5-minute talk I gave at the Recurse Center. I should have pruned the slides by 1/3 at least.

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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