string_bench.exs

defmodule Bench do
  @binary String.duplicate("a", 1024)
  @list String.to_charlist(@binary)

  def binary_utf8(), do: binary_utf8(@binary)
  defp binary_utf8(<<_::utf8, rest::bits>>), do: binary_utf8(rest)
  defp binary_utf8(<<>>), do: :ok

  def binary_byte(), do: binary_byte(@binary)
  defp binary_byte(<<_, rest::bits>>), do: binary_byte(rest)
  defp binary_byte(<<>>), do: :ok

  def list(), do: list(@list)
  defp list([_ | rest]), do: list(rest)
  defp list([]), do: :ok
end

Benchee.run(%{
  "binary_utf8" => &Bench.binary_utf8/0,
  "binary_byte" => &Bench.binary_byte/0,
  "list" => &Bench.list/0
})