# Triangle

Determine if a triangle is equilateral, isosceles, or scalene.

An _equilateral_ triangle has all three sides the same length.<br/>
An _isosceles_ triangle has at least two sides the same length. (It is sometimes
specified as having exactly two sides the same length, but for the purposes of
this exercise we'll say at least two.)<br/>
A _scalene_ triangle has all sides of different lengths.

## Note

For a shape to be a triangle at all, all sides have to be of length > 0, and 
the sum of the lengths of any two sides must be greater than or equal to the 
length of the third side. See [Triangle Inequality](https://en.wikipedia.org/wiki/Triangle_inequality).

## Dig Deeper

The case where the sum of the lengths of two sides _equals_ that of the 
third is known as a _degenerate_ triangle - it has zero area and looks like 
a single line. Feel free to add your own code/tests to check for degenerate triangles.

## Getting Started

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

## Running the tests

To run the test suite, execute the following command:

```bash
stack test
```

#### If you get an error message like this...

```
No .cabal file found in directory
```

You are probably running an old stack version and need
to upgrade it.

#### Otherwise, if you get an error message like this...

```
No compiler found, expected minor version match with...
Try running "stack setup" to install the correct GHC...
```

Just do as it says and it will download and install
the correct compiler version:

```bash
stack setup
```

## Running *GHCi*

If you want to play with your solution in GHCi, just run the command:

```bash
stack ghci
```

## Feedback, Issues, Pull Requests

The [exercism/haskell](https://github.com/exercism/haskell) repository on
GitHub is the home for all of the Haskell 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 Ruby Koans triangle project, parts 1 & 2 [http://rubykoans.com](http://rubykoans.com)

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