Benchmarks different struct creations

create_structs_bench.exs

defmodule Struct do
  defstruct [:a, :b, :c, :d, :e, :f, :g, :h]
end

defmodule CreateStruct do

  def create1() do
    struct(Struct, create1_fields())
  end

  def create3() do
    struct!(Struct, create1_fields())
  end

  defp create1_fields() do
    create1_h([])
  end

  defp create1_h(fields), do: create1_g([{:h, 0} | fields])
  defp create1_g(fields), do: create1_f([{:g, 0} | fields])
  defp create1_f(fields), do: create1_e([{:f, 0} | fields])
  defp create1_e(fields), do: create1_d([{:e, 0} | fields])
  defp create1_d(fields), do: create1_c([{:d, 0} | fields])
  defp create1_c(fields), do: create1_b([{:c, 0} | fields])
  defp create1_b(fields), do: create1_a([{:b, 0} | fields])
  defp create1_a(fields), do: [{:a, 0} | fields]

  def create2() do
    %Struct{}
    |> struct([{:a, 0}])
    |> struct([{:b, 0}])
    |> struct([{:c, 0}])
    |> struct([{:d, 0}])
    |> struct([{:e, 0}])
    |> struct([{:f, 0}])
    |> struct([{:g, 0}])
    |> struct([{:h, 0}])
  end

  def create4() do
    %Struct{}
    |> struct!([{:a, 0}])
    |> struct!([{:b, 0}])
    |> struct!([{:c, 0}])
    |> struct!([{:d, 0}])
    |> struct!([{:e, 0}])
    |> struct!([{:f, 0}])
    |> struct!([{:g, 0}])
    |> struct!([{:h, 0}])
  end

end

# IO.puts "#{inspect CreateStruct.create1()}"
# IO.puts "#{inspect CreateStruct.create2()}"

IO.puts "#{inspect struct(Struct, [{:a, 1}, {:a, 42}])}"

Benchee.run(%{
  "create1" => fn -> Enum.each(1..100000, fn _ -> CreateStruct.create1() end) end,
  "create2" => fn -> Enum.each(1..100000, fn _ -> CreateStruct.create2() end) end,
  "create3" => fn -> Enum.each(1..100000, fn _ -> CreateStruct.create3() end) end,
  "create4" => fn -> Enum.each(1..100000, fn _ -> CreateStruct.create4() end) end,
  },
  formatters: [
    &Benchee.Formatters.HTML.output/1,
    &Benchee.Formatters.Console.output/1
  ],
  html: [file: "benches/decode_output.html"],
  time: 3
)