rulebound

A lightweight, no_std constraint propagation solver for real-time game logic and procedural verification.

Live Demo (WASM + GitHub Pages): https://robdavenport.github.io/rulebound/

WASM Demo Site

• Demo app source: demo-wasm/
• GitHub Pages deploy workflow: .github/workflows/deploy-pages.yml (runs on push to main)
• If you are publishing from a fork, use https://<your-github-username>.github.io/rulebound/

Features

• Game-time constraint solving: Incremental AC-3 propagation for per-frame use
• Built-in constraints: AllDifferent, NotEqual, LessThan, ExactlyN, Table, Implication
• Configurable search: Propagation + optional backtracking with multiple strategies
• Observable: Monitor solving progress via the Observer trait
• no_std compatible: Works in embedded and WASM environments
• Deterministic: Same seed produces same results

Quick Start

use rulebound::*;

let config = SolverConfig::new();
let mut solver = Solver::<2>::new(9, 9, config);

// Add constraints
solver.add_constraint(AllDifferent::new(&[0, 1, 2]));

// Fix known values
solver.assign(0, 5).unwrap();

// Solve
let result = solver.solve(&mut rng).unwrap();

Use Cases

• Verify WFC/procedural generation output is solvable
• Place items/enemies with spatial rules
• NPC scheduling (Stardew Valley-style daily routines)
• Puzzle generation + verification (Sudoku, lock-and-key)
• Crafting/economy balance validation

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.