

If you look at the functional routine, for example, you could call all the values on the left side of the + operator left and those on the right, right. Int sum = stream.reduce( 0, (left, right) -> left + right) IntStream stream = Arrays.stream(values)

Using the reduce() method, this is achieved as: int values = new int In functional programming, finding the sum of those numbers would apply steps such as these: 0 + 11 = 11 Thus, if you have some int values such as, say,, you could use reduce() to find their sum, amongst other results. The reduce() operation equips the Stream API with similar fold capabilities.

That being said - it's one of the most malleable, flexible and applicable operations - and it's very commonly used to calculate aggregate results of collections and widely employed in one form or another in analytical and data-driven applications. Note: Folding is also known as reducing, aggregating, accumulating and compressing, and these terms all apply to the same concept.
