kotlin

name	kotlin
description	Use for idiomatic Kotlin: refactoring, value classes, sealed types, coroutines, nullability, visibility, composition, DRY/SOLID, hexagonal architecture, or /kotlin. Use /kotlin-ktor for Ktor setup.

Kotlin

Contract

• Keep the code DRY and SOLID without introducing shallow abstractions.
• Follow hexagonal architecture: domain depends on nothing; application depends on domain; infrastructure implements ports.
• Prefer composition over inheritance.
• Prefer Kotlin libraries and idioms. Restrict Java APIs to interoperability boundaries.
• Use structured concurrency. Never use GlobalScope. Parallelize only independent suspend calls.
• Keep visibility as narrow as possible: private → internal → public.
• Prefer immutable data and explicit null handling.
• Use value classes for small domain types when they improve type safety.
• Model closed domains with sealed interface, data object, and data class.
• Use exhaustive when expressions without else for sealed hierarchies.
• Use fun interface for ports with a single operation.
• Use extensions and scope functions when they clarify code.
• Keep domain terms Norwegian; technical terms English.

Checklist

1. Choose the correct layer.
2. Implement idiomatic Kotlin.
3. Verify architecture, naming, and concurrency.
4. Run the relevant Gradle task.