#!/usr/local/bin/perl -wl
use strict;

sub a_func_that_returns_false { return 0; }
sub your_func_that_returns_false { return (); }
sub func_that_expects_string_boolean_and_num {
    my $str = shift;
    my $bool = shift;
    my $num = shift;
    print "CALLED FUNC: ", $str;
    print "   bool was ", ($bool ? "true" : "false");
    print "   num was ", (20 < $num ? "bigger" : "smaller"), " then twenty";
}

&func_that_expects_string_boolean_and_num
    ("the zero way", &a_func_that_returns_false(), 42);
&func_that_expects_string_boolean_and_num
    ("the empty list way", &your_func_that_returns_false(), 42);
__DATA__
laptop:~> monk.pl
CALLED FUNC: the zero way
   bool was false
   num was bigger then twenty
CALLED FUNC: the empty list way
   bool was true
Use of uninitialized value in numeric lt (<) at monk.pl line 12.
   num was smaller then twenty