kaidl

Kotlin-first Binder interface generation for Android.

kaidl gives you an AIDL-like workflow using plain Kotlin interfaces and KSP. You define an interface once, annotate it, and use generated proxy/stub glue with strongly-typed APIs.

Why kaidl

• AIDL-like IPC without maintaining .aidl files
• Kotlin interface-centric workflow
• Works with suspend functions
• Handles common Android IPC types, collections, parcelables, and nested binder interfaces

Installation

1. Apply KSP in your module.

   plugins {
     id("com.google.devtools.ksp") version "<ksp-version>"
   }

2. Add the compiler and runtime dependencies.

   dependencies {
     ksp("io.github.goooler.kaidl:kaidl-compiler:<latest>")
     implementation("io.github.goooler.kaidl:kaidl-runtime:<latest>")
   }

3. Sync and build.

   ./gradlew build

Notes:

• Use a KSP version that matches your Kotlin version.
• If generated symbols are not visible in IDE, follow KSP guidance: https://github.com/google/ksp#make-ide-aware-of-generated-code

Quick Start

Define an interface:

import com.github.kr328.kaidl.BinderInterface

@BinderInterface
interface EchoService {
  fun echoInt(value: Int): Int
}

Use generated helpers in service/client code:

class EchoImpl : EchoService {
  override fun echoInt(value: Int): Int = value
}

val localImpl = EchoImpl()
val binder = localImpl.wrap()
val remote = binder.unwrap(EchoService::class)

val result = remote.echoInt(42)

Supported Types

• Primitives: Int, Long, Boolean, Float, Double, String, Byte, Char
• Primitive arrays: BooleanArray, ByteArray, CharArray, DoubleArray, FloatArray, IntArray, LongArray
• Android framework types: Bundle, IBinder, SparseBooleanArray
• Date types: java.util.Date (epoch millis)
• UUID types: java.util.UUID, kotlin.uuid.Uuid (string encoding)
• Generic containers: List<T>, Array<T>, Map<K, V>, Set<T>, Pair<A, B>
• Parcelables: custom Parcelable
• Binder interfaces: other interfaces annotated with @BinderInterface
• Nullable variants where applicable
• Suspend functions

Example Project

See the example interfaces and instrumentation tests:

• example/src/main
• example/src/androidTest

For contribution workflow, see CONTRIBUTING.md.

Credits

• Kotlin Symbol Processing
• KotlinPoet