From: Brian Candler <B.Candler@...>
Date: 2003-08-26T01:35:56+09:00
Subject: Re: Rite/Ruby2.0 & Ruby vs OCaml

On Tue, Aug 26, 2003 at 12:40:45AM +0900, mark wrote:
> Unless I'm mistaken n + sum(n-1) isn't a tail call since it has to add n to 
> the result of sum(n-1) which prevents it from optimizing the call.
> 
> The following code runs without any errors, though it prints the wrong answer 
> (probably due to overflow)
> 
> let rec sum n total = 
> 	if n < 1 then total else sum (n-1) (total + n);;
> 
> print_int(sum 1000000 0);; 

Ah, thank you, and sorry for exposing my ignorance!

I was actually just trying to get some timings out. It seems ocaml is
astoundingly fast for that test: 0.51s uncompiled, 0.37s compiled with
ocamlc, versus 11.6s for the Ruby equivalent:

  def sum(n)
    total = 0
    n.times { |x| total += x }
    total
  end

  puts sum(1000000)

OTOH, the Ruby version gives the right answer :-)

Cheers,

Brian.