Implement the bottle-song exercise

config.json

@@ -1307,6 +1307,22 @@
         ],
         "difficulty": 3
       },
+      {
+        "slug": "bottle-song",
+        "name": "Bottle Song",
+        "uuid": "6c240d6c-d897-4c4e-a556-b595f45c2d3b",
+        "prerequisites": [
+          "strings",
+          "multiple-clause-functions",
+          "ranges",
+          "enum",
+          "recursion"
+        ],
+        "practices": [
+          "multiple-clause-functions"
+        ],
+        "difficulty": 3
+      },
       {
         "slug": "dnd-character",
         "name": "D&D Character",

exercises/practice/bottle-song/.docs/instructions.md

@@ -0,0 +1,57 @@
+# Instructions
+
+Recite the lyrics to that popular children's repetitive song: Ten Green Bottles.
+
+Note that not all verses are identical.
+
+```text
+Ten green bottles hanging on the wall,
+Ten green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be nine green bottles hanging on the wall.
+
+Nine green bottles hanging on the wall,
+Nine green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be eight green bottles hanging on the wall.
+
+Eight green bottles hanging on the wall,
+Eight green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be seven green bottles hanging on the wall.
+
+Seven green bottles hanging on the wall,
+Seven green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be six green bottles hanging on the wall.
+
+Six green bottles hanging on the wall,
+Six green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be five green bottles hanging on the wall.
+
+Five green bottles hanging on the wall,
+Five green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be four green bottles hanging on the wall.
+
+Four green bottles hanging on the wall,
+Four green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be three green bottles hanging on the wall.
+
+Three green bottles hanging on the wall,
+Three green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be two green bottles hanging on the wall.
+
+Two green bottles hanging on the wall,
+Two green bottles hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be one green bottle hanging on the wall.
+
+One green bottle hanging on the wall,
+One green bottle hanging on the wall,
+And if one green bottle should accidentally fall,
+There'll be no green bottles hanging on the wall.
+```

exercises/practice/bottle-song/.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{.meta,config,lib,test}/**/*.{ex,exs}"]
+]

exercises/practice/bottle-song/.gitignore

@@ -0,0 +1,26 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+bottle_song-*.tar
+
+# Temporary files, for example, from tests.
+/tmp/

exercises/practice/bottle-song/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "antoine-duchenet"
+  ],
+  "files": {
+    "solution": [
+      "lib/bottle_song.ex"
+    ],
+    "test": [
+      "test/bottle_song_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "blurb": "Produce the lyrics to the popular children's repetitive song: Ten Green Bottles.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Ten_Green_Bottles"
+}

exercises/practice/bottle-song/.meta/design.md

@@ -0,0 +1,11 @@
+# Design Decisions
+
+## Wording
+
+Since the "verse" term used in the canonical specifications is quite ambiguous, it has been replaced by:
+- "line" for a single metrical line in a poem
+- "stanza" for a group of lines in a poem
+- "poem" form the poem itself
+
+Since this exercise uses only stanzas of 4 lines, it could be replaced by "quatrain".
+"Couplet" could be used for pairs of rhyming lines.

exercises/practice/bottle-song/.meta/example.ex

@@ -0,0 +1,51 @@
+defmodule BottleSong do
+  @moduledoc """
+  Handles lyrics of the popular children song: Ten Green Bottles
+  """
+
+  @quantifiers %{
+    10 => "ten",
+    9 => "nine",
+    8 => "eight",
+    7 => "seven",
+    6 => "six",
+    5 => "five",
+    4 => "four",
+    3 => "three",
+    2 => "two",
+    1 => "one",
+    0 => "no"
+  }
+
+  @spec recite(pos_integer, pos_integer) :: Enum.t()
+  def recite(start_bottle, take_down) do
+    0..(take_down - 1)
+    |> Enum.map(&stanza(start_bottle - &1))
+    |> Enum.intersperse("")
+    |> List.flatten()
+    |> Enum.join("\n")
+  end
+
+  @spec stanza(pos_integer) :: Enum.t()
+  defp stanza(before_the_fall) do
+    after_the_fall = before_the_fall - 1
+
+    [
+      main_line(before_the_fall),
+      main_line(before_the_fall),
+      "And if one green bottle should accidentally fall,",
+      "There'll be #{quantifier(after_the_fall)} green #{bottle(after_the_fall)} hanging on the wall."
+    ]
+  end
+
+  @spec main_line(pos_integer) :: String.t()
+  defp main_line(n),
+    do: "#{n |> quantifier() |> String.capitalize()} green #{bottle(n)} hanging on the wall,"
+
+  @spec quantifier(pos_integer) :: String.t()
+  defp quantifier(n), do: Map.get(@quantifiers, n)
+
+  @spec bottle(pos_integer) :: String.t()
+  defp bottle(1), do: "bottle"
+  defp bottle(_), do: "bottles"
+end

exercises/practice/bottle-song/.meta/tests.toml

@@ -0,0 +1,31 @@
+# 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.
+
+[d4ccf8fc-01dc-48c0-a201-4fbeb30f2d03]
+description = "verse -> single verse -> first generic verse"
+
+[0f0aded3-472a-4c64-b842-18d4f1f5f030]
+description = "verse -> single verse -> last generic verse"
+
+[f61f3c97-131f-459e-b40a-7428f3ed99d9]
+description = "verse -> single verse -> verse with 2 bottles"
+
+[05eadba9-5dbd-401e-a7e8-d17cc9baa8e0]
+description = "verse -> single verse -> verse with 1 bottle"
+
+[a4a28170-83d6-4dc1-bd8b-319b6abb6a80]
+description = "lyrics -> multiple verses -> first two verses"
+
+[3185d438-c5ac-4ce6-bcd3-02c9ff1ed8db]
+description = "lyrics -> multiple verses -> last three verses"
+
+[28c1584a-0e51-4b65-9ae2-fbc0bf4bbb28]
+description = "lyrics -> multiple verses -> all verses"

exercises/practice/bottle-song/lib/bottle_song.ex

@@ -0,0 +1,9 @@
+defmodule BottleSong do
+  @moduledoc """
+  Handles lyrics of the popular children song: Ten Green Bottles
+  """
+
+  @spec recite(pos_integer, pos_integer) :: Enum.t()
+  def recite(_start_bottle, _take_down) do
+  end
+end

exercises/practice/bottle-song/mix.exs

@@ -0,0 +1,28 @@
+defmodule BottleSong.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :bottle_song,
+      version: "1.0.0",
+      elixir: "~> 1.10",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end