DDD by Functional programming with TypeScript

Gunma.web#30のLTスライドです。
勘違いがあればどうかご指摘ください。

参考
https://qiita.com/nunulk/items/7447e6dadae29a41af3d

Transcript

1. with TypeScript υϝΠϯۦಈઃܭͱؔ਺ܕϓϩάϥϛϯά 2017.02.20 Gunma.web#30 Hikaru Otabe
2. ࣗݾ঺հ w େా෦
   ߊɹ!DIJMEIPPPPP
   w ೥લ͸ϩέοτؔ܎ͷ૊ΈࠐΈΤϯδχΞʢ$ ʣ
   w ࠷ۙ͸8FCؔ܎ͷ࢓ࣄ
   w $
   1ZUIPO
   &MJYJS
   +BWB4DSJQU
   1)1
   FUD
   
   
    Profile
3. ؔ਺ܕϓϩάϥϛϯάͱ͍͑͹ What comes to your mind ?
4. ਺ֶ map Ϟφυ ෭࡞༻ ϥϜμࣜ ࢀরಁաੑ ஗ԆධՁ ؔ਺ͷ߹੒ ΧϦʔԽ ΧϦʔԽ ςετ ͳʹͦΕʁ ฒߦॲཧ ύλʔϯϚον ࠶ؼ
5. ਺ֶ map Ϟφυ ෭࡞༻ ϥϜμࣜ ࢀরಁաੑ ஗ԆධՁ ؔ਺ͷ߹੒ ΧϦʔԽ ΧϦʔԽ ςετ ͳʹͦΕʁ ฒߦॲཧ ύλʔϯϚον ࠶ؼ
6. ࠓճ஫໨͢Δಛ௃ lؔ਺ܕϓϩάϥϛϯάͰ͸ࢀরಁաੑ͕อূ͞ΕΔz
   
7. ࠓճ஫໨͢Δಛ௃ lؔ਺ܕϓϩάϥϛϯάͰ͸ࢀরಁաੑ͕อূ͞ΕΔz
   ͞ΕΔͱ͍͏͔ɺ͢Δɻ
8. ࢀরಁաੑΛഁյ͢Δ΋ͷ Who breaks Referential transparency ?
9. 1. ࠶୅ೖ 2. ɹม਺ͷࢀরಁաੑΛഁյ ෭࡞༻ͷ͋Δؔ਺ ɹؔ਺ͷࢀরಁաੑΛഁյ
10. ࠶୅ೖʹΑΔࢀরಁաੑͷഁյ > var x = 1 undefined
11. ࠶୅ೖʹΑΔࢀরಁաੑͷഁյ > var x = 1 undefined > x = 2 2
12. ࠶୅ೖʹΑΔࢀরಁաੑͷഁյ > var x = 1 undefined > x = 2 2 > x 2
13. ࠶୅ೖʹΑΔࢀরಁաੑͷഁյ > var x = 1 undefined > x = 2 2 > x 2 Broken!
14. ࠶୅ೖʹΑΔࢀরಁաੑͷഁյ > var x = 1 undefined > x = 2 2 > x 2 > const y = 1 undefined > y = 2 TypeError Broken!
15. ؔ਺ͷ෭࡞༻ʹΑΔࢀরಁաੑͷഁյ > var counter = 0 undefined > const count = (x) => counter += x undefined > count(3) 3 > count(3) 6
16. ؔ਺ͷ෭࡞༻ʹΑΔࢀরಁաੑͷഁյ > var counter = 0 undefined > const count = (x) => counter += x undefined > count(3) 3 > count(3) 6 Broken!
17. υϝΠϯۦಈઃܭ Domain-Driven Design
18. υϝΠϯϞσϧͷߏ੒ཁૉ w ஋ΦϒδΣΫτ
    w ΤϯςΟςΟ
    w αʔϏε
    w FUD
    ʜ
19. υϝΠϯϞσϧͷߏ੒ཁૉ w ஋ΦϒδΣΫτ
    w ΤϯςΟςΟ
    w αʔϏε
    w FUD
    ʜ
20. υϝΠϯϞσϧͷߏ੒ཁૉ w ஋ΦϒδΣΫτ
    w ΤϯςΟςΟ
    w αʔϏε
    w FUD
    ʜ ؔ਺ܕϓϩάϥϛϯάͰͲͷΑ͏ʹදݱ͢Δ͔ʁ
21. υϝΠϯϞσϧͷߏ੒ཁૉ w ஋ΦϒδΣΫτ
    w ΤϯςΟςΟ
    w αʔϏε
    w FUD
    ʜ ؔ਺ܕϓϩάϥϛϯάͰͲͷΑ͏ʹදݱ͢Δ͔ʁ ʂ ׬ᘳͳ࣮ફ͸೉͍͠Ͱ͢
22. ۜߦޱ࠲ΞϓϦέʔγϣϯͷྫ
23. ΤϯςΟςΟʢؔ਺ܕϓϩάϥϛϯάʣ class Account { constructor(public id: UserID, public balance: Balance) { Object.freeze(this); } debit(amount: number):Balance { if(this.balance.amount < amount) { return [“error”, “This is an error message.”]; } else { return [“success”, ɹnew Account(this.id, new Balance(this.balance.amount - amount))]; } } credit(amount: number):Balance { return [“success”, new Account(this.id, new Balance(this.balance.amount + amount))]; } }
24. จࣈ͕খ͍͞
25. GitHub github.com/childhooooo/ddd-fp-ts
26. ஋ΦϒδΣΫτ w ࢒ߴΛද࣌͢͸ɺ/VNCFSܕͰ͸ͳ͘ɺ#BMBODFܕΛ
    w ෆมੑ
    ʜ
    Ұ౓ੜ੒ͨ͠ΒɺଐੑΛมߋ͢Δ͜ͱ͸ग़དྷͳ͍
    w ౳Ձੑ
    ʜ
    ࢀরઌͰ͸ͳ͘ɺଐੑͰ൑அ Value objects
27. ஋ΦϒδΣΫτ class Balance { constructor(public amount: number = 0) { Object.freeze(this); } } const balance = new Balance(100); balance.amount = 50 //error
28. ΤϯςΟςΟ w ಉҰੑ
    ʜ
    ଐੑ͕ҟͳ͍ͬͯͯ΋ɺ*%͕ಉ͡ͳΒ͹ಉҰͷ΋ ͷͱͯ͠ѻ͏
    w ϥΠϑαΠΫϧͷ࿈ଓੑ Entities
29. ΤϯςΟςΟʢҰൠతͳΦϒδΣΫτࢦ޲ʣ class Account { constructor(public id: UserID, public balance: Balance) {} debit(amount: number):string { if(this.balance.amount < amount) {
 return “error”; } else { this.balance = new Balance(this.balance.amount - amount); return “success”; } } credit(amount: number):string { this.balance = new Balance(this.balance.amount + amount); return “success”; } }
30. ΤϯςΟςΟΛ࢖͏ʢҰൠతͳΦϒδΣΫτࢦ޲ʣ let account = new Account(“A”, new Balance(200)); console.log(account.balance.amount); //200 result = account.debit(100); console.log(result, account.balance.amount); //“success” 100
31. ΤϯςΟςΟΛ࢖͏ʢҰൠతͳΦϒδΣΫτࢦ޲ʣ let account = new Account(“A”, new Balance(200)); console.log(account.balance.amount); //200 result = account.debit(100); console.log(result, account.balance.amount); //“success” 100 Broken!
32. ΤϯςΟςΟʢؔ਺ܕϓϩάϥϛϯάʣ class Account { constructor(public id: UserID, public balance: Balance) { Object.freeze(this); } debit(amount: number):Account { if(this.balance.amount < amount) { return [“error”, “This is an error message.”]; } else { return [“success”, ɹnew Account(this.id, new Balance(this.balance.amount - amount))]; } } credit(amount: number):Account { return [“success”, new Account(this.id, new Balance(this.balance.amount + amount))]; } }
33. ΤϯςΟςΟΛ࢖͏ʢؔ਺ܕϓϩάϥϛϯάʣ const pattern = require(“matches”).pattern; //matches.js const account = new Account(new UserID(1), new Balance(200)); const operated = account.debit(100); pattern({ ‘[“success”, a@Account ]’: (a) => console.log(a.balance.amount), ‘[“error”, message ]’: (message) => console.log(message) })(operated); //100
34. αʔϏε w ஋ΦϒδΣΫτ΍ΤϯςΟςΟʹଐ͞ͳ͍ॏཁͳॲཧ
    w ಠཱͨ͠ΠϯλʔϑΣΠε
    w ঢ়ଶΛ࣋ͨͳ͍ Services
35. αʔϏε const transfer = (from: Account, to: Account, amount: number) => { const [res, debited] = from.debit(amount); return if_success([res, debited, …to.credit(amount)], ([a, credited]) => [“success”, a, credited[1]]); }
36. αʔϏεΛ࢖͏ const pattern = require(“matches”).pattern; //matches.js const from = new Account(new UserID(1), new Balance(500)); const to = new Account(new UserID(2), new Balance(300)); const transferred = transfer(from, to, 300); pattern({ ‘[“success”, f, _]’: (f) => console.log(f.balance.amount), ‘[“error”, message]’: (message) => console.log(message) })(transferred); //200
37. ঢ়ଶΛ൐͏ܭࢉʹ͍ͭͯ State monad
38. ҰൠతͳΦϒδΣΫτࢦ޲ͷ৔߹ > const account = new Account(new UserID(5)) undefined //ҎԼɺ࢒ߴΛฦؔ͢਺showBalance(account)͕ఆٛͯ͋͠Δͱ͢Δɻ > showBalance(account) 0 > account.credit(200) undefined > account.debit(100) undefined > account.debit(50) undefined > showBalance(account) 50
39. ҰൠతͳΦϒδΣΫτࢦ޲ͷ৔߹ > const account = new Account(new UserID(5)) undefined //ҎԼɺ࢒ߴΛฦؔ͢਺showBalance(account)͕ఆٛͯ͋͠Δͱ͢Δɻ > showBalance(account) 0 > account.credit(200) undefined > account.debit(100) undefined > account.debit(50) undefined > showBalance(account) 50 Broken!
40. ؔ਺ܕϓϩάϥϛϯά͸ঢ়ଶΛ࣋ͨͳ͍͸ͣɾɾɾ
41. ؔ਺ܕͰී௨ʹ΍ͬͯΈΔ > const a0 = new Account(new UserID(5)) undefined > showBalance(a0) 0 > const a1 = a0.credit(200) undefined > const a2 = a1.debit(100) undefined > const a3 = a2.debit(50) undefined > showBalance(a3) 50
42. ؔ਺ܕͰී௨ʹ΍ͬͯΈΔ > const a0 = new Account(new UserID(5)) undefined > showBalance(a0) 0 > const a1 = a0.credit(200) undefined > const a2 = a1.debit(100) undefined > const a3 = a2.debit(50) undefined > showBalance(a3) 50 ຊ౰ʹ͜ΕͰ͍͍ͷʁ
43. ؔ਺ܕͰී௨ʹ΍ͬͯΈΔ > const a0 = new Account(new UserID(5)) undefined > showBalance(a0) 0 > const a1 = a0.credit(200) undefined > const a2 = a1.debit(100) undefined > const a3 = a2.debit(50) undefined > showBalance(a3) 50 ݁ہɺBɾBͱ͍ͬͨঢ়ଶΛ͍࣋ͬͯΔ
44. ͦΕͳΒͬͪ͜ͷ΄͏͕Θ͔Γ΍͍͢ > const account = new Account(new UserID(5)) undefined > showBalance(account) 0 > account.credit(200) undefined > account.debit(100) undefined > account.debit(50) undefined > showBalance(account) 50
45. ͦΕͳΒͬͪ͜ͷ΄͏͕Θ͔Γ΍͍͢ > const account = new Account(new UserID(5)) undefined > showBalance(account) 0 > account.credit(200) undefined > account.debit(100) undefined > account.debit(50) undefined > showBalance(account)() 50 Ͱ΋ɺͲ͏΍ͬͯࢀর౳ՁੑΛอͭͷ͔
46. ಄ͷྑ͍ਓ͸ߟ͑ͨ
47. ͜Μͳͷ͸Ͳ͏͔ > const account = new Account(new UserID(5)) undefined > showBalance(account, “Կ΋͍ͯ͠ͳ͍”) 0 > showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”) 50
48. ͜Μͳͷ͸Ͳ͏͔ > const account = new Account(new UserID(5)) undefined > showBalance(account, “Կ΋͍ͯ͠ͳ͍”) 0 > showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”) 50 ঢ়ଶΛ໌ࣔతʹ౉͢
49. ͜Μͳͷ͸Ͳ͏͔ > const account = new Account(new UserID(5)) undefined > showBalance(account, “Կ΋͍ͯ͠ͳ͍”) 0 > showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”) 50 Ҿ਺͕ҧ͏ͷͰɺࢀর౳Ձੑ͕อͨΕͨʂ ঢ়ଶΛ໌ࣔతʹ౉͢
50. ঢ়ଶΛ൐͏ܭࢉʹ͍ͭͯ State monad
51. ঢ়ଶΛ൐͏ܭࢉʹ͍ͭͯ State monad
52. 4UBUF
    Ϟφυ > const account = new Account(new UserID(5)) undefined > const state = new State(“200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”) undefined > showBalance(state.runState(account)) 50 ʂ ͜Ε͸งғؾΛઆ໌͢Δ΋ͷͳͷͰɺ·ͬͨ͘΋ͬͯ ਖ਼֬ͳίʔυͰ͸͋Γ·ͤΜ