use LISP qw(cons);

# Create linked list (Not an array!)
my $list = LISP->new([[1,2,3,4],[5,6,7,8],[9,10,11,12]]);
print $list->string; # Prints ((1 2 3 4) (5 6 7 8) (9 10 11 12))
my $mapcarf = LISP->new(\&LISP::Lambda::mapcar);
my $listf   = LISP->new($list->can('list'));
# We probably ought to go for closure on mapcarf and listf
# But this is OK for now
my $transpose = sub {$mapcarf->apply(cons($listf, shift))};
$list=$transpose->($list);
print $list->string;   # Prints ((1 5 9) (2 6 10) (3 7 11) (4 8 12))
$list=$transpose->($list);
print $list->string;   # Prints ((1 2 3 4) (5 6 7 8) (9 10 11 12))