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Swift async/await Λࢧ͑Δ
Ϟφυɺܧଓɺ
ίϧʔνϯ
2021/09/18 iOSDC Japan 2021
Yasuhiro Inami / @inamiy
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No content
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ඇಉظܭࢉ
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ίʔϧόοΫํࣜʹΑΔඇಉظܭࢉ
func fetch(
request: Request,
completion: @escaping (Result) -> Void
) {
let task = URLSession.shared
.dataTask(with: request) { data, response, error in
if let error = error { completion(.failure(error)) }
decode(data, completion: { response in
completion(.success(response))
})
}
task.resume()
}
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ίʔϧόοΫࠈ
fetch1(request1) { response1 in
fetch2(response1) { response2 in
fetch3(response2) { response3 in
fetch4(response3) { response4 in
fetch5(response4) { response5 in
print(response5)
}
}
}
}
}
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ϦΞΫςΟϒɾϓϩάϥϛϯάʹΑΔඇಉظܭࢉ
func fetch(request: Request) -> Observable {
Observable.create { completion in
let task = URLSession.shared
.dataTask(with: request) { data, response, error in
if let error = error { completion(.failure(error)) }
decode(data, completion: { response in
completion(.success(response))
})
}
task.resume()
return Disposables.create { task.cancel() }
}
}
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qBU.BQʹΑΔϝιουνΣʔϯʢࠈʁʣ
fetch1(request1)
.flatMap { response1 in fetch2(response1) }
.flatMap { response2 in fetch3(response2) }
.flatMap { response3 in fetch4(response3) }
.flatMap { response4 in fetch5(response4) }
.subscribe(onNext: { response5 in
print(response5)
})
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BTZODBXBJUʹΑΔඇಉظܭࢉ
func fetch(request: Request) async throws -> Response {
let (data, _)
= try await URLSession.shared.data(with: request)
return try JSONDecoder()
.decode(Response.self, from: data)
}
BTZODΩʔϫʔυ
BXBJUΩʔϫʔυͰ
ඇಉظܭࢉΛͭ
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BTZODBXBJUʹΑΔʮखଓ͖ܕϓϩάϥϛϯάʯ
Task.detached {
let response1 = try await fetch1(request1)
let response2 = try await fetch2(response1)
let response3 = try await fetch3(response2)
let response4 = try await fetch4(response3)
let response5 = try await fetch5(response4)
print(response5)
}
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ඇಉظܭࢉ͍Ζ͍Ζ
wίʔϧόοΫํࣜ
w1SPNJTF'VUVSFɺϦΞΫςΟϒɾϓϩάϥϛϯά
wBTZODBXBJU खଓ͖
࣮ͲΕಉ͡Α͏ͳͷͱΈͳͤΔʂ
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No content
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ؔܕϓϩάϥϛϯά
ࡾॐ࢜Λ࿈ΕͯདྷͨΑ
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୯ͳΔࣗݾؔखͷݍʹ͓͚Δ
ϞϊΠυରͩΑ
ܧଓJTύϫʔ
ڠௐతͳൃදΛࢦͯ͠
͕ΜΓ·͢
Ϟφυ
ܧଓ
ίϧʔνϯ
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୯ͳΔࣗݾؔखͷݍʹ͓͚Δ
ϞϊΠυରͩΑ
ܧଓJTύϫʔ
ڠௐతͳൃදΛࢦͯ͠
͕ΜΓ·͢
Ϟφυ
ܧଓ
ίϧʔνϯ
ʲ͓அΓʳ
ٙࣅ4XJGUίʔυΛ͍·͢
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Ϟφυ
Monad ! ju" a monoid in # category of endofunctors
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J04%$
ݍͱ4XJGUͷԠ༻
IUUQTTQFBLFSEFDLDPNJOBNJZJPTEDKBQBO
ϓϩάϥϚͷͨΊͷݍษڧձ
ϓϩάϥϚͷͨΊͷϞφυ ݍ
IUUQTTQFBLFSEFDLDPNJOBNJZOVNCFSDBUQH
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Ϟφυ J04%$ΑΓ
protocol Monad[M] where Functor[M] {
static func unit(_ c: C) -> M
static func join(_ mmc: M>) -> M
}
extension Monad {
static func init_() -> M {
.unit(())
}
static func flatMap(_ f: C -> M)
-> M -> M {
return { .join(map(f)($0)) }
}
}
'VODUPS ؔख
ͷTVCQSPUPDPM
'VODUPSNBQΛ࣋ͭ
Ϟφυ͞Βʹ
VOJUPSJOJU@
KPJOPSqBU.BQ
Λ࣋ͭ
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Ϟφυͷྫɿ0QUJPOBM
enum Optional {
case none
case some(T)
init(_ some: T) // unit: T -> Optional
func map(_ transform: (T) -> U) -> U?
func flatMap(_ transform: (T) -> U?) -> U?
}
VOJU
NBQ
qBU.BQΛ࣋ͭͷͰɺ
0QUJPOBMϞφυ
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Ϟφυͷྫɿ"SSBZ
struct Array {
init() // init_: () -> Array
func map(_ transform: (T) -> U) -> [U]
func flatMap(_ transform: (T) -> [U]) -> [U]
}
JOJU@
NBQ
qBU.BQΛ࣋ͭͷͰɺ
"SSBZϞφυ
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Ϟφυͷྫɿ3Y0CTFSWBCMF
struct Observable {
// unit: T -> Observable
static func just(_ element: T)
func map(_ transform: (T) -> U)
-> Observable
func flatMap(_ transform: (T) -> Observable)
-> Observable
}
VOJU
NBQ
qBU.BQΛ࣋ͭͷͰɺ
0CTFSWBCMFϞφυ
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Ϟφυଇ
// ࠨ୯Ґݩ
unit(a).flatMap(f) == f(a)
// ӈ୯Ґݩ
monad.flatMap(unit) == monad
// ݁߹
monad.flatMap(f).flatMap(g)
== monad.flatMap { f($0).flatMap(g) }
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Ϟφυଇͷ݁߹
// ݁߹
monad
.flatMap(f)
.flatMap(g)
==
monad.flatMap {
f($0).flatMap(g)
}
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Ϟφυଇͷ݁߹
// ݁߹ͷࠨล
monad
.flatMap(f)
.flatMap(g)
.flatMap(h)
.flatMap(i)
.flatMap(j)
// ݁߹ͷӈล
monad.flatMap {
f($0).flatMap {
g($0).flatMap {
h($0).flatMap {
i($0).flatMap {
j($0)
}
}
}
}
}
==
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Ϟφυ
ίʔϧόοΫࠈΛ
ϝιουνΣʔϯʹม͢Δ
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qBU.BQνΣʔϯͷྫɿ0QUJPOBM$IBJOJOH
let monad: Optional = …
let bar = monad?.is?.just?.a?.monoid
monad
?.is
?.just
?.a
?.monoid
monad
.flatMap { $0.is }
.flatMap { $0.just }
.flatMap { $0.a }
.flatMap { $0.monoid }
==
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qBU.BQνΣʔϯͷྫɿ0QUJPOBM$IBJOJOH
monad
?.is
?.just
?.a
?.monoid
monad
.flatMap(\.is)
.flatMap(\.just)
.flatMap(\.a)
.flatMap(\.monoid)
==
let monad: Optional = …
let bar = monad?.is?.just?.a?.monoid 4&
,FZ1BUI&YQSFTTJPOT
BT'VODUJPOT
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0QUJPOBM$IBJOJOHͷʮʁʯ
qBU.BQ ,FZ1BUI
HFUUFS
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qBU.BQνΣʔϯͷྫɿ3FTVMU
let monad: Result = …
let bar = monad?.is?.just?.a?.monoid
monad
.flatMap { $0.is }
.flatMap { $0.just }
.flatMap { $0.a }
.flatMap { $0.monoid }
3FTVMUʹ0QUJPOBMͷΑ͏ͳ
ઐ༻ͷҥߏจ͕ͳ͍
2ϕλʹqBU.BQνΣʔϯ͢Δ
Ҏ֎ͷॻ͖ํ͋Δ͔ʁ
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UISPXTUSZΛͬͨखଓ͖
var monad: Foo { get throws { ... } }
func procedure() throws -> Bar {
let monad_ = try monad
let is_ = try monad_.is
let just_ = try is_.just
let a_ = try is_.a
let monoid_ = try is_.monoid
return monoid_
}
4&
&⒎FDUGVM3FBEPOMZ
1SPQFSUJFT 4XJGU
"5ISPXJOHGVODUJPOΛ͏
ʢҙɿΤϥʔܕ͚͕ऑ͘ͳΔʣ
USZΩʔϫʔυ͕
0QUJPOBM$IBJOJOHʹ͓͚ΔA Aʹ૬
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2ඇಉظܭࢉಉ͡ΈͰ
ߟ͑Δ͜ͱ͕Ͱ͖Δʁ
ˣ
"ͦΕ͕BTZODBXBJU
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qBU.BQνΣʔϯͷྫɿ"TZOD
let monad: Async = …
monad
.flatMap { $0.is }
.flatMap { $0.just }
.flatMap { $0.a }
.flatMap { $0.monoid }
"TZODඇಉظϞφυ͕
͋ΔͱԾఆ͢Δ
1SPNJTF'VUVSF0CTFSWBCMF
ͱಉ͡ͱࢥͬͯྑ͍
2ϕλʹqBU.BQνΣʔϯ͢Δ
Ҏ֎ͷॻ͖ํ͋Δ͔ʁ
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BTZODBXBJUΛͬͨखଓ͖
var monad: Foo { get async { ... } }
func procedure() async -> Bar {
let monad_ = await monad
let is_ = await monad_.is
let just_ = await is_.just
let a_ = await is_.a
let monoid_ = await is_.monoid
return monoid_
} UISPXTUSZΛ
BTZODBXBJUΩʔϫʔυʹஔ͖͑Δ͚ͩ
""TZODGVODUJPOΛ͏
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͜͜·Ͱͷ·ͱΊʢϞφυʣ
wϞφυɿNBQVOJUqBU.BQ Ϟφυଇ
wϞφυ݁߹ɿίʔϧόοΫࠈΛϝιουνΣʔϯʹม
w0QUJPOBMɿqBU.BQ˱A Aԋࢉࢠ
w3FTVMUɿqBU.BQ˱USZΩʔϫʔυ
w"TZODɿqBU.BQ˱BXBJUΩʔϫʔυ
ʮϞφυʯͱ
ʮݴޠ༷
ʢखଓ͖ͱΩʔϫʔυʣʯ
ʹରԠ͕ؔ͋Δʂ
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ܭࢉޮՌ
Computational Effect
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ܭࢉޮՌͱʁ
ܭࢉޮՌʹܭࢉͷաఔͰՃͰൃੜ͢Δ ෭
࡞༻
ϞφυʹΑΔܭࢉޮՌ
wqBU.BQʢҙͷܭࢉޮՌʹରͯ͠ڞ௨ͷ໊લʣ
ݴޠ༷ खଓ͖ʷ੍ޚԋࢉࢠʣʹΑΔܭࢉޮՌ
wA A
UISPXTUSZ
BTZODBXBJUͳͲ
֤ʑͷܭࢉޮՌʹରͯ͠ҟͳΔ໊લ
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ܭࢉޮՌͷྫ
wΤϥʔϋϯυϦϯά 3FTVMU
UISPXTUSZ
wඇಉظܭࢉ "TZOD1SPNJTF0CTFSWBCMF
BTZODBXBJU
wঢ়ଶߋ৽ 4UBUF
wඇܾఆੑܭࢉ "SSBZ
ͳͲ
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2Ϟφυͱݴޠ༷ͷ
ΪϟοϓΛຒΊΔʹʁ
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EPه๏
do-notation
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࠶ܝɿqBU.BQνΣʔϯͷྫɿ3FTVMU
let monad: Result = …
monad
.flatMap { $0.is }
.flatMap { $0.just }
.flatMap { $0.a }
.flatMap { $0.monoid }
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3FTVMUͷEPه๏ʹΑΔखଓ͖Խ
var monad: Foo { get throws { ... } }
Result.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
3FTVMU༻ͷEPείʔϓΛ࡞Γɺ
AAΛqBU.BQʹݟཱͯɺ
ଋറมΛࠨଆʹஔ͘
EPه๏qBU.BQνΣʔϯΛ
खଓ͖ॲཧʹݟͤΔҥߏจ
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"TZODͷEPه๏ʹΑΔखଓ͖Խ
var monad: Foo { get async { ... } }
Async.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
"TZOD༻ͷEPείʔϓΛ࡞Γɺ
AAΛqBU.BQʹݟཱͯɺ
ଋറมΛࠨଆʹஔ͘
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Ϟφυ
EPه๏ʹΑͬͯ
खଓ͖ॲཧʹมܗͰ͖Δ
ˣ
2Ϟφυͱݴޠ༷ͲͪΒ
ʮखଓ͖ʯͱΈͳͤΔͷͰಉ͡ʁ
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ϞφυͷɿܭࢉޮՌͷ߹
var monad: Foo { get async throws { ... } }
// try await ͨ͠Γɺtry or await ୯ମݺͼग़͠Ͱ͖Δɻ
func procedure() async throws -> Bar {
let monad_ = try await monad
let is_ = await monad_.is
let just_ = await is_.just
let a_ = try just_.a
let monoid_ = await a_.monoid
return monoid_
}
BTZODUISPXTͷ߹
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// Ϟφυ͕ෳʹωετ͍ͯ͠Δ߹ɺ߹ܭࢉͷѻ͍͕େม
let monad: Async> = …
// AsyncResult.do ͱ؆୯ʹॻ͚ͳ͍ͷͰɺͻͱ·ͣ Async.do ΛͬͯΈΔ
Async.do {
// `<-` ͋͘·Ͱ Async.flatMap ʢResult.flatMap Ͱ͖ͳ͍ʣ
monadResult <- monad
// ͜ͷdoείʔϓͰResultͷதΛऔΓग़͢ํ๏͕ͳ͍ͷͰɺ
// get()! Ͱڧ੍తʹߦ͏ ʹ ΤϥʔϋϯυϦϯάʹͳ͍ͬͯͳ͍ɻ
// ·ͨɺ෦Ͱ Result.do Λͬͯ͏·͍͔͘ͳ͍ɻ
let monad_ = monadResult_.get()!
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a.get()!
monoid_ <- a_.monoid
return monoid_
}
͜ͷΓํͰɺ3FTVMUपΓͷ
ΤϥʔϋϯυϦϯά্͕ख͘දݱͰ͖ͳ͍
ˣ
Ϟφυѻ͍ʹ͍͘ʂ
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Ϟφυͷ߹ʹର͢Δղܾࡦ͍Ζ͍Ζ
wϞφυมࢠ .POBE5SBOTGPSNFS
w5BHMFTT'JOBM
wࣗ༝Ϟφυ$PQSPEVDU ؔखͷ
w&YUFOTJCMF&GGFDU
wࣗ༝Ϟφυ0QFO6OJPO
w$PZPOFEB ༨ถా
ࣗ༝Ϟφυ0QFO6OJPO
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ࣗ༝Ϟφυ 'SFF.POBE
// ࣗ༝Ϟφυɿunit ͱ join ͕࠶ؼతσʔλߏʹఆٛ͞Ε͍ͯΔ
indirect enum Free {
case unit(A)
case join(F>)
}
extension Monad[Free] where Functor[F] {
func flatMap(_ f: A -> Free) -> Free {
switch self {
case let .unit(a): return f(a)
case let .join(x): return .join(x.map { $0.flatMap(f) })
}
}
}
ؔख'Λ༩͑ΔͱɺͦͷߏʹରԠͨ͠
ΠΠײ͡ͷϞφυ͕खʹೖΔ
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// try & await ੍ޚԋࢉࢠΛߏ͢Δϕʔεؔख
// NOTE: `Value -> Next` ͕ίʔϧόοΫʹ૬
enum AsyncThrowsF {
// NOTE: caseδΣωϦΫεʢٙࣅSwiftʣ
case try_(Result, Value -> Next)
case await_(Async, Value -> Next)
}
// async + throws ͷ྆ํʹରԠ͢ΔϞφυʢࣗ༝Ϟφυʴϕʔεؔख͔Β࡞ʣ
typealias AsyncThrows = Free
// try ΩʔϫʔυΛࣗ࡞
func try_(_ r: Result) -> AsyncThrows {
.join(.try_(r, .unit))
}
// await ΩʔϫʔυΛࣗ࡞
func await_(_ a: Async) -> AsyncThrows {
.join(.await_(a, .unit))
}
/05&
͜ͷؔख͢Ͱʹ߹ࡁΈ͕ͩɺ
ղͯ͠߹ͤ͞Δ͜ͱՄೳ
ؔखϨϕϧͰ߹ՄೳͰɺ
ϞφυϨϕϧͰग़དྷͳ͍
ݴޠ༷ΩʔϫʔυΛ
ࣗ࡞Ͱ͖Δʂ
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ࣗ༝ϞφυʹΑΔܭࢉޮՌͷ߹
let monad: AsyncThrows = …
AsyncThrows.do {
monadResult <- await_(monad)
monad_ <- try_(monadResult)
is_ <- await_(monad_.is)
just_ = await_(is_.just)
a_ <- try_(just_.a)
monoid_ <- await_(a_.monoid)
return monoid_
}
ࣗ༝ϞφυΛͬͯ
ݴޠʹಠࣗͷ%4-Λߏங
ˣ
USZBXBJU྆ํΛؚΜͩ
ݴޠ༷ͷॻ͖ํͱ
΄΅มΘΒͳ͍ॻ͖ຯʹͳΔ
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let ast = AsyncThrows.do { /* લϖʔδ */ }
Free.join(.await_(monad, { monadResult in
Free.join(.try_(monadResult, { monad_ in
Free.join(.await_(monad_.is, { is_ in
Free.join(.await_(is_.just, { just_ in
Free.join(.try_(just_.a, { a_ in
Free.join(.await_(a_.monoid, { monoid_ in
Free.unit(monoid_)
}))
}))
}))
}))
}))
}))
ࣗ༝ϞφυʹΑͬͯɺ
ݴޠ%4- ߏจ
ΛߏஙͰ͖Δ
ˠ͜ΕΛͲ͏lղऍz͢Δ͔͕࣍ͷ՝
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// AsyncThrows ߏจ ͔Β࣮ࡍͷඇಉظܭࢉ Async ʹมʢղऍʣ͢Δ
func runAST(_ ast: AsyncThrows) -> Async {
iterate(ast) { (asyncThrowsF: AsyncThrowsF>) -> Async in
switch asyncThrowsF {
case let .try_(result, callback):
switch result {
case let .success(value): return callback(value) // ޭ࣌ʹίʔϧόοΫΛݺͿ
case let .failure(error): return Bar(error) // ࣦഊ࣌ʹίʔϧόοΫΛݺͣૣظग़
}
case let .await_(async_, callback):
return async_.flatMap { callback($0) } // ඇಉظܭࢉ async_ ΛॲཧޙɺίʔϧόοΫΛݺͿ
}
}
}
// ࠶ؼతܭࢉ
func iterate(ast: AsyncThrows, algebra: AsyncThrowsF> -> Async) -> Async {
switch ast {
case let .unit(a):
return a
case let .free(m):
return algebra(m.map { iterate(ast: $0, algebra: algebra) })
}
}
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·ͱΊʢϞφυʣ
wϞφυNBQVOJUqBU.BQ Ϟφυଇ
wϞφυEPه๏Λ͏ͱɺखଓ͖ʹมߋͰ͖Δ
wࣗ༝ϞφυΛ͏ͱɺUSZBXBJUͷ߹͕ࣗ࡞Ͱ͖Δ
wϞφυͱݴޠ༷ʢखଓ͖ʷΩʔϫʔυʣՁͱΈͳͤ
Δ
wܭࢉޮՌʹϞφυʹݴޠ༷Ωʔϫʔυ
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ܧଓ
Continuation ! a POWER
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ܧଓ $POUJOVBUJPO
ͱʁ
wܧଓίʔϧόοΫؔɿܕ"3
wܧଓ͠ελΠϧ $14
ɿܕ "3
3
// ࠶ܝɿൃද಄ͷؔ
// fetch: Request -> (Result -> Void) -> Void
func fetch(
request: Request,
completion: @escaping (Result) -> Void
) -> Void
ܧଓ
$14
$POUJOVBUJPO1BTTJOH4UZMF
ΓͷܭࢉʢίʔϧόοΫʣͷ͜ͱ
ίʔϧόοΫ͕Ҿͷؔ
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ྫɿ4XJGU6OTBGF$POUJOVBUJPO
// stdlib/public/Concurrency/PartialAsyncTask.swift
// NOTE: Result Λແࢹͨ͠όʔδϣϯ
// typealias UnsafeContinuation = T -> Void
struct UnsafeContinuation {
func resume(with value: T)
}
// withUnsafeContinuation: ((T -> Void) -> Void) -> Async
func withUnsafeContinuation(
_ fn: (UnsafeContinuation) -> Void
) async -> T {
...
}
$14
$14͔Β"TZODؔ
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௨ৗͷؔɿελΠϧ EJSFDUTUZMF
// खଓ͖ (Ҿܕ͔ΒฦΓܕͷ direct style ͳؔ)
let f: A -> B = ...
let g: B -> C = ...
let h: C -> D = ...
func foo(a: A) -> D {
let b = f(a)
let c = g(b)
let d = h(c)
return d
}
// foo(a) == h(g(f(a)))
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ܧଓ͠ελΠϧ $14
// खଓ͖Λʮܧଓ͠ελΠϧʯʹม
func fooCPS(a: A, completion: D -> R) -> R {
return fCPS(a, { b in
return gCPS(b, { c in
return hCPS(c, { d in
return completion(d)
})
})
})
}
$14
ελΠϧͷίʔυͱ
ಉͱΈͳͤΔ
Slide 57
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ܧଓ͠ελΠϧ $14
// ैདྷͷҾͱ completion ҾͷॱংΛೖΕସ͑Δ + ΧϦʔԽ
func fooCPS(completion: D -> R) -> A -> R {
return { a in
return fCPS({ b in
return gCPS({ c in
return hCPS({ d in
return completion(d)
})(c)
})(b)
})(a)
}
}
// fooCPS(completion) == fCPS(gCPS(hCPS(completion)))
/05&͜ͷܗ
"%ʹର͢Δ$14
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// CPSม ʹ ถాͷิ͔ΒಘΒΕΔʮถాຒΊࠐΈʯ
// cf. iOSDC 2018 ݍͱSwiftͷԠ༻ p.60
func cpsTransform(_ xToY: X -> Y) -> (Y -> R) -> (X -> R) {
return { yToR in
return { x in yToR(xToY(x)) }
}
}
let f: A -> B = ...
let fCPS: (B -> R) -> (A -> R) = cpsTransform(f)
let g: B -> C = ...
let gCPS: (C -> R) -> (B -> R) = cpsTransform(g)
let h: C -> D = ...
let hCPS: (D -> R) -> (C -> R) = cpsTransform(h)
let foo: A -> D = { a in h(g(f(a))) }
let fooCPS: (D -> R) -> (A -> R) = { k in fCPS(gCPS(hCPS(k))) }
$14มʹΑΓ
ඌ࠶ؼ࠷దԽͳͲ͕ߦ͑Δ
Slide 59
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ܧଓ͠ελΠϧ $14
// ؔͷ߹ʢྫɿ `(g ∘ f)(x) == g(f(x))`ʣ
// NOTE: ࣮ `cpsTransform` ͷҾΛೖΕସ͑ͨόʔδϣϯ
func ∘ (_ g: B -> C, _ f: A -> B) -> A -> C {
return { g(f($0)) }
}
// ελΠϧ
let foo = h ∘ g ∘ f
// CPS (ܧଓ͠ελΠϧ)
let fooCPS = fCPS ∘ gCPS ∘ hCPS
ద༻ॱং͕
I$14ˠH$14ˠG$14
ͰٯʹͳΔ
ؔద༻ͷॱংӈ͔Β
GˠHˠI
Slide 60
Slide 60 text
// खଓ͖Λʮܧଓ͠ελΠϧʯʹม
func fooCPS(a: A, completion: D -> R) -> R {
return fCPS(a, { b in
return gCPS(b, { c in
return hCPS(c, { d in
return completion(d)
})
})
})
}
ܧଓ͠ελΠϧʹΑΔܧଓͷٯ͖߹
GPP$14ͷ
ܧଓ
Slide 61
Slide 61 text
// खଓ͖Λʮܧଓ͠ελΠϧʯʹม
func fooCPS(a: A, completion: D -> R) -> R {
return fCPS(a, { b in
return gCPS(b, { c in
return hCPS(c, { d in
return completion(d)
})
})
})
}
ܧଓ͠ελΠϧʹΑΔܧଓͷٯ͖߹
I$14ͷ
ܧଓ
Slide 62
Slide 62 text
// खଓ͖Λʮܧଓ͠ελΠϧʯʹม
func fooCPS(a: A, completion: D -> R) -> R {
return fCPS(a, { b in
return gCPS(b, { c in
return hCPS(c, { d in
return completion(d)
})
})
})
}
ܧଓ͠ελΠϧʹΑΔܧଓͷٯ͖߹
H$14ͷ
ܧଓ
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// खଓ͖Λʮܧଓ͠ελΠϧʯʹม
func fooCPS(a: A, completion: D -> R) -> R {
return fCPS(a, { b in
return gCPS(b, { c in
return hCPS(c, { d in
return completion(d)
})
})
})
}
ܧଓ͠ελΠϧʹΑΔܧଓͷٯ͖߹
G$14ͷ
ܧଓ
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$14ͷ߹ܧଓΛ
Լ͔Β্ʹ͔ͬͯ߹͢Δ
Slide 65
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ܧଓϞφυ
// ܧଓؔ͠ (CPS) Λแ͢ΔܕɻશͯͷϞφυͷɻ
// ถాͷิ (A -> R) -> F ≅ F ʹ F = ߃ؔख Λద༻ͨ͠ͱ͖ͷࠨลɻ
struct Cont {
let run: (A -> R) -> R
}
extension Monad[Cont] {
func flatMap(_ f: A -> Cont) -> Cont {
Cont { k in
self.run { a in f(a).run(k) }
}
}
}
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ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
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// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
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Slide 68 text
// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
Slide 69
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// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
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Slide 70 text
// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
Slide 71
Slide 71 text
// CPS Λdoه๏Ͱखଓ͖Խ
Cont.do {
monad_ <- monad
is_ <- monad_.is
just_ <- is_.just
a_ <- just_.a
monoid_ <- a_.monoid
return monoid_
}
// ελΠϧ
func procedure() -> Bar {
let monad_ = monad
let is_ = monad_.is
let just_ = is_.just
let a_ = just_.a
let monoid_ = a_.monoid
return monoid_
}
≅
reflect
reify
ܧଓϞφυͷEPه๏≅௨ৗͷίʔυ
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༨ஊɿύΠϓԋࢉࢠc
// Unix pipe ෩ͷԋࢉࢠ
func |> (a: A, f: A -> R) -> R {
f(a)
}
// pipe ͷྫʢࠨ͔ΒӈʹಡΈ͍͢ʣ
let str = 12 |> { $0 * 3 } |> String.init |> { $0 + "!" }
// ࢀߟɿ௨ৗͷ direct style ͷॻ͖ํʢӈ͔Βࠨʹؔద༻ʣ
let str = { $0 + "!" }(String.init({ $0 * 3 }(12)))
$14
/05&qBU.BQ." ".3
.3
ʹ.߃ؔखΛͯͨͷͱΈͳͤΔ
ʢ$14ͱϞφυ
QJQFͱqBU.BQࣅ͍ͯΔʣ
Slide 73
Slide 73 text
Structured
Concurrency
Slide 74
Slide 74 text
ैདྷ (SBOE$FOUSBM%JTQBUDI
ͷඇಉظॲཧ
Dispatch
Queue 0
(Thread 0)
queue1
queue1.async
queue2
queue2.async
RVFVF͕ఀࢭͯ͠
RVFVF͕ಈ࡞͠ଓ͚Δ
ࢠ ೖΕࢠ
ؔʹͳ͘ɺ
ඇಉظHPUP͍ͯ͠ΔΑ͏ͳͷ
Slide 75
Slide 75 text
4USVDUVSFE$PODVSSFODZʹΑΔඇಉظॲཧ
task0
task1
task0.addTask
task2
task1.addTask
UBTL͕ఀࢭ͢Δ·Ͱ
UBTL͕ಈ࡞͠ଓ͚Δ
ࢠ ೖΕࢠ
ؔɺ
ίϧʔνϯΩϟϯηϧͷ
ൖ͕Մೳ
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Slide 76 text
ܧଓʹΑΔϦιʔεཧ
// Ϧιʔεͷ֬อͱղ์Λߦ͏ɻ`bracket` ؔͱݴ͏ɻ
// IO ෭࡞༻ʢPromise/Observable ͷΑ͏ͳͷʣ
func retainRelease(retain value: IO, release: A -> IO)
-> Cont, A> {
Cont { k in
value.flatMap { a in
k(a).flatMapError { _ in release(a) }
.flatMap { r in
release(a).map { _ in r }
}
}
}
}
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Slide 77 text
// ϦιʔεཧͷྫɿෳϑΝΠϧૢ࡞
func openFile(_ filename: String) -> IO { ... }
let value = retainRelease(
retain: openFile("1.txt"),
release: { $0.closeFile() }
).run { handle1 in
// ಡΈऔΓॲཧ
...
retainRelease(
retain: openFile("2.txt"),
release: { $0.closeFile() }
).run { handle2 in
// ॻ͖ࠐΈॲཧ
...
} // είʔϓΛൈ͚Δͱ handle2.closeFile()
} // είʔϓΛൈ͚Δͱ handle1.closeFile()
IBOEMFͷ
ੜଘظؒ
ඞͣIBOEMFͷ
ੜଘظؒʹऩ·Δ
IBOEMFͷ
ੜଘظؒ
IBOEMFͷ
ੜଘظؒ
Slide 78
Slide 78 text
// Swift Structured Concurrency
// (ඇಉظॲཧͷೖΕࢠߏɺCancellation ͷൖ)
let asyncValues = retainRelease( // withTaskGroup
retain: makeTaskGroup(),
release: { $0.cancelAll() }
).run { taskGroup in
for i in 0 ..< 10 {
taskGroup.addTask(
retainRelease( // withTaskCancellationHandler
retain: makeTask(i),
release: { $0.cancel() }
)
)
}
var values = []
for await value in taskGroup { // ݸʑͷ Task ྃ & release
values += [value]
}
return values
} // είʔϓΛൈ͚Δͱ TaskGroup release
֤5BTLͷ
ੜଘظؒ
5BTL(SPVQͷ
ੜଘظؒ
Slide 79
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CallCC
Ca%-wi&-current-continuation
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/// Continuation.
typealias Cont = (@escaping (A) -> R) -> R
///
/// Call with Current Continuation.
/// - Peirce: `((A → B) → A) → A`
/// - CallCC: `((A → M) → M) → M`
///
/// - Note: `callCC` is like control operators e.g. `goto`, `return`, `throw`.
///
func callCC(
_ f: @escaping (_ exit: @escaping (A) -> Cont) -> Cont
) -> Cont
{
{ outer in
f { a in { _ in outer(a) } }(outer)
}
}
J04%$
4XJGUͱཧʙͦͯ͠ؼ͖ͬͯͨݍʙ
IUUQTTQFBLFSEFDLDPNJOBNJZTXJGUBOEMPHJD
BOEDBUFHPSZUIFPSZ
Slide 81
Slide 81 text
DBMM$$ΛͬͨܭࢉޮՌ SFUVSOCSFBLHVBSE
// Early exit
Cont.do {
print("1")
value <- callCC { exit in Cont.do {
print("2")
exit("3 (done)") // return / break / guard
print("͜͜ݺΕͳ͍")
} }
print(value)
}
Slide 82
Slide 82 text
DBMM$$ΛͬͨܭࢉޮՌ EFGFS
// Deferred call
Cont.do {
print("1")
k <- callCC { exit in Cont.do {
print("2")
exit({ _ in print("4 (deferred done)") })
} }
print("3")
k()
}
Slide 83
Slide 83 text
DBMM$$ΛͬͨܭࢉޮՌ ΤϥʔϋϯυϦϯά
// Error handling
let value: Double? = Cont.do {
let x: Double = 1
let y: Double = 0 // or non-zero
callCC { exitOK in Cont.do {
error <- callCC { exitError in Cont.do {
return y == 0
? exitError("Can't be divided by 0")
: exitOK(x / y)
} }
print(error) // Τϥʔ͕ى͖ͨ߹ͷΈ௨Δ
return nil
}}
}
Slide 84
Slide 84 text
༨ஊɿTIJGUSFTFU ݶఆܧଓ
wDBMM$$ʮϓϩάϥϜͷΓͷܭࢉશͯʯΛଋറ͢ΔͷͰɺѻ͍͕େมةݥ
wTIJGUSFTFU ݶఆܧଓ
Λ͏ͱɺଋറ͢ΔܧଓͷൣғΛݶఆతʹͰ͖Δ
wʮDBMM$$ʯʴʮՄมࢀরʯʹݶఆܧଓʹϞφυͱಉͷܭࢉޮՌ
func reset(_ m: Cont) -> Cont {
Cont { k in k(m.run { $0 }) }
}
func shift(_ f: (A -> R) -> Cont) -> Cont {
Cont { k in f(k).run { $0 } }
}
Slide 85
Slide 85 text
༨ஊɿTIJGUSFTFUͷྫ
let value = Cont.do {
x <- reset(Cont.do {
y <- shift { k in Cont.do { // k = { $0 + 3 }
z <- k(10)
return k(z) // k Λෳճ࣮ߦ͢Δ͜ͱՄೳ
}}
return y + 3 // ޙଓͷ͜ͷίʔυ͕ k ʹଋറ͞ΕΔ
})
return x - 1 // reset ͷ֎ͳͷͰ k ʹଋറ͞Εͳ͍
}
// value = ((10 + 3) + 3) - 1 = 15
Slide 86
Slide 86 text
·ͱΊʢܧଓͱ$14ʣ
wܧଓίʔϧόοΫʹΓͷܭࢉ
w$14ܧଓ͠ελΠϧίʔϧόοΫ͕Ҿͷؔ
wܧଓͷྫɿύΠϓॲཧɺ4USVDUVSFE$PODVSSFODZ
wDBMM$$ͱTIJGUSFTFUɿϞφυͱಉͷܭࢉޮՌ
wϞφυΛΘͳͯ͘ɺܧଓΛͬͯܭࢉޮՌΛߟ͑Δ͜
ͱ͕Ͱ͖Δ
Slide 87
Slide 87 text
ίϧʔνϯ
Cooperative multitasking
Slide 88
Slide 88 text
ίϧʔνϯͱʁ
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
தஅɾ࠶։Ͱ͖ΔػೳΛ࣋ͭؔͷ͜ͱ
ڠௐతϚϧνλεΫ
Slide 89
Slide 89 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 90
Slide 90 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 91
Slide 91 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 92
Slide 92 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 93
Slide 93 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 94
Slide 94 text
func getVaccine1() {
print("ϫΫ☆") // (1)
pause() // தஅɿ੍ޚ͕ getVaccine2 ʹҠΔ
print("νϯ☆") // (3)
}
func getVaccine2() {
print("ϫΫ☆") // (2)
pause() // தஅɿ੍ޚ͕ getVaccine1 ͷதஅϙΠϯτʹΔ
print("νϯ☆") // (4)
}
runCoroutines(getVaccine1, getVaccine2) // ϫΫνϯ2ճछ
// 1 → 2 → 3 → 4 ͷॱͰʢҎԼུʣ
ίϧʔνϯͱʁ
Slide 95
Slide 95 text
func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
ʲڠௐతϚϧνλεΫʳ
ҟͳΔλεΫ͕ಉ͡εϨουͰ
ަޓʹߦΘΕΔͷͰ
σʔλڝ߹ʹͳΒͳ͍
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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func receiver() {
// தஅɿ receive Ͱ੍ޚ͕தஅ͠ɺsender ʹҠΔ
// ࠶։ɿ money Λड͚औͬͯ࣍ͷߦ
money /* (4) */ <- receive() // (1)
accountA += money // (5)
} // (6)
func sender() {
accountB -= money // (2)
// தஅɿ send Ͱ money ΛૹΓɺ੍ޚ͕ receiver ʹΔ
send(money) // (3)
} // (7)
runCoroutines(receiver, sender)
// accountB͔Β͓͕ۚҾ͔Εɺૹۚ͞ΕɺaccountAʹ͓͕ۚೖΔʢ͜ͷؒʹׂΓࠐΈ͕ൃੜ͠ͳ͍ʣ
ίϧʔνϯͷྫɿσʔλͷड͚͠
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ࣗ༝ϞφυΛͬͨίϧʔνϯ
/// ෭࡞༻ M Λ͚ͨࣗ༝Ϟφυͱಉ͡ߏ
struct Coroutine {
let resume: M
indirect enum State {
case done(A) // AΛฦͯ͠ऴྃ͢ΔλεΫ
case suspended(F>) // F ʹแ·Ε͍ͯΔɺதஅ͞ΕͨλεΫ
}
}
extension Monad[Coroutine] where Functor[F], Monad[M] {
func flatMap(_ f: A -> Coroutine) -> Coroutine {
self.resume.flatMap { state in
switch state {
case let .done(a): return f(a).resume
case let .suspended(fco): return M.unit(.suspended(fco.map { $0.flatMap(f) }))
}
}
}
}
લճͷࣗ༝Ϟφυ'SFF'
"ʹ
෭࡞༻.͕Ճ͞Εͨܗ
ࣗ༝Ϟφυมࢠ
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ίϧʔνϯมؔ TVTQFOEMJGU
/// F Ͱఆٛ͞ΕͨܭࢉޮՌͷϕʔεߏΛ suspended ঢ়ଶͷίϧʔνϯʹม
func suspend(_ fco: F>)
-> Coroutine
where Functor[F], Monad[M]
{
Coroutine(M.unit(.suspended(fco)))
}
/// ෭࡞༻ M Λίϧʔνϯʹม
func lift(_ effect: M) -> Coroutine
where Functor[F], Monad[M]
{
Coroutine(effect.map(.done))
}
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1BVTFίϧʔνϯϞφυ
// pauseԋࢉΛߏ͢Δϕʔεؔख
struct PauseF {
let next: Next
}
// Trampoline ͱݺΕΔ
typealias Pause = Coroutine
// NOTE: pauseॲཧʹ suspend ͕ؔΘΕΔ
func pause() -> Pause where Monad[M] {
suspend(PauseF(.unit(())))
}
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1BVTFίϧʔνϯϞφυʹΑΔ࣮
let getVaccine = lift(print("ϫΫ☆"))
.flatMap { pause() }
.flatMap { lift(print(“νϯ☆")) }
// ·ͨ do ه๏Λͬͯ
let getVaccine = Pause.do {
lift(print("ϫΫ☆"))
pause()
lift(print("νϯ☆"))
}
runCoroutines(getVaccine, getVaccine)
࠷ॳͷखଓ͖ͷྫͱ
΄΅ಉ͡ܗ
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// ༨ஊɿrunCoroutines ͷதʁ
extension Applicative[Coroutine] where Functor[F], Monad[M] {
static func zipWith(_ f: A -> B -> C)
-> Coroutine -> Coroutine -> Coroutine {
{ coroutineA in { coroutineB in
coroutineA.flatMap { a in
coroutineB.flatMap { b in
.unit(f(a)(b))
}
}
} }
}
}
func runCoroutines(_ pauses: [Pause]) -> M<[A]> where Monad[M] {
func run(_ pause: Pause) -> M where Monad[M] {
pause.resume.flatMap { state in
switch state in {
case let .done(arr): return M.unit(arr)
case let .suspended(fco): return run(fco.next)
}
}
}
let combined = pauses.reduce(Pause.unit([])) { acc, pause in
Pause.zipWith({ [$0] + $1 })(pause)(acc)
}
return run(combined)
}
ྻͷ[JQͱߟ͑ํಉ͡
ͭͷ$PSPVUJOFΛʮ$14ͷྻʯ
ʹݟཱͯɺ$14ϖΞͷྻΛ࡞Δ
͜͜Ͱ͞ΒʹGͰϖΞΛ$ʹม͢Δ
$14ϖΞͷྻΛ
ʮڠௐతʯʹ࣮ߦ͢Δ
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3FDFJWFίϧʔνϯϞφυ
// receiveԋࢉΛߏ͢Δϕʔεؔख
struct ReceiveF {
let receive: A -> Next
}
// Iteratee ͱݺΕΔ
typealias Receive = Coroutine, M, A>
// NOTE: receiveॲཧʹ suspend ͕ؔΘΕΔ
func receive() -> Receive
where Monad[M] {
suspend(ReceiveF(.unit))
}
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// Send-Receive ίϧʔνϯϞφυʹΑΔ࣮
let sender = Send.do {
accountA -= money
send(money)
}
let receiver = Receive.do {
money <- receive()
accountB += money
}
runCoroutines(sender, receiver)
// ༨ஊɿrunCoroutine ͷத (NOTE: fatalError ΛΘͳ͍Ͱ͖Δ)
func runCoroutines(sender: Send, receiver: Receive)
-> M<(A, B)> where Monad[M] {
sender.resume.flatMap { sent in
receiver.resume.flatMap { received in
switch (sent, received) {
case let (.done(a), .done(b)): return .unit((a, b))
case let (.done(a), .suspended(fco)): fatalError("sender ended too soon")
case let (.suspended(a, co), .done(b)): return runCoroutines(co, .unit(b))
case let (.suspended(a, co), .suspended(f)): return runCoroutines(co, f(a))
}
}
}
}
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࠶ܝɿ"TZOD5ISPXTࣗ༝Ϟφυ
// try & await ੍ޚԋࢉࢠΛߏ͢Δϕʔεؔख
enum AsyncThrowsF {
case try_(Result, Value -> Next)
case await_(Async, Value -> Next)
}
typealias AsyncThrows = Free
func try_(_ r: Result) -> AsyncThrows {
.join(.try_(r, .unit))
}
func await_(_ a: Async) -> AsyncThrows {
.join(.await_(a, .unit))
}
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"TZOD$PSPVUJOF
// awaitԋࢉͷΈΛߏ͢Δϕʔεؔख
struct AsyncF {
let await_: (Async, Value -> Next)
}
typealias AsyncCoroutine = Coroutine
// NOTE: awaitॲཧʹ suspend ͕ؔΘΕΔ
func await_(_ a: Async) -> AsyncCoroutine {
suspend(AsyncF(a, .unit))
}
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"TZOD$PSPVUJOF
// t = 19 Ͱ྆ํͷΛड͚औΔ (2ͭͷฒྻ async let + await ʹ૬)
let asyncValues: Async<(C1, C2)> = runCoroutines(
AsyncCoroutine.do {
a1 <- await_(task1a(sleep: 2)) // (1) at t = 0
b1 <- await_(task1b(a1, sleep: 3)) // (4) at t = 2
c1 <- await_(task1c(b1, sleep: 8)) // (5) at t = 5
return c1 // (7) at t = 13
},
AsyncCoroutine.do {
a2 <- await_(task2a(sleep: 1)) // (2) at t = 0
b2 <- await_(task2b(a2, sleep: 5)) // (3) at t = 1
c2 <- await_(task2c(b2, sleep: 13)) // (6) at t = 6
return c2 // (8) at t = 19
}
)
BXBJU@ TVTQFOE
࣌ʹ੍ޚ͕SVO$PSPVUJOFTʹΓɺ
ඇಉظܭࢉΛεέδϡʔϦϯάίʔϧόοΫ ܧଓ
Λอଘ
ˠྃޙʹܧଓΛݺͼɺ੍ޚΛ͢ @$PODVSSFODZ෦࣮
/05&$PSPVUJOFϞφυ ࣗ༝Ϟφυ
ΛΘͣɺ
ܧଓϞφυঢ়ଶϞφυͰදݱ͢Δํ๏͋Δ
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·ͱΊʢίϧʔνϯʣ
wίϧʔνϯதஅɾ࠶։Ͱ͖ΔػೳΛ࣋ͭؔ
wࣗ༝ϞφυมࢠΛͬͯίϧʔνϯΛදݱͰ͖Δ
wKPJO͕TVTQFOEػೳΛ࣋ͭ
wBXBJUͷਖ਼ମTVTQFOE
w"TZODSVO$PSPVUJOFT@$PODVSSFODZϥϯλΠϜʹ࣮
w/05&ʮܧଓϞφυঢ়ଶϞφυʯʹΑΔɺܧଓͷώʔϓ্Ͱͷཧ
ͷํ͕@$PODVSSFODZͷຊདྷͷ࣮ʹ͍͔ۙ 88%$
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BTZODBXBJUΛΔͨΊʹ
ίϧʔνϯ͕ඞཁ
ίϧʔνϯΛΔͨΊʹ
Ϟφυͱܧଓͷཧղ͕ෆՄܽ
Swift 5.5
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୯ͳΔࣗݾؔखͷݍʹ͓͚Δ
ϞϊΠυରͩΑ
ܧଓJTύϫʔ
ڠௐతͳൃදΛࢦͯ͠
͕ΜΓ·͢
Ϟφυ
ܧଓ
ίϧʔνϯ
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"MHFCSBJD&⒎FDUTͳͲ
ݶఆܧଓ
ϞφυΛEJSFDUTUZMFʹ͢Δ
&GGFDU
)BOEMFST
%FMJNJUFE
$POUJOVBUJPO
.POBEJD
3FqFDUJPO
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ࢀߟจݙ BQQMFTXJGU
4XJGU$PNNVOJUZ
• SE-0296 Async/await
• SE-0300 Continuations for interfacing
async tasks with synchronous code
• SE-0304 Structured concurrency
• SE-0317 async let bindings
• Swift concurrency: Behind the scenes
- WWDC21
• Explore structured concurrency in
Swift - WWDC21
• Meet async/await in Swift - WWDC21
• Coroutines in LLVM
• Zewo/Venice
• belozierov/SwiftCoroutine
• Swift Language Updates - Learn
Languages 2021
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ࢀߟจݙ Ϟφυ
• ശͰߟ͑ΔFunctorɺApplicativeͦͯ͠Monad -
Qiita
• Functor, Applicative, Monad | haskell
• Free Monad | haskell
• A Neighborhood of Infinity: The Mother of all
Monads
• The Comonad.Reader » Free Monads for Less (Part
1 of 3): Codensity
• Eugenio Moggi. 1991. Notions of computation
and monads
• Philip Wadler. 1994. Monads and composable
continuations
• Philip Wadler. 1995. Monads for functional
programming
• Gordon Plotkin and John Power. 2002. Notions of
Computation Determine Monads
• W Swierstra. 2008. Data types a la carte.
• Janis Voigtländer. 2008. Asymptotic Improvement
of Computations over Free Monads
• O Kiselyov, A Sabry, C Swords. 2013. Extensible
effects: an alternative to monad transformers
• E Rivas and M Jaskelioff. 2017. Notions of
computation as monoids.
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ࢀߟจݙ ܧଓɺ$14
• Haskell/Continuation passing style -
Wikibooks, open books for an open world
• continuation-passing style in nLab
• ܧଓ | haskell
• ܧଓ͠ͳHaskellϥΠϑ - ϞφυͱΘͨ͠
ͱίϞφυ
• ܧଓϞφυʹΑΔϦιʔεཧ - Qiita
• Scala ʹ͓͚ΔܧଓϞφυͷ࣮ͱ׆༻ -
Speaker Deck
• Deep Dive async/await in Unity with
UniTask(UniRx.Async)
• ฒߦϓϩάϥϛϯάͱܧଓϞφυ
• ઙҪ ݈Ұ. shift/reset ϓϩάϥϛϯάೖ
• Kenichi Asai. 2009. On typing delimited
continuations: three new solutions to the
printf problem
• Continuations and Delimited Control
• The Monad.Reader/Issue2/
FunWithLinearImplicitParameters
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ࢀߟจݙ 4USVDUVSFE$PODVSSFODZ
• 250bpm: Structured
Concurrency
• Notes on structured
concurrency, or: Go
statement considered
harmful — njs blog
• Structured concurrency |
by Roman Elizarov |
Medium
• Roman Elizarov —
Structured concurrency -
YouTube
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ࢀߟจݙ ίϧʔνϯ
• Mario Blazevic. 2011. Coroutine Pipelines. The
Monad.Reader Issue 19
• CoroutineϞφυͱεςʔτϚγϯ - The curse of λ
• stackfulness of coroutines - lilyum ensemble
• Introduction to the C++ coroutines | C++ - don't
panic!
• 20͘Β͍ͰΘ͔ͬͨؾʹͳΕΔC++20ίϧʔ
νϯ
• Coroutines guide | Kotlin
• 2016 LLVM Developers’ Meeting: G. Nishanov
“LLVM Coroutines” - YouTube
• 2018 LLVM Developers’ Meeting: J. McCall
“Coroutine Representations and ABIs in LLVM” -
YouTube
• GeeCON 2019: Dmitry Kandalov - Coroutines
explained by example - YouTube
• Functorial Blog - Stackless Coroutines in
PureScript
• Functorial Blog - Extensible Coeffects
• Roshan James and Amr Sabry. 2011. Yield:
Mainstream Delimited Continuations
• R. P. Pieters and T. Schrijvers. 2020. Faster
Coroutine Pipelines: A Reconstruction
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ࢀߟจݙ "EWBODFEUPQJDT
• Andrzej Filinski. 1989. Declarative Continuations and
Categorical Duality
• O Danvy, A Filinski. 1992. Representing control: A study
of the CPS transformation
• Andrzej Filinski. 1994. Representing Monads.
• Andrzej Filinski. 1999. Representing layered monads.
• Carl Bruggeman et al. 1996. Representing control in the
presence of one-shot continuations
• Gordon Plotkin and Matija Pretnar. 2009. Handlers of
algebraic effects.
• Matija Pretnar. 2015. An Introduction to Algebraic
Effects and Handlers
• yallop/effects-bibliography
• S. Kawahara, et al. 2020. One-shot Algebraic Effects as
Coroutines
• ܧଓͱ͔ͷαʔϕΠ | κeenͷHappy Hacκing Blog
• Ploeg & Kiselyov. 2014. Reflection without Remorse
• Monadic Reflection in Haskell
• ϞφυΛͭ͘Ζ͏
• Monadic Reflectionʹ͍ͭͯ - Arantium Maestum
• Y. Forster, et al. 2017. On the Expressive Power of User-
Defined Effects Effect Handlers, Monadic Reflection,
Delimited Control.
• Toru Kawata. 2018. A Contextual Reconstruction of
Monadic Reflection.
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Thanks!
Yasuhiro Inami
@inamiy