Sealed Classes Opened My Mind: How We Use Kotlin to Tame State at Etsy

on YouTube ↗34m

" summary

Describes using sealed classes plus Kotlin’s when and IDE exhaustiveness checks to model social sign‑in state at Etsy, splitting the flow into three sealed data classes that represent the three API responses (social, sign‑in, 2FA) rather than one huge tree. Shows using filterIsInstance (and RxJava mapping) to get filtered views so when only handles wool‑level cases, compares this to visitor/instanceof patterns, and explains why this reduces bugs and boilerplate.

AI-written summary · about

" chapters (13)

1. 0:00Intro
2. 0:47Managing State
3. 2:01What are Sealed Classes
4. 3:29Example
5. 8:45New Example
6. 14:31Social Signin
7. 16:21Model
8. 18:25Duplication
9. 23:59Why Kotlin
10. 25:57Kotlin Visitor Pattern
11. 27:46Kotlin Delegate Adapter Pattern
12. 29:57Kotlin Switch Statement
13. 31:38What are we trying to solve

" related talks

• 35mSealed Classes, Unsealed ComplexitySanchita Agarwal · droidcon Toronto 2019
• 41mLeveraging Sealed Classes in KotlinSanchita Agarwal · Kotlin/Everywhere 'Namma' Bengaluru 2019
• 42mDissecting Kotlin: Unsealing the Sealed, the SAM, and Other SyntaxHuyen Tue Dao · KotlinConf 2023
• 43mFrom Effective Java to Effective KotlinTy Smith, Israel Ferrer Camacho, Joaquim Verges · droidcon San Francisco 2018
• 39mHow to Kotlin - from the lead Kotlin language designerAndrey Breslav, James Lau · Google I/O 2018
• 32mWhen Clean Architecture met Kotlin, A love storyNicolás Patarino · Greach 2019
• 31mDesign Patterns with KotlinMurat Yener · Devoxx Belgium 2017
• 46mFireside chatConference for Kotliners 2019