Bootstrapping a web server in Scala

Question

The following is possible using Python:

$ apt-get install python
$ easy_install Flask
$ cat > hello.py
from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()
$ python hello.py

4 commands and 7 lines of code to get a web server running is very impressive indeed.

What's the Scala equivalent?