REPL Basics

Welcome to the Clojure Read Eval Print Loop (REPL), a command-line interface that we can use to interact with a running Clojure program. REPL, in the sense that it reads the user's input (where the user is you, the programmer), evaluates the input by instantly compiling and executing the code, and prints (that is, displays) the result to the user. The read-eval-print three-step process repeats over and over again (loop) until you exit the program.

The dynamism provided by the REPL allows you to discover and experiment with a tight feedback loop: your code is evaluated instantly, and you can adjust it until you get it right. Many other programming languages provide interactive shells (notably, other dynamic languages such as Ruby or Python), but in Clojure, the REPL plays an exceptional and essential role in the life of the developer. It is often integrated with the code editor and the line between editing, browsing, and executing code blurs toward a malleable development...