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$ perl -v | head -2 | tail -1
This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-li
+nux-thread-multi
$ alias perle
alias perle='perl -Mstrict -Mwarnings -Mautodie=:all -E'

$ perle 'use constant X => (1,3); my @y = "a".."z"; say for @y[X]'
Scalar value @y[X] better written as $y[X] at -e line 1.
...
$ perle 'use constant X => (1,3); my @y = "a".."z"; say for @y[X()]'
b
d

$ perle 'use constant X => 1,3; my @y = "a".."z"; say for @y[(X)]'
b
d