Specification

P09 (**) Pack consecutive duplicates of list elements into sublists.
       If a list contains repeated elements they should be placed in separate
       sublists.

Example

> pack_dup(<a a a a b c c a a d e e e e>).perl.say
    [["a","a","a","a"],["b"],["c","c"],["a","a"],["d"],["e","e","e","e"]]

use v6;



my @l = <a a a a b c c a a d e e e e>;
sub packit (@in) {
    my @out;
    my @last = [shift @in,];
    for @in -> $t {
        if (@last[0] ne $t) {
            push @out, @last;
            @last := [$t,];
        }
        else {
            push @last, $t;
        }
    }
    if (@last.elems) {
        push @out, @last;
    }
    return @out;
}
say ~@l;
say packit(@l).perl;

# vim: expandtab shiftwidth=4 ft=perl6