house

elixir/house/lib/house.ex

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+defmodule House do
+  @doc """
+  Return verses of the nursery rhyme 'This is the House that Jack Built'.
+  """
+
+  @this_is "This is"
+  @verses [
+    "house that Jack built",
+    "malt that lay in",
+    "rat that ate",
+    "cat that killed",
+    "dog that worried",
+    "cow with the crumpled horn that tossed",
+    "maiden all forlorn that milked",
+    "man all tattered and torn that kissed",
+    "priest all shaven and shorn that married",
+    "rooster that crowed in the morn that woke",
+    "farmer sowing his corn that kept",
+    "horse and the hound and the horn that belonged to"
+  ]
+
+  @spec recite(start :: integer, stop :: integer) :: String.t()
+  def recite(start, stop) do
+    (Enum.map(start..stop, &verse/1) |> Enum.join("\n")) <> "\n"
+  end
+
+  defp verse(i) do
+    verse =
+      @verses
+      |> Enum.take(i)
+      |> Enum.reverse()
+      |> Enum.join(" the ")
+
+    @this_is <> " the " <> verse <> "."
+  end
+end