君だけのオリジナル async / await を作ろう / TSKaigi 2025

TSKaigi 2025 での発表資料です

リポジトリ:
- susisu/tskaigi2025
- susisu/effectful

以前の発表やブログなど:
- エフェクトとジェネレーターと - Object.create(null)
- ドメインモデリングにエフェクトを使う思考実験 - Object.create(null)
- TypeScript で GADT っぽいの - Object.create(null)

古いやつ:
- ジェネレータを有効活用し隊 / Kyoto.js 11 LT - Speaker Deck
- TypeScript で Algebraic Effects - Object.create(null)

Transcript

1. ܅͚ͩͷΦϦδφϧ async / await Λ࡞Ζ͏ susisu 2025-05-24 TSKaigi 2025
2. ݁࿦: TypeScript ໘ന͍ ؾָʹฉ͍͍ͯͩ͘͞
3. • id:susisu / @susisu / @susisu2413 • גࣜձࣾ͸ͯͳ
 Web ΞϓϦέʔγϣϯΤϯδχΞ • TypeScript ͷݶքΛ߈ΊΔͷ͕झຯͰ͢ ͜Μʹͪ͸
4. ϦαʔνͳͲͷΠϯλϏϡʔ݁Ռͷ෼ੳϓϩηεΛࢧԉ͢Δൃ࿩෼ੳιϦϡʔγϣϯ ϑϩϯτΤϯυ΍ϚΠΫϩαʔϏεΛ TypeScript / Next.js / Prisma Ͱ։ൃ͍ͯ͠·͢
6. ࠓ೔࿩͢͜ͱ ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷ ᶄ TypeScript ʹΑΔܕ෇͚ ᶅ Ԡ༻ͦͷ 1: Result ܕ ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ JS TS ᶃ ᶄ ᶅ ᶆ async / await δΣωϨʔλ Result ܕ ΤϑΣΫτ
7. ࠓ೔࿩͢͜ͱ ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷ ᶄ TypeScript ʹΑΔܕ෇͚ ᶅ Ԡ༻ͦͷ 1: Result ܕ ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ JS ᶃ async / await δΣωϨʔλ
8. ࠓ೔࿩͢͜ͱ ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷ ᶄ TypeScript ʹΑΔܕ෇͚ ᶅ Ԡ༻ͦͷ 1: Result ܕ ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ JS TS ᶃ ᶄ async / await δΣωϨʔλ
9. ࠓ೔࿩͢͜ͱ ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷ ᶄ TypeScript ʹΑΔܕ෇͚ ᶅ Ԡ༻ͦͷ 1: Result ܕ ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ JS TS ᶃ ᶄ ᶅ async / await δΣωϨʔλ Result ܕ
10. ࠓ೔࿩͢͜ͱ ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷ ᶄ TypeScript ʹΑΔܕ෇͚ ᶅ Ԡ༻ͦͷ 1: Result ܕ ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ JS TS ᶃ ᶄ ᶅ ᶆ async / await δΣωϨʔλ Result ܕ ΤϑΣΫτ
11. ᶃ async / await Λ δΣωϨʔλͰ࠶࣮૷
12. async / await • Promise Λ࢖ͬͨίʔυΛݟ௨͠ྑ͘ॻͨ͘Ίʹ async / await ͸ෆՄܽ // before doX().then((x) => doY(x).then((y) => doZ(y).then((z) => // ... ) ) ); // after const x = await doX(); const y = await doY(x); const z = await doZ(y); // ...
13. async / await ͷྺ࢙ • Promise ͷඪ४Խ͔Β async / await ͷඪ४Խ·Ͱ͸λΠϜϥά͕͋ͬͨ • Promise: ES2015 • async / await: ES2017 • ਓʑ͸τϥϯεύΠϥΛ࢖ͬͯ async / await ΛઌऔΓ͍ͯͨ͠ • Babel, TypeScript • ͋Δ͍͸δΣωϨʔλΛ࢖ͬͯ async / await ͬΆ͍ίʔυΛॻ͍͍ͯͨ • tj/co, Koa
14. δΣωϨʔλ • ES2015 Ͱඪ४Խ͞Εͨݴޠػೳ • δΣωϨʔλؔ਺ function* ͱ yield ࣜͰΠςϨʔλΛखଓ͖తʹهड़Ͱ͖Δ • ͜Ε͸தஅɾ࠶։Ͱ͖Δܭࢉ (ίϧʔνϯ) ͱͯ͠ݟΔ͜ͱ΋Ͱ͖Δ function* range(from, to, step = 1) { for (let n = from; n < to; n += step) { yield n; } }
15. δΣωϨʔλؔ਺ͷதஅɾ࠶։ function* myFunc() { const x = yield "X"; const y = yield "Y"; return x + y; }
16. δΣωϨʔλؔ਺ͷதஅɾ࠶։ function* myFunc() { const x = yield "X"; const y = yield "Y"; return x + y; } const gen = myFunc(); ← ·࣮ͩߦ͞Ε͍ͯͳ͍
17. δΣωϨʔλؔ਺ͷதஅɾ࠶։ function* myFunc() { const x = yield "X"; const y = yield "Y"; return x + y; } const gen = myFunc(); gen.next(); // { done: false, value: "X" } ← yield Ͱதஅ
18. δΣωϨʔλؔ਺ͷதஅɾ࠶։ function* myFunc() { const x = yield "X"; // x = 1 const y = yield "Y"; return x + y; } const gen = myFunc(); gen.next(); // { done: false, value: "X" } gen.next(1); // { done: false, value: "Y" } ← ࠶։͞Εͯ;ͨͨͼ yield Ͱதஅ
19. δΣωϨʔλؔ਺ͷதஅɾ࠶։ function* myFunc() { const x = yield "X"; // x = 1 const y = yield "Y"; // y = 2 return x + y; } const gen = myFunc(); gen.next(); // { done: false, value: "X" } gen.next(1); // { done: false, value: "Y" } gen.next(2); // { done: true, value: 3 } ← return Ͱऴྃ
20. async / await ͷ࠶࣮૷ • δΣωϨʔλؔ਺ͷதஅɾ࠶։Λར༻͢Ε͹ɺasync / await Λ࠶ݱͰ͖ͦ͏ • await ͸ Promise ͷ׬ྃ·Ͱؔ਺ͷ࣮ߦΛதஅ͢Δ͜ͱʹ΄͔ͳΒͳ͍ • جຊతͳΞΠσΞ: • Promise Λ yield ͯ͠ܭࢉΛதஅ • Promise ͕׬ྃͨ͠ΒܭࢉΛ࠶։
21. async / await ͷ࠶࣮૷ async function myFunc() { const x = await doX(); const y = await doY(x); return y; } const promise = myFunc(); function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc());
22. async / await ͷ࠶࣮૷ async function myFunc() { const x = await doX(); const y = await doY(x); return y; } const promise = myFunc(); function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc()); → ͍͍ײ͡ʹδΣωϨʔλΛ࣮ߦͯ͘͠ΕΔؔ਺ run() Λ࣮૷͢Δ
23. async / await ͷ࠶࣮૷ • εϥΠυதͷίʔυͷ׬શ൛͸ҎԼͷϦϙδτϦʹ͋Γ·͢ • https://github.com/susisu/tskaigi2025
24. run() ͷ࣮૷ (1/3) function run(comp) { function onFulfilled(value) { // Promise 成功時の処理 let res; try { res = comp.next(value); // 計算を再開 } catch (e) { return Promise.reject(e); // throw } if (res.done) return Promise.resolve(res.value); // return return res.value.then(onFulfilled, onRejected); // yield }
25. run() ͷ࣮૷ (1/3) function run(comp) { function onFulfilled(value) { // Promise 成功時の処理 let res; try { res = comp.next(value); // 計算を再開 } catch (e) { return Promise.reject(e); // throw } if (res.done) return Promise.resolve(res.value); // return return res.value.then(onFulfilled, onRejected); // yield }
26. run() ͷ࣮૷ (1/3) function run(comp) { function onFulfilled(value) { // Promise 成功時の処理 let res; try { res = comp.next(value); // 計算を再開 } catch (e) { return Promise.reject(e); // throw } if (res.done) return Promise.resolve(res.value); // return return res.value.then(onFulfilled, onRejected); // yield } δΣωϨʔλؔ਺͔ΒͷԠ౴͸ throw, return, yield ͷ 3 ௨Γ͕͋ΓಘΔ
27. run() ͷ࣮૷ (2/3) function onRejected(error) { // Promise 失敗時の処理 let res; try { res = comp.throw(error); // 計算を再開 } catch (e) { return Promise.reject(e); // throw } if (res.done) return Promise.resolve(res.value); // return return res.value.then(onFulfilled, onRejected); // yield }
28. run() ͷ࣮૷ (2/3) function onRejected(error) { // Promise 失敗時の処理 let res; try { res = comp.throw(error); // 計算を再開 } catch (e) { return Promise.reject(e); // throw } if (res.done) return Promise.resolve(res.value); // return return res.value.then(onFulfilled, onRejected); // yield } onFul fi lled ͱͷࠩ෼͸͚ͩ͜͜ yield ͷՕॴͰ throw ͢Δ
29. run() ͷ࣮૷ (3/3) // 計算を先頭から開始 return onFulfilled(); } function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc());
30. ͜͜·Ͱͷ·ͱΊ • δΣωϨʔλ͸தஅɾ࠶։Ͱ͖Δܭࢉͱͯ͠ݟΔ͜ͱ͕Ͱ͖Δ • ͜ΕΛ࢖͑͹ async / await ૬౰ͷ΋ͷΛ࠶࣮૷Ͱ͖Δ • ͜͜·Ͱ͸શͯ JavaScript ͷ࿩ • ࣮͸͜ͷ··ͩͱ yield ࣜʹ͏·͘ܕ͕෇͚ΒΕͳ͍ʂ
31. ᶄ TypeScript ʹΑΔܕ෇͚
32. TypeScript ʹΑΔܕ෇͚ function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc()); • yield ࣜʹܕ͕෇͚ΒΕΔঢ়ଶΛ໨ࢦ͢ • (run() ͷ࣮૷಺෦ʹର͢Δܕ෇͚͸໨ࢦ͞ͳ͍)
33. yield ࣜʹର͢Δܕ෇͚ͷน • yield ࣜʹܕΛ෇͚Δʹ͋ͨͬͯ͸ 2 ͭͷน͕͋Δ 1. δΣωϨʔλ͕ඞܾͣ·ͬͨํ๏Ͱ࣮ߦ͞ΕΔอূ͕ͳ͍ 2. yield ࣜ͝ͱʹҟͳΔܕ͕෇͚ΒΕͳ͍
34. 1. ܾ·ͬͨํ๏Ͱ࣮ߦ͞ΕΔอূ͕ͳ͍ function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc()); // run() を使っているなら OK const what = [...myFunc()]; // そうでないならダメ
35. 1. ܾ·ͬͨํ๏Ͱ࣮ߦ͞ΕΔอূ͕ͳ͍ function* myFunc() { const x = yield doX(); const y = yield doY(x); return y; } const promise = run(myFunc()); // run() を使っているなら OK const what = [...myFunc()]; // そうでないならダメ → ن໿ͱ͍͏͜ͱʹͯ͠͠·͏... • ໓ଟʹ΍Βͳ͍Ͱ͠ΐ͏ / ඞཁʹͳͬͨΒ Linter Λ࡞Ζ͏
36. 2. yield ࣜ͝ͱʹҟͳΔܕ͕෇͚ΒΕͳ͍ • δΣωϨʔλͷܕ Generator<T, TReturn, TNext> • T ... yield a ͷ a ͷܕ • TReturn ... return a ͷ a ͷܕ • TNext ... gen.next(b) ͷ b ͷܕ = yield a ͷܕ function* myFunc(): Generator<T, TReturn, TNext> { // ... }
37. 2. yield ࣜ͝ͱʹҟͳΔܕ͕෇͚ΒΕͳ͍ • yield ࣜͷܕ = TNext ͕ 1 छྨ͔͠ͳ͍ • ҎԼͷίʔυͰݴ͏ͱ x ͱ y ͷܕ͕ಉ͡ʹͳͬͯ͠·͏ function* myFunc(): Generator<T, TReturn, TNext> { const x = yield doX(); // x: TNext const y = yield doY(x); // y: TNext return y; }
38. • yield ࣜͷܕ = TNext ͕ 1 छྨ͔͠ͳ͍ • ҎԼͷίʔυͰݴ͏ͱ x ͱ y ͷܕ͕ಉ͡ʹͳͬͯ͠·͏ → yield* ࣜΛ࢖͏ function* myFunc(): Generator<T, TReturn, TNext> { const x = yield doX(); // x: TNext const y = yield doY(x); // y: TNext return y; } 2. yield ࣜ͝ͱʹҟͳΔܕ͕෇͚ΒΕͳ͍
39. yield* ࣜΛ࢖͏ • yield* iter ͸ Iterable ΛδΣωϨʔλؔ਺಺Ͱల։͢Δߏจ • yield* iter ͷܕ͸ iter ʹԠܾͯ͡·Δ • iter ͷܕ͕ Iterable<S, SReturn, SNext> ͷͱ͖ɺyield* iter ͷܕ͸ SReturn • → ࣜ͝ͱʹҟͳΔܕΛ࣋ͯΔ
40. yield* ࣜΛ࢖͏ • yield* ࣜʹ༩͑Δ஋͸ Iterable Ͱ͋Δඞཁ͕͋Δ • ୯७ʹ yield a Λ yield* a ͷΑ͏ʹஔ͖׵͑Δ͜ͱ͸Ͱ͖ͳ͍ • yield* toIterable(a) ͷΑ͏ʹ Iterable ʹม׵͠ͳ͍ͱ͍͚ͳ͍ • ม׵͸ͳΜͰ΋ྑ͍Θ͚Ͱ͸ͳ͍ • ݩʑͷ yield a ͱஔ͖׵͑ޙͷ yield* toIterable(a) ͸ಉ͡ಈ͖Λͯ͠΄͍͠
41. Iterable ΁ͷม׵ type Comp<T> = Generator<Promise<any>, T, any>; function* waitFor<T>(promise: Promise<T>): Comp<Awaited<T>> { return yield promise; } • ୯Ұͷ஋Λ yield ͠ɺͦͷ஋Λ return ͢Δ͚ͩͷδΣωϨʔλΛ࡞Δ • yield* waitFor(a) ͸ yield a ͱಉ͡ಈ࡞Λ͢Δ͕ɺܕ৘ใ͕૿͍͑ͯΔ
42. Iterable ʹม׵͢Δ declare function run<T>(comp: Comp<T>): Promise<Awaited<T>>; function* myFunc(): Comp<Y> { const x = yield* waitFor(doX()); // x: X const y = yield* waitFor(doY(x)); // y: Y return y; } const promise = run(myFunc()); // promise: Promise<Y> • run() ʹରͯ͠͸֎͔ΒܕΛ͚ͭΔ͚ͩͰ׬੒
43. ͜͜·Ͱͷ·ͱΊ • ࣗ࡞ async / await ʹܕΛ෇͚Δʹ͸ 2 ͭͷน͕͋Δ • δΣωϨʔλ͕Ͳ͏ݺ͹ΕΔ͔อূ͕ͳ͍ • yield ࣜ͝ͱʹҟͳΔܕ͕෇͚ΒΕͳ͍ • લऀ͸ن໿ԽͰΧόʔՄೳɺޙऀ͸ yield ࣜͷ୅ΘΓʹ yield* ࣜΛ࢖͏͜ͱͰ ৐Γӽ͑ΒΕΔ
44. ᶅ Ԡ༻ͦͷ 1: Result ܕ
45. Promise Ҏ֎΁ͷԠ༻ • ͜͜·ͰͷςΫχοΫ͸ Promise Λ࢖ͬͨॲཧҎ֎ʹ΋Ԡ༻͕Մೳ • δΣωϨʔλ͔Β yield ͞Εͨ஋ͱɺδΣωϨʔλͷ࢒ΓͷܭࢉΛɺ
 ্खʹ͚ͬͭ͘Δ͜ͱ͕Ͱ͖ͨΒΑ͍ (= Ϟφυ) • Promise ͷ৔߹͸ then() ͕͜ͷ໾ׂΛ͍࣋ͬͯΔ
46. Promise Ҏ֎΁ͷԠ༻ • ྫ͑͹ Result ܕ΋͜Εʹ౰ͯ͸·Δ • then() ʹରԠ͢Δͷ͸ԼͷΑ͏ͳ৚݅෼ذ type Result<T, E> = Ok<T> | Err<E>; if (!res.isOk) return res; return cont(res.value);
47. Result ܕ΁ͷԠ༻ • Promise Ͱ͸ then() ͕ await (yield*) ʹஔ͖׵͑ΒΕͨ // before doX().then((x) => doY(x).then((y) => doZ(y).then((z) => // ... ) ) ); // after const x = await doX(); const y = await doY(x); const z = await doZ(y); // ...
48. Result ܕ΁ͷԠ༻ • Result Ͱ΋ಉ͡Α͏ʹஔ͖׵͑ΒΕΔ → ΤϥʔϋϯυϦϯάΛ؆ུԽ // before const x = doX(); if (!x.isOk) return x; const y = doY(x.value); if (!y.isOk) return y; const z = doZ(y.value); if (!z.isOk) return z; // ... // after const x = yield* doX(); const y = yield* doY(x); const z = yield* doZ(y); // ...
49. Result ܕ΁ͷԠ༻ • ࣮૷͸ׂѪ (ઌ΄Ͳͱಉ͡ susisu/tskaigi2025 ʹ׬શ൛͕͋Γ·͢) • run() ͷఆٛ͸ Promise ͷ࣌ͱ΄΅ಉ͡ (then() ͕ҟͳΔ͚ͩ) type Comp<T, E> = Generator<Result<any, E>, T, any>; declare function run<T, E>(comp: Comp<T, E>): Result<T, E>; function* myFunc(): Comp<Y, Error> { /* ... */ } const result = run(myFunc()); // result: Result<Y, Error>
50. Result ܕࣗମΛ Iterable ʹ͢Δ • Promise ͱ͸ҟͳΓɺResult ܕࣗମΛ Iterable ʹ΋Ͱ͖Δ • yield* ࣜΛ࢖͏ͱ͖ͷม׵ΛखͰॻ͘ඞཁ͕ͳ͘ͳͬͯศར class Ok<T> { // ... *[Symbol.iterator](): Comp<T, never> { return yield this; } }
51. ͜͜·Ͱͷ·ͱΊ • δΣωϨʔλΛ࢖ͬͨςΫχοΫ͸ Promise Ҏ֎ʹ΋Ԡ༻͕Մೳ • yield ͞Εͨ஋ͱ࢒ΓͷܭࢉΛ্ख͚ͬͭ͘͘ΒΕͨΒྑ͍ (Ϟφυ) • ྫͱͯ͠ Result ܕͷ৔߹Λ঺հ • ଞʹ΋͍Ζ͍Ζ • neverthrow, E ff ect ͳͲͷϥΠϒϥϦ • ύʔαίϯϏωʔλ • etc.
52. ᶆ Ԡ༻ͦͷ 2: ΤϑΣΫτ
53. ΤϑΣΫτ • ;ͭ͏ϓϩάϥϜ͸࣮ߦ͢Δͱ༷ʑͳΤϑΣΫτΛൃੜͤ͞Δ • ը໘ʹจࣈ΍ը૾Λදࣔ͢ΔɺϑΝΠϧΛಡΈॻ͖͢Δɺ
 ωοτϫʔΫϦΫΤετΛߦ͏ɺݱࡏ࣌ࠁΛऔಘ͢ΔɺͳͲͳͲ • ͜ΕΒͷΤϑΣΫτΛ্खʹऔΓѻ͍͍ͨ → ΤϑΣΫτγεςϜ • ϓϩάϥϜͷͲͷ෦෼͕ωοτϫʔΫϦΫΤετΛߦ͏ͷ͔஌Γ͍ͨ • ςετͰ͸ωοτϫʔΫϦΫΤετΛϞοΫͰ୅༻͍ͨ͠
54. • ͜Μͳ;͏ʹϓϩάϥϜ͕ॻ͚Δͱͨ͠Βʁ ΤϑΣΫτγεςϜ // 発生し得るエフェクトの種類を型でトラッキング function* main(): Eff<void, "net" | "fs"> { const icon = yield* httpGet("https://susisu.ch/icon.svg"); yield* writeFile("./icon.svg", icon); }
55. • ͜Μͳ;͏ʹϓϩάϥϜ͕ॻ͚Δͱͨ͠Βʁ ΤϑΣΫτγεςϜ // 型に現れないエフェクトを発生させたらコンパイルエラー function* main(): Eff<void, "fs"> { const icon = yield* httpGet("https://susisu.ch/icon.svg"); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ yield* writeFile("./icon.svg", icon); }
56. ΤϑΣΫτγεςϜ • ͜Μͳ;͏ʹϓϩάϥϜ͕ॻ͚Δͱͨ͠Βʁ // 通常は実際に読み書き runAsync( interpret(main(), { net: interpretNet, fs: interpretFs, }), ); // テストではモック実装 runPure( interpret(main(), { net: mockNet, fs: mockFs, }), );
57. ΤϑΣΫτγεςϜ • ͜Μͳ;͏ʹϓϩάϥϜ͕ॻ͚Δͱͨ͠Βʁ • → ॻ͚·ͨ͠ (࣮ݧతͳϥΠϒϥϦΛ࡞Γ·ͨ͠) • https://github.com/susisu/e ff ectful • ͜͜·Ͱʹ঺հͨ͠ͷ͸શ࣮ͯࡍʹಈ࡞͢Δίʔυ • ཧ࿦తʹ͸ Algebraic E ff ects & Handlers ͱݺ͹ΕΔύϥμΠϜ
58. ΤϑΣΫτγεςϜͷ࣮૷ • δΣωϨʔλͷܕఆٛ͸ Promise ΍ Result ͷ৔߹ͱجຊ͸ಉ͡ • ͨͩ͠۩ମతͳσʔλ (Ϟφυ) ͷ෦෼͸ΤϑΣΫτͱͯ͠ந৅Խ͓͍ͯͯ͠ɺ
 ޙ͔Β࣮ߦ͢ΔՕॴ (ϋϯυϥ) Ͱܾఆ͢Δ // before type Comp<T> = Generator<Promise<any>, T, any>; type Comp<T, E> = Generator<Result<any, E>, T, any>; // after type Eff<T, Row> = Generator<Effect<Row, any>, T, any>;
59. ࣌ؒͶ͐ʔ • ໘ന͍͜ͱ͕ͨ͘͞Μ͋Δ͚Ͳ࿩͕࣌ؒ͢଍Γͳ͍ʂ • ࣮૷ʹ࢖ͬͨςΫχοΫ • ϢχΦϯܕͰΤϑΣΫτͷ row Λૉ௚ʹදݱ (ׂͱ TypeScript ಛ༗) • interface ͷએݴϚʔδΛ࢖ͬͨߴ֊ܕ (ΤϑΣΫτͷந৅Խʹඞཁ) • GADT (ந৅Խͨ͠ΤϑΣΫτͷ໭Γ஋ͷܕΛݻఆ) • ΤϑΣΫτγεςϜΛ࢖ͬͯ۩ମతʹԿΛ͢Δͷ͔ʁ (࢖͑Δͷ͔ʁ) • Ask the Speaker ΍࠙਌ձͰ࿩͠·͠ΐ͏ :pray:
60. ·ͱΊ
61. ·ͱΊ (1/2) • δΣωϨʔλؔ਺͸தஅɾ࠶։Ͱ͖Δܭࢉͱͯ͠ݟΔ͜ͱ͕Ͱ͖Δ • ͜ΕΛ࢖͑͹ async / await ૬౰ͷه๏Λࣗ࡞Ͱ͖Δ • TypeScript Ͱ͸ͪΐͬͱ͓ͨ͠·͡ͳ͍Ͱ֓Ͷ্ख͘ܕΛ෇͚ΒΕΔ • yield Λ yield* ʹஔ͖׵͑Δ / ͦͷͨΊʹ Iterable ʹม׵͢Δ
62. ·ͱΊ (2/2) • δΣωϨʔλΛ࢖ͬͨςΫχοΫ͸ Promise Ҏ֎ʹ΋Ԡ༻͕Մೳ • yield ͞Εͨ஋ͱ࢒ΓͷܭࢉΛ্ख͚ͬͭ͘͘ΒΕͨΒྑ͍ (Ϟφυ) • ۩ମతʹ͸ Result ܕͳͲ • ͞Βʹ͸ Algebraic E ff ects ͷΑ͏ͳ΋ͷ΋࣮ݱͰ͖Δ • TypeScript ໘ന͍