acc + tail recursion vs no acc in erlang.

acc.erl

-module(acc).
-author('[email protected]').

-export([test/1]).

sum1([]) -> 0; 
sum1([X | XS]) when is_number(X) -> X + sum1(XS); 
sum1([_X | XS]) -> sum1(XS).

sum2([], Acc) -> Acc; 
sum2([X | XS], Acc) when is_number(X) -> sum2(XS, X + Acc); 
sum2([_X | XS], Acc) -> sum2(XS, Acc).

test(N) ->
  {
    benchmark(fun () -> sum1(lists:seq(1, N)) end),
    benchmark(fun () -> sum2(lists:seq(1, N), 0) end)
  }.

benchmark(F) ->
  lists:foreach(fun statistics/1, [runtime, wall_clock]),
  Result = F(),
  Times = lists:map(
    fun (Type) -> {_, T} = statistics(Type), T end,
    [runtime, wall_clock]
  ),
  {Result, Times}.