foo.exs

defmodule Foo do
  @doc """
  Returns sum of items in a list
  """
  def sum(list), do: _sum(list, 0)
  defp _sum([], acc), do: acc
  defp _sum([h|t], acc), do: _sum(t, h + acc)


  @doc """
  Custom map function
  """
  def map2([], _), do: []
  def map2([h|t], func) do
    [func.(h) | map2(t, func)]
  end


  @doc """
  Fizzbuzz implementation
  """
  def fizzbuzz(x) when is_list(x) do
    Enum.map(x, &fizzbuzz/1)
  end
  def fizzbuzz(x) when is_integer(x) and rem(x, 3) == 0 and rem(x, 5) == 0, do: IO.puts "FizzBuzz"
  def fizzbuzz(x) when is_integer(x) and rem(x, 3) == 0, do: IO.puts "Fizz"
  def fizzbuzz(x) when is_integer(x) and rem(x, 5) == 0, do: IO.puts "Buzz"
  def fizzbuzz(x) when is_integer(x), do: IO.puts x


  @doc """
  palindrome predicate
  """
  def palindrome?(word) do
     word == Enum.reduce(word |> String.graphemes, "", &(&1 <> &2))
  end

end

IO.puts "FizzBuzz >>"
Foo.fizzbuzz(1..30 |> Enum.to_list) |> IO.inspect


IO.puts "sum >>"
Foo.sum(1..10 |> Enum.to_list) |> IO.inspect


IO.puts "map >>"
Foo.map2(1..10 |> Enum.to_list, &(&1 * 2)) |> IO.inspect


IO.puts "palindrome? >>"
Enum.map(["racecar", "dog", "tenet"], &Foo.palindrome?/1) |> IO.inspect