gistfile1.pl

#!/usr/bin/perl

use strict;
use warnings FATAL => 'all';
use feature 'say';

sub with_prototype () {
    return 100;
}

sub without_prototype {
    return 100;
}

foreach (1) {
    say with_prototype    / 10 ; # /  ; die "this dies!";
    say without_prototype / 10 ; # /  ; die "this dies!";
}
__END__
OUTPUT:
10
100
this dies! at a.pl line 17.