fish.png)

fishy

This will correctly copy the image to the build folder and will render it in all output formats (HTML, TeX, etc). However, it is limited in the configuration that can be applied, for example setting a width.

As discussed above, MyST allow for directives to be used such as image and figure (see the sphinx documentation):

```{image} img/fun-fish.png
:alt: fishy
:class: bg-primary
:width: 200px
:align: center
```
fishy

Additional options can now be set, however, in contrast to the Markdown syntax, this syntax will not show the image in common Markdown viewers (for example when the files are viewed on GitHub).

The final option is directly using HTML, which is also parsed by MyST. This is usually a bad option, because the HTML is treated as raw text during the build process and so sphinx will not recognise that the image file is to be copied, and will not output the HTML into non-HTML output formats.

HTML parsing to the rescue!

By adding "html_image" to myst_enable_extensions (in the sphinx conf.py configuration file), MySt-Parser will attempt to convert any isolated img tags (i.e. not wrapped in any other HTML) to the internal representation used in sphinx.

<img src="img/fun-fish.png" alt="fishy" width="200px">
<img src="img/fun-fish.png" alt="fishy" width="200px" class="bg-primary">
fishy fishy

Allowed attributes are equivalent to the image directive: src, alt, class, width, height and name. Any other attributes will be dropped.

HTML image can also be used inline!

I’m an inline image: ../_images/fun-fish.png

Markdown Figures#

By adding "colon_fence" to myst_enable_extensions (in the sphinx conf.py configuration file), we can combine the above two extended syntaxes, to create a fully Markdown compliant version of the figure directive named figure-md.

Important

myst_figure_enable with the figure directive is deprecated and replaced by myst_enable_extensions = ["colon_fence"] and figure-md.

The figure block must contain only two components; an image, in either Markdown or HTML syntax, and a single paragraph for the caption.

The title is optional and taken as the reference target of the figure:

:::{figure-md} fig-target
:class: myclass

<img src="img/fun-fish.png" alt="fishy" class="bg-primary mb-1" width="200px">

This is a caption in **Markdown**
:::
fishy

This is a caption in Markdown#

As we see here, the target we set can be referenced:

[Go to the fish!](fig-target)

Go to the fish!

HTML Admonitions#

By adding "html_admonition" to myst_enable_extensions (in the sphinx conf.py configuration file), you can enable parsing of <div class="admonition"> HTML blocks. These blocks will be converted internally to Sphinx admonition directives, and so will work correctly for all output formats. This is helpful when you care about viewing the “source” Markdown, such as in Jupyter Notebooks.

If the first element within the div is <div class="title"> or <p class="title">, then this will be set as the admonition title. All internal text (and the title) will be parsed as MyST-Markdown and all classes and an optional name will be passed to the admonition:

<div class="admonition note" name="html-admonition" style="background: lightgreen; padding: 10px">
<p class="title">This is the **title**</p>
This is the *content*
</div>

This is the title

This is the content

During the Sphinx render, both the class and name attributes will be used by Sphinx, but any other attributes like style will be discarded.

Warning

There can be no empty lines in the block, otherwise they will be read as two separate blocks. If you want to use multiple paragraphs then they can be enclosed in <p>:

<div class="admonition note">
<p>Paragraph 1</p>
<p>Paragraph 2</p>
</div>

Note

Paragraph 1

Paragraph 2

You can also nest HTML admonitions:

<div class="admonition">
<p>Some **content**</p>
  <div class="admonition tip">
  <div class="title">A *title*</div>
  <p>Paragraph 1</p>
  <p>Paragraph 2</p>
  </div>
</div>

Note

Some content

A title

Paragraph 1

Paragraph 2

Direct LaTeX Math#

By adding "amsmath" to myst_enable_extensions (in the sphinx conf.py configuration file), you can enable direct parsing of amsmath LaTeX equations. These top-level math environments will then be directly parsed:

equation, multline, gather, align, alignat, flalign, matrix, pmatrix, bmatrix, Bmatrix, vmatrix, Vmatrix, eqnarray.

As expected, environments ending in * will not be numbered, for example:

\begin{gather*}
a_1=b_1+c_1\\
a_2=b_2+c_2-d_2+e_2
\end{gather*}

\begin{align}
a_{11}& =b_{11}&
  a_{12}& =b_{12}\\
a_{21}& =b_{21}&
  a_{22}& =b_{22}+c_{22}
\end{align}
\[\begin{gather*} a_1=b_1+c_1\\ a_2=b_2+c_2-d_2+e_2 \end{gather*}\]
(2)#\[\begin{align} a_{11}& =b_{11}& a_{12}& =b_{12}\\ a_{21}& =b_{21}& a_{22}& =b_{22}+c_{22} \end{align}\]

Note

\labels inside the environment are not currently identified, and so cannot be referenced. We hope to implement this in a future update (see executablebooks/MyST-Parser#202)!

This syntax will also work when nested in other block elements, like lists or quotes:

- A list
- \begin{gather*}
  a_1=b_1+c_1\\a_2=b_2+c_2-d_2+e_2
  \end{gather*}

> A block quote
> \begin{gather*}
  a_1=b_1+c_1\\a_2=b_2+c_2-d_2+e_2
  \end{gather*}
  • A list

  • \[\begin{gather*} a_1=b_1+c_1\\a_2=b_2+c_2-d_2+e_2 \end{gather*}\]

A block quote

\[\begin{gather*} a_1=b_1+c_1\\a_2=b_2+c_2-d_2+e_2 \end{gather*}\]