.. _repl:

The Python REPL
===============

Try out Python using the REPL -- the Read, Evaluate, Print Loop.

Open up a command prompt, or the Terminal app on a Mac and type: ::

  python3

Or you could use an online service such as https://repl.it/

You'll see something like this: ::

  Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 16:52:21) 
  [Clang 6.0 (clang-600.0.57)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>>

Your numbers will certainly be different to what you see above.

That string :code:`>>>` is your prompt. Type something like this: ::

  1+2

Python will respond with :code:`3` and then give you another prompt. Try this: ::

  hello python

You'll see this: ::

    File "<stdin>", line 1
    hello python
               ^
               SyntaxError: invalid syntax

That's not very helpful! In simple terms it means we didn't follow the
rules of the language. Head over to :ref:`basics` to start learning how
to write Python.