Functional Thinking

Chapter 6. Advance

If the primary paradigm that your language supports is objects, it’s easy to start thinking about solutions to every problem in those terms. However, most modern languages are multiparadigm, meaning that they support object, metaobject, functional, and other paradigms. Learning to use different paradigms for suitable problems is part of the evolution toward being a better developer.

Design Patterns in Functional Languages

Some contingents in the functional world claim that the concept of the design pattern is flawed and isn’t needed in functional programming. A case can be made for that view under a narrow definition of pattern—but that’s an argument more about semantics than use. The concept of a design pattern—a named, cataloged solution to a common problem—is alive and well. However, patterns sometimes take different guises under different paradigms. Because the building blocks and approaches to problems are different in the functional world, some of the traditional Gang of Four patterns disappear, while others preserve the problem but solve it radically differently.

In the functional programming world, traditional design patterns generally manifest in one of three ways:

• The pattern is absorbed by the language.
• The pattern solution still exists in the functional paradigm, but the implementation details differ.
• The solution is implemented using capabilities other languages or paradigms lack. (For example, many solutions that use metaprogramming are clean and ...