Lucas WintherandClaude Fable 5.2
edd57f0148
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>
66 lines
3.4 KiB
FSharp
66 lines
3.4 KiB
FSharp
/// m07b safeio (optional): a stack-safe IO. Same idea as m07's IO, plus one more case, so that `bind` only builds
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/// data and no program shape can overflow the stack, however deeply its `bind`s are nested.
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/// - `Pure a` done, with a value
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/// - `Effect (op, k)` perform `op`, then continue with `k result`
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/// - `FlatMap (io, f)` run `io`, then continue with `f result`
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/// The ops, their answers and the result of `trace` are m07's `IO.Op`, `IO.OpResult` and `IO.Traced`.
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/// (Not `open Snake.IO`: its cases are also called Pure and Effect.)
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module Snake.SafeIO
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/// `FlatMap`'s inner program produces some type `X` that only its continuation knows. A union case cannot have a
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/// type parameter of its own, so `X` is erased to `obj`; only `bind` builds a `FlatMap`, and it keeps the two in step.
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type SafeIO<'a> =
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| Pure of 'a
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| Effect of IO.Op * (IO.OpResult -> SafeIO<'a>)
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| FlatMap of SafeIO<obj> * (obj -> SafeIO<'a>)
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// Given: the same program, seen as a SafeIO<obj>. Constant work: continuations are wrapped, not called.
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let rec private erase (io: SafeIO<'a>) : SafeIO<obj> =
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match io with
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| Pure a -> Pure(box a)
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| Effect(op, k) -> Effect(op, fun r -> erase (k r))
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| FlatMap(m, g) -> FlatMap(m, fun x -> erase (g x))
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let pure (a: 'a) : SafeIO<'a> = Pure a
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let effect (op: IO.Op) : SafeIO<IO.OpResult> = Effect(op, pure)
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// Only builds a node: never calls f, not even when io is Pure. The unbox cannot fail: x is the result of `io`.
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let bind (f: 'a -> SafeIO<'b>) (io: SafeIO<'a>) : SafeIO<'b> = FlatMap(erase io, fun x -> f (unbox<'a> x))
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let map (f: 'a -> 'b) (io: SafeIO<'a>) : SafeIO<'b> = io |> bind (fun a -> Pure(f a))
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// A left fold on purpose: with SafeIO the nesting no longer matters.
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let sequence (ios: SafeIO<unit> list) : SafeIO<unit> = List.fold (fun acc io -> acc |> bind (fun () -> io)) (pure ()) ios
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// One rewrite towards a program whose top is a Pure or an Effect. Constant work, no recursion.
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// FlatMap(Pure a, f) -> f a
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// FlatMap(Effect(op, k), f) -> Effect(op, fun r -> FlatMap(k r, f))
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// FlatMap(FlatMap(m, g), f) -> FlatMap(m, fun x -> FlatMap(g x, f)) (re-association)
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// Pure and Effect are already in that shape and come back unchanged.
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let step (io: SafeIO<'a>) : SafeIO<'a> =
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match io with
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| FlatMap(Pure x, f) -> f x
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| FlatMap(Effect(op, k), f) -> Effect(op, fun r -> FlatMap(k r, f))
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| FlatMap(FlatMap(m, g), f) -> FlatMap(m, fun x -> FlatMap(g x, f))
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| other -> other
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// Given: the canned answer of the pure interpreter, as in m07. SafeIO keeps Module 7's two operations; the stored
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// best score of Module 10 is not part of it, so its operations are refused loudly rather than given a meaning here.
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let private answer (seed: uint32) (op: IO.Op) : IO.OpResult =
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match op with
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| IO.RandomSeed -> IO.Seed seed
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| IO.Draw _ -> IO.Done
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| IO.LoadBest
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| IO.SaveBest _ -> failwith "SafeIO.trace answers only Module 7's operations (Draw and RandomSeed)"
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// `loop` calls itself only in tail position, so the compiler turns it into a loop: the stack stays flat.
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let trace (seed: uint32) (io: SafeIO<'a>) : IO.Traced<'a> =
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let rec loop (current: SafeIO<'a>) (performed: IO.Op list) : IO.Traced<'a> =
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match current with
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| Pure a -> { IO.Result = a; IO.Ops = List.rev performed }
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| Effect(op, k) -> loop (k (answer seed op)) (op :: performed)
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| FlatMap _ -> loop (step current) performed
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loop io []
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