#!/usr/bin/perl

use strict;
use warnings;
use Benchmark qw(cmpthese);
 
our @foo = 1 .. 10;

sub a {
    my @list = @{shift()};
    $_ += 1 foreach @list;
    return \@list;
}
    
sub b {
    my @list = @{shift()};
    return [map {$_ += 1} @list];
}

sub c {
    my @list = @{shift()};
    map {$_ += 1} @list;
    return \@list;
}

sub d {
    my @list = @{shift()};
    map $_ += 1, @list;  
    return \@list;
}
    
cmpthese(250_000, {
    a1 => sub {a(\@foo)},
    b1 => sub {b(\@foo)},
    c1 => sub {c(\@foo)},
    d1 => sub {d(\@foo)},
    a2 => 'my @list = @foo; $_ += 1 foreach @list; \@list',
    b2 => 'my @list = @foo; [map {$_ += 1} @list]',
    c2 => 'my @list = @foo; map {$_ += 1} @list; \@list',
    d2 => 'my @list = @foo; map $_ += 1, @list; \@list',
});
    
__END__

       Rate   b1   b2   c1   c2   a1   d1   a2   d2
b1  68493/s   --  -9% -11% -24% -38% -44% -51% -57%
b2  75529/s  10%   --  -2% -16% -32% -38% -46% -53%
c1  76687/s  12%   2%   -- -14% -31% -37% -45% -52%
c2  89606/s  31%  19%  17%   -- -19% -27% -36% -44%
a1 110619/s  62%  46%  44%  23%   --  -9% -21% -31%
d1 121951/s  78%  61%  59%  36%  10%   -- -13% -24%
a2 140449/s 105%  86%  83%  57%  27%  15%   -- -12%
d2 160256/s 134% 112% 109%  79%  45%  31%  14%   --