Collecting data with gather and take

Preparing data lists can be very expressively organized with a pair of keywords in Perl 6—gather and take. The easiest way to understand how that works is by taking a look at the following example:

my @data = gather {
    take 'a';
    take 'b';
}

say @data;

The block of code after the gather keyword returns a sequence that is saved in the @data array. The elements of the sequence are provided by the take keywords. So, there will be two elements in @data, as you can see here:

[a b]

Let's consider a bigger example. It contains a two-dimensional matrix of integer numbers and a list of instructions. The instructions are the four directions—left, right, up, and down, and a command— take-it. You should start at the center of the matrix, then move the current position according to the instructions, and pick up numbers if the instruction tells you to.

my @matrix = (
    [ 8, 10, 3, 16, 11],
    [ 4, 13, 5, 1, 6],
    [20, 9, 0, 15, 19],
    [14, 2, 24, 7, 23],
...