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with TypeScript
υϝΠϯۦಈઃܭͱؔܕϓϩάϥϛϯά
2017.02.20 Gunma.web#30
Hikaru Otabe
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ࣗݾհ
w େా෦ߊɹ!DIJMEIPPPPP
w લϩέοτؔͷΈࠐΈΤϯδχΞʢ$ʣ
w ࠷ۙ8FCؔͷࣄ
w $
1ZUIPO
&MJYJS
+BWB4DSJQU
1)1FUD
Profile
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ؔܕϓϩάϥϛϯάͱ͍͑
What comes to your mind ?
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ֶ
map
Ϟφυ
෭࡞༻
ϥϜμࣜ
ࢀরಁաੑ
ԆධՁ
ؔͷ߹
ΧϦʔԽ
ΧϦʔԽ
ςετ
ͳʹͦΕʁ
ฒߦॲཧ
ύλʔϯϚον
࠶ؼ
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ֶ
map
Ϟφυ
෭࡞༻
ϥϜμࣜ
ࢀরಁաੑ
ԆධՁ
ؔͷ߹
ΧϦʔԽ
ΧϦʔԽ
ςετ
ͳʹͦΕʁ
ฒߦॲཧ
ύλʔϯϚον
࠶ؼ
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ࠓճ͢Δಛ
lؔܕϓϩάϥϛϯάͰࢀরಁաੑ͕อূ͞ΕΔz
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ࠓճ͢Δಛ
lؔܕϓϩάϥϛϯάͰࢀরಁաੑ͕อূ͞ΕΔz
͞ΕΔͱ͍͏͔ɺ͢Δɻ
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ࢀরಁաੑΛഁյ͢Δͷ
Who breaks Referential transparency ?
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1. ࠶ೖ
2.
ɹมͷࢀরಁաੑΛഁյ
෭࡞༻ͷ͋Δؔ
ɹؔͷࢀরಁաੑΛഁյ
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࠶ೖʹΑΔࢀরಁաੑͷഁյ
> var x = 1
undefined
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࠶ೖʹΑΔࢀরಁաੑͷഁյ
> var x = 1
undefined
> x = 2
2
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࠶ೖʹΑΔࢀরಁաੑͷഁյ
> var x = 1
undefined
> x = 2
2
> x
2
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࠶ೖʹΑΔࢀরಁաੑͷഁյ
> var x = 1
undefined
> x = 2
2
> x
2
Broken!
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࠶ೖʹΑΔࢀরಁաੑͷഁյ
> var x = 1
undefined
> x = 2
2
> x
2
> const y = 1
undefined
> y = 2
TypeError
Broken!
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ؔͷ෭࡞༻ʹΑΔࢀরಁաੑͷഁյ
> var counter = 0
undefined
> const count = (x) => counter += x
undefined
> count(3)
3
> count(3)
6
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ؔͷ෭࡞༻ʹΑΔࢀরಁաੑͷഁյ
> var counter = 0
undefined
> const count = (x) => counter += x
undefined
> count(3)
3
> count(3)
6
Broken!
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υϝΠϯۦಈઃܭ
Domain-Driven Design
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υϝΠϯϞσϧͷߏཁૉ
w ΦϒδΣΫτ
w ΤϯςΟςΟ
w αʔϏε
w FUDʜ
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υϝΠϯϞσϧͷߏཁૉ
w ΦϒδΣΫτ
w ΤϯςΟςΟ
w αʔϏε
w FUDʜ
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υϝΠϯϞσϧͷߏཁૉ
w ΦϒδΣΫτ
w ΤϯςΟςΟ
w αʔϏε
w FUDʜ
ؔܕϓϩάϥϛϯάͰͲͷΑ͏ʹදݱ͢Δ͔ʁ
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υϝΠϯϞσϧͷߏཁૉ
w ΦϒδΣΫτ
w ΤϯςΟςΟ
w αʔϏε
w FUDʜ
ؔܕϓϩάϥϛϯάͰͲͷΑ͏ʹදݱ͢Δ͔ʁ
ʂ ᘳͳ࣮ફ͍͠Ͱ͢
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ۜߦޱ࠲ΞϓϦέʔγϣϯͷྫ
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ΤϯςΟςΟʢؔܕϓϩάϥϛϯάʣ
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))];
}
}
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จࣈ͕খ͍͞
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GitHub
github.com/childhooooo/ddd-fp-ts
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ΦϒδΣΫτ
w ߴΛද࣌͢ɺ/VNCFSܕͰͳ͘ɺ#BMBODFܕΛ
w ෆมੑʜҰੜͨ͠ΒɺଐੑΛมߋ͢Δ͜ͱग़དྷͳ͍
w ՁੑʜࢀরઌͰͳ͘ɺଐੑͰஅ
Value objects
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ΦϒδΣΫτ
class Balance {
constructor(public amount: number = 0) {
Object.freeze(this);
}
}
const balance = new Balance(100);
balance.amount = 50 //error
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ΤϯςΟςΟ
w ಉҰੑʜଐੑ͕ҟͳ͍ͬͯͯɺ*%͕ಉ͡ͳΒಉҰͷ
ͷͱͯ͠ѻ͏
w ϥΠϑαΠΫϧͷ࿈ଓੑ
Entities
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ΤϯςΟςΟʢҰൠతͳΦϒδΣΫτࢦʣ
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”;
}
}
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ΤϯςΟςΟΛ͏ʢҰൠతͳΦϒδΣΫτࢦʣ
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
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ΤϯςΟςΟΛ͏ʢҰൠతͳΦϒδΣΫτࢦʣ
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!
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ΤϯςΟςΟʢؔܕϓϩάϥϛϯάʣ
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))];
}
}
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ΤϯςΟςΟΛ͏ʢؔܕϓϩάϥϛϯάʣ
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
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αʔϏε
w ΦϒδΣΫτΤϯςΟςΟʹଐ͞ͳ͍ॏཁͳॲཧ
w ಠཱͨ͠ΠϯλʔϑΣΠε
w ঢ়ଶΛ࣋ͨͳ͍
Services
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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]]);
}
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αʔϏεΛ͏
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
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ঢ়ଶΛ͏ܭࢉʹ͍ͭͯ
State monad
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ҰൠతͳΦϒδΣΫτࢦͷ߹
> const account = new Account(new UserID(5))
undefined
//ҎԼɺߴΛฦؔ͢showBalance(account)͕ఆٛͯ͋͠Δͱ͢Δɻ
> showBalance(account)
0
> account.credit(200)
undefined
> account.debit(100)
undefined
> account.debit(50)
undefined
> showBalance(account)
50
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ҰൠతͳΦϒδΣΫτࢦͷ߹
> const account = new Account(new UserID(5))
undefined
//ҎԼɺߴΛฦؔ͢showBalance(account)͕ఆٛͯ͋͠Δͱ͢Δɻ
> showBalance(account)
0
> account.credit(200)
undefined
> account.debit(100)
undefined
> account.debit(50)
undefined
> showBalance(account)
50
Broken!
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ؔܕϓϩάϥϛϯάঢ়ଶΛ࣋ͨͳ͍ͣɾɾɾ
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ؔܕͰී௨ʹͬͯΈΔ
> 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
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ؔܕͰී௨ʹͬͯΈΔ
> 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
ຊʹ͜ΕͰ͍͍ͷʁ
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ؔܕͰී௨ʹͬͯΈΔ
> 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
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ͦΕͳΒͬͪ͜ͷ΄͏͕Θ͔Γ͍͢
> 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
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ͦΕͳΒͬͪ͜ͷ΄͏͕Θ͔Γ͍͢
> 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
ͰɺͲ͏ͬͯࢀরՁੑΛอͭͷ͔
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಄ͷྑ͍ਓߟ͑ͨ
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͜ΜͳͷͲ͏͔
> const account = new Account(new UserID(5))
undefined
> showBalance(account, “Կ͍ͯ͠ͳ͍”)
0
> showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”)
50
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͜ΜͳͷͲ͏͔
> const account = new Account(new UserID(5))
undefined
> showBalance(account, “Կ͍ͯ͠ͳ͍”)
0
> showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”)
50
ঢ়ଶΛ໌ࣔతʹ͢
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͜ΜͳͷͲ͏͔
> const account = new Account(new UserID(5))
undefined
> showBalance(account, “Կ͍ͯ͠ͳ͍”)
0
> showBalance(account, “200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”)
50
Ҿ͕ҧ͏ͷͰɺࢀরՁੑ͕อͨΕͨʂ
ঢ়ଶΛ໌ࣔతʹ͢
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ঢ়ଶΛ͏ܭࢉʹ͍ͭͯ
State monad
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ঢ়ଶΛ͏ܭࢉʹ͍ͭͯ
State monad
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4UBUFϞφυ
> const account = new Account(new UserID(5))
undefined
> const state = new State(“200आΓͯɺ100ିͯ͠ɺ50ିͨ͠”)
undefined
> showBalance(state.runState(account))
50
ʂ ͜ΕงғؾΛઆ໌͢ΔͷͳͷͰɺ·ͬͨͬͯ͘
ਖ਼֬ͳίʔυͰ͋Γ·ͤΜ