# This software is Copyright 2005 by Elsevier Inc.  You may use it
# under the terms of the license at http://perl.plover.com/hop/LICENSE.txt .
###
### upto
###

## Chapter 4 section 2.1

sub upto {
  my ($m, $n) = @_;
  return sub {
    return $m <= $n ? $m++ : undef;
  };
}
my $it = upto(3,5);
my $value->it();
print "$value\n";

##</code><code>##

sub upto {
  my ($m, $n) = @_;
  return Iterator {
    return $m <= $n ? $m++ : undef;
  };
}
sub Iterator (&) { return $_[0]; }