Merge pull request #162 from srufle/master

Demonstrate put_in to manipulate nested struct values

CONTRIBUTORS.md

@@ -12,6 +12,7 @@
 *  Ria Cataquian
 *  Simone D'Amico
 *  snikolau
+*  Stephen Rufle
 *  Trung Lê
 *  Uku Taht
 *  Zander Mackie

lib/koans/11_structs.ex

@@ -45,4 +45,23 @@ defmodule Structs do
 
     assert Map.fetch(silvia, :age) == ___
   end
+
+  defmodule Airline do
+    defstruct plane: %Plane{}, name: "Southwest"
+  end
+
+  koan "Use the put_in macro to replace a nested value" do
+    airline = %Airline{plane: %Plane{maker: :boeing}}
+    assert put_in(airline.plane.maker, :airbus) == ___
+  end
+
+  koan "Use the update_in macro to modify a nested value" do
+    airline = %Airline{plane: %Plane{maker: :boeing, passengers: 200}}
+    assert update_in(airline.plane.passengers, &(&1 + 2)) == ___
+  end
+
+  koan "Use the put_in macro with atoms to replace a nested value in a non-struct" do
+    airline = %{plane: %{maker: :boeing}, name: "Southwest"}
+    assert put_in(airline[:plane][:maker], :cessna) == ___
+  end
 end

test/koans/structs_koans_test.exs

@@ -10,6 +10,9 @@ defmodule StructsTests do
       33,
       {:multiple, [true, false]},
       {:ok, 22},
+      %Structs.Airline{plane: %Structs.Plane{maker: :airbus}, name: "Southwest"},
+      %Structs.Airline{plane: %Structs.Plane{maker: :boeing, passengers: 202}, name: "Southwest"},
+      %{plane: %{maker: :cessna}, name: "Southwest"},
     ]
 
     test_all(Structs, answers)