Hola monks!

I wrote the following snippet to compare various basic sorts: 

use strict;
use warnings;
use Benchmark 'cmpthese';

srand 0;
my @n = map int(rand(2**7)), 1..1000;
my @a = map chr($_), @n;

cmpthese( -1,
          {
           default_n => sub { ( sort               @n )[ 0 ] },
           cmp_n     => sub { ( sort { $a cmp $b } @n )[ 0 ] },
           '<=>'     => sub { ( sort { $a <=> $b } @n )[ 0 ] },
           default_a => sub { ( sort               @a )[ 0 ] },
           cmp_a     => sub { ( sort { $a cmp $b } @a )[ 0 ] },
          }
        );

__END__
            Rate     cmp_n default_n     cmp_a default_a       <=>
cmp_n      667/s        --       -0%       -3%       -3%      -40%
default_n  667/s        0%        --       -3%       -3%      -40%
cmp_a      691/s        4%        4%        --        0%      -38%
default_a  691/s        4%        4%        0%        --      -38%
<=>       1110/s       66%       66%       61%       61%        --

[download]

I'm having a hard time rationalizing why <=> did so much better than the default alphabetic sort, since it was my understanding that the latter should be better. I think the comparison above is fair; am I wrong?

BTW, I figure that the reason why default_n fares worse than default_a is that the former is comparing strings of length up to 3, while the latter is comparing strings of length 1.

the lowliest monk

In reply to Yet Another Sort Benchmarking Question by tlm

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