# Prime Factors

Compute the prime factors of a given natural number.

A prime number is only evenly divisible by itself and 1.

Note that 1 is not a prime number.

## Example

What are the prime factors of 60?

- Our first divisor is 2. 2 goes into 60, leaving 30.
- 2 goes into 30, leaving 15.
  - 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.
- 3 goes cleanly into 15, leaving 5.
  - 3 does not go cleanly into 5. The next possible factor is 4.
  - 4 does not go cleanly into 5. The next possible factor is 5.
- 5 does go cleanly into 5.
- We're left only with 1, so now, we're done.

Our successful divisors in that computation represent the list of prime
factors of 60: 2, 2, 3, and 5.

You can check this yourself:

- 2 * 2 * 3 * 5
- = 4 * 15
- = 60
- Success!


## Getting Started
For installation and learning resources, refer to the
[exercism help page](http://exercism.io/languages/ocaml).

## Installation
To work on the exercises, you will need `Opam` and `Core`. Consult [opam](https://opam.ocaml.org) website for instructions on how to install `opam` for your OS. Once `opam` is installed open a terminal window and run the following command to install core:

```bash
opam install core
```

To run the tests you will need `OUnit`. Install it using `opam`:

```bash
opam install ounit
```

## Running Tests
A Makefile is provided with a default target to compile your solution and run the tests. At the command line, type:

```bash
make
```

## Interactive Shell
`utop` is a command line program which allows you to run Ocaml code interactively. The easiest way to install it is via opam:
```bash
opam install utop
```
Consult [utop](https://github.com/diml/utop/blob/master/README.md) for more detail.

## Feedback, Issues, Pull Requests
The [exercism/ocaml](https://github.com/exercism/ocaml) repository on
GitHub is the home for all of the Ocaml exercises.

If you have feedback about an exercise, or want to help implementing a new
one, head over there and create an issue.  We'll do our best to help you!

## Source

The Prime Factors Kata by Uncle Bob [http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata](http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata)

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