Kotlin Patterns

This is a comprehensive reference for writing idiomatic Kotlin that goes beyond basic syntax. It covers the patterns that make Kotlin code actually feel like Kotlin: null safety with Elvis operators instead of force-unwrapping, sealed classes for exhaustive when expressions, structured concurrency with coroutineScope and async/await, and type-safe DSL builders. The examples are practical, showing things like modeling API errors with sealed interfaces and using value classes for zero-overhead type safety. Use this when you want your Kotlin to look like it was written by someone who understands the language's strengths, not just Java with different keywords.

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GitHub stars: 300.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add affaan-m/ecc --skill kotlin-patterns --agent claude-code

Installs into .claude/skills of the current project.

Files

Kotlin Development Patterns

Idiomatic Kotlin patterns and best practices for building robust, efficient, and maintainable applications.

When to Use

Writing new Kotlin code
Reviewing Kotlin code
Refactoring existing Kotlin code
Designing Kotlin modules or libraries
Configuring Gradle Kotlin DSL builds

How It Works

This skill enforces idiomatic Kotlin conventions across seven key areas: null safety using the type system and safe-call operators, immutability via val and copy() on data classes, sealed classes and interfaces for exhaustive type hierarchies, structured concurrency with coroutines and Flow, extension functions for adding behaviour without inheritance, type-safe DSL builders using @DslMarker and lambda receivers, and Gradle Kotlin DSL for build configuration.

Examples

Null safety with Elvis operator:

fun getUserEmail(userId: String): String {
    val user = userRepository.findById(userId)
    return user?.email ?: "unknown@example.com"
}

SKILL.md on GitHub

Details

Repository: github.com/affaan-m/ecc
Categories: Mobile Development, Java & JVM
First seen: Jul 14, 2026