Clojure Android Sample

A sample Android app built with Clojure, demonstrating AOT compilation, the neko UI DSL, and REPL-driven development via nREPL.

The app has two activities:

• Neko UI Demo (launcher) — a declarative UI built with neko's Clojure DSL, with a counter and buttons. The UI can be hot-reloaded from an nREPL session.
• Validation Tests — runs diagnostics on the Clojure runtime, classloader, and nREPL infrastructure. Provides controls to start/stop the nREPL server.

Prerequisites

• JDK 17+
• Android SDK with platform API 35 installed. Set sdk.dir in local.properties or the ANDROID_HOME environment variable to point to your SDK installation.

Dependencies

This app depends on several libraries from the clj-android organization:

Dependency	Role
android-clojure-plugin	Gradle plugin — AOT-compiles Clojure sources and wires them into the Android build
neko	Idiomatic Clojure wrappers for Android APIs (UI DSL, activities, logging)
runtime-core	Core Android runtime support (ClojureApp, ClojureActivity base classes)
runtime-repl	nREPL server with on-device DEX compilation for REPL-driven development
clojure-patched	Clojure 1.12.0 with Android-aware classloader (used automatically in debug builds)

Dependencies are resolved automatically: on the first build, settings.gradle.kts clones them from GitHub into build/deps/ and includes them as Gradle composite builds. No manual setup is required.

If you prefer to install dependencies to your local Maven repository instead of using composite builds:

./gradlew publishDepsToMavenLocal

This cleans, builds, and publishes all five dependencies in the correct order. If cloning fails (e.g. no network), you can clone the repositories manually into build/deps/:

mkdir -p build/deps
for repo in android-clojure-plugin neko runtime-core runtime-repl clojure-patched; do
  git clone https://github.com/clj-android/$repo.git build/deps/$repo
done

Building

# Debug APK (includes nREPL server)
./gradlew assembleDebug

# Release APK (AOT-only, no REPL infrastructure)
./gradlew assembleRelease

The APK is written to app/build/outputs/apk/.

Running

Install and launch on a connected device or emulator:

./gradlew installDebug
adb shell am start -n com.example.clojuredroid/.MainActivity

Connecting to the nREPL

Debug builds start an nREPL server on port 7888. Forward the port and connect:

adb forward tcp:7888 tcp:7888

Then connect from any nREPL client (Calva, CIDER, lein repl :connect, etc.) to localhost:7888.

Example — hot-reload the UI from the REPL:

(require '[com.example.clojuredroid.main-activity :as ui])

(reset! ui/*ui-tree
  [:linear-layout {:orientation :vertical :padding [32 32 32 32]}
   [:text-view {:text "Modified from REPL!" :text-size [24 :sp]}]])

(ui/reload-ui!)

Project structure

app/
  src/main/
    clojure/        Clojure source (AOT-compiled into the APK)
    java/           Java source (activities)
    res/            Android resources
    AndroidManifest.xml
  build.gradle.kts  App-level build config
build.gradle.kts    Top-level plugin declarations
settings.gradle.kts Repository and composite build configuration

License

This sample app is released under CC0 1.0. The Gradle wrapper files (gradlew, gradlew.bat, gradle/wrapper/gradle-wrapper.jar) are from the Gradle project and licensed under the Apache License 2.0.