map_lookup_vs_pattern_matching.exs

defmodule Lookup.Slow do
  @lookup %{
    "one"   => 1,
    "two"   => 2,
    "three" => 3,
    "four"  => 4,
    "five"  => 5
  }

  def int_for(str) do
    @lookup[str]
  end
end

defmodule Lookup.Fast do
  def int_for(str) do
    do_int_for(str)
  end

  def do_int_for("one"),   do: 1
  def do_int_for("two"),   do: 2
  def do_int_for("three"), do: 3
  def do_int_for("four"),  do: 4
  def do_int_for("five"),  do: 5
end

defmodule Lookup.Benchmark do
  def benchmark do
    Benchee.run(%{
      "Pattern Matching" => fn -> bench_func(Lookup.Fast) end,
      "Map Lookup"       => fn -> bench_func(Lookup.Slow) end
    }, time: 10, print: [fast_warning: false])
  end

  def bench_func(module) do
    module.int_for("one")
    module.int_for("two")
    module.int_for("three")
    module.int_for("four")
    module.int_for("five")
    module.int_for("one")
    module.int_for("two")
    module.int_for("three")
    module.int_for("four")
    module.int_for("five")
    module.int_for("one")
    module.int_for("two")
    module.int_for("three")
    module.int_for("four")
    module.int_for("five")
  end
end

Lookup.Benchmark.benchmark()