Perl 6 Deep Dive

Higher-order functions and lambdas

The [+] reduction operator that we have just seen in the previous section is performing the action of the + operator as many times as needed to add up all the elements of the provided data.

In Perl 6, there is an alternative way of doing reduction operations. There exists a built-in function reduce that expects a code block that will execute the action. First, we will use the function add($a, $b) that we created in Chapter 2, Writing Code:

sub add($a, $b) {    return $a + $b;}say reduce &add, 10..15;

The reduce function takes the reference to a function as the first argument and a flattened list of values. In &add, the ampersand before the name of the function tells Perl 6 that this is not a function call but ...