Why does lua interpreter need = in front of variables?

[Matthew Wilson <matt@...>]

I am learning lua after using python for the last few years.

In the lua toplevel, why do I either have to either put a "=" in front
of a variable?

In python, the toplevel evaluates everything automatically:

    $ python
    Python 2.5.1 (r251:54863, May  2 2007, 16:56:35)
    >>> 1 + 1
    2
    >>>

    $ lua
    Lua 5.1.2  Copyright (C) 1994-2007 Lua.org, PUC-Rio
    > 1 + 1
    stdin:1: unexpected symbol near '1'
    > = 1 + 1
    2
    >

I started thinking about this, and I wondered if maybe the "=" forces
the toplevel to evaluate the object.

I'm just curious, but this detail stumps me.

Thanks in advance.

Matt