Getting Started with Haskell: A Beginner's Guide

Are you interested in learning Haskell, but don't know where to start? Look no further! In this beginner's guide, we'll cover the basics of Haskell and get you up and running in no time.

What is Haskell?

Haskell is a functional programming language that was first developed in the late 1980s. It is named after the logician Haskell Curry and is known for its strong type system and lazy evaluation.

Haskell is used in a variety of applications, including web development, data analysis, and scientific computing. It is also a popular language for teaching computer science concepts, due to its clear and concise syntax.

Installing Haskell

Before we can start writing Haskell code, we need to install the Haskell compiler. The easiest way to do this is by downloading the Haskell Platform, which includes the compiler and a number of useful libraries.

To download the Haskell Platform, visit the official website and select the appropriate version for your operating system. Once the download is complete, run the installer and follow the prompts.

Your First Haskell Program

Now that we have Haskell installed, let's write our first program. Open up your favorite text editor and create a new file called hello.hs. In this file, type the following code:

main = putStrLn "Hello, world!"

Save the file and open up a terminal. Navigate to the directory where you saved hello.hs and type the following command:

$ runhaskell hello.hs

You should see the following output:

Hello, world!

Congratulations, you've just written your first Haskell program!

Basic Syntax

Let's take a closer look at the code we just wrote. The first line, main =, defines the main function of our program. In Haskell, every program must have a main function that is executed when the program is run.

The second line, putStrLn "Hello, world!", is a function call that prints the string "Hello, world!" to the console. In Haskell, function calls are written by placing the function name first, followed by any arguments in parentheses.

Haskell is a statically typed language, which means that every variable and function must have a defined type. Types are written after the variable or function name, separated by a double colon (::). For example, the type of the main function is IO (), which means that it performs input/output operations and returns no value.


Functions are the building blocks of Haskell programs. In Haskell, functions are defined using the = symbol. For example, here is a function that takes two integers and returns their sum:

add :: Int -> Int -> Int
add x y = x + y

In this example, the add function takes two arguments of type Int and returns an Int. The function body is defined using the = symbol, and the + operator is used to add the two arguments together.

Functions in Haskell are pure, which means that they do not have side effects and always return the same output for a given input. This makes Haskell programs easier to reason about and test.


Lists are a fundamental data structure in Haskell. A list is a collection of values of the same type, separated by commas and enclosed in square brackets. For example, here is a list of integers:

numbers :: [Int]
numbers = [1, 2, 3, 4, 5]

In this example, the numbers variable is a list of integers. Lists in Haskell are immutable, which means that once they are created, their contents cannot be changed.

Haskell provides a number of useful functions for working with lists, such as map, filter, and foldl. These functions allow you to transform and manipulate lists in a variety of ways.

Pattern Matching

Pattern matching is a powerful feature of Haskell that allows you to match values against specific patterns and execute different code depending on the match. For example, here is a function that takes a list of integers and returns the first element:

first :: [Int] -> Int
first (x:xs) = x

In this example, the first function takes a list of integers and matches it against the pattern (x:xs). This pattern matches any non-empty list and binds the first element to the variable x and the rest of the list to the variable xs. The function then returns the value of x.

Pattern matching is a powerful tool for writing concise and expressive Haskell code. It allows you to handle complex data structures with ease and makes your code more readable and maintainable.


In this beginner's guide, we've covered the basics of Haskell and written our first program. We've learned about functions, lists, pattern matching, and more. With these tools, you're well on your way to becoming a Haskell programmer.

Haskell is a powerful and expressive language that is well-suited for a wide range of applications. Whether you're interested in web development, data analysis, or scientific computing, Haskell has something to offer.

So what are you waiting for? Start exploring Haskell today and see what you can create!

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