2016 Update

Task/Langtons-ant/Elixir/langtons-ant.elixir

@@ -1,27 +1,25 @@
 defmodule Langtons do
   def ant(sizex, sizey) do
     {px, py} = {div(sizex,2), div(sizey,2)}     # start position
-    move(HashSet.new, sizex, sizey, px, py, {1,0}, 0)
+    move(MapSet.new, sizex, sizey, px, py, {1,0}, 0)
   end
 
   defp move(plane, sx, sy, px, py, _, step) when px<0 or sx<px or py<0 or sy<py, do:
     print(plane, sx, sy, px, py, step)
   defp move(plane, sx, sy, px, py, dir, step) do
-    {plane2, {dx,dy}} = if Set.member?(plane, {px,py}),
-                          do:   {Set.delete(plane, {px,py}), turn(dir, :right)},
-                          else: {Set.put(plane, {px,py}), turn(dir, :left)}
+    {plane2, {dx,dy}} = if {px,py} in plane,
+                          do:   {MapSet.delete(plane, {px,py}), turn_right(dir)},
+                          else: {MapSet.put(plane, {px,py}), turn_left(dir)}
     move(plane2, sx, sy, px+dx, py+dy, {dx,dy}, step+1)
   end
 
-  defp turn({dx, dy}, :right), do: {dy, -dx}
-  defp turn({dx, dy},      _), do: {-dy, dx}
+  defp turn_right({dx, dy}), do: {dy, -dx}
+  defp turn_left({dx, dy}), do: {-dy, dx}
 
   defp print(plane, sx, sy, px, py, step) do
     IO.puts "out of bounds after #{step} moves: (#{px}, #{py})"
     Enum.each(0..sy, fn j ->
-      Enum.map(0..sx, fn i ->
-        if Set.member?(plane, {i,j}), do: "#", else: "."
-      end) |> Enum.join |> IO.puts
+      IO.puts Enum.map(0..sx, fn i -> if {i,j} in plane, do: "#", else: "." end)
     end)
   end
 end