AsyncSequenceとAsyncStreamのプロポーザルを全部読む！！

https://japan-region-swift.connpass.com/event/365671/

1. S_Shimotori AsyncSequenceͱ
 AsyncStreamͷϓϩϙʔβϧΛ
 શ෦ಡΉʂʂ kanagawa.swift #2
2. S_Shimotori • Kotlin Festͷํ޲͔Βདྷ·ͨ͠ • ਆಸ઒ཁૉɿͳ͍ɻɻ • ΞϧϑΝϕοςΟΧϑΣ͞Μʹ͸
 ͍͔ͭߦ͖͍ͨ☕
3. എܠ
4. Concurrencyؔ࿈ͷproposalશ෦ಡΉ͔ʙ • Synchronizationͷཧղʹ͸΍͸ΓConcurrencyͷ׬શͳཧղ͕ෆՄܽͩΑͳʙ • Swift Evolution͔ΔͨͰࢂഊͨ͘͠ͳ͍͠ͳʙ • ࣾ಺ษڧձͰຖ݄1ຊͣͭൃදͯ͠΍Ζʙ
5. ͤͬͤͱൃදʂʢࣾ಺Ͱʣ • ະެ։ࢿྉ
6. ऴΘΒͶʙʙ
7. ղܾࡦɿಡΉϖʔεͱൃදͷϖʔεΛ্͛Δ • AsyncSequenceͱAsyncStreamΛҰؾಡΈͩʂ • ͔Δͨڧऀͷਆಸ઒ݝຽͷօ͞ΜͳΒ࿩Λฉ͍ͯ͘Εͦ͏
8. ຊ೔ͷϓϩϙʔβϧ
9. ଟ͍ʙ • SE-0298 Async/Await: Sequences • SE-0314 AsyncStream and AsyncThrowingStream • SE-0388 Convenience Async[Throwing]Stream.makeStream methods • SE-0406 Backpressure support for AsyncStream • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
10. ࿩͢͜ͱ • ࿩͢͜ͱ • S_ShimotoriͷউखͳಡΈ৺஍ϨϏϡʔɹ˒˒˒ ⭐︎ ⭐︎ • S_Shimotori͕໘ന͍ͱࢥͬͨ࿩ • ࿩͞ͳ͍͜ͱ • AsyncSequenceͱAsyncStreamͷ࢖͍ํ
11. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences • SE-0314 AsyncStream and AsyncThrowingStream • SE-0388 Convenience Async[Throwing]Stream.makeStream methods • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
12. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences • SE-0314 AsyncStream and AsyncThrowingStream • SE-0388 Convenience Async[Throwing]Stream.makeStream methods • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
13. SE-0298 Async/Await: Sequences
14. SE-0298 • https://github.com/swiftlang/swift-evolution/blob/main/proposals/0298- asyncsequence.md • Swift 5.5ʢ2021೥ʣ • iOS 13.0΁ͷόοΫϙʔτ͋Γ • λΠτϧ΍ϑΝΠϧ໊ͷ௨ΓAsyncSequenceͷ࿩ https://developer.apple.com/documentation/Swift/AsyncSequence
15. ͜Εͷ͜ͱͰ͢ʂ • ͳΜ͔Α͘for awaitจͰ͙Δ͙Δճ͞ΕͯΔ΍ͭ for try await line in myFile.lines() { // Do something with each line } https://developer.apple.com/documentation/Swift/AsyncSequence ͜Ε
16. SE-0298ϨϏϡʔʢʁʣ ೉қ౓ ˒ˑˑˑˑ લఏͷSE-0296ΛࠐΈͰߟ͑Δͱ ͪΐͬͱCSͷ஌͕ࣝඞཁ ௕͞ ˒ˑˑˑˑ .md্Ͱ͸362ߦ
 ͘͢͝୹ͯ͘ಡΈ΍͍͕͢ɺ಺༰͸૬Ԡʹബ͍ ॏཁ౓ ˒ˑˑˑˑ ਎͕ۙͩɺಡ·ͳͯ͘΋ੜ͖͍͚ͯΔ
17. SE-0298 Introductionͷ༁ • Swiftͷasync/awaitػೳ͸ɺ͍͔ͭকདྷͷ͋Δ࣌఺Ͱ୯Ұͷ஋Λฦؔ͢਺Λॻ ͍ͨΓ࢖ͬͨΓ͢ΔͨΊͷɺ௚ײత͔ͭϏϧτΠϯͷํ๏Λఏڙ͍ͯ͠Δɻ • զʑ͸ɺ࣌ؒͷܦաͱͱ΋ʹෳ਺ͷ஋Λฦؔ͢਺Λॻ͍ͨΓ࢖ͬͨΓ͢Δͨ Ίͷ௚ײత͔ͭϏϧτΠϯͷํ๏Λ࡞੒͢ΔͨΊɺ͜ͷػೳΛϕʔεʹங͘͜ ͱΛఏҊ͢Δɻ 👇SE-0296 Async/await 👆SE-0296 Async/await
18. SE-0296 Async/awaitʢલఏͷϓϩϙʔβϧʣ • ͍͔ͭকདྷͷ͋Δ࣌఺Ͱ୯Ұͷ஋Λฦ͢ let dataResource = try await loadWebResource("dataprofile.txt") https://github.com/swiftlang/swift-evolution/blob/main/proposals/0296-async-await.md
19. SE-0298 Async/Await: Sequences • ࣌ؒͷܦաͱͱ΋ʹෳ਺ͷ஋Λฦ͢ for try await line in myFile.lines() { // Do something with each line } https://github.com/swiftlang/swift-evolution/blob/main/proposals/0298-asyncsequence.md
20. ײ૝ • SE-0296 Async/awaitΛಡΜͩ΄͏͕͍͍ • ͜Μͳਓʹ͓͢͢Ί • AsyncSequenceΛ࢖͍͗ͯ͢ເʹग़͖ͯͨਓ
21. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences ✅ • SE-0314 AsyncStream and AsyncThrowingStream • SE-0388 Convenience Async[Throwing]Stream.makeStream methods • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
22. SE-0314
 AsyncStream and AsyncThrowingStream
23. SE-0314 • https://github.com/swiftlang/swift-evolution/blob/main/proposals/0314- async-stream.md • Swift 5.5ʢ2021೥ʣ • iOS 13.0΁ͷόοΫϙʔτ͋Γ • λΠτϧ΍ϑΝΠϧ໊ͷ௨ΓAsyncStreamͷ࿩ https://developer.apple.com/documentation/Swift/AsyncStream
24. SE-0314ϨϏϡʔʢʁʣ ೉қ౓ ˒ˑˑˑˑ AsyncStreamΛ࢖ͬͨ͜ͱ͕͋Ε͹ಡΊΔ CS஌ࣝ΋΄΅ෆཁ ௕͞ ˒˒ˑˑˑ .md্Ͱ͸554ߦ
 ιʔείʔυ͕ଟ͍ͷͰ௕͘͸ײ͡ͳ͍͔΋ ॏཁ౓ ˒ˑˑˑˑ ਎ۙͳଘࡏ……ͳͷ͔ͳ͋
25. AsyncStreamΛ࡞Δํ๏ • init(_:bufferingPolicy:_:) • init(unfolding:onCancel:) • makeStream(of:bufferingPolicy:)
26. AsyncStreamΛ࡞Δํ๏ • init(_:bufferingPolicy:_:) • init(unfolding:onCancel:) • makeStream(of:bufferingPolicy:) 👈 SE-0388Ͱޙ͔Β௥Ճ
27. init(_:bufferingPolicy:_:) class QuakeMonitor { var quakeHandler: ((Quake) -> Void)? func startMonitoring() { ... } func stopMonitoring() { ... } static var quakes: AsyncStream<Quake> { AsyncStream { continuation in let monitor = QuakeMonitor() monitor.quakeHandler = { quake in continuation.yield(quake) } continuation.onTermination = { @Sendable _ in monitor.stopMonitoring() } monitor.startMonitoring() } } } https://developer.apple.com/documentation/Swift/AsyncStream ͜Ε
28. SE-0314 Introductionͷ༁ • SE-0300Ͱ௥Ճ͞Εͨܧଓܕ͸ɺσϦήʔτϝιου΍ίʔϧόοΫؔ਺ͷݺ ͼग़͠ʹΑΓ׬ྃΛ௨஌͢Δಉظίʔυʹରͯ͠Ξμϓλʔͱͯ͠ػೳ͢Δɻ • ͦͷ୅ΘΓʹ࣌ؒͷܦաͰෳ਺ͷ஋Λੜ੒͢Δίʔυʹରͯ͠͸ɺ͜ͷఏҊ ͕AsyncSequenceΠϯλʔϑΣʔεͷ࣮૷Λαϙʔτ͢ΔͨΊͷ৽͍͠ܕΛ ௥Ճ͢Δɻ
29. SE-0314 Introductionͷ༁ • SE-0300Ͱ௥Ճ͞Εͨܧଓܕ͸ɺσϦήʔτϝιου΍ίʔϧόοΫؔ਺ͷݺ ͼग़͠ʹΑΓ׬ྃΛ௨஌͢Δಉظίʔυʹରͯ͠Ξμϓλʔͱͯ͠ػೳ͢Δɻ • ͦͷ୅ΘΓʹ࣌ؒͷܦաͰෳ਺ͷ஋Λੜ੒͢Δίʔυʹରͯ͠͸ɺ͜ͷఏҊ ͕AsyncSequenceΠϯλʔϑΣʔεͷ࣮૷Λαϙʔτ͢ΔͨΊͷ৽͍͠ܕΛ ௥Ճ͢Δɻ
30. ܧଓ……ʁ https://developer.apple.com/documentation/swift/withcheckedcontinuation(isolation:function:_:) func withCheckedContinuation<T>( isolation: isolated (any Actor)? = #isolation, function: String = #function, _ body: (CheckedContinuation<T, Never>) -> Void ) async -> sending T
31. Continuationͩʂ • withCheckedContinuation { continuation in } ͬͯ΍ͭ func withCheckedContinuation<T>( _ body: (CheckedContinuation<T, Never>) -> Void ) async -> sending T https://developer.apple.com/documentation/swift/withcheckedcontinuation(isolation:function:_:)
32. ܧଓ……ʁ class QuakeMonitor { var quakeHandler: ((Quake) -> Void)? func startMonitoring() { ... } func stopMonitoring() { ... } static var quakes: AsyncStream<Quake> { AsyncStream { continuation in let monitor = QuakeMonitor() monitor.quakeHandler = { quake in continuation.yield(quake) } continuation.onTermination = { @Sendable _ in monitor.stopMonitoring() } monitor.startMonitoring() } } } https://developer.apple.com/documentation/Swift/AsyncSequence
33. class QuakeMonitor { var quakeHandler: ((Quake) -> Void)? func startMonitoring() { ... } func stopMonitoring() { ... } static var quakes: AsyncStream<Quake> { AsyncStream { continuation in let monitor = QuakeMonitor() monitor.quakeHandler = { quake in continuation.yield(quake) } continuation.onTermination = { @Sendable _ in monitor.stopMonitoring() } monitor.startMonitoring() } } } AsyncStream { continuation in continuation.yield(quake) continuation.onTermination = { } } Continuationͩʂ https://developer.apple.com/documentation/Swift/AsyncSequence AsyncStream.Continuation
34. AsyncStream.Continuation • ಉظίʔυͱඇಉظίʔυؒΛ݁ͼ͚ͭΔػߏɻ • init(_:bufferingPolicy:_:)ͰAsyncStreamʹ౉ͨ͠Ϋϩʔδϟ͸ɺ ݺͼग़͞ΕΔͱ͜ͷܕͷΠϯελϯεΛड͚औΔɻ͜ͷܧଓΛ࢖ͬͯɺyield ϝιουͷ͍ͣΕ͔ΛݺͿ͜ͱͰετϦʔϜʹཁૉΛ౉͠ɺfinish()ϝιο υΛݺͿ͜ͱͰετϦʔϜΛਖ਼ৗʹऴྃ͢Δɻ • SwiftͷଞͷܧଓͱҟͳΓɺAsyncStream.Continuation͸ΤεέʔϓΛα ϙʔτ͢Δɻ https://developer.apple.com/documentation/swift/asyncstream/continuation
35. AsyncSequenceͱAsyncStreamͷཱͪҐஔ 1. Swiftʹඇಉظؔ਺Λಋೖ͠ɺ୯Ұͷ஋ΛฦͤΔΑ͏ʹ͢ΔʢSE-0296ʣ 2. SwiftʹAsyncSequenceΛಋೖ͠ɺ࣌ؒܦաͰෳ਺ͷ஋ΛฦͤΔΑ͏ʹ͢ΔʢSE-0298ʣ 3. withCheckedContinuationʢSE-0300ʣ͸1౓͚ͩ׬ྃΛ௨஌͠ɺ
 ಉظؔ਺ͱඇಉظؔ਺ͷڮ౉͠Λ୲͏ • ͦΕΛ࣮ݱ͢ΔͨΊʹܧଓΛ࢖͍ͬͯΔ 4. AsyncStreamʢSE-0314ʣ͸ෳ਺ճʹΘͨͬͯ஋Λ௨஌͠ɺ
 ಉظؔ਺ͱඇಉظؔ਺ͷڮ౉͠Λ୲͏ • ͦΕΛ࣮ݱ͢ΔͨΊʹܧଓͱAsyncSequenceΛ࢖͍ͬͯΔ
36. AsyncSequenceͱAsyncStreamͷཱͪҐஔ 1. Swiftʹඇಉظؔ਺Λಋೖ͠ɺ୯Ұͷ஋ΛฦͤΔΑ͏ʹ͢ΔʢSE-0296ʣ 2. SwiftʹAsyncSequenceΛಋೖ͠ɺ࣌ؒܦաͰෳ਺ͷ஋ΛฦͤΔΑ͏ʹ͢ΔʢSE-0298ʣ 3. withCheckedContinuationʢSE-0300ʣ͸1౓͚ͩ׬ྃΛ௨஌͠ɺ
 ಉظؔ਺ͱඇಉظؔ਺ͷڮ౉͠Λ୲͏ • ͦΕΛ࣮ݱ͢ΔͨΊʹܧଓΛ࢖͍ͬͯΔ 4. AsyncStreamʢSE-0314ʣ͸ෳ਺ճʹΘͨͬͯ஋Λ௨஌͠ɺ
 ಉظؔ਺ͱඇಉظؔ਺ͷڮ౉͠Λ୲͏ • ͦΕΛ࣮ݱ͢ΔͨΊʹܧଓͱAsyncSequenceΛ࢖͍ͬͯΔ
37. AsyncStreamΛ࡞Δํ๏ʢ࠶ܝʣ • init(_:bufferingPolicy:_:) 👈 ܧଓΛ࢖͏ • init(unfolding:onCancel:) • makeStream(of:bufferingPolicy:) 👈 SE-0388Ͱޙ͔Β௥Ճ
38. AsyncStreamΛ࡞Δํ๏ʢ࠶ܝʣ • init(_:bufferingPolicy:_:) 👈 ܧଓΛ࢖͏ • init(unfolding:onCancel:) • makeStream(of:bufferingPolicy:) 👈 SE-0388Ͱޙ͔Β௥Ճ
39. init(unfolding:onCancel:) • () async -> Element?Λड͚औͬͯޙ͸Α͠ͳʹ΍ͬͯ͘ΕΔ΍ͭ • ͜ͷΠχγϟϥΠβ͸ΫϩʔδϟΛ”ల։”ͯ͠ඇಉظετϦʔϜʹ͢Δɻ࡞੒ ͞ΕͨετϦʔϜ͸ɺऴྃॲཧʢΩϟϯηϧ͢Δ͔൓෮ॲཧͷऴྃͷͨΊʹ Ϋϩʔδϟ͔ΒnilΛฦ͢ʣ΋ؚΊͯAsyncSequenceϓϩτίϧ΁ࣗಈతʹ ४ڌ͢Δɻ https://developer.apple.com/documentation/swift/asyncstream/init(unfolding:oncancel:)
40. init(unfolding:onCancel:) • () async -> Element?Λड͚औͬͯޙ͸Α͠ͳʹ΍ͬͯ͘ΕΔ΍ͭ • ͜ͷΠχγϟϥΠβ͸ΫϩʔδϟΛ”ల։”ͯ͠ඇಉظετϦʔϜʹ͢Δɻ࡞੒ ͞ΕͨετϦʔϜ͸ɺऴྃॲཧʢΩϟϯηϧ͢Δ͔൓෮ॲཧͷऴྃͷͨΊʹ Ϋϩʔδϟ͔ΒnilΛฦ͢ʣ΋ؚΊͯAsyncSequenceϓϩτίϧ΁ࣗಈతʹ ४ڌ͢Δɻ https://developer.apple.com/documentation/swift/asyncstream/init(unfolding:oncancel:) unfold
41. Haskellͷunfolding • unfoldr :: (b -> Maybe (a, b)) -> b -> [a] • SwiftͰॻ͘ͱ
 func unfoldr<T, U>(f: (U) -> (T, U)?, seed: U) -> [T] • SwiftͬΆ͘આ໌͢Δͱ
 Ϋϩʔδϟ͸γʔυ஋seedΛड͚औΓɺArrayͷੜ੒͕׬͍ྃͯ͠Ε͹nil Λฦ͢ɻͦ͏Ͱͳ͚Ε͹(t, u)Λฦ͠ɺt͸Arrayͷઌ಄ʹ௥Ճ͞Εɺu͸࣍ ͷ࠶ؼݺͼग़͠Ͱ࢖͏γʔυ஋ͱͳΔɻ • c.f. HaskellͷfoldrɺSwiftͷreduce(_:_:) https://hackage.haskell.org/package/base-4.21.0.0/docs/Data-List.html#v:unfoldr
42. AsyncStreamΛ࡞Δํ๏ʢ࠶ܝʣ • init(_:bufferingPolicy:_:) 👈 ܧଓΛ࢖͏ • init(unfolding:onCancel:) 👈 ΫϩʔδϟΛ”ల։”͢Δ • makeStream(of:bufferingPolicy:) 👈 SE-0388Ͱޙ͔Β௥Ճ
43. ײ૝ • SE-0300ΛಡΜͩ΄͏͕ͨΊʹͳΓͦ͏ • ݁ߏڍಈ͕΍΍͍͜͠Β͍͠ɻɻ • ͜Μͳਓʹ͓͢͢Ί • Continuation͕޷͖ͳਓ • AsyncStreamΛ࢖͍͗ͯ͢ເʹग़͖ͯͨਓ https://zenn.dev/kntk/articles/0001fdd2a4f76d
44. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences ✅ • SE-0314 AsyncStream and AsyncThrowingStream ✅ • SE-0388 Convenience Async[Throwing]Stream.makeStream methods • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
45. SE-0388 Convenience Async[Throwing]Stream.makeStream methods
46. SE-0388 • https://github.com/swiftlang/swift-evolution/blob/main/proposals/0388- async-stream-factory.md • Swift 5.9ʢ2023೥ʣ • iOS 13.0΁ͷόοΫϙʔτ͋Γ • AsyncStreamͷmakeStream(of:bufferingPolicy:)ͷ࿩ https://developer.apple.com/documentation/swift/asyncstream/makestream(of:bu ff eringpolicy:)
47. ͜Εͷ͜ͱͰ͢ʂ let (stream, continuation) = AsyncStream.makeStream(of: Int.self) await withTaskGroup(of: Void.self) { group in group.addTask { for i in 0...9 { continuation.yield(i) } continuation.finish() } group.addTask { for await i in stream { print(i) } } } ͜Ε
48. SE-0388ϨϏϡʔʢʁʣ ೉қ౓ ˒ˑˑˑˑ ʢAsyncʣStreamΛ࢖ͬͨ͜ͱ͕͋Ε͹ಡΊΔ CS஌ࣝෆཁ ௕͞ ˒ˑˑˑˑ .md্Ͱ͸164ߦ ͢ʙʙʙͬ͘͝୹͍ʂ ॏཁ౓ ˒ˑˑˑˑ ͋Μ·Γɻɻ
49. class QuakeMonitor { var quakeHandler: ((Quake) -> Void)? func startMonitoring() { ... } func stopMonitoring() { ... } static var quakes: AsyncStream<Quake> { AsyncStream { continuation in let monitor = QuakeMonitor() monitor.quakeHandler = { quake in continuation.yield(quake) } continuation.onTermination = { @Sendable _ in monitor.stopMonitoring() } monitor.startMonitoring() } } } AsyncStream { continuation in continuation.yield(quake) continuation.onTermination = { } } Continuationͩʂʢ࠶ʣ https://developer.apple.com/documentation/Swift/AsyncSequence
50. AsyncStream.Continuationʢ࠶ʣ • ಉظίʔυͱඇಉظίʔυؒΛ݁ͼ͚ͭΔػߏɻ • init(_:bufferingPolicy:_:)ͰAsyncStreamʹ౉ͨ͠Ϋϩʔδϟ͸ɺ ݺͼग़͞ΕΔͱ͜ͷܕͷΠϯελϯεΛड͚औΔɻ͜ͷܧଓΛ࢖ͬͯɺyield ϝιουͷ͍ͣΕ͔ΛݺͿ͜ͱͰετϦʔϜʹཁૉΛ౉͠ɺfinish()ϝιο υΛݺͿ͜ͱͰετϦʔϜΛਖ਼ৗʹऴྃ͢Δɻ • SwiftͷଞͷܧଓͱҟͳΓɺAsyncStream.Continuation͸ΤεέʔϓΛα ϙʔτ͢Δɻ https://developer.apple.com/documentation/swift/asyncstream/continuation
51. ࣮͸Ϋϩʔδϟͷ֎ʹऔΓग़ͤͪΌ͏ͷͰ͢ʂ • ݟͨ໨ʹ൓͢Δ • ͔͠΋ͳΜ͔μα͍ var continuation: AsyncStream<Int>.Continuation! AsyncStream<Int> { continuation = $0 } continuation.finish()
52. ετϦʔϜͱܧଓͷ྆ํΛฦ͢ʂ let (stream, continuation) = AsyncStream.makeStream(of: Int.self) await withTaskGroup(of: Void.self) { group in group.addTask { for i in 0...9 { continuation.yield(i) } continuation.finish() } group.addTask { for await i in stream { print(i) } } }
53. ؾʹͳΔ… let (stream, continuation) = AsyncStream.makeStream(of: Int.self) await withTaskGroup(of: Void.self) { group in group.addTask { for i in 0...9 { continuation.yield(i) } continuation.finish() } group.addTask { for await i in stream { print(i) } } } ໭Γ஋͕௝͘͠λϓϧ
54. ͳΜ͔ͷܕͰ͸ͳ͘λϓϧͰฦ͢ར఺ • ฦ٫͞ΕͨܕΛ෼ղ͢ΔΑ͏Ϣʔβʹଅ͢ɻ͜Ε͸ɺϓϩσϡʔαͱίϯ γϡʔϚ͕ͦΕͧΕܧଓͱετϦʔϜΛอ࣋͢΂͖ͳͷͰ๬·͍͜͠ͱͰ͋ Δɻ • ͜ͷϝιουΛόοΫσϓϩΠͰ͖Δɻ
55. ͦΕͧΕߦ͖ઌ͕ҧ͏ʂ let (stream, continuation) = AsyncStream.makeStream(of: Int.self) await withTaskGroup(of: Void.self) { group in group.addTask { for i in 0...9 { continuation.yield(i) } continuation.finish() } group.addTask { for await i in stream { print(i) } } } ܧଓ͸producer͕࢖͏ ετϦʔϜ͸consumer͕࢖͏
56. makeStream΋iOS 13.0+ https://developer.apple.com/documentation/swift/asyncstream/makestream(of:bu ff eringpolicy:)
57. Swift 5.5ʢ2021೥ʣͷࠒͷ৘੎ • ΄΅ಉ࣌ʹiOS 15.0͕ग़ͨ • ଟ෼ΈΜͳ3όʔδϣϯͿΜʢiOS 13.0·Ͱʣ͘Β͍Λαϙʔτͯ͠Δ • جຊతʹ͸৽API͕ग़ͯ΋աڈόʔδϣϯͷαϙʔτΛ΍ΊΔ·Ͱ࢖͑ͳ͍ Swift Concurrency͕iOS 13.0Ͱ΋࢖͑Ε͹ϋοϐʔʂʂʂʂʂ όοΫϙʔτ͞ΕΕ͹
58. όοΫϙʔτ͞Εͨྫ • Swift Concurrency • viewIsAppearing(_:) • ͱ͔ • ৄ͘͠͸ڈ೥ͷiOSDC Japanͷauramagi͞ΜͷൃදΛ͝ཡ͍ͩ͘͞ https://fortee.jp/iosdc-japan-2024/proposal/f30647c8-dd78-4853-8718-7bcb856b1239
 https://www.docswell.com/s/usami-k/5M1P4L-uiviewcontroller-viewisappearing
59. ೥ද • 2021೥9݄ Swift 5.5ͰSwift ConcurrencyσϏϡʔ • 2021೥12݄ Xcode 13.2ͰSwift Concurrency͕iOS 13.0΁όοΫϙʔτ͞ΕΔ • 2023೥3݄ Swift 5.8Ͱ@backDeployed͕௥Ճ͞ΕΔ • 2023೥9݄ Swift 5.9ͰmakeStream͕௥Ճ͞ΕΔɺόοΫσϓϩΠ΋͞ΕΔ https://speakerdeck.com/satotakeshi/swift-concurrencyru-men
 https://team-blog.mitene.us/%E5%AE%B6%E6%97%8F%E3%82%A2%E3%83%AB%E3%83%90%E3%83%A0-%E3%81%BF%E3%81%A6%E3%81%AD-%E3%81%ABswift- concurrency%E3%82%92%E5%B0%8E%E5%85%A5%E3%81%97%E3%81%BE%E3%81%97%E3%81%9F-1bafc45ab3f3
60. ೥ද • 2021೥9݄ Swift 5.5ͰSwift ConcurrencyσϏϡʔ • 2021೥12݄ Xcode 13.2ͰSwift Concurrency͕iOS 13.0΁όοΫϙʔτ͞ΕΔ • 2023೥3݄ Swift 5.8Ͱ@backDeployed͕௥Ճ͞ΕΔ • 2023೥9݄ Swift 5.9ͰmakeStream͕௥Ճ͞ΕΔɺόοΫσϓϩΠ΋͞ΕΔ https://speakerdeck.com/satotakeshi/swift-concurrencyru-men
 https://team-blog.mitene.us/%E5%AE%B6%E6%97%8F%E3%82%A2%E3%83%AB%E3%83%90%E3%83%A0-%E3%81%BF%E3%81%A6%E3%81%AD-%E3%81%ABswift- concurrency%E3%82%92%E5%B0%8E%E5%85%A5%E3%81%97%E3%81%BE%E3%81%97%E3%81%9F-1bafc45ab3f3 👇ʁʁʁʁʁ👆
61. όοΫϙʔτʁόοΫσϓϩΠʁ • ຊൃදͰ͸ҎԼͷΑ͏ʹఆΊ·͢ • όοΫϙʔτɿݹ͍OSͰ΋৽ػೳ͕࢖͑Δͱ͍͏͜ͱɺͦͯ͠ख๏શൠ • όοΫσϓϩΠɿ@backDeployedʹΑΔόοΫϙʔτ
62. ೥ද • 2021೥9݄ Swift 5.5ͰSwift ConcurrencyσϏϡʔ • 2021೥12݄ Xcode 13.2ͰSwift Concurrency͕iOS 13.0΁όοΫϙʔτ͞ΕΔ • 2023೥3݄ Swift 5.8Ͱ@backDeployed͕௥Ճ͞ΕΔʢSE-0376ʣ • 2023೥9݄ Swift 5.9ͰmakeStream͕௥Ճ͞ΕΔɺόοΫσϓϩΠ΋͞ΕΔ https://speakerdeck.com/satotakeshi/swift-concurrencyru-men
 https://team-blog.mitene.us/%E5%AE%B6%E6%97%8F%E3%82%A2%E3%83%AB%E3%83%90%E3%83%A0-%E3%81%BF%E3%81%A6%E3%81%AD-%E3%81%ABswift- concurrency%E3%82%92%E5%B0%8E%E5%85%A5%E3%81%97%E3%81%BE%E3%81%97%E3%81%9F-1bafc45ab3f3
63. @backDeployed͕͍Δʂ https://developer.apple.com/documentation/swift/asyncstream/init(_:bu ff eringpolicy:_:)
 https://developer.apple.com/documentation/swift/asyncstream/makestream(of:bu ff eringpolicy:)
64. Ͱɺ@backDeployed͕Կͩͬͯʁ • چOSʹଘࡏ͠ͳ͍ؔ਺Λίϐʔ͖ͯͯ͠࢖͑ΔΑ͏ʹ͢Δ࢓૊Έ • makeStreamͷ໭Γ஋Λ৽نͷܕʹ͢Δͱɺ@backDeployedΛཔΕͳ͘ͳΔ struct ৽͍͠ܕ { var continuation: Continuation var stream: AsyncStream } @backDeployed(ུ) func makeStream() -> ৽͍͠ܕ // ແཧͦ͏
65. ͳΜ͔ͷܕͰ͸ͳ͘λϓϧͰฦ͢ར఺ • ฦ٫͞ΕͨܕΛ෼ղ͢ΔΑ͏Ϣʔβʹଅ͢ɻ͜Ε͸ɺϓϩσϡʔαͱίϯ γϡʔϚ͕ͦΕͧΕܧଓͱετϦʔϜΛอ࣋͢΂͖ͳͷͰ๬·͍͜͠ͱͰ͋ Δɻ • ͜ͷϝιουΛόοΫσϓϩΠͰ͖Δɻ
66. ײ૝ • ໘ന͍ͱ͸ࢥ͏ • ஌ͬͯͯ໾ʹཱ͔ͭͱ͍͏ͱɾɾ • ͜Μͳਓʹ͓͢͢Ί • Continuation͸޷͖͚ͩͲΫϩʔδϟ͸ͳ͍͍͔ͯ͘ͳͬͯਓ
67. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences ✅ • SE-0314 AsyncStream and AsyncThrowingStream ✅ • SE-0388 Convenience Async[Throwing]Stream.makeStream methods ✅ • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
68. SE-0421 Generalize effect polymorphism for AsyncSequence and AsyncIteratorProtocol
69. SE-0421 • https://github.com/swiftlang/swift-evolution/blob/main/proposals/0421- generalize-async-sequence.md • Swift 6.0ʢ2024೥ʣ • Throwsͱisolationͷ؍఺ͰAsyncSequenceΛվྑͨ͠΍ͭ • ຊ೔ͷڧఢ
70. ͜Ε͕૿͑·ͨ͠ʂ protocol AsyncIteratorProtocol<Element, Failure> { associatedtype Failure: Error = any Error mutating func next( isolation actor: isolated (any Actor)? ) async throws(Failure) -> Element? }
71. SE-0421ϨϏϡʔʢʁʣ ೉қ౓ ˒˒˒ˑˑ ཁٻ͞ΕΔSwiftͷ஌͕ࣝଟ͍ ௕͞ ˒ˑˑˑˑ .md্Ͱ͸271ߦ ॻ͍ͯ͋Δ಺༰ࣗମ͸؆ܿ ॏཁ౓ ˒ˑˑˑˑ ஌Βͳͯ͘΋Αͦ͞͏
72. SE-0421ͷ͓΋͠ΖτϐοΫ • AsyncSequenceͱprimary associated type • AsyncIteratorProtocolͱ@rethrows • AsyncIteratorProtocolͱisolation
73. SE-0421ͷ͓΋͠ΖτϐοΫ • AsyncSequenceͱprimary associated type • AsyncIteratorProtocolͱ@rethrows • AsyncIteratorProtocolͱisolation
74. ͜Εͷ͜ͱͰ͢ʂʢ࠶ʣ protocol AsyncIteratorProtocol<Element, Failure> { associatedtype Failure: Error = any Error mutating func next( isolation actor: isolated (any Actor)? ) async throws(Failure) -> Element? }
75. SE-0346ʢSwift 5.7ʣͰॻ͚ΔΑ͏ʹͳͬͨ protocol AsyncIteratorProtocol<Element, Failure> { associatedtype Failure: Error = any Error }
76. Primary associated typeͰͰ͖Δ͜ͱ • 👇͕࣮૷Ͱ͖Δ extension AsyncSequence { public func map<Transformed>( _ transform: @Sendable @escaping (Element) async throws -> Transformed ) -> some AsyncSequence<Transformed, any Error> { ... } } ΊͬͪΌmap΍ fi lterΛͯ͠΋ೖΕࢠʹͳΒͳ͍🎉 ※ඪ४ϥΠϒϥϦͷmap(_:)ͷ໭Γ஋ͷܕ͸૬มΘΒͣAsyncThrowingMapSequence ࣗ෼Ͱsome AsyncSequenceʹ͠Α͏ʂ
77. Primary associated typeಋೖ࡞ۀ • @rethrowsʢ👈୭͓ͩલʣͷ࢖༻Λ΍Ί·͢
78. SE-0421ͷ͓΋͠ΖτϐοΫ • AsyncSequenceͱprimary associated type ✅ • AsyncIteratorProtocolͱ@rethrows • AsyncIteratorProtocolͱisolation
79. AsyncIteratorProtocolͱthrow • next()͸ྫ֎Λ౤͛͏Δ͕ɺඞཁͳ͍΋ͷʹ·ͰtryΛॻ͘ͷ͸ͩΔ͍ • ίϯύΠϥ͕ඞཁͰͳ͍͜ͱΛݕ஌͢Ε͹ɺলུΛೝΊΒΕΔ for try await value in throwingAsyncSequence { } for await value in nonThrowingAsyncSequence { } ͍Δ ͍Βͳ͍
80. ίϯύΠϥ͕ݕ஌͢Δํ๏ • AsyncSequence΍AsyncSequenceIteratorࣗମʹ@rethrows͕͍ͭͯͨ • աڈܗ @rethrows public protocol AsyncSequence { @rethrows public protocol AsyncIteratorProtocol { https://github.com/swiftlang/swift/blob/9067148bc9c9a72730dbeebef32965b3aaeb34fb/stdlib/public/Concurrency/AsyncSequence.swift#L75-L76
 https://github.com/swiftlang/swift/blob/9067148bc9c9a72730dbeebef32965b3aaeb34fb/stdlib/public/Concurrency/AsyncIteratorProtocol.swift#L90-L91
81. @rethrows protocol • Experimental featureʢͩͬͨΒ͍͠ʣ • some AsyncSequenceͱซ༻͍͕ͨͦ͠͏͢Δͱ@rethrows͕ػೳ͠ͳ͍ • ͳͷͰSwift 6.0͔Β@rethrowsΛ࢖͏ͷΛ΍ΊͨͬΆ͍ • ৄ͘͠͸Point-Freeͷهࣄɺ΋͘͠͸ڈ೥ͷtreastrain͞Μͷൃද https://github.com/swiftlang/swift/commit/bb7a563e6c7756dc6c3c910db7ecacab2e1698b7
 https://fortee.jp/iosdc-japan-2024/proposal/c0c62dc1-992c-4d9f-8812-02994593d96c
 https://www.pointfree.co/blog/posts/73-parser-errors
82. SE-0421ͷ͓΋͠ΖτϐοΫ • AsyncSequenceͱprimary associated type ✅ • AsyncIteratorProtocolͱ@rethrows ✅ • AsyncIteratorProtocolͱisolation
83. AsyncIteratorProtocolͱisolation ʢ5.9ҎԼͷ࣌ʣ • next()͸nonisolatedͳͷͰִ཭͞Εͨॴ͔Β࢖͏ͱ͍Ζ͍ΖڥքΛӽ͑Δ • ໭Γ஋Ͱ͋ΔElement͕ڥքΛӽ͑Δ • Element͕ඇSendableͳ࣌ʹcheckʹҾ͔͔ͬΔ • AsyncIteratorProtocolࣗ਎΋ڥքΛӽ͑Δ • ΠςϨʔλ͕ඇSendableͳ࣌ʹcheckʹҾ͔͔ͬΔ
84. ӽ͑Δͱ͖ͬͯͲΜͳͱ͖ @MainActor func iterate(over stream: AsyncStream<Int>) async { var iterator = stream.makeAsyncIterator() while let element = await iterator.next() { // do something with 'element' } } https://github.com/swiftlang/swift-evolution/blob/main/proposals/0420-inheritance-of-actor-isolation.md
85. ӽ͑Δͱ͖ͬͯͲΜͳͱ͖ @MainActor func iterate(over stream: AsyncStream<Int>) async { var iterator = stream.makeAsyncIterator() while let element = await iterator.next() { // do something with 'element' } } warning:
 passing argument of non-sendable type 'inout AsyncStream<Int>.Iterator'
 outside of main actor-isolated context may introduce data races https://github.com/swiftlang/swift-evolution/blob/main/proposals/0420-inheritance-of-actor-isolation.md
86. ӽ͑Δͱ͖ͬͯͲΜͳͱ͖ @MainActor func iterate(over stream: AsyncStream<Int>) async { var iterator = stream.makeAsyncIterator() while let element = await iterator.next() { // do something with 'element' } } ؔ਺ࣗମ͸MainActorʹִ཭͞ΕͯΔ ͍ͭ͜͸nonisolated https://github.com/swiftlang/swift-evolution/blob/main/proposals/0420-inheritance-of-actor-isolation.md
87. ӽ͑Δͱ͖ͬͯͲΜͳͱ͖ @MainActor func iterate(over stream: AsyncStream<Int>) async { var iterator = stream.makeAsyncIterator() while let element = await iterator.next() { // do something with 'element' } } next()ͷҾ਺ͱ໭Γ஋Ͱ͋Δ͜ͷ2ͭ͸ڥքΛӽ͑Δ͜ͱʹͳΔ https://github.com/swiftlang/swift-evolution/blob/main/proposals/0420-inheritance-of-actor-isolation.md
88. AsyncIteratorProtocolͱisolation ʢ5.10ҎԼͷ࣌ʣ • next()͸nonisolatedͳͷͰִ཭͞Εͨॴ͔Β࢖͏ͱ͍Ζ͍ΖڥքΛӽ͑Δ • ໭Γ஋Ͱ͋ΔElement͕ڥքΛӽ͑Δ • Element͕ඇSendableͳ࣌ʹcheckʹҾ͔͔ͬΔ • AsyncIteratorProtocolࣗ਎΋ڥքΛӽ͑Δ • ΠςϨʔλ͕ඇSendableͳ࣌ʹcheckʹҾ͔͔ͬΔ ݩڟ
89. AsyncIteratorProtocolͱisolation ʢ6.0Ҏ্ͷ࣌ʣ • #isolationΛड͚औΕΔΑ͏ͳnextϝιου͕͋Δ • func next(isolation actor: isolated (any Actor)?) • SE-0414 Region based isolationͷ໊લ͕ग़͍ͯΔ͕ɺ
 SE-0414͕͜ͷ໰୊Λղܾ͍ͯ͠ΔΘ͚Ͱ͸ͳ͍ɾɾͱࢥ͏ next(isolation: #isolation)Λۦ࢖͢Δ͜ͱͰɺRegion based isolationΛՃຯͨ͠ݱࡏͷconcurrency checkΛύε͠Α͏ͶɺͱಡΊͳ͍͜ͱ΋ͳ͍
90. AsyncIteratorProtocolͱisolation ʢ6.0Ҏ্ͷ࣌ʣ • #isolationΛड͚औΕΔΑ͏ͳnextϝιου͕͋Δ • func next(isolation actor: isolated (any Actor)?) • SE-0414 Region based isolationͷ໊લ͕ग़͍ͯΔ͕ɺ
 SE-0414͕͜ͷ໰୊Λղܾ͍ͯ͠ΔΘ͚Ͱ͸ͳ͍ɾɾͱࢥ͏ next(isolation: #isolation)Λۦ࢖͢Δ͜ͱͰɺRegion based isolationΛՃຯͨ͠ݱࡏͷconcurrency checkΛύε͠Α͏ͶɺͱಡΊͳ͍͜ͱ΋ͳ͍ SE-0313ʢSwift 5.5ʣ͔Β͋Δ
91. AsyncIteratorProtocolͱisolation ʢ6.0Ҏ্ͷ࣌ʣ • #isolationΛड͚औΕΔΑ͏ͳnextϝιου͕͋Δ • func next(isolation actor: isolated (any Actor)?) • SE-0414 Region based isolationͷ໊લ͕ग़͍ͯΔ͕ɺ
 SE-0414͕͜ͷ໰୊Λղܾ͍ͯ͠ΔΘ͚Ͱ͸ͳ͍ɾɾͱࢥ͏ next(isolation: #isolation)Λۦ࢖͢Δ͜ͱͰɺRegion based isolationΛՃຯͨ͠ݱࡏͷconcurrency checkΛύε͠Α͏ͶɺͱಡΊͳ͍͜ͱ΋ͳ͍ non-isolatedΛදݱ͢ΔͨΊʹඞཁ ݺͼग़͠ଆͷִ཭
92. SE-0421ͷ͓΋͠ΖτϐοΫ • AsyncSequenceͱprimary associated type ✅ • AsyncIteratorProtocolͱ@rethrows ✅ • AsyncIteratorProtocolͱisolation ✅
93. Ͱɺpolymorphism͕ͳΜͩͬͯʁ • Polymorphismͷجຊతͳҙຯ͸ɺʮ1 ͭͷؔ਺ (͋Δ͍͸ϝιουɺࣜͳͲ) ͕ɺ༷ʑͳܕΛ΋ͭҾ਺ʹద༻Ͱ͖Δʯͱ͍͏ҙຯ by ஜ೾େֶतۀ https://www.cs.tsukuba.ac.jp/~kam/lecture/plm2010/12.pdf protocol AsyncIteratorProtocol<Element, Failure> { associatedtype Failure: Error = any Error mutating func next( isolation actor: isolated (any Actor)? ) async throws(Failure) -> Element? }
94. ײ૝ • Swift 6.0ɺΠϚυΩ͔ͬͯΜ͡ʙ • Swift 6Λཧղ͢Δඞཁ͸ʢଟ෼ʣ͋Δ͕͜Ε͡Όͳͯ͘SE-0420ΛಡΉ΂͖ • ͜Μͳਓʹ͓͢͢Ί • ࣗ෼ͷSwift 6΁ͷཧղྗΛࢼ͍ͨ͠ਓ
95. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences ✅ • SE-0314 AsyncStream and AsyncThrowingStream ✅ • SE-0388 Convenience Async[Throwing]Stream.makeStream methods ✅ • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol ✅ • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
96. SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation
97. ContinuationʹHashableΛ͚ͭͨΑɻ @available(SwiftStdlib 6.2, *) extension AsyncStream.Continuation: Hashable { https://github.com/swiftlang/swift/blob/b916be3b6270cf844075ca9ac4ed1a015334b6b5/stdlib/public/Concurrency/AsyncStream.swift#L478-L479 EquatableͰ΋͋Δ
98. SE-0468ϨϏϡʔʢʁʣ ೉қ౓ ˒ˑˑˑˑ લఏ஌͕ࣝͱͯ΋͍Βͳ͍ ௕͞ ˒ˑˑˑˑ .md্Ͱ͸130ߦ
 ͱʙʙʙͬͯ΋୹͍ʂ ॏཁ౓ ˒ˑˑˑˑ ಛචࣄ߲ͳ͠
99. SE-0468 Motivationͷ༁ʢൈਮʣ • ෳ਺ͷAsyncStreamΛૢ࡞͢ΔϢʔεέʔεͰ͸ɺෳ਺ͷܧଓΛอ࣋͢Δඞ ཁ͕͋Δ͔΋͠Εͳ͍ɻ • ؔ࿈͢ΔܧଓΛಛఆ͢ΔͨΊɺΫϥΠΞϯτίʔυ͸ܧଓಉ࢜ΛൺֱͰ͖Δ ඞཁ͕͋Δɻ
100. αϯϓϧίʔυ var value: Int = 0 { didSet { for c in continuations { c.yield(value) } } } var values: some AsyncSequence<Int, Never> { AsyncStream<Int>(bufferingPolicy: .bufferingNewest(1)) { continuation in continuation.yield(value) self.continuations.insert(continuation) continuation.onTermination = { _ in DispatchQueue.main.async { self.continuations.remove(continuation) } } } } private var continuations: Set<AsyncStream<Int>.Continuation> = []
101. αϯϓϧίʔυ var value: Int = 0 { didSet { for c in continuations { c.yield(value) } } } var values: some AsyncSequence<Int, Never> { AsyncStream<Int>(bufferingPolicy: .bufferingNewest(1)) { continuation in continuation.yield(value) self.continuations.insert(continuation) continuation.onTermination = { _ in DispatchQueue.main.async { self.continuations.remove(continuation) } } } } private var continuations: Set<AsyncStream<Int>.Continuation> = [] where Element: Hashable
102. ContinuationΛͲ͏΍ͬͯHashableʹ͢Δͷ • Continuationͷத਎͸class _StorageͳͷͰ͍ͦͭΛ࢖͏ • static func == (Self, Self) -> Bool • _StorageͷಉҰੑΛݟΕ͹OK • func hash(into: inout Hasher) • ObjectIdentifier(storage)ΛࠞͥΕ͹OK https://github.com/swiftlang/swift/blob/8c1cc1b78a7bd4b46d53706e92ab864c25f09f04/stdlib/public/Concurrency/AsyncStream.swift#L478-L492
103. ײ૝ • ͦ͏Ͱ͢Ͷ
104. ΍͍ͬͯͥ͘ʂ • SE-0298 Async/Await: Sequences ✅ • SE-0314 AsyncStream and AsyncThrowingStream ✅ • SE-0388 Convenience Async[Throwing]Stream.makeStream methods ✅ • SE-0421 Generalize e ff ect polymorphism for AsyncSequence and AsyncIteratorProtocol ✅ • SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation ✅
105. ·ͱΊ
106. ࠓճొ৔ͨ͠օ͞Μ • A
107. ײ૝ • ͜ΕΒͷϓϩϙʔβϧΛಡΉඞཁ͸ͳ͍Ͱ͢ • جຊతʹ͸௥Ճ͞ΕΔϝιουͷҰཡ͕ࡌͬͯΔ͚ͩͳͷͰ… • AsyncSequence΍AsyncStreamͷڍಈʹ͍ͭͯ͸Կ΋৮ΕΒΕͯͳ͍ • ֤छݴޠػೳͷཱ೿ͳ࢖༻ྫͰ͸͋Δ