Squire is an incomplete chess engine written in Scala.
Since my intent was to familiarize myself with the search techniques in board games, the engine uses as few chess-specific optimizations as possible. In particular, the move generation is a vanilla implementation that does not use bitboards or other efficient representations.
Squire consists of two parts: chess implementation and search logic.
An interface called State allows the search logic to deal with any kind of game as long as a proper subclass of
State implementing that game is defined.
The chess implementation is slow, because optimizing a chess engine was not the purpose of the project. At least it's tested to some extent using perft.
The search algorithm is minimax (negamax) with alpha-beta pruning and moves ordering to increase the number of cut-offs. The engine uses iterative deepening. The evaluation function comes from a post by Tomasz Michniewski.
Build Squire with sbt assembly.
Squire can interface with XBoard.
The class squire.chess.connectors.xboard.Main is a client to will print instructions to the standard input and read from
the standard output.
In XBoard, Squire can be loaded with a command line like
scala -classpath /path/to/squire/squire/jar/squire-assembly-0.1-SNAPSHOT.jar squire.chess.connectors.xboard.Main
For chess:
- Test search logic
- Learn evaluation function
- Implement quiescence search
- Implement tests for all draw rules
Outside of chess:
- Implement other games that require MCTS instead of exhaustive search
- Learn evaluation functions using RL