Add twelve-days exercise (#331)

config.json

@@ -440,6 +440,14 @@
           "lists"
         ]
       },
+      {
+        "slug": "twelve-days",
+        "name": "Twelve Days",
+        "uuid": "d3799ff2-5cf4-4148-ba2a-e40137cfe2ce",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "all-your-base",
         "name": "All Your Base",

exercises/practice/twelve-days/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Your task in this exercise is to write code that returns the lyrics of the song: "The Twelve Days of Christmas."
+
+"The Twelve Days of Christmas" is a common English Christmas carol.
+Each subsequent verse of the song builds on the previous verse.
+
+The lyrics your code returns should _exactly_ match the full song text shown below.
+
+## Lyrics
+
+```text
+On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+
+On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+```

exercises/practice/twelve-days/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "twelve-days.sml"
+    ],
+    "test": [
+      "test.sml"
+    ],
+    "example": [
+      ".meta/example.sml"
+    ]
+  },
+  "blurb": "Output the lyrics to 'The Twelve Days of Christmas'.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)"
+}

exercises/practice/twelve-days/.meta/example.sml

@@ -0,0 +1,18 @@
+fun recite (startVerse: int, endVerse: int): string =
+  let
+    val ordinals = [ "", "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth", "tenth", "eleventh", "twelfth" ]
+
+    val ordinal = List.nth (ordinals, startVerse)
+
+    val offsets = [ 0, 235, 213, 194, 174, 157, 137, 113, 90, 69, 48, 26, 0 ]
+
+    val offset = List.nth (offsets, startVerse)
+
+    val gifts = "twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+
+    val gift = String.substring (gifts, offset, String.size gifts - offset)
+
+    val suffix = if startVerse = endVerse then "" else "\n" ^ recite (startVerse + 1, endVerse)
+  in
+    "On the " ^ ordinal ^ " day of Christmas my true love gave to me: " ^ gift ^ suffix
+  end

exercises/practice/twelve-days/.meta/tests.toml

@@ -0,0 +1,55 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[c0b5a5e6-c89d-49b1-a6b2-9f523bff33f7]
+description = "verse -> first day a partridge in a pear tree"
+
+[1c64508a-df3d-420a-b8e1-fe408847854a]
+description = "verse -> second day two turtle doves"
+
+[a919e09c-75b2-4e64-bb23-de4a692060a8]
+description = "verse -> third day three french hens"
+
+[9bed8631-ec60-4894-a3bb-4f0ec9fbe68d]
+description = "verse -> fourth day four calling birds"
+
+[cf1024f0-73b6-4545-be57-e9cea565289a]
+description = "verse -> fifth day five gold rings"
+
+[50bd3393-868a-4f24-a618-68df3d02ff04]
+description = "verse -> sixth day six geese-a-laying"
+
+[8f29638c-9bf1-4680-94be-e8b84e4ade83]
+description = "verse -> seventh day seven swans-a-swimming"
+
+[7038d6e1-e377-47ad-8c37-10670a05bc05]
+description = "verse -> eighth day eight maids-a-milking"
+
+[37a800a6-7a56-4352-8d72-0f51eb37cfe8]
+description = "verse -> ninth day nine ladies dancing"
+
+[10b158aa-49ff-4b2d-afc3-13af9133510d]
+description = "verse -> tenth day ten lords-a-leaping"
+
+[08d7d453-f2ba-478d-8df0-d39ea6a4f457]
+description = "verse -> eleventh day eleven pipers piping"
+
+[0620fea7-1704-4e48-b557-c05bf43967f0]
+description = "verse -> twelfth day twelve drummers drumming"
+
+[da8b9013-b1e8-49df-b6ef-ddec0219e398]
+description = "lyrics -> recites first three verses of the song"
+
+[c095af0d-3137-4653-ad32-bfb899eda24c]
+description = "lyrics -> recites three verses from the middle of the song"
+
+[20921bc9-cc52-4627-80b3-198cbbfcf9b7]
+description = "lyrics -> recites the whole song"

exercises/practice/twelve-days/test.sml

@@ -0,0 +1,151 @@
+(* version 1.0.0 *)
+
+use "testlib.sml";
+use "twelve-days.sml";
+
+infixr |>
+fun x |> f = f x
+
+val testsuite =
+  describe "twelve-days" [
+    describe "verse" [
+      test "first day a partridge in a pear tree"
+        (fn _ => let
+          val expected =
+            "On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree."
+        in
+          recite (1, 1) |> Expect.equalTo expected
+        end),
+
+      test "second day two turtle doves"
+        (fn _ => let
+          val expected =
+            "On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (2, 2) |> Expect.equalTo expected
+        end),
+
+      test "third day three french hens"
+        (fn _ => let
+          val expected =
+            "On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (3, 3) |> Expect.equalTo expected
+        end),
+
+      test "fourth day four calling birds"
+        (fn _ => let
+          val expected =
+            "On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (4, 4) |> Expect.equalTo expected
+        end),
+
+      test "fifth day five gold rings"
+        (fn _ => let
+          val expected =
+            "On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (5, 5) |> Expect.equalTo expected
+        end),
+
+      test "sixth day six geese-a-laying"
+        (fn _ => let
+          val expected =
+            "On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (6, 6) |> Expect.equalTo expected
+        end),
+
+      test "seventh day seven swans-a-swimming"
+        (fn _ => let
+          val expected =
+            "On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (7, 7) |> Expect.equalTo expected
+        end),
+
+      test "eighth day eight maids-a-milking"
+        (fn _ => let
+          val expected =
+            "On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (8, 8) |> Expect.equalTo expected
+        end),
+
+      test "ninth day nine ladies dancing"
+        (fn _ => let
+          val expected =
+            "On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (9, 9) |> Expect.equalTo expected
+        end),
+
+      test "tenth day ten lords-a-leaping"
+        (fn _ => let
+          val expected =
+            "On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (10, 10) |> Expect.equalTo expected
+        end),
+
+      test "eleventh day eleven pipers piping"
+        (fn _ => let
+          val expected =
+            "On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (11, 11) |> Expect.equalTo expected
+        end),
+
+      test "twelfth day twelve drummers drumming"
+        (fn _ => let
+          val expected =
+            "On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (12, 12) |> Expect.equalTo expected
+        end)
+    ],
+
+    describe "lyrics" [
+      test "recites first three verses of the song"
+        (fn _ => let
+          val expected =
+            "On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.\n\
+            \On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (1, 3) |> Expect.equalTo expected
+        end),
+
+      test "recites three verses from the middle of the song"
+        (fn _ => let
+          val expected =
+            "On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (4, 6) |> Expect.equalTo expected
+        end),
+
+      test "recites the whole song"
+        (fn _ => let
+          val expected =
+            "On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.\n\
+            \On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n\
+            \On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree."
+        in
+          recite (1, 12) |> Expect.equalTo expected
+        end)
+    ]
+  ]
+
+val _ = Test.run testsuite