Merge remote-tracking branch 'remotes/upstream/master' into add_map_sets_koans

Conflicts:
	lib/runner.ex

CONTRIBUTORS.md

@@ -0,0 +1,16 @@
+"Thank you!" to all the contributors (alphabetical order):
+
+*  Alex
+*  Fabien Townsend
+*  Felipe Seré
+*  gemcfadyen
+*  Jay Hayes
+*  kamidev
+*  Mahmut Surekci
+*  Makis Otman
+*  Rabea Gleissner
+*  Ria Cataquian
+*  snikolau
+*  Trung Lê
+*  Uku Taht
+*  Zander Mackie

README.md

@@ -43,3 +43,5 @@ $ mix meditate --no-clear-screen
 We welcome contributions! If something does not make sense along the way or you feel
 like an important lesson is missing from the koans, feel free to fork the project
 and open a pull request.
+
+List of [contributors](CONTRIBUTORS.md).

lib/koans/16_protocols.ex

@@ -0,0 +1,51 @@
+defmodule Protocols do
+  use Koans
+
+  @intro "Wan't to follow the rules? Adhere to the protocol!"
+
+  defprotocol School, do: def enrol(person)
+
+  defimpl School, for: Any do
+    def enrol(_) do
+      "Pupil enrolled at school"
+    end
+  end
+
+  defmodule Student do
+    @derive School
+    defstruct name: ""
+  end
+
+  defmodule Musician, do: defstruct name: "", instrument: ""
+  defmodule Dancer,  do: defstruct name: "", dance_style: ""
+  defmodule Baker, do: defstruct name: ""
+
+  defimpl School, for: Musician do
+    def enrol(musician) do
+      "#{musician.name} signed up for #{musician.instrument}"
+    end
+  end
+
+  defimpl School, for: Dancer do
+    def enrol(dancer), do: "#{dancer.name} enrolled for #{dancer.dance_style}"
+  end
+
+  koan "Sharing an interface is the secret at school" do
+    musician = %Musician{name: "Andre", instrument: "violin"}
+    dancer = %Dancer{name: "Darcy", dance_style: "ballet"}
+
+    assert School.enrol(musician) == ___
+    assert School.enrol(dancer) == ___
+  end
+
+  koan "Sometimes we all use the same" do
+    student = %Student{name: "Emily"}
+    assert School.enrol(student) == ___
+  end
+
+  koan "If you don't comply you can't get in" do
+    assert_raise ___, fn ->
+      School.enrol(%Baker{name: "Delia"})
+    end
+  end
+end

lib/runner.ex

@@ -16,6 +16,7 @@ defmodule Runner do
     Processes,
     Tasks,
     Agents,
+    Protocols,
     MapSets,
   ]
 

mix.lock

@@ -1,2 +1,2 @@
-%{"exfswatch": {:hex, :exfswatch, "0.1.1"},
-  "fs": {:hex, :fs, "0.9.2"}}
+%{"exfswatch": {:hex, :exfswatch, "0.1.1", "7ccf6fc9b443d04dada3e50b21f910b4d0e4546ce7772dc6d4181fb929ea186f", [:mix], [{:fs, "~> 0.9", [hex: :fs, optional: false]}]},
+  "fs": {:hex, :fs, "0.9.2", "ed17036c26c3f70ac49781ed9220a50c36775c6ca2cf8182d123b6566e49ec59", [:rebar], []}}

test/koans/protocols_koans_test.exs

@@ -0,0 +1,14 @@
+defmodule ProtocolsTests do
+  use ExUnit.Case
+  import TestHarness
+
+  test "Protocols" do
+    answers = [
+      {:multiple, ["Andre signed up for violin", "Darcy enrolled for ballet"]},
+      "Pupil enrolled at school",
+      Protocol.UndefinedError
+    ]
+
+    test_all(Protocols, answers)
+  end
+end