There is much debate and different materials on object-oriented programming (OOP) and functional programming, yet insightful information on the distinctions between these programming paradigms that is comprehensive and digestible is limited.
Given that most of the present programming languages can work with both paradigms, it may sometimes be challenging to identify the best option for a project.
The purpose of this article will be to break down these concepts and explain their distinctions in the simplest way possible.
Object-oriented programming is a programming paradigm that uses objects to represent a subject matter or a thing that is part of the program. OOP is familiar to the human brain as objects provide an easy way to translate real-world concepts into code. For instance, a car could easily be represented as an object within code. But so could all of the accessories on a car such as the wheels. Object-oriented programming is friendly to the human mind.
OOP creates interactive objects with related variables and functions that work together to solve problems. It describes what the object is and what the object can do. ‘What the object is’ refers to the properties, features, and attributes of the object, while ‘what the object can do’ refers to the object’s functions, methods, or behavior.
Object-oriented programming simplifies programming by setting up a blueprint that defines or specifies the attributes of an object and prescribes the methods it uses to achieve results.
Once you create an instance of an object belonging to a class, you can then specify the attributes of the object and prescribe its methods. With this template, it is easier to create as many unique entities or instances as possible without implementing functions for each.
Object-oriented programming is divided into four core concepts that include:
Encapsulation is the combination of related variables and functions into a class or unit in such a way that the data and components of this unit are not visible from the outside.
This is one reason why OOP stands out. It can hide the properties and functions of an object from the outside world. Therefore, users can interact with the application without accessing the set of data behind the program.
Let’s revisit the concept of a car as an object in code again. A car can have wheels, windows, doors, and seats, all of which can have their open representation. A seat might have a fabric, which could be a property of the seat or an entirely separate object itself. Encapsulation allows us to not worry about thinking about all of these things at once. Technically, a car can be extremely complex. But, similar to how we don’t think of every detail of a car when driving one, encapsulation allows us to not have to think of every detail of a card in code, as the details are tucked away in their respective objects and places in the code.
Abstraction simplifies reality and hides unnecessary details from the users, thus focusing only on what is important or relevant.
It is a technique used to hide some of the properties of an object-oriented program to ensure a simpler interface that is easy to use.
With this technique, it is also a lot easier to change codes in the background without these changes reflecting on the face of the program.
A car can actually represent an abstraction as well as an object. A car, technically, can represent an SUV, an electric vehicle, a sedan, a minivan, etc. In this way, the term car is an abstraction that represents more detailed implementations of a car.
A class can derive its methods and properties from another class of objects under the same group or category. Thus, codes can be copied and reused with minimal complications. Inheritance is a way to think about different classes in object-oriented programming.
The example of a car and the various types of cars can be used here as well. If a car is a superclass (or parent class) of a sedan, then a Sedan would “inherit” from the Car class in code. Inheritance is only appropriate to use in object-oriented programming when the details of a superclass are relevant to all children that inherit from it. In other words, it would be odd to have a Moped inherit from the Car class, even though technically a Moped actually shares a ton of similar features. A more appropriate parent class for these two classes might be a Vehicle, which could have properties that are relevant to all children.
This means that a class can implement its method of inheritance in its own way. The class of objects that derives or inherits properties from the general class can save data and use such data in whatever way it pleases.
In other words, the component classes of an object can take on different forms while retaining the general properties that make it a part of the general object class.
Some of the most commonly used object-oriented programming languages include:
This is an open-source, object-oriented programming language. Developed by Yukihiro Matsumoto in 1990, Ruby is simple and easy to use, although it is not as popular as some other more prominent languages like Python. Ruby is commonly found used within the Ruby on Rails framework. Ruby is actually one of the purest OOP programming languages that exist. That is to say, Ruby is an OOP language where literally everything is an object. While in other classes there are usually numerous data structures, in Ruby all concepts (even integers) are represented as objects, and you can perform object manipulation on them.
Officially released in 1995, PHP was developed by Rasmos Lerdorf. PHP is another popular language used in creating websites and web pages. It is mostly used with HTML and CSS. PHP is largely used within web applications. Today, popular applications of PHP include Laravel and WordPress. WordPress accounts for a huge portion of sites on the web, and Laravel is a great framework for creating complex applications using an MVC model.
This multi-paradigm programming language was developed in 2000 by Microsoft’s Anders Hejlsberg. C# was designed to be a modern object-oriented language, and it has since been used to design several applications for internet use. It can be used to build desktop apps, mobile applications, web applications, and video games. C# was originally a close source programming language that you could only build or run-on Windows. It is now a cross-platform programming language that is open source. C# and Ruby were early and popular adaptations of MVC frameworks for the web.
Python is one of the most popular multi-purpose programming languages today. It is very flexible and useful to not just programmers and software engineers but a host of other professionals ranging from data analysts, mathematicians, data scientists, accountants, network engineers, and a host of other disciplines. Because Python is used in data science, machine learning, and artificial intelligence, it is an attractive programming language for many developers and businesses.
Released in 1995, this programming language is especially appreciated by beginners because it is easy to learn. It is also a highly efficient system used to code different applications and games. Many enterprise applications use Java and it has remained popular for many years. Today, many Java web applications rely on the Spring MVC framework.
Functional programming is a style of programming that follows mathematical principles. It is expressed as a function that runs on an input and output system.
Functional programming falls into two sections: pure functional programming language and impure functional programming language.
Because functional programming is missing the object representation found in OOP, it is often harder to think about than object-oriented programming is. There is a less direct translation from real-world concepts to code, making the initial learning curve a bit steeper.
In the case of pure functional programming, the output of a program is strictly tied to the input. An input should produce an output without modifying or changing the input. As such, functional codes do not produce any side effects, and neither do they rely on any outside value to produce an output.
These are the exceptional cases of functions that have been influenced by side effects so that the output does not strictly derive from the input. Rather, the input data has been influenced by another factor that has produced a different result.
There are many functional programming languages. Some of the notable ones include:
Named after Haskell Curry, the Haskell program was first released in 1990. Haskell falls among the earlier purely functional programming language. It is an open-source, lightweight language embedded with type inference.
Haskell is used in several programs today. It is used in filtering spam on Facebook. It also helped build ImagineAI, Bitnominal, and many other platforms.
While the language is not functional, it does support functional programming and object-oriented programming.
Platforms like Twitter, Coursera, and LinkedIn are some companies that use Scala as part of their programming language.
While it can function as an object-oriented language, it can also be used to write functional codes.
Python has set itself apart as a language that can be used to execute almost every meaningful task. It is an open-source language with a strong community of ever-growing users.
This language can be used in just about any sector requiring mathematical, analytical, and computational assistance.
While it can be used to write object-oriented codes, Java Script also encourages the use of functional programming paradigms.
In 2012, Evan Czaplicki released a functional programming language known as Elm. The language is popularly used by developers to create users interface.
The language uses type inference to give programmers hints to guide users through the programming process.
Created by Jose Valim in 2012, Elixir is a dynamic multi-purpose programming language designed to build scalable concurrent applications with special functional syntax. Platforms like Discord, Pinterest, Phoenix, and other web applications use it.
While these are some of the more popular languages that support functional programming, there are still several others like Erlang, F#, PureScript, Kotlin, Clojure, Racket, OCaml, Idris, Common Lisp, and a few others.
Now that you understand the difference between functional programming vs. object-oriented programming, don’t get stuck on embracing one over the other. The different forms of programming are simply the different ways that you can approach writing code and different ways to approach software development. Different developers and different applications may use one or another based on personal preferences, business needs, or application requirements. That being said, you will find that many object-oriented developers stick with object-oriented programming languages, whereas many functional developers stick with functional programming languages.
As much as we try to distinguish these concepts, there are no rigid borders guarding these programming languages. The parts of both concepts flow into each other. What matters is understanding the task’s objective, executing it creatively and effectively, and producing the best possible results.