Upgrade to Python 3.12+ and optimize hot-path performance

.github/workflows/benchmark.yml

@@ -87,7 +87,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.10'
+        python-version: '3.12'
 
     - name: Install dependencies
       run: make install

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ['3.12', '3.13']
     env:
       UV_SYSTEM_PYTHON: 1
 
@@ -31,25 +31,21 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.10'
+        python-version: ${{ matrix.python-version }}
 
     - name: Install dev requirements
-      run: |
-        make install
+      run: uv pip install -e .
 
     - name: Test moonfish import
-      shell: bash -l {0}
       run: |
         python -c "import moonfish"
         python -c "import moonfish; import chess; board = chess.Board(); move = moonfish.search_move(board)"
 
     - name: Test CLI functionality
-      shell: bash -l {0}
       run: |
         moonfish --help
 
     - name: Run unit tests
-      shell: bash -l {0}
       run: |
         python -m unittest tests/test.py
 
@@ -72,12 +68,11 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.10'
+          python-version: '3.12'
 
       - name: Install dev requirements
-        run: |
-          make install
-
+        run: uv pip install -e .
+
       - name: Run ufmt
         run: ufmt check moonfish tests
 
@@ -100,12 +95,11 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.10'
+          python-version: '3.12'
 
       - name: Install dev requirements
-        run: |
-          make install
-
+        run: uv pip install -e .
+
       - name: Run Flake8
         run: flake8 moonfish tests
 
@@ -128,11 +122,10 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.10'
+          python-version: '3.12'
 
       - name: Install dev requirements
-        run: |
-          make install
+        run: uv pip install -e .
 
       - name: Run mypy
         run: mypy moonfish tests

.github/workflows/nps-benchmark.yml

@@ -42,7 +42,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.10'
+        python-version: '3.12'
 
     - name: Install dependencies
       run: make install

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     environment: pypi-publish
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4

moonfish/config.py

@@ -1,13 +1,12 @@
 from dataclasses import dataclass
-from typing import Optional
 
 # Score for checkmate.
 CHECKMATE_SCORE = 10**8
 # Threshold to differentiate checkmates from other moves.
 CHECKMATE_THRESHOLD = 999 * (10**4)
 
 
-@dataclass
+@dataclass(slots=True)
 class Config:
     """
     Configuration for the engine.
@@ -19,7 +18,7 @@ class Config:
     null_move: bool
     null_move_r: int
     quiescence_search_depth: int
-    syzygy_path: Optional[str]
+    syzygy_path: str | None
     syzygy_pieces: int
     checkmate_score: int = CHECKMATE_SCORE
     checkmate_threshold: int = CHECKMATE_THRESHOLD

moonfish/engines/alpha_beta.py

@@ -1,6 +1,4 @@
-from copy import copy
 from multiprocessing.managers import DictProxy
-from typing import Dict, Optional, Tuple
 
 import chess.syzygy
 from chess import Board, Move
@@ -9,10 +7,14 @@
 from moonfish.move_ordering import organize_moves, organize_moves_quiescence
 from moonfish.psqt import board_evaluation, count_pieces
 
-CACHE_KEY = Dict[
-    Tuple[str, int, bool, float, float], Tuple[float | int, Optional[Move]]
+CACHE_KEY = dict[
+    tuple[object, int, bool, float, float], tuple[float | int, Move | None]
 ]
 
+INF = float("inf")
+NEG_INF = float("-inf")
+NULL_MOVE = Move.null()
+
 
 class AlphaBeta:
     """
@@ -53,16 +55,16 @@ def eval_board(self, board: Board) -> float:
         Returns:
             - score: the score for the current board
         """
-        pieces = sum(count_pieces(board))
-
-        # Use pre-opened tablebase for endgame positions
-        if pieces <= self.config.syzygy_pieces and self.tablebase is not None:
-            try:
-                dtz = self.tablebase.probe_dtz(board)
-                return dtz
-            except (chess.syzygy.MissingTableError, KeyError):
-                # Position not in tablebase, fall through to normal evaluation
-                pass
+        # Short-circuit: only count pieces if a tablebase is loaded
+        if self.tablebase is not None:
+            pieces = sum(count_pieces(board))
+            if pieces <= self.config.syzygy_pieces:
+                try:
+                    dtz = self.tablebase.probe_dtz(board)
+                    return dtz
+                except (chess.syzygy.MissingTableError, KeyError):
+                    # Position not in tablebase, fall through to normal evaluation
+                    pass
 
         return board_evaluation(board)
 
@@ -118,7 +120,7 @@ def quiescence_search(
                 # (not ideal but prevents infinite recursion)
                 return stand_pat
 
-            best_score = float("-inf")
+            best_score = NEG_INF
             moves = list(board.legal_moves)  # All evasions
         else:
             # Not in check: normal quiescence behavior
@@ -146,10 +148,10 @@ def quiescence_search(
                 score = 0.0  # Draw score
             else:
                 score = -self.quiescence_search(
-                    board=board,
-                    depth=depth - 1,
-                    alpha=-beta,
-                    beta=-alpha,
+                    board,
+                    depth - 1,
+                    -beta,
+                    -alpha,
                 )
 
             board.pop()
@@ -172,9 +174,9 @@ def negamax(
         depth: int,
         null_move: bool,
         cache: DictProxy | CACHE_KEY,
-        alpha: float = float("-inf"),
-        beta: float = float("inf"),
-    ) -> Tuple[float | int, Optional[Move]]:
+        alpha: float = NEG_INF,
+        beta: float = INF,
+    ) -> tuple[float | int, Move | None]:
         """
         This functions receives a board, depth and a player; and it returns
         the best move for the current board based on how many depths we're looking ahead
@@ -204,7 +206,7 @@ def negamax(
         Returns:
             - best_score, best_move: returns best move that it found and its value.
         """
-        cache_key = (board.fen(), depth, null_move, alpha, beta)
+        cache_key = (board._transposition_key(), depth, null_move, alpha, beta)
 
         self.nodes += 1
 
@@ -224,10 +226,10 @@ def negamax(
         if depth <= 0:
             # evaluate current board
             board_score = self.quiescence_search(
-                board=board,
-                depth=copy(self.config.quiescence_search_depth),
-                alpha=alpha,
-                beta=beta,
+                board,
+                self.config.quiescence_search_depth,
+                alpha,
+                beta,
             )
             cache[cache_key] = (board_score, None)
             return board_score, None
@@ -240,14 +242,14 @@ def negamax(
         ):
             board_score = self.eval_board(board)
             if board_score >= beta:
-                board.push(Move.null())
+                board.push(NULL_MOVE)
                 board_score = -self.negamax(
-                    board=board,
-                    depth=depth - 1 - self.config.null_move_r,
-                    null_move=False,
-                    cache=cache,
-                    alpha=-beta,
-                    beta=-beta + 1,
+                    board,
+                    depth - 1 - self.config.null_move_r,
+                    False,
+                    cache,
+                    -beta,
+                    -beta + 1,
                 )[0]
                 board.pop()
                 if board_score >= beta:
@@ -257,20 +259,20 @@ def negamax(
         best_move = None
 
         # initializing best_score
-        best_score = float("-inf")
+        best_score = NEG_INF
         moves = organize_moves(board)
 
         for move in moves:
             # make the move
             board.push(move)
 
             board_score = -self.negamax(
-                board=board,
-                depth=depth - 1,
-                null_move=null_move,
-                cache=cache,
-                alpha=-beta,
-                beta=-alpha,
+                board,
+                depth - 1,
+                null_move,
+                cache,
+                -beta,
+                -alpha,
             )[0]
             if board_score > self.config.checkmate_threshold:
                 board_score -= 1
@@ -313,7 +315,7 @@ def search_move(self, board: Board) -> Move:
         cache: CACHE_KEY = {}
 
         best_move = self.negamax(
-            board, copy(self.config.negamax_depth), self.config.null_move, cache
+            board, self.config.negamax_depth, self.config.null_move, cache
         )[1]
         assert best_move is not None, "Best move from root should not be None"
         return best_move

moonfish/engines/l1p_alpha_beta.py

@@ -1,4 +1,3 @@
-from copy import copy
 from multiprocessing import cpu_count, Manager, Pool
 
 from chess import Board, Move
@@ -25,8 +24,8 @@ def search_move(self, board: Board) -> Move:
             board.push(move)
             arguments.append(
                 (
-                    copy(board),
-                    copy(self.config.negamax_depth) - 1,
+                    board.copy(),
+                    self.config.negamax_depth - 1,
                     self.config.null_move,
                     shared_cache,
                 )

moonfish/engines/l2p_alpha_beta.py

@@ -1,9 +1,7 @@
 from collections import defaultdict
-from copy import copy
 from functools import partial
 from multiprocessing import cpu_count, Manager, Pool
 from multiprocessing.managers import DictProxy
-from typing import List, Tuple
 
 from chess import Board, Move
 from moonfish.config import Config
@@ -32,7 +30,7 @@ def __init__(self, config: Config):
 
     def generate_board_and_moves(
         self, og_board: Board, board_to_move_that_generates_it: DictProxy, layer: int
-    ) -> List[Tuple[Board, Board, int]]:
+    ) -> list[tuple[Board, Board, int]]:
         """
         Generate all possible boards with their layer depth for each board.
 
@@ -48,7 +46,7 @@ def generate_board_and_moves(
                 - layer depth
         """
         boards_and_moves = []
-        board = copy(og_board)
+        board = og_board.copy()
 
         # if board has no legal moves, we leave it as is
         # we need to run this board through negamax to get its value
@@ -69,7 +67,7 @@ def generate_board_and_moves(
             else:
                 board_to_move_that_generates_it[board.fen()] = move
             # add new board, original board, and current layer to our output
-            boards_and_moves.append((copy(board), og_board, layer + 1))
+            boards_and_moves.append((board.copy(), og_board, layer + 1))
 
             board.pop()
 
@@ -101,7 +99,7 @@ def search_move(self, board: Board) -> Move:
         negamax_arguments = [
             (
                 board,
-                copy(self.config.negamax_depth) - START_LAYER,
+                self.config.negamax_depth - START_LAYER,
                 self.config.null_move,
                 shared_cache,
             )

moonfish/engines/lazy_smp.py

@@ -1,8 +1,7 @@
-from copy import copy
 from multiprocessing import cpu_count, Manager, Pool
 
 from chess import Board, Move
-from moonfish.engines.alpha_beta import AlphaBeta
+from moonfish.engines.alpha_beta import AlphaBeta, INF, NEG_INF
 
 
 class LazySMP(AlphaBeta):
@@ -20,7 +19,7 @@ def search_move(self, board: Board) -> Move:
             [
                 (
                     board,
-                    copy(self.config.negamax_depth),
+                    self.config.negamax_depth,
                     self.config.null_move,
                     shared_cache,
                 )
@@ -31,10 +30,10 @@ def search_move(self, board: Board) -> Move:
         # return best move for our original board
         return shared_cache[
             (
-                board.fen(),
+                board._transposition_key(),
                 self.config.negamax_depth,
                 self.config.null_move,
-                float("-inf"),
-                float("inf"),
+                NEG_INF,
+                INF,
             )
         ][1]