Specialized adaptors

In the case of a summation or a multiplication, there are specialized methods: the sum() and the product() methods. These methods will do the same as the fold() method that is used to add all the numbers in an iterator or to multiply all the items of the iterator. The example we saw before can be reduced to this:

let arr = [10u32, 14, 5, 76, 84, 35, 23, 94, 100, 143, 23, 200, 12, 94, 72];

let sum: u32 = arr.iter().sum();
println!("{}", sum);

Type annotations are required for now, but the code looks much simpler. You can also use the product() function in the same way, and it will be equivalent to this code:

let arr = [10u32, 14, 5, 76, 84, 35, 23, 94, 100, 143, 23, 200, 12, 94, 72];

let prod = arr.iter().fold(0u32, |acc, elm| acc * elm);
println!("{}", prod);