One complication I can immediately see is that, I presume by "deep constant" you would want this entire thing to be readonly: const $x = [ [ 1, 2, 3 ] ]; But what about references to *existing* variables that happen to be found inside a data structure: my @nums = ( 1, 2, 3 ); # normal mutable array variable const $y = [ \@nums ]; How would perl tell the difference between the two? -- Paul "LeoNerd" Evans leonerd@leonerd.org.uk | https://metacpan.org/author/PEVANS http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/Thread Previous | Thread Next