The Scala REPL is a great tool for trying out code interactively.
It lets you write expressions in a terminal window, and immediately prints the return value as well as any outputs to the console.
Whether you're learning the language, exploring an API, or sketching out a new idea, the immediate feedback after evaluating an expression is a great enabler for hands-on learning and rapid prototyping.
The easiest way to get started is the default REPL because it's part of the Scala distribution and is also available in any SBT project as the
The default REPL lacks many convenience features though.
Ammonite is a modern REPL implementation created by Li Haoyi. It comes with many features that make working in the REPL more convenient. Probably the most important one is dynamic maven dependency loading in the REPL itself (through Coursier