#!/usr/bin/perl --
use strict;
use warnings;
use Benchmark qw( cmpthese );

# Make bytes:: functions available, but use character semantics.
use bytes; 
no bytes;

cmpthese(
    -3,
    {   bytes => sub { 
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while bytes::length($smileys);
        },  
        utf8 => sub { 
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while length($smileys);
        },  
        substr => sub {
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while ord substr($smileys,0,1);
        },
        notnot => sub {
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while !! $smileys;
        },
        '!!bytes' => sub {
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while !! bytes::length($smileys);
        },
        '!!utf8' => sub {
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while !! length $smileys;
        },
        'ne""' => sub {
            my $smileys = "\x{263a}" x 10_000;
            chop($smileys) while $smileys ne "";
        },
    }   
);
__END__


          Rate  substr    utf8  !!utf8   bytes !!bytes    ne""  notnot
substr  3.75/s      --     -3%     -4%    -97%    -97%    -99%    -99%
utf8    3.86/s      3%      --     -1%    -97%    -97%    -99%    -99%
!!utf8  3.90/s      4%      1%      --    -97%    -97%    -99%    -99%
bytes    119/s   3066%   2972%   2942%      --     -0%    -71%    -74%
!!bytes  119/s   3081%   2987%   2956%      0%      --    -71%    -74%
ne""     406/s  10740%  10419%  10314%    242%    241%      --    -10%
notnot   451/s  11928%  11572%  11455%    280%    278%     11%      --