Object-Oriented vs Functional Programming: An Honest Comparison

TL;DR: Being two of the most commonly used programming paradigms, both have specific moments and situations where they shine.

By Jerry Wallis
13 min read

In this article, we explore the fundamental differences between Object-Oriented vs Functional Programming, and discuss which one may be the better fit for your project.

If you’ve always wondered how these two programming paradigms compare and measure up against each other, keep reading further!

The Two Much-Debated Programming Methods 👨‍💻🗣️

Object-Oriented programming is better than Functional Programming, or is it the other way around? Or is there another programming language better than both of them?

These are questions that developers regularly debate and discuss, and they tend to side with one or the other. But what are the differences? And does it even matter if one is superior to the other?

​​The two programming technologies in contention: Object-Oriented and Functional Programming, both have advantages and disadvantages. Choosing one over the other for a particular project depends on the requirements and circumstances.

Object-Oriented Programming (OOP) has been around for longer and is more popular, but Functional Programming (FP) is starting to catch up. The apparent difference is that OOP uses objects and methods as the key coding elements, while FP emphasises functional factors such as variables and functions.

But the question we all have — Object-Oriented vs Functional Programming, which one is better? In this article, we will go over both of these programming concepts in great detail, and hopefully, by the end, we will have a concrete answer to this question. (Spoiler alert – It’s not as simple as that!)

Object-Oriented Programming 🧱

Let’s start things off with Object-Oriented Programming. As the name implies, Object-Oriented Programming is all about using entities called “objects,” which pretty much governs the whole framework of this programming language. Unlike Functional Programming, which is more of a result-oriented programming concept, the Object-Oriented Programming approach is concerned with how you end up at a result rather than the result itself.

Objects and classes are the foundational data structures used in this programming language. The exciting part is that these data structures have specific properties, attributes, methods, or procedures. Essentially, this means that each object is a unique entity and that objects can interact with each other. This will make more sense later — trust us!

If all of this is starting to sound a bit techy, don’t worry, we will use a real-world example to illustrate our points and make everything a lot clearer. 

Let’s use an example of a restaurant to explain the Object-Oriented Programming concept. As with any restaurant, each has its name, theme, menu, operating style, and other specific characteristics unique to the restaurant. 

If we view the above example from an Object-Oriented Programming lens, “Restaurant” would be the object. Its specific characteristics would be the data attributes and methods of the object that make it unique from other objects (or restaurants in this example). Makes sense? 

Object-Oriented Programming is a diverse programming language that provides a clear structure for a program, making it easier to maintain, manage, debug, and reuse the code. This is perhaps the most significant reason why this programming language is so popular.

Speaking of examples of Object-Oriented Programming languages, Java, C++, C#, Python, and Javascript are the most popular and widely used ones. However, there is a caveat here, as these popular Object-Oriented programming languages are class-based, where objects are class instances, which implies a relationship between objects and the blueprint in which they are created, i.e. classes.

Hopefully, you got the basics of Object-Oriented Programming, and now we’ll look into “the four fundamental concepts of Object-Oriented Programming.” Understanding these concepts will help us better understand Object-Oriented programming as a paradigm and its role in a programmer’s arsenal.

Four Major Concepts Of Object-Oriented Programming 💭

The first object-oriented concept comes in the form of Encapsulation — a big part of this programming paradigm. Encapsulation is the principle that dictates and ensures that all attributes and methods of an object are private and separate from other objects, thereby ensuring their uniqueness.

Each object can have attributes and methods that are public and private, with the difference being private ones are prohibited from being called or used, whereas public ones have no such limitations.

To further understand this concept, let’s use the same restaurant example. Attributes such as theme, menu, and the restaurant name would be private, but you could have a method called “order,” which could be called(or used) by another object called “customer,” for example, making “order” a public method.

The next Object-Oriented programming concept we need to discuss is Abstraction, which displays essential information and hides unwanted information, such as the inner details of how objects are implemented, from the user. Abstraction is vital to reduce programming complexity as it allows programmers to display only the relevant information of the object to the user.

The third critical Object-Oriented programming concept is called Inheritance. This concept lets programmers create new objects with the same attributes as old or existing objects. In essence, we are inheriting the attributes of parent objects to child objects. 

This is an excellent feature as it allows programmers to replicate previous work and build on what was already done instead of creating new objects from scratch — increasing coding efficiency.

Lastly, we have Polymorphism which allows programmers to run a child object exactly like the parent whilst retaining their specific methods. 

Let’s take a new example to understand this concept further. Say we have an object called “Vehicle”, and we create new child objects, called “Car,” “Bus,” and “Train.”

Consider that the vehicle object has a method called “run.”

Now according to the principles of Polymorphism, this method can be passed on to the child objects as well, but the way each child object implements this method will be different and specific to them. 

So, that was a relatively high-level overview of Object-Oriented Programming, its use, benefits, types and the core concepts of this unique programming paradigm. 

Next, we will look at the other programming language in question, Functional Programming and understand similar properties and concepts.

Functional Programming 🖨️

In the simplest form, as the name itself points out, Functional Programming involves using functions and the possibility to create clean and manageable programs.

This programming language involves understanding the outcome rather than how we reach the result – notice the difference in this aspect between Functional and Object-Oriented Programming.

On a more technical level, Functional Programming is a method of problem-solving using functions that focus on avoiding changing states. 

If you are confused or unsure what all of this means, don’t worry. We’ve got you covered. All of this will make more sense as you read on.

An Example To Put Things Into Perspective 💡

Like with Object-Oriented Programming, we’ll be using some familiar examples to further elaborate and understand the concepts behind this programming language.

Let’s take an example of a mathematical function taught in Algebra and Calculus, 

F(x) = x-2. 

Here, x is the input parameter and returns x-2 as the result depending on the input value, such that, F(0) = -2, F(1) = -1, F(2) = 0, and so on. 

Another example that we can consider is let’s say we have a function defined as 

sum(x,y): Return x+y, such that sum(10,2)=12, sum(10,10)=20 and so forth.

This same concept of mathematical functions is used in programming but obviously in a much more complex and technical manner. 

To further elaborate on this, let’s use an example of a function called getSum(). The role of this function is to calculate the sum of input values and return an output value or an answer. More importantly, what this means is that if the input values are the same, then the output is also always the same. 2+2 is always equal to 4, for example. Functions never lie, you know!

As you can see from the examples above, with Functional Programming, we are more concerned about the output based on the different input values than how we got those output values. This programming language involves coding to achieve the same tentative results, provided the inputs are the same. This is why the focus of this programming language is to avoid changing states — as mentioned above while defining Functional Programming.

This, in essence, is the basic concept behind what Functional Programming is all about. Next, we will go over some of the key characteristics and features of Functional Programming to further understand how it works and what it offers to developers.

The concept of “pure functions” is an essential aspect of Functional Programming. A pure function shows no “side-effects”, which, as we’ve already established, if the input values are the same, the function will always return the same output. 

Speaking of which, avoiding side effects is an integral part of Functional Programming. Side-effects are caused by the creation of intermediate variables which have to be stored in system memory. 

These intermediate variables store temporary calculations with results not shown in the final output but are used to decrease the complexity of the analysis. But with Functional Programming, these intermediate variables are not created. They would only add another layer to the calculation, making it unnecessarily lengthy and producing side effects as they would have to be stored in some storage system.

This is essentially the science behind side-effects in programming, and it is avoided in Functional Programming to enhance the problem-solving rate.

Another essential characteristic of Functional Programming that cannot be forgotten is its fixed control flow. Again, this is facilitated by the absence of intermediate variables.

As no intermediary variables are used, the results are returned directly without causing any side effects. This is because additional elements are not created that would have required system memory to manage outside of the function’s scope, and no other object or state is changed outside of the function. 

Essentially, this implies that the input is directly mapped to the output. 

Thus, this approach of negating and eliminating side effects results in a fixed control flow, which is unique and special in Functional Programming.

Before wrapping up this section of the article, we’ll quickly go over some of the applications of Functional Programming. 

Due to the tolerance for zero side-effects, weird and unexpected bugs and glitches are massively minimised in this framework – allowing the programmer to manage and understand the system.

Functional Programming supports parallel programming, which is a development process where multiple calculations are carried out simultaneously to increase efficiency and solve problems quickly. This is not possible with Object-Oriented Programming — but more on this later.

Head-To-Head Differences: Object-Oriented vs Functional Programming 👩‍💻

Now that we have a clearer understanding of the two programming technologies and their specific characteristics let’s compare them and see how they differ.

In the simplest form, Functional Programming is concerned with the “what,” while Object-Oriented Programming focuses on the “how.” But as we know by now, it is much more complex than that, and we’ll use the following criteria to compare and contrast these two programming languages in greater detail.

Object-Oriented vs Functional Programming
Object-Oriented Programming vs Functional Programming

👉 Learning Curve

  • Object-Oriented Programming is far more complex than Functional Programming and, as a consequence, will be more challenging to learn, understand and master.

👉 Elements In Use

  • In Object-Oriented Programming, objects and methods are the primary elements around which the programming technology is built.
  • With Functional Programming, however, variables and functions are the essential elements.

👉 Programming Model

  • Object-Oriented Programming uses the imperative programming model, which focuses on achieving the end goal and uses statements (or objects) to manipulate data and change the program’s state.
  • On the other hand, Functional Programming follows the declarative programming model, where the focus is on expressing the logic and providing the output without any concerns about how things are happening.

👉 Data Usage

  • OOP uses mutable data, i.e., a data structure that can be changed. The use of mutable data in this programming model is evident because of the imperative programming model adopted.
  • On the flip side, Functional Programming uses immutable data, as the focus is on the input and output elements; therefore, there is no need for changeable data.

👉 Parallel Programming

  • Parallel programming is when multiple programmers are working simultaneously on a single program. The Object-Oriented Programming framework doesn’t support parallel programming, but Functional Programming does.
  • This is because Functional Programming uses immutable data and avoids side effects and intermediary data structures, making it suitable for parallel programming.

👉 Execution Model

  • The programming statements in OOP must be executed in a specific order whereas, in Functional Programming, there are no such restrictions, and programming statements can be performed in any order. 
  • This is mainly because functions used in Functional Programming are independent of each other and do not require a specific order to work.

👉 Iterations

  • Iterations in a programming context refer to the processes wherein a set of methodologies are repeated until a particular condition is reached. 
  • OOP uses FOR-LOOP for the iterative data, while Functional Programming uses Recursion for the same purpose.

So The Big Question Is — Which Is Better? 🤔

Well, the short answer to this greater question is, it depends! The long answer would be…

Object-Oriented Programming is a clear standout in programming solutions that require continuous programming of multiple features.

In such a scenario, the architectural framework of Functional Programming becomes a major stumbling block, as you would have to write specific code for every feature of the program over and over again whilst having to remove the redundancies between features manually and constantly repeat this process until the entire program is coded.

This process takes unnecessarily long as Object-Oriented Programming offers a much faster and more efficient way of doing the same thing. Furthermore, if you find a bug in the code’s structure, you would have to go through each line of code for every feature and manually correct them one by one. 

With Object-Oriented Programming, you will create a general “blueprint” called classes — used to describe data structures with attributes and methods. Objects that inherit from classes can be made upon completing classes, including their data. 

Ultimately, the model-based approach of Object-Oriented Programming allows developers to navigate and explore relationships more clearly and find the root of any problem that they find themselves troubleshooting. This is a clear advantage over a functional program — which doesn’t allow room for much navigation as intermediate relationships are minimised to write less code and create more stable systems. 

However, Functional Programming should be the obvious choice in projects that involve processing very few input elements but require plenty of operations.

Final Thoughts On The Comparison 🤗

There are plenty of online resources comparing and contrasting these two paradigms, but understanding which one is better is wholly subjective and depends on multiple project-specific factors.

Object-Oriented Programming is better for projects that require more complex data structures or Inheritance. At the same time, Functional Programming is better for projects that require more complex algorithms or higher performance.

Both have their pros and cons and practical situations where one is more suitable than the other. From our own development team’s perspective, Object-Oriented Programming tends to be the right choice for complex projects requiring scalability and robust solutions. On the other hand, Functional Programming’s innate architecture makes it an acceptable option for smaller projects with short deadlines.

If you are interested in learning more about the programming paradigm best suited for your website, book a free discovery consultation call with us. We’ll guide you in the right direction to digital dominance!

Published on April 11, 2022

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