That result highly surprised me, because sort is optimized for the {$a <=> $b}, {$b <=> $a}, {$a cmp $b} and {$b cmp $a} blocks (in the sense it recognises those blocks and does the compare internally instead of calling the block).

But then I realized that the current sort implementation is also implemented to take advantage of long runs of increasing/decreasing values - and in particulary sorted arrays.

So I decided to run the benchmark again, this time with shuffled values: 

#!/usr/bin/perl

use strict;
use warnings;

use Benchmark 'cmpthese';
use List::Util 'shuffle';

our @data = shuffle 1 .. 10000;

cmpthese -1, {
    '<=>'  => q[@s1=sort{$b<=>$a} @data],
    ' - '  => q[@s2=sort{$b - $a} @data],
};

__END__
      Rate   -   <=>
 -  36.5/s   -- -30%
<=> 52.3/s  43%   --

[download]
That's what I'd expect.
Perl --((8:>*

In reply to Re^5: sort direction by Perl Mouse
in thread sort direction by rsiedl

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