Author: Scott Penrose

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"]]

Source code: P09-scottp.pl

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;