sub test_wantarray{
   wantarray ? Y : N;
}

print "Hello" . &test_wa . "World\n";
print "Hello", &test_wa, "World\n";

output:

HelloNWorld
HelloYWorld


##</code><code>##

  sub print_context {
    if (not defined wantarray) {
      print "[void context]";
    } elsif (wantarray) {
      print "[list context]";
    } else {
      print "[scalar context]";
    }
    return undef;
  }
  "Hello", print_context, "World\n";               # void context
  print "\n";
  "Hello " . print_context . "World\n";            # scalar context
  print "\n";
  print "Hello " . print_context . "World\n";      # scalar context
  print "\n";
  print "Hello", print_context, "World\n";         # list context
  print "\n";
  join print_context,                              # scalar context
    print_context, print_context;                  # both list context
  print "\n";


##</code><code>##

  print_context() ? print_context() : print_context();
  print "\n";


##</code><code>##

sub test_wantarray{
wantarray ? @array: \@array;
}


##</code><code>##

  print_context() ? print_context() : print_context();
print "\n";
print print_context() ? print_context() : print_context();
print "\n";
print join(print_context() ? print_context() : print_context()), print_context(), "\n";


##</code><code>##

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/