poirebot

A chess engine and bot written in Rust.

Playing against poirebot

The bot is occasionally up on Lichess.org with the account @poirebot.

Until the bot is live 24/7, you may want to run it locally to try it out. You should create a new Lichess.org that will
then become a BOT account.

1. Create a new Lichess.org account for the bot
2. Generate a new Personal Access Token (PAT) by going to https://lichess.org/account/oauth/token/create
3. Give it a description, and select all options except: Read Preferences, Write preferences, Read email address
4. Store the token in the LICHESS_TOKEN environment variable (or you can also use the --token flag later)
5. You can now install and run the bot

Download latest release (does not require Rust): https://github.com/aramperes/poirebot/releases/latest

Or to build and install latest release using Cargo (Rust 1.50+):

rustup update stable
cargo install poirebot-lichess

Or to build bleeding edge (master branch) instead (Rust 1.50+):

rustup update stable
git clone https://github.com/aramperes/poirebot.git
cd poirebot
cargo build --release
# (The poirebot-lichess binary will be in ./target/release)

Running

The poirebot-lichess upgrade-account command is only required for the first run (it converts the Lichess account into
a BOT account).

poirebot-lichess upgrade-account
poirebot-lichess start

Use poirebot-lichess start --help for a list of flags that can be used when running the bot.

Architecture

poirebot keeps track of board state in a collection of 64-bit Bitboards.
Specifically, the board state is stored in a collection of Bitboards for each side (color):

• pawns
• knights
• bishops
• queens
• king
• unmoved rooks
• en passant target square

It also stores whether the king has moved (bool).

In addition, after the mutation of a side (color) is “committed”, it generates “inherited” bitboards for move-generation
purposes:

• pieces (the union of pawns, knights, bishops, queens, and king)
• attacks (squares threatened by any piece of that color)

Move Generation

poirebot does not have a functioning brain right now. The current goal is to be able to generate all potential moves,
and later use some flavor of the MiniMax algorithm.

Dependencies

poirebot depends on Rust stable 1.50+, or nightly, as it uses the <number>::clamp function.

• anyhow: for error handling
• tokio, tokio-stream: async runtime
• rayon: parallelism library for expensive board operations on the CPU
• licorice: Lichess.org API client (forked)
• clap: CLI parsing
• rand: PRNG

Inspiration

This bot was made for a friendly competition with Jeff. As a fairness rule,
neither bot uses a chess library to manage board state and implement movement rules.

License

MIT, see LICENSE.