# Forth

Implement an evaluator for a very simple subset of Forth.

[Forth](https://en.wikipedia.org/wiki/Forth_%28programming_language%29)
is a stack-based programming language. Implement a very basic evaluator
for a small subset of Forth.

Your evaluator has to support the following words:

- `+`, `-`, `*`, `/` (integer arithmetic)
- `DUP`, `DROP`, `SWAP`, `OVER` (stack manipulation)

Your evaluator also has to support defining new words using the
customary syntax: `: word-name definition ;`.

To keep things simple the only data type you need to support is signed
integers of at least 16 bits size.

You should use the following rules for the syntax: a number is a
sequence of one or more (ASCII) digits, a word is a sequence of one or
more letters, digits, symbols or punctuation that is not a number.
(Forth probably uses slightly different rules, but this is close
enough.)

Words are case-insensitive.

## Hints
- To parse the text, you could try to use the [Sprache](https://github.com/sprache/Sprache/blob/develop/README.md) library. You can also find a good tutorial [here](https://www.thomaslevesque.com/2017/02/23/easy-text-parsing-in-c-with-sprache/).


### Submitting Exercises

Note that, when trying to submit an exercise, make sure the solution is in the `exercism/python/<exerciseName>` directory.

For example, if you're submitting `bob.py` for the Bob exercise, the submit command would be something like `exercism submit <path_to_exercism_dir>/python/bob/bob.py`.


For more detailed information about running tests, code style and linting,
please see the [help page](http://exercism.io/languages/python).

## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.