Learning Clojure/REPL

Part of the power of languages in the Lisp family comes from the way that you can alter the code of a running program. Traditionally, languages in the Lisp family offer a type of command-line shell environment called the REPL, which stands for Read, Evaluate, Print Loop. This refers to the fact that the REPL first reads an expression from the user, evaluates that expression, and prints out the result before looping back to the beginning. The REPL will continue allowing you to execute expressions until it receives an EOF (Ctrl-D) or is otherwise killed.