#!/usr/bin/perl -l

sub generate {
  my $base = $_[0];
  my $interval = $_[1];

  sub { $base += $interval }
}                                      # create incrementor generator

$first_inc = generate( 5, 2 );         # generate first incrementor
print $first_inc->();                  # output: 7
print $first_inc->();                  # output: 9

$second_inc = generate( 3, 1 );        # generate second incrementor
print $second_inc->();                 # output: 4
print $second_inc->();                 # output: 5

print $first_inc->();                  # output: 11
print $first_inc->();                  # output: 13

print $second_inc->();                 # output: 6
print $second_inc->();                 # output: 7

=cut

All Output:

7
9
4
5
11
13
6
7

=end