ジェネレータを有効活用し隊 / Kyoto.js 11 LT

Kyoto.js 11 http://kyotojs.connpass.com/event/39462/

Transcript

1. δΣω Ϩ ʔ λ Λ
   ༗ ޮ ׆ ༻ ͠ ୂ
   2 0 1 6 - 1 0 - 2 2 K y o t o . j s 1 1
   Twitter @susisu2413 / GitHub @susisu
   

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2. Q .
   δΣω Ϩ ʔ λ ͸
   Կ ʹ ࢖ ͑Δʁ
   

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3. 1 . ί ϧ ʔ νϯ
   

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4. app.use(function* (next) {
   const start = new Date(); // (1)
   yield next;
   const end = new Date(); // (3)
   // log (4)
   });
   !
   app.use(function* (next) {
   yield next;
   // respond (2)

   });
   ྫ: Koa
   

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5. 2 . ஗ Ԇ Ϧε τ
   

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6. function range(a, b, s = 1) {
   const arr = [];
   for (let n = a; n < b; n += s) {
   arr.push(n);
   }
   return arr;
   }
   !
   for (const n of range(1, 10)) {
   doSomething(n); // from 1 to 9
   }
   

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7. function* xrange(a, b, s = 1) {
   for (let n = a; n < b; n += s) {
   yield n;
   }
   }
   !
   for (const n of xrange(1, 10)) {
   doSomething(n); // from 1 to 9
   }
   

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8. function* fibonacci() {
   let [a, b] = [1, 1];
   while (true) {
   yield a;
   [a, b] = [b, a + b];
   }
   }
   !
   for (const n of fibonacci()) {
   doSomething(n); // 1, 1, 2, 3, 5, ...
   }
   

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9. 3 . Π ς Ϩ ʔ λ ͷ Ճ ޻
   

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10. function* concat(iter1, iter2) {
    yield* iter1;
    yield* iter2;
    }
    !
    for (const x of concat(arr1, arr2)) {
    doSomething(x);
    }
    

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11. function* map(func, iter) {
    for (const x of iter) {
    yield func(x);
    }
    }
    !
    for (const n of map(n => n ** 2, arr)) {
    doSomething(n);
    }
    

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12. 4 . ඇ ಉ ظ ॲ ཧ
    

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13. fetch().then(x =>
    fetch().then(y =>
    fetch().then(z =>
    doSomething(x, y, z)
    )
    )
    );
    before (Promise)
    

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14. co(function* () {
    const x = yield fetch();
    const y = yield fetch();
    const z = yield fetch();
    return doSomething(x, y, z);
    });
    after (Promise + Generator + co)
    

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15. Q .
    ଞ ʹ ΋ δΣω Ϩ ʔ λ ͕
    ࢖ ͑Δ ৔ ໘ ͸ ͋ Δʁ
    

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16. ͦ ΋ ͦ ΋ δΣω Ϩ ʔ λ ͱ ͸
    

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17. g e n . n e x t ( )
    

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18. { d o n e : f a l s e ,
    v a l u e : * }
    g e n . n e x t ( )
    

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19. { d o n e : f a l s e ,
    v a l u e : * }
    g e n . n e x t ( )
    g e n . n e x t ( )
    gen.next ͷத਎΋มΘ͍ͬͯΔ
    

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20. { d o n e : f a l s e ,
    v a l u e : * }
    { d o n e : f a l s e ,
    v a l u e : * }
    g e n . n e x t ( )
    g e n . n e x t ( )
    g e n . n e x t ( )
    

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21. { d o n e : f a l s e ,
    v a l u e : * }
    { d o n e : f a l s e ,
    v a l u e : * }
    { d o n e : t r u e ,
    v a l u e : * }
    g e n . n e x t ( )
    g e n . n e x t ( )
    g e n . n e x t ( )
    

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22. ݟํΛม͑Δͱ͍͔ʹ΋஗ԆϦετ
    d o n e : f a l s e
    v a l u e ( ) = > d o n e : f a l s e
    v a l u e ( ) = > d o n e : t r u e
    v a l u e
    

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23. d o n e : f a l s e
    v a l u e x = > d o n e : f a l s e
    v a l u e y = > d o n e : t r u e
    v a l u e
    .next() ͸Ҿ਺ΛͱΕΔ
    

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24. fetch().then(x =>
    fetch().then(y =>
    fetch().then(z =>
    doSomething(x, y, z)
    )
    )
    );
    PromiseΛ࢖ͬͨඇಉظॲཧ
    

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26. d o n e : f a l s e
    v a l u e x = > d o n e : f a l s e
    v a l u e y = > d o n e : t r u e
    v a l u e
    

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27. t h e n
    v a l u e x = > t h e n
    v a l u e y = > re s o l v e
    v a l u e
    .then() Ͱͭͳ͗߹ΘͤΔ
    

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28. co(function* () {
    const x = yield fetch();
    const y = yield fetch();
    const z = yield fetch();
    return doSomething(x, y, z);
    });
    Promise + Generator + co
    

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29. Q .
    ଞ ʹ ΋ δΣω Ϩ ʔ λ ͕
    ࢖ ͑Δ ৔ ໘ ͸ ͋ Δʁ
    

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30. A .
    ͋ Γ · ͢
    

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31. 5 . ύ ʔ α ί ϯ Ϗω ʔ λ
    

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32. symbol("(").bind(_ =>
    expr.bind(x =>
    symbol(")").bind(_ =>
    pure(x)
    )
    )
    );
    ׅހ (ʙ) ʹೖͬͨࣜͷύʔα
    

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33. qo(function* () {
    yield symbol("(");
    const x = yield expr;
    yield symbol(")");
    return x;
    });
    ద౰ͳؔ਺Λ࢖͑͹……
    

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34. 6 . * ద ౰ ͳ Ϟ φ υ
    ※ Ͳ ΕͰ ΋ ྑ ͍ ͱ ͍ ͏ Θ ͚ Ͱ ͸ ͳ ͍
    

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35. δΣω Ϩ ʔ λ Λ
    ༗ ޮ ׆ ༻ ͠ ୂ
    ׆ ಈ ใ ࠂ
    

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36. δΣω Ϩ ʔ λ ͸
    ஗ Ԇ Ϧε τ Λ
    Ұ ൠ Խ ͠ ͨ Α ͏ ͳ ΋ ͷ
    

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37. · ͩ · ͩ
    ࢖ ͑Δ ৔ ໘ ͕ ͋ Γ ͦ ͏
    ྫ : ύ ʔ α ί ϯ Ϗω ʔ λ
    

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38. ଞ ʹ ׆ ༻ ࣄ ྫ ͕ ͋ Ε ͹
    ͓ ڭ ͑͘ ͩ ͞ ͍
    

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39. { d o n e : t r u e ,
    v a l u e : " T h a n k s " }
    

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