Cursor rule

1---
2description: "Kotlin coding style extending common rules"
3globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
4alwaysApply: false
5---
6# Kotlin Coding Style
7 
8> This file extends the common coding style rule with Kotlin-specific content.
9 
10## Formatting
11 
12- Auto-formatting via **ktfmt** or **ktlint** (configured in `kotlin-hooks.md`)
13- Use trailing commas in multiline declarations
14 
15## Immutability
16 
17The global immutability requirement is enforced in the common coding style rule.
18For Kotlin specifically:
19 
20- Prefer `val` over `var`
21- Use immutable collection types (`List`, `Map`, `Set`)
22- Use `data class` with `copy()` for immutable updates
23 
24## Null Safety
25 
26- Avoid `!!` -- use `?.`, `?:`, `require`, or `checkNotNull`
27- Handle platform types explicitly at Java interop boundaries
28 
29## Expression Bodies
30 
31Prefer expression bodies for single-expression functions:
32 
33```kotlin
34fun isAdult(age: Int): Boolean = age >= 18
35```
36 
37## Reference
38 
39See skill: `kotlin-patterns` for comprehensive Kotlin idioms and patterns.
40