# Roman Numerals

Write a function to convert from normal numbers to Roman Numerals.

The Romans were a clever bunch. They conquered most of Europe and ruled
it for hundreds of years. They invented concrete and straight roads and
even bikinis. One thing they never discovered though was the number
zero. This made writing and dating extensive histories of their exploits
slightly more challenging, but the system of numbers they came up with
is still in use today. For example the BBC uses Roman numerals to date
their programmes.

The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice
these letters have lots of straight lines and are hence easy to hack
into stone tablets).

```text
 1  => I
10  => X
 7  => VII
```

There is no need to be able to convert numbers larger than about 3000.
(The Romans themselves didn't tend to go any higher)

Wikipedia says: Modern Roman numerals ... are written by expressing each
digit separately starting with the left most digit and skipping any
digit with a value of zero.

To see this in practice, consider the example of 1990.

In Roman numerals 1990 is MCMXC:

1000=M
900=CM
90=XC

2008 is written as MMVIII:

2000=MM
8=VIII

See also: http://www.novaroma.org/via_romana/numbers.html

## Setup

Check out [Exercism Help](http://exercism.io/languages/common-lisp) for instructions to
get started writing Common Lisp. That page will explain how to install and setup
a Lisp implementation and how to run the tests.

## Formatting

While Common Lisp doesn't care about indentation and layout of code,
nor whether you use spaces or tabs, this is an important consideration
for submissions to exercism.io. Excercism.io's code widget cannot
handle mixing of tab and space characters well so using only spaces is recommended to make
the code more readable to the human reviewers. Please review your
editors settings on how to accomplish this. Below are instructions for
popular editors for Common Lisp.

### VIM

Use the following commands to ensure VIM uses only spaces for
indentation:

```vimscript
:set tabstop=2
:set shiftwidth=2
:set expandtab
```

(or as a oneliner `:set tabstop=2 shiftwidth=2 expandtab`). This can
be added to your `~/.vimrc` file to use it all the time.

### Emacs

Emacs is very well suited for editing Common Lisp and has many
powerful add-on packages available. The only thing that one needs to
do with a stock emacs to make it work well with exercism.io is to
evaluate the following code:

`(setq indent-tab-mode nil)`

This can be placed in your `~/.emacs` (or `~/.emacs.d/init.el`) in
order to have it set whenever Emacs is launched.

One suggested add-on for Emacs and Common Lisp is
[SLIME](https://github.com/slime/slime) which offers tight integration
with the REPL; making iterative coding and testing very easy.

## Source

The Roman Numeral Kata [http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals](http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals)

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