ChessFidget is a chess app created by the author to address their personal shortcomings at chess by playing against an AI they can always beat. The app is designed to provide dopamine rather than build skill. Currently, the computer plays random moves worse than the author's own chess ability. The author struggled with modeling the objects and rules of chess in Swift but overcame those challenges with help from Swift features. Future goals for the app include incorporating a third-party library to add weak AI and additional gameplay features while avoiding overloading the author with Swift details again.

1. ChessFidget
You call that chess?
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2. The itch
• Like to play chess
• Dislike losing so much
• Too much work to get good
- (For me it would be a dangerous rabbit hole.)
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3. The scratch
• Write software to address personal shortcomings
• ChessFidget: a chess app I (currently) always beat
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4. Currently looks like this
In lieu of a demo, I'll post code and (Mac) binaries
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5. Dev goals/guidelines
• Design for dopamine, not skill
- E.g. no move history
• Computer mostly plays worse chess than I do
- Currently random moves
- That will get boring; see above re: dopamine
• META: Exercise in Swift and reasoning about code
- NOT an exercise in chess programming or AI
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6. 😬:Agonizing re: modeling
• What are my objects? (Board, Piece, Move, ...)
• In how many places do "business rules" live?
- E.g. MoveValidator and MoveGenerator
- OTOH, might help with mutual unit-testing
• Sometimes the problem was a Swift difficulty
- Extending Grid<T>, T is Piece? vs. T is Bool
• Sometimes the answer was a Swift feature
- Type constraints?
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7. "Move" as struct+moveType
enum MoveType {
case resignation
case plainMove
case pawnTwoSquares
case captureEnPassant
case pawnPromotion(type: PromotionType)
case castleKingSide
case castleQueenSide
}
struct Move {
let start: Square
let end: Square
let type: MoveType
}
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8. Works fine
awaitingHumanMove
Invalid move e1-g1:
cannotCastleBecauseKingOrRookHasMoved
d1-d2 (plainMove) played by White (Human)
awaitingComputerMove
b8-d7 (plainMove) played by Black (Computer)
awaitingHumanMove
e1-c1 (castleQueenSide) played by White (Human)
awaitingComputerMove
d7-b6 (plainMove) played by Black (Computer)
awaitingHumanMove
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9. "Move" as class hierarchy
protocol MoveProtocol {
func updateBoard(_ board: Board)
}
/* The classes would be something like:
Move: MoveProtocol
Resignation
MoveWithStart
PawnTwoSquares
CastleKingSide
CastleQueenSide
MoveWithStartAndEnd
PlainMove
CaptureEnPassant
PawnPromotion */
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10. 😬:Swift overwhelm
• Building my mental model, esp. re: type system
• Finally past the squirmy phase! 😬➞😊
- New info now gets added to mental framework
• Maybe pairing would have helped?
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11. Thoughts about learning
• Know thy brain
- Came to terms with my jumpy learning
- Shlemiel the painter (stay tuned for blog post)
• Be aware when/how reach out to people
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12. Other thoughts
• Wow do I suck at chess
• Does writing this app mean I'm a bully at heart?
• Am I weird for sensing uncanny illusion of intent?
- Feels like it's capturing back "on purpose"
- Feels intentional when it checks me
- This despite knowing there is *zero* AI
- WTF it played Fool's Mate
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13. Actual early test (Computer=Black)
(manually recreated; wish I'd taken a screenshot)
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14. Next (current thinking)
• Find a third-party library, add (weak) AI
• Distinguish between stalemate and checkmate
• Add keyboard input
- Might help me learn algebraic notation
• Add multi-game play
• Move on to other project ideas
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