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functional-programming-snake/fsharp/solutions/Model.fs
T
Lucas WintherandClaude Fable 5.2 edd57f0148 feat(course): audit fixes and twelve extensions (Modules 7b, 12, 13)
Audit pass:
- Frame rule counts frames since the last move, so every step lasts
  exactly movesEvery(score) frames, also right after a speed-up
- clampTime + MAX_GAP_MS: a hidden tab no longer replays the whole gap
- Pong Restart keeps held keys
- Fact corrections (mulberry32 output coverage, Haskell IO, uniform)
- New fixture cases from a mutation analysis

Extensions (all three tracks, shared fixtures, course text):
- Turn queue (Exercise 10.6), persisted high score (10.7),
  replay viewer (10.8), play() end-to-end helper (9.5)
- Optional State (4.7) and optional Module 7b, stack-safe IO
- Module 12, property-based testing with generators, shrinking,
  invariants and a model-based oracle
- Module 13, Conway's Life with a Click event
- JS type checking via jsconfig, JSDoc and types.d.ts
- Maintainer tools: scripts/mutate.mjs, scripts/typecheck-js.sh,
  Playwright end-to-end suite (e2e/, scripts/e2e.sh)

Docs: docs/contract.md is the canonical contract; specs and build log
under docs/superpowers.

Verified: JS 728, Scala 689, F# 691 unit tests; stubs and progression
M01-M13 and M07b; 176 end-to-end tests on Chromium and WebKit.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>
2026-11-11 12:05:29 +01:00

68 lines
1.5 KiB
FSharp

/// m02 model: the data the whole game is built from. Records and unions are immutable.
module Snake.Model
/// A grid cell. Records compare structurally: two points with the same X and Y are `=`.
type Point = { X: int; Y: int }
type Direction =
| Up
| Down
| Left
| Right
type Status =
| Playing
| Paused
| GameOver
| Won
/// Everything that can happen to the game, as data.
type Action =
| Tick
| Turn of Direction
| TogglePause
| Restart
| Frame
/// The whole game. `Snake` is head first; `Seed` is the unsigned 32-bit random seed.
/// `Frame` and `Queued` stay unused until m10 (`Queued` holds a turn waiting for the next step).
type GameState =
{ Width: int
Height: int
Snake: Point list
Dir: Direction
NextDir: Direction
Apple: Point option
Seed: uint32
Score: int
Status: Status
Frame: int
Queued: Direction option }
let delta (dir: Direction) : Point =
match dir with
| Up -> { X = 0; Y = -1 }
| Down -> { X = 0; Y = 1 }
| Left -> { X = -1; Y = 0 }
| Right -> { X = 1; Y = 0 }
let opposite (dir: Direction) : Direction =
match dir with
| Up -> Down
| Down -> Up
| Left -> Right
| Right -> Left
let initialState (seed: uint32) : GameState =
{ Width = 20
Height = 20
Snake = [ { X = 10; Y = 10 }; { X = 9; Y = 10 }; { X = 8; Y = 10 } ]
Dir = Right
NextDir = Right
Apple = None
Seed = seed
Score = 0
Status = Playing
Frame = 0
Queued = None }