Mull 📖

Mull is a tool for managing a wiki stored in a plain text file. It has a Visual Studio Code / Cursor extension which provides syntax highlighting, hover previews, completions, diagnostics, formatting, refactoring, etc.

Since Mull runs in Visual Studio Code or Cursor, you can use it with your favorite settings and extensions. The screenshot above features the Berkeley Mono typeface with the Monokai Pro (Filter Spectrum) color theme.

A quick tour

Pages and links

A wiki is a text file with a .mull extension. It contains pages which link to each other, all in the same file. Here's a little wiki with 3 pages:

# Home

Try my [Pancakes] with fresh [Lemons].

# Lemons

Great on [Pancakes].

# Pancakes

- 1 cup of flour
- 1 cup of milk
- 1 egg
- A squeeze of [Lemons]

Each page starts with a # Title, followed by the contents of the page. To link to a page, use square brackets like [Lemons]. When you type the opening [, autocomplete kicks in to help you find the page you're looking for.

Mull formats the wiki when you save the file, or when you explicitly request it. It chooses the ordering of the pages in the file based on the links between them, so you don't have to think about it. Linking to pages is the only way to organize them.

Every wiki starts with a Home page. Mull requires that every other page is reachable (directly or indirectly) by following links, starting from Home. This rule promotes a basic form of organization that doesn't involve any hierarchical structure. In computer jargon, pages serve the roles traditionally filled by both files and directories.

Linking to files and directories

If you've got receipts, spreadsheets, or any other kinds of external files you want to track, you can link to them from the wiki. Such files go in a directory next to the wiki which has the name of the wiki, with the .mull extension replaced with _files. For example, if the wiki is my_wiki.mull, the files go in my_wiki_files.

You can link to a file called my_wiki_files/photos/beach.jpg with [/photos/beach.jpg]. You can also link to subdirectories like [/photos/]. Mull will check that those things actually exist, and you can preview them without leaving the editor.

Autocomplete will help you enter the names of files and directories. You can also drag-and-drop (while holding the Shift key) or paste files directly into the editor, and they'll get copied into <wiki>_files and linked to automatically.

Just as every page must be reachable from Home, every file in <wiki>_files (if it exists) must be linked to from the wiki. A link to a directory implicitly counts as linking to everything inside it.

Embedding a page inside another

If you want to keep multiple copies of some content in sync, you can embed a page inside other pages. For example, you can embed a page called Pancakes as follows:

::: embed [Pancakes]
This sentence will be replaced by the pancake recipe.
:::

When the wiki is formatted, the source page will automatically be replicated to all the embedded copies. The replication is unidirectional; any edits to the copies will be discarded.

Orthography

To use a special symbol like [ or ] literally, put a backslash before it, like \[. You can also use backticks to denote verbatim text like `this`, as in Markdown. Fenced code blocks are supported too, with syntax highlighting for common languages. No escaping is necessary inside page titles or code.

Keyboard shortcuts

These common keyboard shortcuts are helpful when navigating and editing a wiki:

Most of these keyboard shortcuts are built into Visual Studio Code and Cursor, so they may be familiar to you already. You can remap them.

Usage

Once Mull is installed for Visual Studio Code or Cursor, you can run it by opening a .mull file in the editor.

You can also run Mull from the command line (e.g., in a CI job) as follows:

mull check --path wiki.mull

Here are the supported command-line options:

Usage: mull [COMMAND]

Commands:
  check            Check a wiki
  format           Format a wiki (default)
  language-server  Start the language server (editors use this)
  help             Print this message or the help of the given subcommand(s)

Options:
  -v, --version  Print version
  -h, --help     Print help

Installation instructions

To use Mull, you must install the binary and optionally the Visual Studio Code / Cursor extension. The binary does all the work and can be used by itself from the command line. The IDE extensions use the binary to provide a rich wiki editing experience.

Installation on macOS or Linux (AArch64 or x86-64)

If you're running macOS or Linux (AArch64 or x86-64), you can install Mull with this command:

curl https://raw.githubusercontent.com/stepchowfun/mull/main/install.sh -LSfs | sh

The same command can be used again to update to the latest version.

If Visual Studio Code or Cursor is installed, that command also installs the Mull extension in each editor it finds.

The installation script supports the following optional environment variables:

• VERSION=x.y.z (defaults to the latest version)
• PREFIX=/path/to/install (defaults to /usr/local/bin)

For example, the following will install the binary into the working directory:

curl https://raw.githubusercontent.com/stepchowfun/mull/main/install.sh -LSfs | PREFIX=. sh

Note that if you change the installation path, you may also need to change the mull.executablePath accordingly in Visual Studio Code or Cursor.

If you prefer not to use this installation method, you can download the binary from the latest release, make it executable (e.g., with chmod), and place it in some directory in your PATH (e.g., /usr/local/bin). You can then follow the instructions below to install the Visual Studio Code / Cursor extension.

Installing the binary on Windows (AArch64 or x86-64)

If you're running Windows (AArch64 or x86-64), download the binary from the latest release and rename it to mull (or mull.exe if you have file extensions visible). Create a directory called Mull in your %PROGRAMFILES% directory (e.g., C:\Program Files\Mull), and place the renamed binary in there. Then, in the "Advanced" tab of the "System Properties" section of Control Panel, click on "Environment Variables..." and add the full path to the new Mull directory to the PATH variable under "System variables". Note that the Program Files directory might have a different name if Windows is configured for a language other than English.

To update an existing installation, simply replace the existing binary.

Installing the binary with Cargo

If you have Cargo, you can install Mull as follows:

cargo install mull

You can run that command with --force to update an existing installation.

Installing the Visual Studio Code / Cursor extension

First, make sure you have Visual Studio Code or Cursor installed.

To install the Mull extension, download the mull.vsix file from the latest release and install it via the "Install from VSIX..." option in the ... menu at the top of the Extensions view of the Primary Side Bar.

Note that the macOS / Linux installation command will install the extension automatically, so you can skip this section if you use that installation method.

To update an existing installation, simply re-install it.