REPL: Read-Eval-Print-Loop

A REPL is an interactive program that allows the programmer to execute code and view the output in a piecewise pattern. The name explains the pattern.

* R - First some command is entered by the programmer and 'Read' by the program.

* E - The program 'evaluates' the input

* P - The output is 'printed'

*L - The cycle then continues, just like a 'loop', until the programmer exits.

A REPL is useful for experimenting with different features of a programming language.