my $sorter = \&some_function;
sort $sorter (1,2,3);

##</code><code>##

sort \&some_function (1,2,3);

##</code><code>##

 
sort make_sorter() (1,2,3)

##</code><code>##

use strict;
use warnings;

my $sorter = get_numeric();
my @sorted2 = sort $sorter (3,2,1);
print join(', ', @sorted2);

sub get_numeric {
    return \&numeric;
}

sub numeric($$) {
    my ($a,$b) = @_;
    $a <=> $b;
}

##</code><code>##

use strict;
use warnings;

my @sorted2 = sort get_numeric() (3,2,1);
print join(', ', @sorted2);

sub get_numeric {
    return \&numeric;
}

sub numeric($$) {
    my ($a,$b) = @_;
    $a <=> $b;
}

##</code><code>##

syntax error at pmsort line 4, near ") ("