Comparison between C style for loop and Erlang on a sum function example

c_erlang

//
// C - style
//
int sum( int boundary )
{
  int i, sum = 0;
  
  for( i = 1; i <= boundary; i++ )
    sum += 1;

  return sum;
}

%
% Erlang
%
sum( Boundary ) -> sum_acc( 1, Boundary, 0 ).

sum_acc(Index, Boundary, Sum) when Index =< Boundary ->
  sum_acc( Index + 1, Boundary, Sum + Index );
sum_acc( _I, _B, Sum + Index ) ->
  Sum.