Diago

Diago is a diagram toolkit for MoonBit. It supports a D2-compatible text format and renders diagrams through multiple layout engines.

Overview

This repository contains:

• A CLI (cmd/diago) with explicit subcommands (render, fmt, validate, layout, themes, version)
• A WASM-based playground (web/) deployed via GitHub Pages
• Multiple layout engines: dagre, elk, and railway

Installation

moon update
moon build

Quick Start

moon run cmd/diago -- render diagram.txt

CLI

Show help:

moon run cmd/diago -- --help

Common usage:

# Render SVG (default output: input.svg)
moon run cmd/diago -- render diagram.txt
moon run cmd/diago -- render diagram.txt diagram.svg
moon run cmd/diago -- render diagram.txt --output diagram.svg

# Choose layout engine
moon run cmd/diago -- render --layout elk diagram.txt diagram.svg
moon run cmd/diago -- render -l dagre diagram.txt diagram.svg

# ASCII / Unicode text
moon run cmd/diago -- render --format ascii diagram.txt --output diagram.ascii.txt
moon run cmd/diago -- render --format unicode diagram.txt --output diagram.unicode.txt

# Format / validate
moon run cmd/diago -- fmt diagram.txt
moon run cmd/diago -- fmt --check diagram.txt
moon run cmd/diago -- validate diagram.txt

# Watch mode (rebuilds output on file changes)
moon run cmd/diago -- render --watch diagram.txt

# Introspection
moon run cmd/diago -- layout
moon run cmd/diago -- layout elk
moon run cmd/diago -- themes
moon run cmd/diago -- version

Example

Create a file example.txt:

server: Web Server
database: Database {
  shape: cylinder
}
cache: Cache {
  shape: oval
}

server -> database: queries
server -> cache: reads
cache -> database: fallback

Compile it:

moon run cmd/diago -- render example.txt example.svg

Pipeline

At a high level:

Source → Lexer → Parser → AST → IR → Graph → Layout (dagre/elk/railway) → Render (SVG/ASCII/Unicode)

Tests

moon test        # Run all tests
moon test -v     # Verbose output

License

Apache-2.0 (see LICENSE).