Re: [Chicken-users] multiple values in chicken

[Zbigniew]

On 1/31/08, John Cowan <address@hidden> wrote:
> Well, as I said, in Chicken values (multiple or otherwise) become the
> arguments of the continuation function, so they may or may not be on
> the C stack depending on what gcc does with them.

A multiple-value call takes the following route under Chicken: 
C_call_with_values -> C_do_apply -> C_values -> values_continuation -> 
C_do_apply.  A single-value call is compiled to a function call.  You can see 
why returning a single list value and destructuring it should be a lot faster.

I ran Alex's test on a fast machine (Intel C2D 2GHz).  Compiled with `csc -Ob 
values.scm`, Chicken 3.0.1 macosx-unix-gnu-x86, results below.  I got the same 
disparity as Alex.  I would be curious as to what platform you're running on, 
because I want it.

None of this would usually matter because benchmarks are next to useless.  
However, one major argument advanced for multiple values seems to be that the 
compiler has a chance to optimize them (which sounds like premature 
optimization to me, but I digress).  So, if you're going to use multiple 
values, don't do it because of a theoretical speedup, but because it 
semantically fits the problem.

---- VALUES --------------------------------------------------
  22.512 seconds elapsed
   0.302 seconds in (major) GC
       0 mutations
    5036 minor GCs
     821 major GCs
---- LIST ----------------------------------------------------
   0.364 seconds elapsed
       0 seconds in (major) GC
       0 mutations
    7326 minor GCs
       0 major GCs