use Readonly;
Readonly my $LOW  =>  9;
Readonly my $HIGH => 14;
...
my $count = $some_variable eq 'x' ? $HIGH : $LOW;
for $i (0 .. $count) {
    ...
}

##</code><code>##

use Readonly;
Readonly my %VALUES => (x => 14, y => 9);
...
for $i (0 .. $VALUE{$some_variable}) {
    ...
}