It can be done like this (using Data::Lock)

#!/usr/bin/perl 
use strict;
use warnings;
use Data::Lock qw(dlock);

my @folks = qw(larry curly moe);
dlock(\@folks);

eval { 
    shift @folks; 
    print "removed larry\n"; 
} or warn $@;

eval { 
    $folks[2] = 'joe';
    print "replaced moe\n"; 
} or warn $@;
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output:

Modification of a read-only value attempted at /home/arun/test/dlock.p
+l line 10.
Modification of a read-only value attempted at /home/arun/test/dlock.p
+l line 15.
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