Demonstrate update_in to manipulate nested struct values

2017-01-22 11:12:49 -07:00
parent 516be35df9
commit d467985778
2 changed files with 6 additions and 0 deletions
--- a/lib/koans/11_structs.ex
+++ b/lib/koans/11_structs.ex
@@ -54,4 +54,9 @@ defmodule Structs 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
 end