Learn Coroutine

Learning project for Kotlin concurrency/coroutine concepts with an Angular frontend and local Kotlin JVM examples.

Project Layout

• frontend/ - Angular app for lessons and the Kotlin Lab UI.
• coroutine-examples/ - Maven/Kotlin project used by the local Kotlin runner.

Requirements

• Node.js 22
• npm 10+
• Java 21
• Maven

Run The App

Open two terminals.

1. Start Angular

cd frontend
nvm use 22
npm start -- --host 127.0.0.1

Angular runs at:

http://127.0.0.1:4200/

2. Start Kotlin Runner

cd frontend
nvm use 22
npm run kotlin-runner

The local Kotlin runner runs at:

http://127.0.0.1:3001

The Kotlin Lab sends selected lesson programs to this runner so examples execute on the local JVM instead of the embedded Kotlin Playground.

If the UI keeps showing Starting Kotlin through local JVM runner..., restart the runner terminal after code changes. A successful request prints start/finish lines in the runner terminal.

Quick runner check:

curl -sS -X POST http://127.0.0.1:3001/run-kotlin \
  -H 'Content-Type: application/json' \
  --data '{"code":"fun main() { println(\"Hello, world!\") }","timeoutMs":600000}'

That start call returns a runId. Poll it to read the latest output:

curl -sS http://127.0.0.1:3001/run-kotlin/1

Useful Commands

From frontend/:

npm run build
npx tsc -p tsconfig.app.json --noEmit
npm run kotlin-runner

From coroutine-examples/:

mvn -q -DskipTests compile exec:java