Programmer Passport: Elixir

Implement a Polygon

Roughly stated, a polygon is a shape made up of the area between connected lines. For example, triangles are polygons with three sides. Let’s create a module for working with polygons.

We’ll start with a few constructors. Here are a couple of constructors for building squares and rectangles:

defmodule Polygon do
  def rectangle({x, y}, height, width) do
    [{x, y}, {x+width, y}, {x+width, y+height}, {x, y+height}]
  end

  def square(point, length) do
    rectangle(point, length, length)
  end
end

Both of these functions take the building blocks of the shape and return a polygon, a list of points. Now, let’s build some reducers. We’ve already done the bulk of the work in the Point module. The functions in ...