What is a "REPL" in javascript?

javascript node.js read-eval-print-loop
Mark Harrison picture Mark Harrison · Nov 28, 2012 · Viewed 17.8k times · Source

I saw a reference to creating a "REPL". What is a REPL?

var arDrone = require('ar-drone');
var client  = arDrone.createClient();
client.createRepl();

Answer

tomlogic picture tomlogic · Nov 28, 2012

Good information in the tag right here on Stack Overflow:

About read-eval-print-loop

A Read-Eval-Print Loop (REPL) is an interactive interpreter to a programming language. It originated with LISP systems, but many other languages (Python, Ruby, Haskell, Tcl, etc.) use REPL's to manage interactive sessions. They allow for simple experimentation with a language by bypassing the compile stage of the "code -> compile -> execute" cycle.

There are 4 components to a REPL (named in LISP notation):

  • A read function, which reads input from the keyboard
  • An eval function, which evaluates code passed to it
  • A print function, which formats and displays results
  • A loop function, which runs the three previous commands until termination

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