Add new two-fer exercise

config.json

@@ -14,6 +14,16 @@
         "strings"
       ]
     },
+    {
+      "slug": "two-fer",
+      "uuid": "0118175a-761f-4d05-8857-fe93745f490f",
+      "core": true,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "strings"
+      ]
+    },
     {
       "slug": "bob",
       "uuid": "11ce2a73-3f43-4b14-b755-6c52dc71bdda",

exercises/two-fer/README.md

@@ -0,0 +1,48 @@
+# Two Fer
+
+`Two-fer` or `2-fer` is short for two for one. One for you and one for me.
+
+```text
+"One for X, one for me."
+```
+
+When X is a name or "you".
+
+If the given name is "Alice", the result should be "One for Alice, one for me."
+If no name is given, the result should be "One for you, one for me."
+
+
+## Elm Installation
+
+Refer to the [Exercism help page](http://exercism.io/languages/elm) for Elm
+installation and learning resources.
+
+## Writing the Code
+
+The first time you start an exercise, you'll need to ensure you have the
+appropriate dependencies installed. Thankfully, Elm makes that easy for you and
+will install dependencies when you try to run tests or build the code.
+
+Execute the tests with:
+
+```bash
+$ elm-test
+```
+
+Automatically run tests again when you save changes:
+
+```bash
+$ elm-test --watch
+```
+
+As you work your way through the test suite, be sure to remove the `skip <|`
+calls from each test until you get them all passing!
+
+## Source
+
+[https://en.wikipedia.org/wiki/Two-fer](https://en.wikipedia.org/wiki/Two-fer)
+
+## Submitting Incomplete Solutions
+
+It is possible to submit an incomplete solution so you can see how others have
+completed the exercise.

exercises/two-fer/TwoFer.elm

@@ -0,0 +1,11 @@
+module TwoFer exposing (twoFer)
+
+
+twoFer : Maybe String -> String
+twoFer name =
+    case name of
+        Just name_ ->
+            "One for " ++ name_ ++ ", one for me."
+
+        Nothing ->
+            "One for you, one for me."

exercises/two-fer/TwoFer.example.elm

@@ -0,0 +1,5 @@
+module TwoFer exposing (twoFer)
+
+
+twoFer name =
+    Debug.todo "Please implement this function"

exercises/two-fer/elm.json

@@ -0,0 +1,19 @@
+{
+    "type": "application",
+    "source-directories": [
+        "."
+    ],
+    "elm-version": "0.19.0",
+    "dependencies": {
+        "direct": {
+            "elm/core": "1.0.0"
+        },
+        "indirect": {}
+    },
+    "test-dependencies": {
+        "direct": {
+          "elm-explorations/test": "1.0.0"
+        },
+        "indirect": {}
+    }
+}

exercises/two-fer/tests/Tests.elm

@@ -0,0 +1,27 @@
+module Tests exposing (tests)
+
+import Expect
+import String
+import Test exposing (..)
+import TwoFer exposing (twoFer)
+
+
+tests : Test
+tests =
+    describe "Two-fer"
+        [ test "No name given" <|
+            \() ->
+                Expect.equal "One for you, one for me." (twoFer Nothing)
+
+        -- Once you get the first test passing, remove the
+        -- `skip <|` (just leave the comma) on the next two
+        -- lines to continue!
+        , skip <|
+            test "A name given" <|
+                \() ->
+                    Expect.equal "One for Alice, one for me." (twoFer (Just "Alice"))
+        , skip <|
+            test "Another name given" <|
+                \() ->
+                    Expect.equal "One for Bob, one for me." (twoFer (Just "Bob"))
+        ]