Source   Edit  

A chess library that provides fast move generation, position manipulation, and support for common chess formats like FEN and PGN. The library uses bitboards for efficient board representation and move generation.

GitHub

Overview

The library is organized into several core modules:

Core Types and Board Representation

• types: Fundamental chess types (Square, Color, Piece)
• bitboard: Efficient bitboard operations for fast computation
• position: Chess position representation and manipulation

Move Generation and Validation

• move: Move representation and basic operations
• movegen: Fast legal move generation

Game Management and Formats

• game: Complete chess game representation
• pgn: PGN (Portable Game Notation) reading and writing
• strchess: String parsing utilities (FEN, SAN, UCI)

Quick Start

Creating and working with positions:

Example:

import src/nimchess
# Create starting position from FEN
let pos = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1".toPosition

# Display the position
echo pos # Shows board with Unicode pieces

# Generate all legal moves
for move in pos.legalMoves:
  echo move.toSAN(pos) # Show move in algebraic notation

# Make a move
let newPos = pos.doMove("e4".toMove(pos))
echo newPos.fen() # Get FEN string of new position

Working with games and PGN:

Example:

import src/nimchess
let games = readPgnFile("tests/testdata/pgns.pgn")
for game in games:
  echo game.headers.getOrDefault("Event", "?")
  echo "Result: ", game.result

Working with bitboards:

Example:

import src/nimchess
let
  position =
    "1rbn1rk1/p2p2q1/1p2p1pp/2b5/2P1NP2/P3P3/1P2BNP1/1KQR3R b - - 4 21".toPosition
  bishopAttack = position.attacksFrom(bishop, c5)
  attackedPawns = position[white, pawn] and bishopAttack

echo attackedPawns

for attackedPawnSquare in attackedPawns:
  echo attackedPawnSquare