LANG.txt

#

- command stack
- data stack (is really a stack of stacks)

- command stack consists of parsed objects... maybe CmdString, CmdInteger,
  CmdFloat, CmdSymbol, CmdName, etc. When executed, these do something, like
  pushing a value onto the stack, or executing a word.

- data stack contains Python objects whenever possible (to make bridging with
  Python code easier).  not always possible, e.g. with symbols and word
  references.

A word can be:

- an integer                3, -1
- a float                   3.1415
- a string literal          "hello world"
- a symbol                  :foo
- a name                    bar

All these should have their own little command classes.

On the data stack, we can have:

- Python integer
- Python float
- Python string
- Python boolean
- Symbol
- Lambda
- Python function?
- Python list
- Python module?
- ...