You can declare it, yes, but it's not read only. The reference itself remains constant, but the data that it's referring to can be changed:

use constant HASH_REF => { key => 'value' };
HASH_REF->{new_key} = 'new value';
HASH_REF->{key} = 'modified';
use Data::Dumper;
print Dumper HASH_REF;

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In reply to Re^5: Using Constants in Perl by jhourcle
in thread Using Constants in Perl by qazwart

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