Function and Code Organization

Section

defmodule Point do
  def right({x, y}), do: {x + 1, y}
  def left({x, y}), do: {x - 1, y}
  def up({x, y}), do: {x, y - 1}
  def down({x, y}), do: {x, y + 1}
  def mirror({x, y}, w), do: {w - x, y}
  def flip({x, y}, h), do: {x, h - y}
  def transpose({x, y}), do: {y, x}
  def move({x, y}, {cx, cy}), do: {x + cx, y + cy}

  def rotate(point, 0, _w, _h) do
    point
  end

  def rotate(point, 90, w, _h) do
    point
    |> transpose
    |> mirror(w)
  end

  def rotate(point, 180, w, h) do
    point
    |> flip(h)
    |> mirror(w)
  end

  def rotate(point, 270, _w, h) do
    point
    |> flip(h)
    |> transpose
  end
end

{:module, Point, <<70, 79, 82, 49, 0, 0, 12, ...>>, {:rotate, 4}}

import Point

origin = {0, 0}

origin
|> right
|> right
|> down

point2 = {1, 3}
IO.inspect(Point.mirror(point2, 5))
IO.inspect(Point.flip(point2, 5))
IO.inspect(Point.transpose(point2))

{4, 3}
{1, 2}
{3, 1}

{3, 1}

point3 = {0, 0}
IO.inspect(point3 |> rotate(270, 5, 4))
IO.inspect(point3 |> rotate(180, 5, 4))
IO.inspect(point3 |> rotate(90, 5, 4))

{4, 0}
{5, 4}
{5, 0}

{5, 0}