everything-claude-code / rules

---
description: "Kotlin coding style extending common rules"
globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
alwaysApply: false
---
# Kotlin Coding Style

> This file extends the common coding style rule with Kotlin-specific content.

## Formatting

- Auto-formatting via **ktfmt** or **ktlint** (configured in `kotlin-hooks.md`)
- Use trailing commas in multiline declarations

## Immutability

The global immutability requirement is enforced in the common coding style rule.
For Kotlin specifically:

- Prefer `val` over `var`
- Use immutable collection types (`List`, `Map`, `Set`)
- Use `data class` with `copy()` for immutable updates

## Null Safety

- Avoid `!!` -- use `?.`, `?:`, `require`, or `checkNotNull`
- Handle platform types explicitly at Java interop boundaries

## Expression Bodies

Prefer expression bodies for single-expression functions:

```kotlin
fun isAdult(age: Int): Boolean = age >= 18
```

## Reference

See skill: `kotlin-patterns` for comprehensive Kotlin idioms and patterns.

More agent context in tpavanipradeep/everything-claude-code

81 other files this repository gives its agents, the first 60 shown.

Also found in 16 other repositories

The same file, byte for byte, in the weekly crawl of public GitHub; the 10 with the most stars.

• affaan-m/ECC246k
• loulanyue/awesome-claude-notes272
• mturac/everything-openai-codex89
• mit-network/everything-claude-code76
• Fmarzochi/EGC52
• ysyecust/everything-claude-code44
• yapota2018/affaan-m-everything-claude-code4
• ArogyaReddy/https-github.com-affaan-m-everything-claude-code12
• divenhuang88/everything-claude-code1
• elainesmithburkel-code/everything-claude-code1