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Introduction to Functional Programming

what is functional programming

In this current remote work setup, employers have upgraded their standards when it comes to hiring programmers. They look for individuals who possess the ability to use multiple functional paradigms to solve business problems. Functional programming has gained popularity due to its adaptability and efficiency to solve real-world problems. This article will cover the core concepts and the advantages of functional programming.

What is functional programming?

Functional programming is a declarative programming paradigm style where one applies pure functions in sequence to solve complex problems. Functions take an input value and produce an output value without being affected by the program. Functional programming mainly focuses on what to solve and uses expressions instead of statements. Functional programming excels mostly at mathematical functions where the values don’t have any correlation and doesn’t make use of concepts like shared state and mutable data used in object-oriented programming.

Functional Programming Concepts

Functional programming is built with various core concepts which we will explore below:

First-class functions

First-class functions in functional programming are treated as data type variables and can be used like any other variables. These first-class variables can be passed to functions as parameters, or stored in data structures.


Unlike object-oriented programming, functional programming doesn’t make use of “while” or ”for” loops or “if-else” statements. Functional programs avoid constructions that create different outputs on every execution. Instead, recursive functions call themselves repeatedly until they reach the desired state or solution known as the base case.


In functional programming, we can’t modify a variable after being created. The reason for this is that we would want to maintain the program's state throughout the runtime of the program. It is best practice to program each function to produce the same result irrespective of the program's state. This means that when we create a variable and assign a value, we can run the program with ease fully knowing that the value of the variables will remain constant and can never change.

Pure functions

what is functional programming

Pure functions form the foundation of functional programming and have two major properties:

  • They produce the same output if the given input is the same
  • They have no side effects

Pure functions work well with immutable values as they describe how inputs relate to outputs in declarative programs. Because pure functions are independent this means that they are reusable, easy to organize, and debug, making programs flexibly and adaptable to changes. Another advantage of using pure functions is memoization. This is when we cache and reuse the results after computing the outputs from the given inputs.

High order functions

A function that accepts other functions as parameters or returns functions as outputs is called a high order function. This process applies a function to its parameters at each iteration while returning a new function that accepts the next parameter.

Advantages of functional programming

Easy to debug

Since pure functions produce the same output as the given input, this means they aren’t any changes or any other hidden output produced. Functional programming functions are immutable, this also means that it’s easier to check for errors in code faster.

Lazy evaluation

Functional programming adopts the lazy evaluation concept, whereby the computations are only evaluated the moment they are needed. This gives programs the ability to reuse results produced from previous computations.

Supports parallel programming

Because functional programming uses immutable variables, creating parallel programs is easy as they reduce the amount of change within the program. Each function only has to deal with an input value and have the guarantee that the program state will remain constant.

Easy to read

Functions in functional programming are easy to read and understand. Since functions are treated as values, immutable, and can be passed as parameters, it is easier to understand the codebase and purpose.


Since functional programs don’t rely on any external sources or variables to function, they are easily reusable across the program. This makes them more efficient as there isn’t extra computation needed to source the programs or run operations on runtime.

Drawbacks of Functional Programming

Terminology Problems

Because of its mathematical roots, functional programming has a lot of terminologies that may be difficult to explain to a layman. Terms like “pure functions” can easily scare off people looking to learn more about functional programming.


Although recursion is one of the best features in functional programming, it is very expensive to use. Writing recursive functions requires higher memory usage which can be costly.

Functional programming languages

Now as you can imagine not all programming languages support functional programming. Some languages however were designed to be specifically for functional programming, while others do support both functional and object-oriented programming. Below is a list of some of these programming languages:

  • Haskell - Made specifically for functional programming, Haskell is a statically typed programming language. It compiles code faster, is memory safe, efficient, and easier to read.

  • Python - Although python supports functional programming, however, it was designed to prioritize object-oriented programming first.

  • Erlang - Although it is not popularly used like Haskell, Erlang is best suited for concurrent systems. Messaging apps like WhatsApp and Discord make use of Erlang because of its scalability.

  • JavaScript - Similar to Python, JavaScript isn't specifically designed for functional programming. However, functional programming features like lambda expressions and attributes are supported making JavaScript a top used language among multi-paradigm languages.

  • Clojure - Clojure is a functional programming language that provides tools to avoid mutable states. Although it supports both mutable and immutable data types, it is less strict than other languages.

  • Scala - Supporting both functional and object-oriented programming, Scala was designed to address the shortcomings of Java. It also comes with a built-in static typed system similar to Haskell.


As we have covered some general core concepts found in functional programming, there is so much more to be explored. Learning more about functional paradigms can give you the leverage to use their tools and techniques to solve business problems. This will in turn put you in a better position when looking for a remote job and increasing your chances of standing out in the global talent pool. Visit Turing to find out more about our incredible remote job offers.

Frequently Asked Questions

Python, Scala, and JavaScript are the best programming languages for functional programming.

Because of the flexibility, easy debugging process, and parallelism that comes with functional programming.

Functional programming provides high performance when it comes to processing large amounts of data when building applications that OOP is not good at, making it the best choice.

Yes, functional programming is definitely the future as it solves a lot of problems when it comes to big data processing.

Learning functional programming is beneficial for any developer looking to write scalable, easy-to-read, and clean code.

Functional programming can be used in Machine learning, Computer vision, Language processing, or anything related to big data.

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