Using map, reduce, and filter

Next, we'll look at a specialized set of standard library functions that take closure parameters:

• map returns an Array containing the results of applying a function to each item in a collection.
• filter returns a collection containing only those items of a collection that satisfy a specified match
• reduce returns a single value calculated by iterating through a collection, and applying a supplied function to each element and the accumulated results of the previous elements

Each of the functions and matches in this list are typically supplied as inline closures.