Remove fast immutable collections

CLAUDE.md

@@ -5,8 +5,8 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ## Commands
 
 ```bash
-# Run all tests
-dart test
+# Run all tests (exclude slow full_perft tests)
+dart test -x full_perft
 
 # Run a single test file
 dart test test/position_test.dart
@@ -51,7 +51,7 @@ This is a pure Dart chess rules library (`package:dartchess`) supporting standar
 
 **`position.dart`** — the heart of the library. `Position` is an immutable abstract base class; each variant subclasses it: `Chess`, `Antichess`, `Atomic`, `Crazyhouse`, `KingOfTheHill`, `ThreeCheck`, `RacingKings`, `Horde`. Concrete private implementations (`_Chess`, etc.) are returned by `fromSetup`. Key API:
 - `Position.setupPosition(rule, setup)` — variant-aware factory
-- `pos.legalMoves` — `IMap<Square, SquareSet>` (king-to-rook encoding for castling)
+- `pos.legalMoves` — `Map<Square, SquareSet>` (king-to-rook encoding for castling)
 - `pos.play(move)` / `pos.playUnchecked(move)` — returns new position
 - `pos.parseSan(san)` / `pos.makeSan(move)` — SAN I/O
 - `pos.isCheckmate`, `pos.isStalemate`, `pos.isGameOver`, `pos.outcome`
@@ -65,7 +65,7 @@ This is a pure Dart chess rules library (`package:dartchess`) supporting standar
 
 ### Immutability
 
-All `Position`, `Board`, `Setup`, `Castles` instances are immutable (`@immutable`). The library uses `fast_immutable_collections` (`IMap`, `ISet`) for collections stored in positions.
+All `Position`, `Board`, `Setup`, `Castles` instances are immutable (`@immutable`). Standard Dart collections are used throughout; immutability is enforced by the library's internal discipline rather than FIC types.
 
 ### Chess960
 

lib/src/board.dart

@@ -1,5 +1,4 @@
 import 'package:meta/meta.dart';
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import './square_set.dart';
 import './models.dart';
 import './attacks.dart';
@@ -185,7 +184,7 @@ class Board {
   }
 
   /// Gets the number of pieces of each [Role] for the given [Side].
-  IMap<Role, int> materialCount(Side side) => IMap.fromEntries(
+  ByRole<int> materialCount(Side side) => Map.fromEntries(
       Role.values.map((role) => MapEntry(role, piecesOf(side, role).size)));
 
   /// A [SquareSet] of all the pieces matching this [Side] and [Role].

lib/src/castles.dart

@@ -105,30 +105,30 @@ abstract class Castles {
 
   /// Gets rooks positions by side and castling side.
   BySide<ByCastlingSide<Square?>> get rooksPositions {
-    return BySide({
-      Side.white: ByCastlingSide({
+    return {
+      Side.white: {
         CastlingSide.queen: _whiteRookQueenSide,
         CastlingSide.king: _whiteRookKingSide,
-      }),
-      Side.black: ByCastlingSide({
+      },
+      Side.black: {
         CastlingSide.queen: _blackRookQueenSide,
         CastlingSide.king: _blackRookKingSide,
-      }),
-    });
+      },
+    };
   }
 
   /// Gets rooks paths by side and castling side.
   BySide<ByCastlingSide<SquareSet>> get paths {
-    return BySide({
-      Side.white: ByCastlingSide({
+    return {
+      Side.white: {
         CastlingSide.queen: _whitePathQueenSide,
         CastlingSide.king: _whitePathKingSide,
-      }),
-      Side.black: ByCastlingSide({
+      },
+      Side.black: {
         CastlingSide.queen: _blackPathQueenSide,
         CastlingSide.king: _blackPathKingSide,
-      }),
-    });
+      },
+    };
   }
 
   /// Gets the rook [Square] by side and castling side.

lib/src/models.dart

@@ -1,5 +1,4 @@
 import 'package:meta/meta.dart';
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import './square_set.dart';
 
 /// The chessboard side, white or black.
@@ -337,9 +336,9 @@ extension type const Square._(int value) implements int {
   static const h8 = Square(63);
 }
 
-typedef BySide<T> = IMap<Side, T>;
-typedef ByRole<T> = IMap<Role, T>;
-typedef ByCastlingSide<T> = IMap<CastlingSide, T>;
+typedef BySide<T> = Map<Side, T>;
+typedef ByRole<T> = Map<Role, T>;
+typedef ByCastlingSide<T> = Map<CastlingSide, T>;
 
 /// Describes a chess piece kind by its color and role.
 enum PieceKind {

lib/src/pgn.dart

@@ -1,5 +1,4 @@
 import 'dart:math' as math;
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 
 import 'package:meta/meta.dart';
 import './setup.dart';
@@ -494,7 +493,7 @@ class PgnEvaluation {
 class PgnComment {
   const PgnComment(
       {this.text,
-      this.shapes = const IListConst([]),
+      this.shapes = const [],
       this.clock,
       this.emt,
       this.eval})
@@ -504,7 +503,7 @@ class PgnComment {
   final String? text;
 
   /// List of comment shapes.
-  final IList<PgnCommentShape> shapes;
+  final List<PgnCommentShape> shapes;
 
   /// Player's remaining time.
   final Duration? clock;
@@ -571,7 +570,7 @@ class PgnComment {
 
     return PgnComment(
         text: text.isNotEmpty ? text : null,
-        shapes: IList(shapes),
+        shapes: List.unmodifiable(shapes),
         emt: emt,
         clock: clock,
         eval: eval);
@@ -601,17 +600,18 @@ class PgnComment {
 
   @override
   bool operator ==(Object other) {
-    return identical(this, other) ||
-        other is PgnComment &&
-            text == other.text &&
-            shapes == other.shapes &&
-            clock == other.clock &&
-            emt == other.emt &&
-            eval == other.eval;
+    if (identical(this, other)) return true;
+    if (other is! PgnComment) return false;
+    if (text != other.text || clock != other.clock || emt != other.emt || eval != other.eval) return false;
+    if (shapes.length != other.shapes.length) return false;
+    for (var i = 0; i < shapes.length; i++) {
+      if (shapes[i] != other.shapes[i]) return false;
+    }
+    return true;
   }
 
   @override
-  int get hashCode => Object.hash(text, shapes, clock, emt, eval);
+  int get hashCode => Object.hash(text, Object.hashAll(shapes), clock, emt, eval);
 }
 
 /// A frame used for parsing a line

lib/src/position.dart

@@ -1,6 +1,5 @@
 import 'package:meta/meta.dart';
 import 'dart:math' as math;
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'attacks.dart';
 import 'castles.dart';
 import 'models.dart';
@@ -191,13 +190,13 @@ abstract class Position {
   ///
   /// Use the [makeLegalMoves] helper to get all the legal moves including alternative
   /// castling moves.
-  IMap<Square, SquareSet> get legalMoves {
+  Map<Square, SquareSet> get legalMoves {
     final context = _makeContext();
-    if (context.isVariantEnd) return IMap(const {});
-    return IMap({
+    if (context.isVariantEnd) return const {};
+    return {
       for (final s in board.bySide(turn).squares)
         s: _legalMovesOf(s, context: context)
-    });
+    };
   }
 
   /// Gets all the legal drops of this position.

lib/src/setup.dart

@@ -1,5 +1,4 @@
 import 'package:meta/meta.dart';
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'dart:math' as math;
 import './square_set.dart';
 import './models.dart';
@@ -255,23 +254,31 @@ class Pockets {
 
   /// Increments the number of pieces in the pocket of that [Side] and [Role].
   Pockets increment(Side side, Role role) {
-    final newPocket = value[side]!.add(role, of(side, role) + 1);
-    return Pockets(value: value.add(side, newPocket));
+    final newPocket = {...value[side]!, role: of(side, role) + 1};
+    return Pockets(value: {...value, side: newPocket});
   }
 
   /// Decrements the number of pieces in the pocket of that [Side] and [Role].
   Pockets decrement(Side side, Role role) {
-    final newPocket = value[side]!.add(role, of(side, role) - 1);
-    return Pockets(value: value.add(side, newPocket));
+    final newPocket = {...value[side]!, role: of(side, role) - 1};
+    return Pockets(value: {...value, side: newPocket});
   }
 
   @override
   bool operator ==(Object other) {
-    return identical(this, other) || other is Pockets && other.value == value;
+    if (identical(this, other)) return true;
+    if (other is! Pockets) return false;
+    for (final side in Side.values) {
+      for (final role in Role.values) {
+        if (of(side, role) != other.of(side, role)) return false;
+      }
+    }
+    return true;
   }
 
   @override
-  int get hashCode => value.hashCode;
+  int get hashCode => Object.hashAll(
+      Side.values.expand((s) => Role.values.map((r) => of(s, r))));
 }
 
 Pockets _parsePockets(String pocketPart) {
@@ -398,16 +405,16 @@ int _nthIndexOf(String haystack, String needle, int nth) {
   return index;
 }
 
-const ByRole<int> _emptyPocket = IMapConst({
+const ByRole<int> _emptyPocket = {
   Role.pawn: 0,
   Role.knight: 0,
   Role.bishop: 0,
   Role.rook: 0,
   Role.queen: 0,
   Role.king: 0,
-});
+};
 
-const BySide<ByRole<int>> _emptyPocketsBySide = IMapConst({
+const BySide<ByRole<int>> _emptyPocketsBySide = {
   Side.white: _emptyPocket,
   Side.black: _emptyPocket,
-});
+};

pubspec.yaml

@@ -15,7 +15,6 @@ environment:
   sdk: ">=3.3.0 <4.0.0"
 
 dependencies:
-  fast_immutable_collections: ^11.0.0
   meta: ^1.8.0
 
 dev_dependencies:

test/castles_test.dart

@@ -1,4 +1,3 @@
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:dartchess/dartchess.dart';
 import 'package:test/test.dart';
 
@@ -40,34 +39,29 @@ void main() {
       expect(Castles.standard.discardRookAt(Square.a4), Castles.standard);
       expect(
           Castles.standard.discardRookAt(Square.h1).rooksPositions[Side.white],
-          IMap(const {CastlingSide.queen: Square.a1, CastlingSide.king: null}));
+          const {CastlingSide.queen: Square.a1, CastlingSide.king: null});
     });
 
     test('discard side', () {
       expect(
           Castles.standard.discardSide(Side.white).rooksPositions,
-          equals(BySide({
-            Side.white: ByCastlingSide(
-              const {CastlingSide.queen: null, CastlingSide.king: null},
-            ),
-            Side.black: ByCastlingSide(
-              const {
-                CastlingSide.queen: Square.a8,
-                CastlingSide.king: Square.h8,
-              },
-            )
-          })));
+          equals({
+            Side.white: const {CastlingSide.queen: null, CastlingSide.king: null},
+            Side.black: const {
+              CastlingSide.queen: Square.a8,
+              CastlingSide.king: Square.h8,
+            },
+          }));
 
       expect(
           Castles.standard.discardSide(Side.black).rooksPositions,
-          equals(BySide({
-            Side.white: ByCastlingSide(const {
+          equals({
+            Side.white: const {
               CastlingSide.queen: Square.a1,
               CastlingSide.king: Square.h1,
-            }),
-            Side.black: ByCastlingSide(
-                const {CastlingSide.queen: null, CastlingSide.king: null})
-          })));
+            },
+            Side.black: const {CastlingSide.queen: null, CastlingSide.king: null},
+          }));
     });
   });
 }

test/pgn_test.dart

@@ -1,6 +1,5 @@
 import 'package:dartchess/dartchess.dart' hide File;
 import 'package:test/test.dart';
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'dart:io';
 
 import 'pgn_fixtures.dart';
@@ -111,7 +110,7 @@ void main() {
               '[%csl Ya1][%cal Ra1a1,Be1e2]commentary [%csl Gh8]'),
           const PgnComment(
               text: 'commentary',
-              shapes: IListConst([
+              shapes: [
                 PgnCommentShape(
                     color: CommentShapeColor.yellow,
                     from: Square.a1,
@@ -128,7 +127,7 @@ void main() {
                     color: CommentShapeColor.green,
                     from: Square.h8,
                     to: Square.h8)
-              ])));
+              ]));
 
       expect(
           PgnComment.fromPgn('prefix [%eval .99,23]'),
@@ -147,12 +146,12 @@ void main() {
           PgnComment.fromPgn('[%csl Ga1]foo'),
           const PgnComment(
               text: 'foo',
-              shapes: IListConst([
+              shapes: [
                 PgnCommentShape(
                     color: CommentShapeColor.green,
                     from: Square.a1,
                     to: Square.a1)
-              ])));
+              ]));
 
       expect(
           PgnComment.fromPgn(
@@ -169,7 +168,7 @@ void main() {
                   Duration(hours: 1, minutes: 2, seconds: 3, milliseconds: 400),
               eval: PgnEvaluation.pawns(pawns: 10),
               clock: Duration(seconds: 1),
-              shapes: IListConst([
+              shapes: [
                 PgnCommentShape(
                     color: CommentShapeColor.yellow,
                     from: Square.a1,
@@ -182,7 +181,7 @@ void main() {
                     color: CommentShapeColor.red,
                     from: Square.a1,
                     to: Square.c1)
-              ])).makeComment(),
+              ]).makeComment(),
           'text [%csl Ya1] [%cal Ra1b1,Ra1c1] [%eval 10.00] [%emt 1:02:03.4] [%clk 0:00:01]');
 
       expect(

test/position_test.dart

@@ -1,4 +1,3 @@
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:dartchess/dartchess.dart';
 import 'package:test/test.dart';
 import 'dart:io' as io;
@@ -361,7 +360,7 @@ void main() {
     });
 
     test('standard position legal moves', () {
-      final moves = IMap({
+      final moves = {
         Square.a1: SquareSet.empty,
         Square.b1: const SquareSet.fromSquare(Square.a3).withSquare(Square.c3),
         Square.c1: SquareSet.empty,
@@ -378,7 +377,7 @@ void main() {
         Square.f2: const SquareSet.fromSquare(Square.f3).withSquare(Square.f4),
         Square.g2: const SquareSet.fromSquare(Square.g3).withSquare(Square.g4),
         Square.h2: const SquareSet.fromSquare(Square.h3).withSquare(Square.h4),
-      });
+      };
       expect(Chess.initial.legalMoves, equals(moves));
     });
 
@@ -665,10 +664,10 @@ void main() {
             .play(const NormalMove(from: Square.h1, to: Square.f1));
         expect(
             pos.castles.rooksPositions[Side.white],
-            equals(IMap(const {
+            equals(const {
               CastlingSide.queen: Square.a1,
               CastlingSide.king: null
-            })));
+            }));
         expect(pos.castles.castlingRights.has(Square.h1), false);
       });
 

utils_test.dart

@@ -1,5 +1,4 @@
 import 'package:dartchess/dartchess.dart';
-import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:test/test.dart';
 
 void main() {
@@ -61,7 +60,7 @@ void main() {
     );
     expect(
       makeLegalMoves(pos, includeAlternateCastlingMoves: false)[Square.b8],
-      equals(ISet(const {Square.a8, Square.c8, Square.e8})),
+      equals(const {Square.a8, Square.c8, Square.e8}),
     );
   });
 }