gistfile1.PL

use v6;

role Keyed[*@keys] is Associative {
    my %index;

    submethod BUILD() {
        for @keys.kv -> $i, $v {
            %index{$v} = $i;
        }
    }

    multi method postcircumfix:<{ }>() {
        self;
    }

    multi method postcircumfix:<{ }>(*@keys) {
        my @result;
        for @keys -> $key {
            @result.push: self[%index{$key}];
        }
        @result;
    }
}

my $a = [32, 64] but Keyed[<first second>];
$a<second>.say;