Kotlin Programming: The Big Nerd Ranch Guide, First Edition

Why Functional Programming?

Look back at the example using zip in Listing 19.7. Imagine implementing the same task in the object-oriented paradigm or its broader class, called imperative programming. In Java, for example, this task might look something like this:

    List<String> employees = Arrays.asList("Denny", "Claudette", "Peter");
    List<String> shirtSizes = Arrays.asList("large", "x-large", "medium");
    Map<String, String> employeeShirtSizes = new HashMap<>();
    for (int i = 0; i < employees.size; i++) {
        employeeShirtSizes.put(employees.get(i), shirtSizes.get(i));
    }

At first glance, the imperative version here may look like it accomplishes the task in roughly the same number of lines as the functional version in Listing 19.7. But ...