https://devops-monk.com/tags/functional-programming/Recent content in Functional-Programming on Devops MonkHugoen-usMon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java8/java8-overview/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java8/java8-overview/Why Java 8 Matters Java 8 was released on 18 March 2014 — nearly three years after Java 7 — and it changed Java more fundamentally than any release before or since. For the first time, Java developers could write functional-style code natively, without external libraries or workarounds. The headline features — lambda expressions and the Streams API — solved a problem that had frustrated Java developers for years: the verbosity of iteration.https://devops-monk.com/tutorials/java8/lambdas/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java8/lambdas/The Problem Lambdas Solve Before Java 8, passing behaviour as a value required an anonymous inner class: // Java 7: sort a list of strings by length Collections.sort(names, new Comparator<String>() { @Override public int compare(String a, String b) { return Integer.compare(a.length(), b.length()); } }); // Run in a new thread new Thread(new Runnable() { @Override public void run() { System.out.println("Hello from thread"); } }).start(); This works, but the boilerplate-to-intent ratio is terrible.https://devops-monk.com/tutorials/java8/method-references/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java8/method-references/What Are Method References? A method reference is a compact syntax for a lambda expression that does nothing except call an existing method. If a lambda’s entire body is a method call, a method reference is almost always clearer. // Lambda names.forEach(s -> System.out.println(s)); // Method reference — identical behaviour, fewer characters, clearer intent names.forEach(System.out::println); The :: operator is the method reference operator. It does not call the method — it creates a reference to it, which the compiler wraps into a lambda that calls the method.https://devops-monk.com/tutorials/java8/streams-introduction/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java8/streams-introduction/The Problem Streams Solve Consider filtering a list of orders to find the names of active premium customers who spent over $500, sorted alphabetically: // Java 7 List<String> result = new ArrayList<>(); for (Order order : orders) { if (order.isActive() && order.isPremium() && order.getTotal() > 500) { result.add(order.getCustomerName()); } } Collections.sort(result); This code is correct but reveals nothing about the structure of the computation at a glance. You have to read every line to understand what’s happening.