Bunny

eat.exs

list = Enum.to_list(1..10_000)
map_fun = fn(i) -> [i, i * i] end

Bunny.eat(%{
  "flat_map"    => fn -> Enum.flat_map(list, map_fun) end,
  "map.flatten" => fn -> list |> Enum.map(map_fun) |> List.flatten end
})

output

tobi@speedy ~/github/bunny $ mix run samples/eat.exs 
Bunny will take care of that for you!

   ( Y)
  ( . .)
 o(") (")

Operating System: Linux
CPU Information: Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz
Number of Available Cores: 8
Available memory: 15.61 GB
Elixir 1.6.3
Erlang 20.2
Benchmark suite executing with the following configuration:
warmup: 2 s
time: 5 s
parallel: 1
inputs: none specified
Estimated total run time: 14 s


Benchmarking flat_map...
Benchmarking map.flatten...

Name                  ips        average  deviation         median         99th %
flat_map           2.23 K      448.25 μs    ±14.33%         430 μs         790 μs
map.flatten        1.17 K      857.84 μs    ±21.57%         796 μs     1426.98 μs

Comparison: 
flat_map           2.23 K
map.flatten        1.17 K - 1.91x slower

Bunny is done!

 () ()
 (* *)
o( 0 )