mi-flatland 3.0.2

Model text file + layout text file -> beautiful diagram

Flatland Model Diagram

June 29, 2026 -- 3.0 Released with SVG and PDF Diagram Output

Flatland generates beautiful, readable model diagrams from plain text — laid out exactly the way you want, without pushing a single pixel.

You write two text files for each diagram:

• a model file that captures only the semantics — classes, states, transitions, generalizations, and so on, and
• a layout file that describes how to arrange those elements on the page.

Flatland combines them to produce SVG or PDF. Want to change the layout? Edit the layout file. Want to change the model? Edit the model, and adjust the layout only if you need to. Because the two are separate, a version-control diff tells you immediately whether a change touched the model itself or merely its presentation.

Layout is specified with a single, simple row-and-column markup — a kind of spreadsheet for your diagram — that works across every model type. No pixel coordinates, no fragile alignment or stacking rules. You get precise control with a minimum of specification.

I built Flatland after years of frustration with the two usual options: wrestling the wonky GUI of a monolithic modeling tool (good luck maintaining and version-controlling a large model set), or accepting the minimal layout control of text-based tools like PlantUML. Flatland gives you the text-first workflow and the layout you actually want.

Benefits

• Model and layout stay fully separate. Edit one without disturbing the other, and diff your models with the layout excluded to see whether the meaning changed or just the picture.
• Precise layout, minimal specification. A spreadsheet-style row/column markup places nodes, connectors, and text exactly where you want them — no pixel pushing, no carpal tunnel.
• One layout language for every model type. If your model can be expressed as nodes and labeled connectors — most can — the same markup applies.
• Built for industrial-scale models. Stays consistent and readable across hundreds or thousands of model elements.
• Text-first and toolchain-friendly. Use your favorite editor and IDE, and put your models under proper configuration management — diff, branch, and merge like any other source.
• AI-ready. Feed a model alone for lean, low-token prompting and code generation, or hand the AI an SVG to refine the layout by updating the markup. (UML / SysML v2 standards support is easily added.)
• Beautiful output in multiple formats. SVG and PDF today, with more to come.

Installation

Flatland is a command-line program published on PyPI as mi-flatland. You install it once into an isolated Python virtual environment and then run it with the flatland command. The steps below assume no prior Python experience — if you're already comfortable with Python, just run the commands in the code blocks and skip the explanations.

What you'll need

• Python 3.11 or 3.12. (Python 3.13 and newer are not yet supported.)
• macOS, Linux, or Windows.

1. Install Python

If you don't already have a supported version, download Python 3.12 from python.org and run the installer for your platform. Any install method is fine (the official installer, Homebrew, etc.) as long as the version is 3.11 or 3.12. Having other Python versions already on your machine is not a problem.

Confirm it's available:

python3 --version

You should see something like Python 3.12.7. (On Windows the command is usually py --version.)

2. Create a virtual environment

A virtual environment is just a folder that holds a private copy of Python and the packages flatland needs, kept separate from the rest of your system so nothing conflicts. Python has this built in — no extra tools required. Create one (here named flatland-env, but you can call it anything):

macOS / Linux

python3 -m venv ~/flatland-env

Windows (PowerShell)

py -m venv $HOME\flatland-env

3. Activate the environment

Activating tells your terminal to use the environment you just created.

macOS / Linux

source ~/flatland-env/bin/activate

Windows (PowerShell)

& $HOME\flatland-env\Scripts\Activate.ps1

Your prompt now starts with (flatland-env), which means it's active. You'll need to run this activate command again each time you open a new terminal before using flatland.

4. Install flatland

pip install --upgrade pip
pip install mi-flatland

5. Check the version

flatland -V

This prints something like Flatland version: 3.0.0, confirming the install worked.

6. Generate your first diagram

Flatland ships with example models. Copy them into your current folder:

flatland -E

This creates an examples/ directory. Move into the elevator example and generate a class diagram:

cd examples/elevator
flatland -m elevator.xcm -l elevator_xUML.mls -d elevator.pdf

That command supplies three things:

• -m elevator.xcm — the model file (.xcm = class model, .xsm = state-machine model)
• -l elevator_xUML.mls — the layout file (.mls), which positions everything
• -d elevator.pdf — the output file to generate

The extension you give to -d selects the output format. Use .pdf for PDF or .svg for SVG — so the same model and layout produce an SVG just by changing the name:

flatland -m elevator.xcm -l elevator_xUML.mls -d elevator.svg

A layout file refers to specific model content, so each .mls only works with its matching model. A single model can have several layouts (e.g. elevator_xUML.mls and elevator_Starr.mls here), grouped together so you can tell which files belong with which.

Run flatland -h to see every option (grid overlay, rulers, no-color, and more).

Where your settings live

The first time you run flatland it creates two folders of YAML configuration files under your home directory at ~/.config:

• flatland — layout, title-block, and positional parameters.
• mi_tablet — graphics and text styles, plus any logos or other media.

You can browse and edit these (each file has explanatory comments), but edit carefully. If anything breaks, just delete the folder and flatland will recreate the defaults on its next run.

Coming back later

Whenever you open a new terminal, re-activate the environment (step 3) before running flatland. Prefer not to activate every time? Installing with pipx (pipx install mi-flatland) puts the flatland command on your PATH globally while keeping it isolated.