The Difference between Functional Programming and Object-Oriented Programming

The introduction

It is worth to start with the basics, so below we present a short definition of both Functional Programming and Object-Oriented Programming. If you are not in the subject you can find out what are the differences between these programming methods. If you’re already on the topic, you may want to refresh some of the information, and maybe you’ll look at the opposite side a bit differently. It is always worth knowing your opponent and their strengths as well as their weaknesses.

Functional Programming

Functional programming is a programming technique that focuses on evaluating functions and developing the structure as well as elements of computer programs. It is not about executing commands or statements, but about evaluating expressions, it also provides excellent support for structural programming.

Functional programming supports various programming languages such as Lisp, Wolfram, Erlang, Haskell and others. FP is also ideal for work in the data related scientific sector.

Object-Oriented Programming

Object-oriented programming is a programming paradigm that uses abstraction to create models based on the real world. It uses several techniques from previously established paradigms, such as modularity, polymorphism or encapsulation. Currently, many popular programming languages such as Java, C++, Python and PHP support object-oriented programming.

In OOP, each object can receive messages, process data and send messages to other objects. Each object can be understood as an independent small machine with a separate role or responsibility. Object programming is intended to promote greater flexibility and ease of development in programming and is very popular in large scale software development.

Fundamental difference

To make things simpler, it can be described that all programmes have two basic components, data – what the programme knows – and behaviour – what the programme can do with that data. So object-oriented programming states that combining data and related behaviours in one place, is called “object”, which makes it easier to understand how a particular program works. On the other hand, functional programming argues that data and behaviour are different things and should be separated to ensure their clarity.

think different

Difference in usage

Each programming paradigm has its advantages and disadvantages, so it is worth knowing them before actually using them.

On Stack Overflow you can find the answers to many of the questions that we are concerned about, that is why below you can find the information found on this platform, which concerns the use of these two programming tools.

Object-oriented languages work well when you have a fixed set of operations on things, and as your code develops, you mainly add new things to it. This can be achieved by adding new classes that implement existing methods while leaving the existing classes to themselves.

Functional languages work well when you have a fixed set of things, and as your code develops, you mainly add new operations on existing things. This can be achieved by adding new functions that perform calculations using existing data types, and existing functions are left to themselves.

Difference base on key criteria

It is very important to break down these two concepts into individual key criteria, which include, among others, the relationship of FO and OOP to date, model, support and others.

  • Definition:
  • Functional Programming – focus on function evaluation
  • Object-Oriented Programming – focus on the concept of objects
  • Data:
  • Functional Programming – uses immutable data
  • Object-Oriented Programming – uses the mutable data
  • Model:
  • Functional Programming – follows a declarative programming model
  • Object-Oriented Programming – follows an imperative programming model
  • Support:
  • Functional Programming – supports parallel programming
  • Object-Oriented Programming – doesn’t support parallel programming
  • Execution:
  • Functional Programming – statements can be excecuted in any order
  • Object-Oriented Programming – statements should be executed in particular order
  • Iteration:
  • Functional Programming – uses recursion
  • Object-Oriented Programming – uses loops
  • Basic element:
  • Functional Programming – functions & variables
  • Object-Oriented Programming – objects & methods

Functional Programming Pros and Cons:

  • + Using clean and transparent functions leads to reliable results without side effects that deliver and return exactly what you expect.
  • + It uses a more declarative style that focuses more on what needs to be done and less on how to do it, with an emphasis on efficiency and optimisation.
  • – It is a relatively new paradigm and sometimes it is not so easy to find documentation or information compared to Object-oriented Programming.
  • – Sometimes it may not become illegible due to a very large number of functions compared to Object-oriented Programming.

Object-oriented Programming Pros and Cons:

  • + Objects and methods are very clear and understandable.
  • + Use an imperative style, in which the code is read like a simple set of instructions, just like a computer would read it.
  • – May lead to unspecified and unexpected results in the sense that a parallel code that would have access to a common resource could do so in a way that produces unspecified results.
  • – Its methods can have side effects and may put an impact on processors.

As you can easily see, it is very difficult to clearly determine which option is better. There is no denying that object-oriented programming has been around for longer and exists in leading programming languages, which can be considered an advantage, but functional programming is much cleaner in its form and can, therefore, be easier and more pleasant to use. It is also important to emphasise that the concepts of the two programs are very different and their purpose is also diverse.

It is always up to developers to choose a programming language concept that will make their development productive and effortless.


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