Cursor rule

1---
2description: "Kotlin patterns extending common rules"
3globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
4alwaysApply: false
5---
6# Kotlin Patterns
7 
8> This file extends the common patterns rule with Kotlin-specific content.
9 
10## Sealed Classes
11 
12Use sealed classes/interfaces for exhaustive type hierarchies:
13 
14```kotlin
15sealed class Result<out T> {
16    data class Success<T>(val data: T) : Result<T>()
17    data class Failure(val error: AppError) : Result<Nothing>()
18}
19```
20 
21## Extension Functions
22 
23Add behavior without inheritance, scoped to where they're used:
24 
25```kotlin
26fun String.toSlug(): String =
27    lowercase().replace(Regex("[^a-z0-9\\s-]"), "").replace(Regex("\\s+"), "-")
28```
29 
30## Scope Functions
31 
32- `let`: Transform nullable or scoped result
33- `apply`: Configure an object
34- `also`: Side effects
35- Avoid nesting scope functions
36 
37## Dependency Injection
38 
39Use Koin for DI in Ktor projects:
40 
41```kotlin
42val appModule = module {
43    single<UserRepository> { ExposedUserRepository(get()) }
44    single { UserService(get()) }
45}
46```
47 
48## Reference
49 
50See skill: `kotlin-patterns` for comprehensive Kotlin patterns including coroutines, DSL builders, and delegation.
51