I was looking on CPAN for something else and stumbled across just the module you're looking for: Readonly.

The POD's first line says:

Readonly - Facility for creating read-only scalars, arrays, and hashes.

use Readonly;
Readonly::Array   my @arr => @values;
[download]

It appears to be just that easy. Read the POD though. Apparently there is a considerable speed-performance hit. The POD states that if you can also install the Readonly::XS module on your system, the performance hit is substantially mitigated.

Hope this helps!