Universe

This package enables you to write CommonMark Markdown, and import it directly into Typst.

simple.typ simple.md 
#import "@preview/cmarker:0.1.6"

#cmarker.render(read("simple.md"))

# We can write Markdown!

*Using* __lots__ ~of~ `fancy` [features](https://example.org/).
simple.pdf

This document is available in Markdown and rendered PDF formats.

API

We offer a single function:

render(
  markdown,
  smart-punctuation: true,
  math: none,
  h1-level: 1,
  raw-typst: true,
  html: (:),
  label-prefix: "",
  prefix-label-uses: true,
  scope: (:),
  show-source: false,
  blockquote: none,
) -> content

The parameters are as follows:

  • markdown: The CommonMark Markdown string to be processed. Parsed with the pulldown-cmark Rust library. You can set this to read("somefile.md") to import an external markdown file; see the documentation for the read function.

    • Accepted values: Strings and raw text code blocks.
    • Required.

  • smart-punctuation: Automatically convert ASCII punctuation to Unicode equivalents:

    • nondirectional quotations (" and ') become directional (“” and ‘’);
    • three consecutive full stops (…) become ellipses (…);
    • two and three consecutive hypen-minus signs (-- and —) become en and em dashes (– and —).

    Note that although Typst also offers this functionality, this conversion is done through the Markdown parser rather than Typst.

    • Accepted values: Booleans.
    • Default value: true.

  • math: A callback to be used when equations are encountered in the Markdown, or none if it should be treated as normal text. Because Typst does not support LaTeX equations natively, the user must configure this.

    • Accepted values: Functions that take a boolean argument named block and a positional string argument (often, the mitex function from the mitex package), or none.
    • Default value: none.

    For example, to render math equation as a Typst math block, one can use:

    #import "@preview/mitex:0.2.4": mitex
#cmarker.render(`$\int_1^2 x \mathrm{d} x$`, math: mitex)

  • h1-level: The level that top-level headings in Markdown should get in Typst. When set to zero, top-level headings are treated as text, ## headings become = headings, ### headings become == headings, et cetera; when set to 2, # headings become == headings, ## headings become === headings, et cetera.

    • Accepted values: Integers in the range [0, 255].
    • Default value: 1.

  • raw-typst: Whether to allow raw Typst code to be injected into the document via HTML comments. If disabled, the comments will act as regular HTML comments.

    • Accepted values: Booleans.
    • Default value: true.

    For example, when this is enabled, <!--raw-typst #circle(radius: 10pt) --> will result in a circle in the document (but only when rendered through Typst). See also <!--typst-begin-exclude--> and <!--typst-end-exclude-->, which is the inverse of this.

  • html: The dictionary of HTML elements that cmarker will support.

    • Accepted values: Dictionaries whose keys are the tag name (without the surrounding <>) and whose values can be:
      • ("normal", (attrs, body) => [/* … */]): Defines a normal element, where attrs is a dictionary of strings, body is content, and the function returns content.
      • ("void", (attrs) => [/* … */]): Defines a void element (e.g. <br>, <img>, <hr>).
      • ("raw-text", (attrs, body) => [/* … */]): Defines a raw text element (e.g. <script>, <style>), where body is a string.
      • ("escapable-raw-text", (attrs, body) => [/* … */]): Defines an escapable raw text element (e.g. <textarea>), where body is a string.
      • (attrs, body) => [/* … */]: Shorthand for ("normal", (attrs, body) => [/* … */]).
    • Default value: (:).
    • Overridable keys: The following HTML elements are provided by default, but you are free to override them: <sub>, <sup>, <mark>, <h1>–<h6>, <ul>, <ol>, <li>, <dl>, <dt>, <dd>, <table>, <thead>, <tfoot>, <tr>, <th>, <td>, <hr>, <a>, <em>, <strong>, <s>, <code>, <br>, <blockquote>, <figure>, <figcaption>, <img>.

    For example, the following code would allow you to write <circle radius="25"> to render a 25pt circle:

    #cmarker.render(read("input.md"), html: (
  circle: ("void", attrs => circle(radius: int(attrs.radius) * 1pt))
))

  • label-prefix: If present, any labels autogenerated by footnotes and headings will be prefixed by this string. This is useful to avoid collisions.

    • Accepted values: A valid label or the empty string.
    • Default value: The empty string.

  • prefix-label-uses: Whether references to labels such as [@label] and [link](#label) should be prefixed by label-prefix.

    • Accepted values: Booleans.
    • Default value: true.

  • scope: A dictionary providing the context in which the evaluated Typst code runs. It is useful to pass values in to code inside <!--raw-typst--> blocks, but can also be used to override element functions generated by cmarker itself.

    • Accepted values: Any dictionary.
    • Default value: (:).
    • Overridable keys:
      • All built-in Typst functions.
      • rule: Expected to be a function returning content. Will be used when thematic breaks (--- in Markdown) are encountered. Defaults to line.with(length: 100%).

  • show-source: A debugging tool. When set to true, the Typst code that would otherwise have been displayed will be instead rendered in a code block.

    • Accepted values: Booleans.
    • Default value: false.

  • blockquote: Deprecated! This used to control how blockquotes were rendered, but we now default to quote(block: true). If you want to override how blockquotes look, either use #show quote.where(block: true) or use scope: (quote: …).

    • Accepted values: Functions accepting content and returning content, or none.
    • Default value: none.

This function returns the rendered content.

Resolving Paths Correctly

Because of how Typst handles paths, elements like images will by default resolve relative to the project root of cmarker itself and not your project.

To fix this, one can override the image function in the scope the Typst code is evaluated.

#import "@preview/cmarker:0.1.6"

#cmarker.render(
  read("yourfile.md"),
  scope: (image: (path, alt: none) => image(path, alt: alt))
)

References, Labels, Figures and Citations

cmarker.typ integrates well with Typst’s native references and labels. Where in Typst you would write @foo, in Markdown you write [@foo]; where in Typst you would write @foo[Chapter], in Markdown you’d write [Chapter][@foo]. You can also write [some text](#foo) to have “some text” be a link that points at foo. Headings are automatically given references according to their name, but lowercased and with spaces replaced by hyphens:

# My nice heading

We can make a link to [this section](#my-nice-heading).
We can refer you to [@my-nice-heading]. <!-- generates “We can refer you to Section 1.” -->
Or to [Chapter][@my-nice-heading]. <!-- generates “We can refer you to Chapter 1.” -->

If you have two headings with the same title, they’ll be numbered sequentially in the fashion of GitHub Markdown: heading, heading-1, heading-2, etc.

If you want to cite something from a bibliography, you can do it much the same way: [@citation].

If you want to customize the label of a heading from the default, you can use id= in HTML:

<h1 id="my-nice-section">My nice heading</h1>

See [@my-nice-section]. <!-- generates “See Section 1.” -->

This can also be used with figures, which is very powerful:

Please refer to [@my-graph]. <!-- generates “Please refer to Figure 1.” -->

<figure id="my-graph">

![a graph](graph.png)</figure>

If you encounter collision errors across multiple Markdown files, you can set the label-prefix option. For example, setting label-prefix: "file-a-" will convert the label of # My Heading into file-a-my-heading. By default, references within the file will expect the unprefixed name; this can be changed by setting prefix-label-uses: false.

Supported Markdown Syntax

We support CommonMark with a couple extensions.

  • Paragraph breaks: Two newlines, i.e. one blank line.

  • Hard line breaks (used more in poetry than prose): Put two spaces at the end of the line.

  • *emphasis* or _emphasis_: emphasis

  • **strong** or __strong__: strong

  • ~strikethrough~: ~strikethrough~

  • [links](https://example.org): links

  • ### Headings, where # is a top-level heading, ## a subheading, ### a sub-subheading, etc

  • `inline code blocks`: inline code blocks

  • ```
out of line code blocks
```

    Syntax highlighting can be achieved by specifying a language after the opening backticks:

    ```rust
let x = 5;
```

    giving:

    let x = 5;

  • ---, making a horizontal rule. This corresponds to the Typst code #rule(), which, if not overridden by the scope parameter, defaults to #line(length: 100%):

  • - Unordered
- lists
    • Unordered
    • Lists
  • 1. Ordered
1. Lists
    1. Ordered
    2. Lists

  • $x + y$ or $$x + y$$: math equations, if the math parameter is set.

  • > blockquotes, if the blockquote parameter is set.

  • Images: ![Some tiled hexagons](examples/hexagons.png), giving Some tiled hexagons

  • Tables:

    | Column 1 | Column 2 |
| -------- | -------- |
| Row 1 Cell 1 | Row 1 Cell 2 |
| Row 2 Cell 1 | Row 2 Cell 2 |
Column 1 Column 2
Row 1 Cell 1 Row 1 Cell 2
Row 2 Cell 1 Row 2 Cell 2
  • Footnotes:
    Some text[^footnote]
[^footnote]: content
  • HTML, e.g. <sub>subscript</sub> for subscript.

Interleaving Markdown and Typst

Sometimes, you might want to render a certain section of the document only when viewed as Markdown, or only when viewed through Typst. To achieve the former, you can simply wrap the section in <!--typst-begin-exclude--> and <!--typst-end-exclude-->:

<!--typst-begin-exclude-->
Hello from not Typst!
<!--typst-end-exclude-->

Most Markdown parsers support HTML comments, so from their perspective this is no different to just writing out the Markdown directly; but cmarker.typ knows to search for those comments and avoid rendering the content in between.

Note that when the opening comment is followed by the end of an element, cmarker.typ will close the block for you. For example:

> <!--typst-begin-exclude-->
> One

Two

In this code, “Two” will be given no matter where the document is rendered. This is done to prevent us from generating invalid Typst code.

Conversely, one can put Typst code inside a HTML comment of the form <!--raw-typst […]--> to have it evaluated directly as Typst code (but only if the raw-typst option to render is set to true, otherwise it will just be seen as a regular comment and removed):

<!--raw-typst Hello from #text(fill:blue)[Typst]!-->

Limitations

Although I tried my best to escape everything correctly, I won’t provide a hard guarantee that everything is fully sandboxed even if you set raw-typst: false. That said, Typst itself is well-sandboxed anyway.

FAQ

Typst is saying it can’t find my image – it’s looking inside cmarker for some reason!

See Resolving Paths Correctly.

How do I include multiple Markdown files in one project?

See the multi-file example.

Note that this example uses a single call to render with concatenated Markdown, i.e. cmarker.render(read("file-a.md") + read("file-b.md")). If you instead wish to use cmarker.render(read("file-a.md")) followed by cmarker.render(read("file-b.md")), you may encounter collision issues if two headings have the same name. This can be resolved in two ways:

  • Giving the headings an explicit ID: <h1 id="my-id">My Heading</h1> instead of # My Heading.
  • Setting a label prefix, e.g. label-prefix: "my-file-".

My image file contains spaces, but it gets rendered as text!

This is a Markdown quirk – ![alt](image path.png) is seen as plain text instead of an image. To fix it, use ![alt](<image path.png>).

My Markdown after an open HTML tag is getting rendered as text!

Another Markdown quirk – in code like <p>hello _world_</p> or <!-- -->hello _world_, italics will not be generated.

There are two fixes: either insert some empty inline-level HTML at the start, e.g. <span></span><p>hello _world_</p>, or insert two newlines after the opening tag:

<p>

hello _world_</p>

How do I centre tables? How do I have them span the page width?

This can be achieved via show rules. For example, centring:

#show table: t => align(center, t)
#cmarker.render("
  | a | b |
  | - | - |
  | c | d |
")

And having them span the page width:

#show table: t => {
  if t.columns.all(c => c == auto) {
    table(columns: (1fr,) * t.columns.len(), align: t.align, ..t.children)
  } else {
    t
  }
}

Development

  • Build the plugin with ./build.sh, which produces the plugin.wasm necessary to use this.
  • Compile examples with typst compile examples/{name}.typ.
  • Compile this README to PDF with typst compile README.typ.
  • Run tests with cargo test --workspace and cargo run -p test-runner.
  • Fuzz the library with cargo +nightly fuzz run fuzz.