recursively grep arrays with test

deepgrep.pl

use v6;

sub deepgrep(&test,@array) {
    @array.map: {
        when Positional { |deepgrep(&test, $_) }
        default { $_ when test $_ }
    }
}

say deepgrep * %% 2,   [[1], 2, [[3,4], 5],
                        [[[]]], [[[6]]], 7, 8, []];