MermaidSlate.jl 🧜

Mermaid diagrams for Kaimon Slate notebooks. Text in, diagram out — which makes a diagram something you compute, rather than a .png you maintain alongside the code it describes.

Install

MermaidSlate is in SlateRegistry, so it lists in Slate's Extensions gallery and installs from the package panel. From the REPL:

pkg> registry add https://github.com/kahliburke/SlateRegistry
pkg> add MermaidSlate

Or straight from this repo, no registry needed:

pkg> add https://github.com/kahliburke/MermaidSlate.jl

Use

Fenced blocks in a markdown cell render in place:

```mermaid
flowchart LR
    parse --> analyse --> run
```

The same diagram is also an ordinary value, so any cell can return one — and any function can build one:

using MermaidSlate

mermaid("flowchart LR; A --> B")

# a diagram that follows the data
stages = ["parse", "analyse", "run"]
mermaid("flowchart LR\n" * join(stages, " --> "))

Mermaid infers the diagram type from the first keyword, so one function covers flowcharts, sequence and state diagrams, class and ER diagrams, Gantt charts and the rest.

Themes

mermaid(src; theme = "forest")   # per diagram
set_theme!("neutral")            # notebook-wide default
themes()                         # ("auto", "dark", "default", "base", "forest", "neutral")

"auto" is the default and follows the notebook's light/dark setting, re-drawing when you switch.

Notes

Nothing is vendored here. The Mermaid runtime is declared once as an import-map entry, so it's shared by every notebook that loads the package — and an offline export inlines it, giving a self-contained HTML file with no remote fetches. Override the build with a notebook-level @use "mermaid" => ….

MermaidDiagram deliberately has no Base.show(::MIME"text/html") method: outside Slate it stays a plain value, so the same code reads normally in the REPL, IJulia and VS Code.

Built against the lean SlateExtensionsBase SDK — no KaimonSlate dependency. Requires KaimonSlate ≥ 1.2.1 to install into an already-open notebook without a reload.

Demo notebook: notebooks/mermaid.jl.