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Provides idiomatic Kotlin implementation patterns including coroutine concurrency, Flow stream handling, multiplatform architecture, Compose UI construction, Ktor server setup, and type-safe DSL desig
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Paste the copied command in a terminal. It installs this SKILL.md into that agent.
npx skills add Jeffallan/claude-skills --skill kotlin-specialist -a cursor -y
Provides idiomatic Kotlin implementation patterns including coroutine concurrency, Flow stream handling, multiplatform architecture, Compose UI construction, Ktor server setup, and type-safe DSL design. Use when building Kotlin applications requiring coroutines, multiplatform development, or Android with Compose. Invoke for Flow API, KMP projects, Ktor servers, DSL design, sealed classes, suspend function, Android Kotlin, Kotlin Multiplatform.
Provides idiomatic Kotlin implementation patterns including coroutine concurrency, Flow stream handling, multiplatform architecture, Compose UI construction, Ktor server setup, and type-safe DSL design. Use when building Kotlin applications requiring coroutines, multiplatform development, or Android with Compose. Invoke for Flow API, KMP projects, Ktor servers, DSL design, sealed classes, suspend function, Android Kotlin, Kotlin Multiplatform.
Senior Kotlin developer with deep expertise in coroutines, Kotlin Multiplatform (KMP), and modern Kotlin 1.9+ patterns.
detekt and ktlint; verify coroutine cancellation handling and null safety
runTest, Turbine)Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Coroutines & Flow | references/coroutines-flow.md | Async operations, structured concurrency, Flow API |
| Multiplatform | references/multiplatform-kmp.md | Shared code, expect/actual, platform setup |
| Android & Compose | references/android-compose.md | Jetpack Compose, ViewModel, Material3, navigation |
| Ktor Server | references/ktor-server.md | Routing, plugins, authentication, serialization |
| DSL & Idioms | references/dsl-idioms.md | Type-safe builders, scope functions, delegates |
sealed class UiState<out T> {
data object Loading : UiState<Nothing>()
data class Success<T>(val data: T) : UiState<T>()
data class Error(val message: String, val cause: Throwable? = null) : UiState<Nothing>()
}
// Consume exhaustively — compiler enforces all branches
fun render(state: UiState<User>) = when (state) {
is UiState.Loading -> showSpinner()
is UiState.Success -> showUser(state.data)
is UiState.Error -> showError(state.message)
}
// Use structured concurrency — never GlobalScope
class UserRepository(private val api: UserApi, private val scope: CoroutineScope) {
fun userUpdates(id: String): Flow<UiState<User>> = flow {
emit(UiState.Loading)
try {
emit(UiState.Success(api.fetchUser(id)))
} catch (e: IOException) {
emit(UiState.Error("Network error", e))
}
}.flowOn(Dispatchers.IO)
private val _user = MutableStateFlow<UiState<User>>(UiState.Loading)
val user: StateFlow<UiState<User>> = _user.asStateFlow()
}
// Anti-pattern — blocks the calling thread; avoid in production
// runBlocking { api.fetchUser(id) }
// Prefer safe calls and elvis operator
val displayName = user?.profile?.name ?: "Anonymous"
// Use let to scope nullable operations
user?.email?.let { email -> sendNotification(email) }
// !! only when the null case is a true contract violation and documented
val config = requireNotNull(System.getenv("APP_CONFIG")) { "APP_CONFIG must be set" }
// apply — configure an object, returns receiver
val request = HttpRequest().apply {
url = "https://api.example.com/users"
headers["Authorization"] = "Bearer $token"
}
// let — transform nullable / introduce a local scope
val length = name?.let { it.trim().length } ?: 0
// also — side-effects without changing the chain
val user = createUser(form).also { logger.info("Created user ${it.id}") }
?, ?., ?:, !! only when contract guarantees non-null)sealed class for state modelingsuspend functions for async operationsFlow for reactive streamslet, run, apply, also, with)detekt and ktlint before committingrunBlocking in production code!! without documented justificationGlobalScope.launch (use structured concurrency)When implementing Kotlin features, provide:
Kotlin 1.9+, Coroutines, Flow API, StateFlow/SharedFlow, Kotlin Multiplatform, Jetpack Compose, Ktor, Arrow.kt, kotlinx.serialization, Detekt, ktlint, Gradle Kotlin DSL, JUnit 5, MockK, Turbine
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions