“The functional style of programming is very charming,” insists Venkat Subramaniam. “The code begins to read like the problem statement. We can relate to what the code is doing and we can quickly understand it.” Not only that, Subramaniam explains in his keynote address for Oracle Code Online, but as implemented in Java 8 and beyond, functional-style code is lazy—and that laziness makes for efficient operations because the runtime isn’t doing unnecessary work.
Subramaniam, president of Agile Developer and an instructional professor at the University of Houston, believes that laziness is the secret to success, both in life and in programming. Pretend that your boss tells you on January 10 that a certain hourlong task must be done before April 15. A go-getter might do that task by January 11.
That’s wrong, insists Subramaniam. Don’t complete that task until April 14. Why? Because the results of the boss’s task aren’t needed yet, and the requirements may change before the deadline, or the task might be canceled altogether. Or you might even leave the job on March 13. This same mindset should apply to your programming: “Efficiency often means not doing unnecessary work.”
Subramaniam received the JavaOne RockStar award three years in a row and was inducted into the Java Champions program in 2013 for his efforts in motivating and inspiring software developers around the world. In his Oracle Code Online keynote, he explored how functional-style programming is implemented in the latest versions of Java, and why he’s so enthusiastic about using this style for applications that process lots and lots of data—and where it’s important to create code that is easy to read, easy to modify, and easy to test.
Functional Versus Imperative Programming
The old mainstream of imperative programming, which has been a part of the Java language from day one, relies upon developers to explicitly code not only what they want the program to do, but also how to do it. Take software that has a huge amount of data to process; the programmer would normally create a loop that examines each piece of data, and if appropriate, take specific action on that data with each iteration of the loop. It’s up to the developer to create the loop and manage it—in addition to coding the business logic to be performed on the data.
The imperative model, argues Subramaniam, results in what he calls “accidental complexity”—each line of code might perform multiple functions, which makes it hard to understand, modify, test, and verify. And, the developer must do a lot of work to set up and manage the data and iterations. “You get bogged down with the details,” he said. This not only introduces complexity, but makes code hard to change.”
By contrast, when using a functional style of programming, developers can focus almost entirely on what is to be done, while ignoring the how. The how is handled by the underlying library of functions, which are defined separately and applied to the data as required. Subramaniam says that functional-style programming provides highly expressive code, where each line of code does only one thing: “The code becomes easier to work with, and easier to write.”
Subramaniam adds that in functional-style programming, “The code becomes the business logic.” Read more in my essay published in Forbes, “Lazy Java Code Makes Applications Elegant, Sophisticated — And Efficient at Runtime.”