Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Lens introduction
Search
to4iki
February 18, 2018
Programming
0
520
Lens introduction
in `swift` implementation
see:
https://github.com/to4iki/LensKit
to4iki
February 18, 2018
Tweet
Share
More Decks by to4iki
See All by to4iki
Claude Code の活用事例
to4iki
0
92
Swift Concurrencyを利用したUIViewController表示の排他制御の実装
to4iki
0
3.3k
ケースに応じたUICollectionViewのレイアウト実装パターン
to4iki
1
4.8k
ビューインプレッションの計測方法
to4iki
1
1.1k
秘伝の `gitconfig`
to4iki
1
450
Abema iOS Architecture
to4iki
12
3.4k
timetable-bot
to4iki
0
14k
BLoC Pattern Introduction with Swift
to4iki
2
1.3k
nel
to4iki
0
160
Other Decks in Programming
See All in Programming
Git Sync を超える!OSS で実現する CDK Pull 型デプロイ / Deploying CDK with PipeCD in Pull-style
tkikuc
4
480
バイブコーディング超えてバイブデプロイ〜CloudflareMCPで実現する、未来のアプリケーションデリバリー〜
azukiazusa1
2
740
リッチエディターを安全に開発・運用するために
unachang113
1
310
Gemini CLI のはじめ方
ttnyt8701
1
110
オホーツクでコミュニティを立ち上げた理由―地方出身プログラマの挑戦 / TechRAMEN 2025 Conference
lemonade_37
1
300
Amazon Q CLI開発で学んだAIコーディングツールの使い方
licux
3
130
ソフトウェア設計とAI技術の活用
masuda220
PRO
25
7k
Vibe coding コードレビュー
kinopeee
0
340
SQLアンチパターン第2版 データベースプログラミングで陥りがちな失敗とその対策 / Intro to SQL Antipatterns 2nd
twada
PRO
35
10k
AI Ramen Fight
yusukebe
0
120
マッチングアプリにおけるフリックUIで苦労したこと
yuheiito
0
250
202507_ADKで始めるエージェント開発の基本 〜デモを通じて紹介〜(奥田りさ)The Basics of Agent Development with ADK — A Demo-Focused Introduction
risatube
PRO
5
1.3k
Featured
See All Featured
Designing for Performance
lara
610
69k
Designing for humans not robots
tammielis
253
25k
Six Lessons from altMBA
skipperchong
28
3.9k
Music & Morning Musume
bryan
46
6.7k
Typedesign – Prime Four
hannesfritz
42
2.7k
Put a Button on it: Removing Barriers to Going Fast.
kastner
60
3.9k
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
mongodb
47
9.6k
Become a Pro
speakerdeck
PRO
29
5.4k
Producing Creativity
orderedlist
PRO
346
40k
Why Our Code Smells
bkeepers
PRO
337
57k
Statistics for Hackers
jakevdp
799
220k
Docker and Python
trallard
45
3.5k
Transcript
Lens Shinjuku.LT#17 @to4iki 1
Me • Takezawa • • ! • ☕ •
♨ 2
what Lens? 3
Def. / Feature • getter/setterͷநԽɾম͖͠(൚༻Խ) • ༷ʑͳσʔλΛڞ௨ͷI/FͰૢ࡞Ͱ͖Δ • ಛఆͷݴޠʹґଘ͠ͳ͍֓೦/ܕ •
functional • ෆมߏ / ߹Մೳ • Lens Laws 4
ekmett/lens 5
• Monocle.Lens - elm-monocle • julien-truffaut/Monocle 6
https://github.com/julien-truffaut/Monocle/blob/master/image/class- diagram.png 7
getter setter 8
getter • ΦϒδΣΫτS͔ΒAΛऔΓग़͢ • get: (S) -> A setter •
ΦϒδΣΫτSͷҙͷΛAʹมߋ͢Δ • set: (S, A) -> S == set: (S) -> A -> S 9
͜ΕΒͷ͍͢͝ getter/setter1Λ ҙͷΦϒδΣΫτͷ ҙͷϝϯόʹద༻͢Δͷ͕ Lens 1 https://qiita.com/to4iki/items/f0cc28e1102cf53be85d 10
࣮ͯ͠ΈΔ 11
struct Lens<S, T> { private let _get: (S) -> T
private let _set: (S, T) -> S init(get: @escaping (S) -> T, set: @escaping (S, T) -> S) func get(_ source: S) -> T func set(_ source: S, value: T) -> S } 12
͜Μ͚ͩ 13
struct User { let name: String } let user =
User(name: "hoge") let nameLens = Lens<User, String>( get: { $0.name }, set: { User(name: $1) } ) nameLens.get(user) // "hoge" nameLens.set("fuga") // User(name:"fuga)" 14
Usecase? 15
ωετͨ͠σʔλͷ͋ΔҰ෦ ͚ͩΛมߋ͍ͨ͠ struct Street { let name: String } struct
Address { let street: Street } struct Company { let address: Address } struct Employee { let company: Company } let employee = Employee(company: Company(address: Address(street: Street(name: "street")))) 16
! let updatedEmployee = Employee(company: Company(address: Address(street: Street(name: employee.company.address.street.name.capitalizedString) )
) ) 17
Lens߹Λ͍ɺ ෆมߏΛอͪͳ͕Β ΞΫηεग़དྷΔ 18
struct Lens<S, T> { ... func compose<U>(_ other: Lens<T, U>)
-> Lens<S, U> { return Lens<S, U>( get: { (source: S) -> U in other.get(self.get((source))) }, set: { (source: S, value: U) -> S in self.set(source, value: other.set(self.get(source), value: value)) } ) } } 19
(operatorఆٛ͠ͱ͘) /// Left-to-Right Composition infix operator >>> : MultiplicationPrecedence func
>>> <S, T, U>(lhs: Lens<S, T>, rhs: Lens<T, U>) -> Lens<S, U> { return lhs.compose(rhs) } 20
Demo 21
! let nameLens = Lens<Street, String>(get: { $0.name }, set:
{ Street(name: $1) } ) let streetLens = Lens<Address, Street> ... let addressLens = Lens<Company, Address> ... let companyLens = Lens<Employee, Company> ... let lens: Lens<Employee, String> = companyLens >>> addressLens >>> streetLens >>> nameLens let employee = Employee(company: Company(address: Address(street: Street(name: "street")))) let updatedEmployee = lens.modify(employee) { $0.capitalized } // Employee(Company(Address(Street(name: "Street") 22
https://github.com/ to4iki/LensKit 23
Conclusion • Lens ͍͢͝getter/setter • ෆมߏΛอͪͳ͕Β • ਂ͍ߏͰ •
ʹΞΫηεग़དྷΔ • Ϣʔεέʔεਖ਼͍͠ • ςετ࣌ͷαϙʔτͱͯ͠͏? 24
See also • ࠓ͔Β࢝ΊΔ Lens/Prism 25