#!/usr/bin/env perl                                                             
                                                                                
use strict;                                                                     
use warnings;                                                                   
                                                                                
sub say (_) {                                                                   
    print @_, "\n";                                                   
}                                                                               
                                                                                
my @a = qw(1 2 3);                                                              
                                                                                
# using implicit $_ does not work:                                              
say foreach (@a);                                                               
                                                                                
# ...and of course explicit $_ works.                                           
say $_ foreach (@a);                                                            
                                                                                
# works:                                                                        
say "uncle bob";

##</code><code>##

Illegal character in prototype for main::say : _ at a.pl line 6.
Not enough arguments for main::say at a.pl line 13, near "say foreach "
Malformed prototype for main::say: _ at a.pl line 16.