What Are Functional Programming Languages? (With Examples)

Updated September 30, 2022

It's usually challenging to pick the best programming language for a particular task. The challenge occurs because many programming languages have excellent overlapping capabilities suitable for various tasks. Understanding functional programming languages can help you determine the most appropriate programming languages for your assignments. In this article, we discuss the meaning of functional programming languages, outline their characteristics, highlight their benefits, and provide some examples of these programming languages.

What are functional programming languages?

Functional programming languages are computerized linguistic systems that consist of mathematical functions. These functions help coders to perform computations by stringing conditional expressions. The programming languages themselves are immutable, as they possess referential transparency, meaning that the same mathematical arguments give the same results every time. Notable examples of these programming languages include Python, Haskell, Clojure, Lisp, and Erlang.

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Characteristics of a functional programming language

Here's an overview of the common characteristics that every functional computer language possesses:

Lazy evaluation

Functional programming ensures efficiency in writing code. It allows the evaluation of code only at the necessary moment. Such efficiency ensures no repeat of evaluations in the computer program. Instead of repeating, a functional computer language reuses the result of the program's last evaluation, creating an efficient workflow.

Pure functions

Functions in a functional computer language give the same result for the same arguments because of referential transparency. Also, the functions don't have any side effects, as there's no change after their execution. For example, 1 + 1 always produces 2, and 1 + 1 never changes after execution. This characteristic allows a coder to memorize the function's unchanging results instead of performing its execution repeatedly.

List processing

A functional computer language provides you with an opportunity to manipulate a list of data. You use the programming language to formulate lists, link them to other lists, and analyze the information in the lists. You can add, subtract, divide, or multiply the information present in the list.

Immutable data

A functional computer language ensures that created data can not undergo modification. Data in a functional program doesn't change, allowing you to reference past data quickly. Once you create data, you're confident in its ability to maintain its state through the program's run-time.


A functional computer language uses simple solutions to solve complex problems. The programming language operates by calling the mathematical function to solve itself from its base case. More complex functions may call other functions to solve them because of their computational complexity.

First-class functions

A functional computer language may have first-class functions that are versatile in their uses. These first-class functions may act as variables, results of other functions, or as arguments for different functions. For example, you can use the first-class function with defined variables to create a computation that produces other functions.

Benefits of a functional computer language

These are some of the benefits that a functional computer language can offer you:

Efficiency from lazy evaluation

When you want to perform an evaluation, a functional computer language checks for a previous evaluation iteration and reuses it, ensuring you don't needlessly replicate evaluations in a program whenever you want to create one.

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Improvement of parallel programming ability

A functional computer language can create a single function with multiple uses. You can use the multi-use function in various simultaneous arguments to get results faster. The programming language can also help you run numerous computations simultaneously, ensuring you do more work in less time.

Support for nested functions

A functional computer language supports using nested functions in the computation of data. Nested functions are systems in other functions that ensure the performance of multiple calculations in shorter lines of code. The programming language helps you compute data with minimal effort and without long strings of unnested functions.

Reduction of errors

A functional computer language prevents errors through immutable data. Data in a functional computer language doesn't change during the program run-time, and this characteristic can help you eliminate errors. With immutable data, you can be sure that there are no errors from the side effects of data change.

Enhanced readability

A functional computer language makes the programming code more readable. The readability can help you comprehend the code in any program better. The functions in a functional language are also high-level, and you can regard them as values. You can quickly memorize these values and recognize their use when you go through a program's code.

Examples of languages for functional programming

These are some of the popular languages for functional programming:


A general-purpose and high-level language that you can use for a wide variety of programs, Java is a prevalent programming language for creating backend applications, with over 12 million developers and 20 years of operation. You can also use it on any operating system and benefit from the programming language's vast community by getting support, upgrades, and other resources from the community. Similarly, it supports multi-threaded application creation and an automated memory management system.


This is a low-latency and high-concurrency programming language. It's valuable for creating applications that can process a high volume of server requests. You can use it to develop a scalable and maintainable application. You can also use it to work on Python, JS, and Typescript applications. It also supports data immutability, which you can use for multi-threaded computations.


This programming language is a general-purpose one that merges sound infrastructure with interactive development. It's a compiled language that still permits interpreted development features, adopts great design from other programming languages, and it has easy access to Java. It can be invaluable for handling high-processing programming.


This programming language merges object-oriented and functional programming into a single language. It's easy to learn and understand, and it enjoys seamless interoperability with the Java framework. It also helps you merge the best features in dynamic and static languages. Similarly, you can use its statical features to check for type errors and improve type inference. It also gives you excellent iDE support, which is valuable for when you run into any error that requires developer help.


Haskell is an advanced open-source and compile-type programming language that you can use to formulate declarative statical code. It also consists of various concurrency primitives that can help you use concurrent multi-threaded programming. Similarly, it enables you to identify incorrect syntax quickly by showing a compiler error when there's incorrect syntax.


This programming language is helpful for building web applications. The language has virtual DOM implementation, which ensures that applications using its framework can render very fast. It has an intelligent compiler that can make refactoring easy for you, and it also provides seamless interoperability with Java. You can also benefit from the language's user-friendly error notifications, enhanced readability, and how it helps you model your domain entirely by having a type check that doesn't possess run-time exceptions.


It's a functional general-purpose programming language that helps you create programs swiftly. It has an easily readable syntax, enabling it to be a popular language for many machine learning works. Due to its large user base, you can access many community-built libraries using Python. You can also use Python to run many operations using a single program. The language can also benefit you through its high-speed programming that allows you to program five to ten times faster than older languages.

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Erlang is a programming language that can help build scalable applications that are always available. The applications are usually messaging, banking, or blockchain applications. It's a process-oriented language in which processes communicate with one another through messages. It also has an automated storage management system, which can help you build responsive applications. The language also has well-documented libraries to support you whenever you run into some errors.


This is a cross-platform, open-source programming language helpful in creating robust code. The language uses a data-oriented paradigm that transforms data using functions. It's an easily understandable and lightweight language, which ensures you can easily comprehend your code. It's also suitable for creating multi-threaded applications due to its possession of the data immutability characteristic. It also offers you total type safety for your code, as it ensures that it checks all the types at compile time.


Javascript is a lightweight programming language that uses functions as first-class constructs. It's a popular language for coders building web application front ends. It can offer you outstanding speed when building applications because of its lightweight nature. The language is also easy to learn and use, and you can leverage its large user base and get good community support when you need help.

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PHP means hypertext processor, and it's a popular general-purpose scripting programming language that can power web platforms. It's likewise beneficial for creating web content management systems. The language is flexible, and you can embed it with Javascript, HTML, XML, and other languages. It's also genuinely cross-platform and platform-independent, meaning that you can run it on any operating system.

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