This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 14.1, “How to get started with the Scala REPL.”
You want to get started using the Scala REPL, including understanding some of its basic features, such as tab completion, starting the REPL with different options, and dealing with errors.
To start the Scala REPL, type
scala at your operating system command line: