kitchen-async: a promising (?) Promise library, or a poor man's core.async

Transcript

1. LJUDIFOBTZOD
   B
   QSPNJTJOH
   
   
   1SPNJTF
   MJCSBSZ
   
   PS
   B
   QPPS
   NBO`T
   DPSFBTZOD -JTQ
   NFFUVQ
   
   !BUIPT

2. ࣗݾ঺հ ‣ 5XJUUFS
   !BUIPT
   ‣ (JU)VC
   BUIPT
   ‣ $MPKVSF 4DSJQU
   ॻ͍ͯ·͢
   

   3FBDU
   /BUJWFΞϓϦΛ$MPKVSF4DSJQUͰ
    "MFYB
   4LJMMΛ$MPKVSF4DSJQUͰ

3. 5-%3 ‣ $MPKVSF$MPKVSF4DSJQUͰඇಉظϓϩάϥϛϯάͱ͍͏ͱ DPSFBTZOD͕༗໊͕ͩৗʹ࠷ྑͷબ୒ࢶͱ͸ݶΒͳ͍
   ‣ +BWB4DSJQU &$."4DSJQU ͸1SPNJTF΍BTZODBXBJU Λݴޠ࢓༷ʹऔΓೖΕ͍ͯͯɺ+4ͱͷJOUFSPQΛߟ͑Δͱ 1SPNJTFΛʮ͏·͘ʯѻ͑Δ͜ͱ΋ඞཁ
   

   ‣ 1SPNJTFͱ΋DPSFBTZODͱ΋͏·͘΍͍ͬͯͨ͘Ίͷϥ ΠϒϥϦLJUDIFOBTZODΛ࡞ͬͨɺͱ͍͏࿩

4. ࠓ೔࿩͢͜ͱ ‣ എܠ
    +BWB4DSJQUք۾ͷඇಉظϓϩάϥϛϯάࣄ৘
    $MPKVSF4DSJQUք۾ͷඇಉظϓϩάϥϛϯάࣄ৘
   ‣ $MPKVSF4DSJQUͰͷඇಉظϓϩάϥϯάͷ໰୊
   ‣

   LJUDIFOBTZODͷ঺հ

5. എܠ

6. +BWB4DSJQUք۾ͷඇಉظࣄ৘ ‣ +BWB4DSJQUͷଟ͘ͷॲཧܥ͸γϯάϧεϨου
   ‣ *0ॲཧ౳ͷ׬ྃΛಉظతʹ଴ͪ߹Θͤͯ͠·͏ͱɺͦͷ εϨου͸ॲཧ׬ྃ·ͰԿ΋Ͱ͖ͳ͘ͳΔ
   ‣ *0ͷ׬ྃ଴ͪ౳ͷؒεϨουΛଞͷॲཧʹ໌͚౉͢͜ͱ ͰεϨουΛޮ཰తʹ࢖͑ΔΑ͏ʹͳΔ
   ˠ
   ඇಉظϓϩάϥϛϯά

7. ίʔϧόοΫ ‣ ॲཧ͕׬ྃͨ͠ޙʹ࣮ߦ͢ΔॲཧΛ౉͢
   ‣ +BWB4DSJQUͱͯ͠͸΋ͬͱ΋ݪ࢝తͳඇಉظ"1*ͷ࡞Γํ
   ‣ ඇಉظॲཧ͕ଟஈʹͳΔͱίʔϧόοΫ͕ωετͯ͠ίʔυͷ Մಡੑ͕ѱ͘ͳΔ ͍ΘΏΔʮίʔϧόοΫ஍ࠈʯ const

   fs = require(‘fs’) fs.readFile(‘input.txt’, (err, data) => { console.log(data) })

8. 1SPNJTF ‣ 1SPNJTF͸ඇಉظͳܭࢉ݁ՌΛอ࣋͢Δσʔλܕ
   ‣ ίʔϧόοΫΛҾ਺ʹड͚Δ୅ΘΓʹ1SPNJTFΛฦ͢Α͏ ʹ͓ͯ͘͠ͱʜ const readFileAsync = (path)

   => { return new Promise((resolve, reject) => { fs.readFile(path, (err, data) => { if (err) return reject(err) resolve(data) }) }) }

9. 1SPNJTF ‣ ॲཧͷ׬ྃޙʹ࣮ߦ͢ΔॲཧΛޙ͔ΒઃఆͰ͖Δ
   ‣ ϝιουνΣʔϯͰଟஈͷॲཧΛܨ͛ΒΕΔ readFileAsync(‘input.txt’) .then((text) => { return

   JSON.parse(text) }) .then((json) => { console.log(json) }) .catch((err) => { console.log(err) })

10. BTZODBXBJU ‣ 1SPNJTFΛ࢖ͬͨॲཧΛ௚઀ܗࣜͰ͔͋ͨ΋ಉظతͳॲཧͷΑ͏ʹ هड़Ͱ͖Δ
    ‣ ଟ͘ͷ৔߹1SPNJTFΛ௚઀࢖͏ΑΓ੍ޚϑϩʔ͕෼͔Γ΍͘͢ͳΔ (async () => {

    try { const text = await readFileAsync(‘input.txt’) return JSON.parse(text) } catch (err) { console.log(err) } })()

11. +BWB4DSJQUք۾ͷඇಉظࣄ৘ ‣ &$."4DSJQU
    &4 ͷ࢓༷΁ͷऔΓࠐΈ
     &4
    
    1SPNJTF
     &4
    
    BTZODBXBJU
    ‣

    8FCඪ४ͷ"1*Ͱͷར༻
     'FUDI
    "1*
     8FC35$ͷϝσΟΞऔಘ
     4FSWJDF
    8PSLFS
    FUD
    FUD
    ‣ αʔυύʔςΟͷOQNϞδϡʔϧͰͷར༻ +BWB4DSJQUͷ༷ʑͳ"1*ʹ1SPNJTF͕࢖ΘΕͭͭ͋Δ

12. $MPKVSF4DSJQUք۾ͷඇಉظࣄ৘ ‣ ΄΅DPSFBTZODҰ୒ͳงғؾ
    ‣ DPSFBTZOD͸$41 ڠௐεϨουͱνϟωϧΛհͨ͠ϝο ηʔδύογϯά ΛϞσϧʹ͍ͯ͠Δ
    ‣ 1SPNJTFͱಉ༷ͷ࢖͍ํ΋Ͱ͖Δ͕ɺͭͷνϟωϧ͔Β

    ෳ਺ճ஋Λड͚औͬͨΓɺ஋ΛૹΓฦͤΔ෼ΑΓڧྗ

13. DPSFBTZODͰͷඇಉظॲཧ (require ‘[clojure.core.async :as a]) (defn read-file [path] (let [ch

    (a/chan)] (fs.readFile path (fn [err data] (a/put! ch (or err data)))) ch)) (a/go (let [data (a/<! (read-file “input.txt”))] (js/console.log data)))

14. ར༻ऀ͔Βͷ͓೰Έ ʮ$MPKVSF4DSJQU͔Βͩͱ1SPNJTFΛѻ͏ίʔυ Λ͖ͬ͢Γॻ͚·ͤΜʯ ୅உੑձࣾһ ˞
    ͜Ε͸ݸਓͷײ૝Ͱײ͡ํʹ͸ݸਓ͕ࠩ͋Γ·͢

15. ར༻ऀ͔Βͷ͓೰Έ ʮ$MPKVSF4DSJQU͔Βͩͱ1SPNJTFΛѻ͏ίʔυ Λ͖ͬ͢Γॻ͚·ͤΜʯ ୅உੑձࣾһ (-> (readFileAsync “input.txt”) (.then (fn [text]

    (js/JSON.parse text))) (.then (fn [json] (js/console.log json))) (.catch (fn [err] (js/console.log err)))) ˞
    ͜Ε͸ݸਓͷײ૝Ͱײ͡ํʹ͸ݸਓ͕ࠩ͋Γ·͢

16. ར༻ऀ͔Βͷ͓೰Έ ʮ$MPKVSF4DSJQU͔Βͩͱ1SPNJTFΛѻ͏ίʔυ Λ͖ͬ͢Γॻ͚·ͤΜʯ ୅உੑձࣾһ (-> (puppeteer/launch) (.then (fn [browser] (->

    (.newPage browser) (.then (fn [page] (.then (.goto page “https://www.google.com") #(.screenshot page #js{:path “image.png"})))) (.then #(.close browser))))))) ˞
    ͜Ε͸ݸਓͷײ૝Ͱײ͡ํʹ͸ݸਓ͕ࠩ͋Γ·͢

17. ར༻ऀ͔Βͷ͓೰Έ ‣ ͦ΋ͦ΋1SPNJTF͸+4Ͱॻ͖΍͍͢Α͏ʹઃܭ͞Ε͍ͯΔ
    ‣ ෳࡶͳ৔߹ͩͱ݁ہ1SPNJTFΛωετͤͯ͞࢖͏ඞཁ͕͋Δ
    ‣ BTZODBXBJU͘Β͍͖ͬ͢ΓͱඇಉظͳίʔυΛॻ͖͍ͨ ʮ$MPKVSF4DSJQU͔Βͩͱ1SPNJTFΛѻ͏ίʔυ Λ͖ͬ͢Γॻ͚·ͤΜʯ ୅உੑձࣾһ

    ˞
    ͜Ε͸ݸਓͷײ૝Ͱײ͡ํʹ͸ݸਓ͕ࠩ͋Γ·͢

18. ར༻ऀ͔Βͷ͓೰Έ ‣ 1SPNJTFϔϏʔͳ"1*Λ࢖͏ͱ͖ʹ౎౓νϟωϧʹม׵ͨ͘͠ͳ͍
    ‣ HPϒϩοΫ͸े෼ʹෳࡶͳϚΫϩ
     ల։ܗ΋σΧ͍
     XFC
    "1*Λճୟͨ͘Ί͚ͩʹHPϒϩοΫΛॻ͖ͨ͘ͳ͍
    ‣

    DPSFBTZOD͸Τϥʔॲཧ͕͏·͘ͳ͍
    ‣ TFMGIPTUFE
    $-+4
    -VNP1MBODL Ͱ͸ͦͷ··Ͱ͸ಈ͔ͳ͍ ʮDPSFBTZOD͸͔ͨ͠ʹڧྗͳಓ۩ͳΜ͚ͩͲɺ ͬ͘͠Γ͜ͳ͍৔߹΋͋Γ·͢ΑͶʯ ୅உੑձࣾһ ˞
    ͜Ε͸ݸਓͷײ૝Ͱײ͡ํʹ͸ݸਓ͕ࠩ͋Γ·͢

19. ސ٬͕ຊ౰ʹඞཁͩͬͨ΋ͷ ‣ ʮෳ਺ͷඇಉظॲཧΛஞ࣍తʹ࣮ߦ͢Δʯͱ͍͏໨తͷͨΊʹ ͸DPSFBTZOD͸ΦʔόʔΩϧ ‣ ඇಉظϓϩάϥϛϯάͷதఔ౓ʹෳࡶͳίʔυΛॻ͘ͷʹదͨ͠ ಓ۩͕΄͍͠ ໰୊ͷෳࡶ͞ ίʔϧόοΫ Promise

    core.async

20. ސ٬͕ຊ౰ʹඞཁͩͬͨ΋ͷ ‣ ʮෳ਺ͷඇಉظॲཧΛஞ࣍తʹ࣮ߦ͢Δʯͱ͍͏໨తͷͨΊʹ ͸DPSFBTZOD͸ΦʔόʔΩϧ ‣ ඇಉظϓϩάϥϛϯάͷதఔ౓ʹෳࡶͳίʔυΛॻ͘ͷʹదͨ͠ ಓ۩͕΄͍͠ ໰୊ͷෳࡶ͞ ίʔϧόοΫ Promise

    core.async

21. ސ٬͕ຊ౰ʹඞཁͩͬͨ΋ͷ ‣ ʮෳ਺ͷඇಉظॲཧΛஞ࣍తʹ࣮ߦ͢Δʯͱ͍͏໨తͷͨΊʹ ͸DPSFBTZOD͸ΦʔόʔΩϧ ‣ ඇಉظϓϩάϥϛϯάͷதఔ౓ʹෳࡶͳίʔυΛॻ͘ͷʹదͨ͠ ಓ۩͕΄͍͠ ‣ ႩఆόαϛͰ΋νΣʔϯιʔͰ΋ͳ͍מΓࠐΈόαϛ͕΄͍͠ʂ ໰୊ͷෳࡶ͞

    ίʔϧόοΫ Promise core.async

22. LJUDIFOBTZOD

23. LJUDIFOBTZOD ‣ 1SPNJTFΛத৺ͱͯ͠ɺ$MPKVSF4DSJQUͰඇಉظͳίʔυ Λॻ͖΍͘͢͢ΔϥΠϒϥϦ
     $MPKVSFͷΠσΟΦϜతͳॻ͖ํͰ1SPNJTFΛѻ͑Δߏจ
     DPSFBTZODͷνϟωϧ౳ͱγʔϜϨεʹ࿈ܞͰ͖Δ਌࿨ੑ
    ‣ ໊લ͸
    lFWFSZUIJOH
    CVU
    UIF
    LJUDIFO
    TJOLz
    

    ԿͰ΋͔ΜͰ΋
    Λ΋ͬͨ͡΋ͷ

24. LJUDIFOBTZOD͕ఏڙ͢Δ"1* ‣ 1SPNJTF༝དྷͷؔ਺ɾϚΫϩ
     QSPNJTFɾUIFOɾDBUDI
     BMMɾSBDF
    ‣ $MPKVSFͷߏจͰ1SPNJTFΛѻ͏౶ҥߏจ
    

     QMFU
     εϨοσΟϯάϚΫϩ
     ϧʔϓ
     ྫ֎ॲཧ

25. QSPNJTFɾUIFOɾDBUDI ‣ +4ͷ1SPNJTFͱ ΄΅ ౳Ձͳ"1*Λఏڙ͍ͯ͠Δ (require ‘[kitchen-async.promise :as p]) (->

    (p/promise [resolve reject] (resolve 42)) (p/then (fn [x] (js/console.log x))) (p/catch* (fn [err] (js/console.log err))))

26. QMFUϚΫϩ (p/let [<var1> <init1> <var2> <init2> …] <body>) (p/then <init1>

    (p/then (fn [<var1>] (p/then <init2> (fn [<var2>] … <body> …))))) ্ͷϑΥʔϜ͸͓͓ΉͶҎԼͷΑ͏ʹల։͞ΕΔ

27. QMFUϚΫϩ (p/let [browser (puppeteer/launch) page (.newPage browser)] (.goto page "https://www.example.com")

    (.screenshot page #js{:path "image.png"}) (.close browser)) (-> (puppeteer/launch) (.then (fn [browser] (-> (.newPage browser) (.then (fn [page] (.then (.goto page “https://www.example.com”) #(.screenshot page #js{:path "image.png"})))) (.then #(.close browser))))))) ্ͷίʔυ͸
    QMFU
    Λ࢖ͬͯҎԼͷΑ͏ʹॻ͖׵͑ΒΕΔ

28. εϨοσΟϯάϚΫϩ (p/let [x (f) y (g x)] (h y)) (p/->

    (f) g h) ্ͷίʔυ͸
    Q
    Λ࢖ͬͯҎԼͷΑ͏ʹॻ͖׵͑ΒΕΔ w Q
    QTPNF
    QTPNF΋ಉ༷ʹ࢖͑Δ

29. ϧʔϓ ‣ QMPPQɾQSFDVS
    Λ࢖ͬͯ௨ৗͱಉ༷ʹϧʔϓ͕ॻ͚Δ
    ‣ QSFDVS
    ͸
    QMPPQ
    ͷதͰͷΈ࢖༻Ͱ͖Δ (p/loop [i (p/timeout 1000 0)]

    (when (<= i 10) (prn i) (p/recur (p/timeout 1000 (inc i)))))

30. ྫ֎ॲཧ ‣ QUSZɾQDBUDIɾQpOBMMZ
    Λ࢖ͬͯ௨ৗͱಉ༷ʹྫ֎ॲཧ͕ॻ͚Δ
    ‣ QDBUDIɾQpOBMMZ
    ͸
    QUSZ
    ͷதͰͷΈ࢖༻Ͱ͖Δ (p/try (write-async fd content) (p/catch

    :default e (js/console.log e)) (p/finally (close fd)))

31. DPSFBTZODͱͷ
    γʔϜϨεͳ࿈ܞ

32. QSPNJTF ‣ ೚ҙͷ஋Λ1SPNJTFʹม׵ DPFSDJPO ͢Δؔ਺ (defprotocol Promisable (->promise [this])) (extend-protocol

    Promisable js/Promise (->promise [this] this) default (->promise [this] (p/promise [resolve] (resolve this)))

33. ҉໧ͷQSPNJTF ‣ LJUDIFOBTZODͷ͢΂ͯͷ"1*͸҉໧ʹQSPNJTFΛద༻
    ‣ 1SPNJTFҎ֎ͷ஋΋1SPNJTFͱ۠ผͳ͘࢖͏͜ͱ͕Ͱ͖Δ (p/let [x (f), y (g

    x)] (h y)) (p/then p f) (p/then (->promise p) f) (p/let [x (->promise (f)), y (->promise (g x))] (h y))

34. DPSFBTZODνϟωϧͱͷ࿈ܞ (ns kitchen-async.promise.from-channel (:require [clojure.core.async :as a] [clojure.core.async.impl.channels :refer [ManyToManyChannel]]

    [kitchen-async.promise :as p])) (extend-protocol p/Promisable ManyToManyChannel (->promise [ch] (p/promise [resolve reject] (a/go (let [x (a/<! ch)] (if (instance? js/Error x) (reject x) (resolve x)))))))

35. DPSFBTZODνϟωϧͱͷ࿈ܞ ‣ dQSPNJTFGSPNDIBOOFMΛϩʔυ͢Ε͹νϟωϧͱ 1SPNJTFΛγʔϜϨεʹ࢖͑ΔΑ͏ʹͳΔ (require ‘kitchen-async.promise.from-channel) (def ch (a/chan)) (p/loop

    [i 0, x ch] (prn x) (when (<= i 10) (p/recur (inc i) ch)))

36. ࣮༻ྫ ‣ DPSFBTZODͱಉ౳ͷ͜ͱ͕HPϚΫϩΛ࢖ΘͣʹͰ͖Δ
    ‣ ͨͩ͠ɺύϑΥʔϚϯεతʹ͸DPSFBTZODͷํ͕͍͍ (defn debounce ([c ms] (debounce

    (a/chan) c ms)) ([c' c ms] (p/loop [start nil loc c] (if (nil? start) (do (a/put! c' loc) (p/recur (js/Date.) nil)) (p/let [loc c] (if (>= (- (js/Date.) start) ms) (p/recur nil loc) (p/recur (js/Date.) loc))))) c'))

37. ·ͱΊ ‣ $MPKVSF$MPKVSF4DSJQUͰඇಉظϓϩάϥϛϯάͱ͍͏ͱ DPSFBTZOD͕༗໊͕ͩৗʹ࠷ྑͷબ୒ࢶͱ͸ݶΒͳ͍
    ‣ +BWB4DSJQU &$."4DSJQU ͸1SPNJTF΍BTZODBXBJU Λݴޠ࢓༷ʹऔΓೖΕ͍ͯͯɺ+4ͱͷJOUFSPQΛߟ͑Δͱ 1SPNJTFΛʮ͏·͘ʯѻ͑Δ͜ͱ΋ඞཁ
    

    ‣ 1SPNJTFͱ΋DPSFBTZODͱ΋͏·͘΍͍ͬͯͨ͘Ίͷϥ ΠϒϥϦLJUDIFOBTZODΛ࡞ͬͨɺͱ͍͏࿩

38. LJUDIFOBTZOD ‣ 1SPNJTFΛத৺ͱͯ͠ɺ$MPKVSF4DSJQUͰඇಉظͳίʔυ Λॻ͖΍͘͢͢ΔϥΠϒϥϦ
    ‣ $MPKVSFͷΠσΟΦϜతͳॻ͖ํͰ1SPNJTFΛѻ͑Δߏจ
    ‣ DPSFBTZODͷνϟωϧͱγʔϜϨεʹ࿈ܞͰ͖Δ਌࿨ੑ