Haskell Programming Language – How to Use Haskell Tutorial

The Haskell programming language is often referred to as a purely functional language, and a non-strict language. It has been around for a long time – in fact, it was one of the first to be developed as such. The first iterations of it were developed in the 1980s, when researchers were working on various language developments. It would take nearly 10 years for it to finally be published.

Why do we study and still need to learn programming in Haskell? It has a variety of benefits to offer, and is certainly a reliable solution for those who are looking for a functional programming and non-strict language. It is also noted for its ability to handle numerous applications including those that are numerical but also those that are symbolic. It was designed for and continues to serve large-scale industrial production applications for the most part. That is due to its outstanding, rich built architecture.

There are plenty of reasons you may be looking for a tutorial or Haskell program example, perhaps even because you are considering Haskell programming jobs. There is one key factor to keep in mind. Haskell has much to offer, and even with the most comprehensive programming in Haskell book, it is going to take some time to learn and develop the skill. That is not to say it is hard or not warranted. Yet, this is an intro level into Haskell and what this programming language has to offer.

What Is the Haskell Programming Language?

As noted, Haskell is a purely functional programming language. The best way to see how this applies is to consider the difference in imperative languages and functional programming.

In imperative languages, programmers give the computer a sequence of tasks and then it executes those tasks. In the execution phase, it can change state. You must control the flow structures for doing some type of action more than once.

In a purely functional programming language like Haskell, the programmer does not tell the computer what to do in the same way. Instead, the programmer tells the computer what stuff is. In that way, the factorial of a number is the product of all the numbers from 1 to that number. You express this in the form of functions. In this way, you cannot set a variable to one thing and change that later, as you could with imperative languages.

That may make Haskell seem far less beneficial or even limiting in its application. One of the consequences of this is that if a function is called twice in the same parameters, it will return the same result every time. This is called referential transparency.

Haskell also will not execute functions or even calculate anything until it is forced to provide a result to you. This aligns well with referential transparency. As a programmer, this allows you to think of programs like a series of transformations on data – that’s much different than you may be using otherwise.

Haskell Programming Language Ecosystem

Before we go further, it is critical to start out with understanding the development environment of Haskell. It is not too bad considering the complexity that often comes with others.

First, to install and set up Haskell, you must get the Haskell ecosystem. In a moment, you’ll learn more about the Haskell installer options.

However, what you also need to know is what the Haskell ecosystem includes:

• The compiler is called Glasgow Haskell Compiler (GHC)
• The Interpreter is called Glasgow Haskell Interpreter ( GHCi)
• The Stock tool is used to manage Haskell projects
• There are other Haskell packages available as well.

Also, note that it is a widely used and long-time used programming language, and there is a full database available for Haskell libraries. You can find that at Hackage.

What You Need to Know About Haskell Programming Language to Get Started

Before you can explore Haskell programming from first principles, there are a few things to keep in mind.

• Haskell was designed to handle symbolic computations and list-processing applications
• As functional programming, its operations are built on mathematical functions.
• In functional programming, all computations are considered a combination of separate mathematical functions.
• Haskell is often called a lazy language. That means it does not evaluate expressions without any reason. If the evaluation engine determines an expression needs to be evaluated, it creates a thunk data structure. This then collects the necessary data for that specific evaluation and a point to the thunk data structure.
• It is also modular. It is a series of functions and nothing more. Another way to see it as a collection of numerous small Haskell applications.
• Static: Another key factor to know is that this is a statically typed language. Haskell is a type of inference language, meaning the Haskell compiler is smart enough to figure out the type of the variable declared. You do not need to specifically mention the type of the variable being used.

Overall, Haskel applications are very modular in design. This makes them easy to maintain and also helps make them more cost-effective to operate over time.

Haskell programming language was developed to handle multithreading effectively. That is much like any other type of functional programming language.

Here’s an example.

The traditional Hello World example can help to demonstrate what occurs in Haskell.

To print “Hello World” you just need one line. It reads:

Main = putStrLn “Hello Word”

This allows the computer system to create the following output:

Hello World

That’s simple enough, right?

Programming in Haskell is more complex than this, but you can see the importance and benefits of its functionality from this simple demonstration.

Programming with Haskell: Installers

To use Haskell, you will need to download the available setup at the official webpage: Download official webpage. Once you do this, you can choose from one of three installers. Choose which works for your needs.

• Minimal installer: This installer offers tools for The Glasgow Haskell Compiler (GHC), Common Architecture for Building Applications and Libraries (CABAL), as well as Stack tools.
• Stack installer: This option allows the GHC to be downloaded in a cross-platform manner on a managed toll chain. It installs the application globally giving the developer the ability to update its API tools when there is a need. This option also automatically resolves all of the dependencies on Haskell.
• Haskell Platform: The third option is generally the best option overall. It allows you to install the entire platform directly to your computer. You can do this from a single location. It is also straightforward.

You may find other platform installer options out there. The Haskell Platform is still the best option in most situations.

The Code Editor for Haskell Programming Language

One key thing to keep in mind about Haskell is that it does not have a specifically suitable code editor. That means that to write its programs, you will need to use another option. There are several that are a good option, but some of the most notable used include:

• Visual Studio Code with Haskell plugins
• IntelliJ IDEA with Haskell Plugin installed
• Neovim
• Emacs in Haskell Mode

These are fairly standard and easily adaptable options. If you want to do so, you could use Notepadd++ as well as Sublime Text – that’s the best way to write in the simplest of manners. If you did this, you would then compile with the GHC.

One of the things you will learn about Haskell programming as you move through it is that it teaches you to write code in small modules or small portions at a time. You will then need to reiterate that completed component to ensure the model is accurate. It must be perfect, of course, for production. That’s important because, like other solutions, the code editor you use will not really make a big difference in the long term. You will be checking it and verifying accuracy throughout the process.

Get Programming with Haskell: Environment Setup

For those using Windows, to set up the Haskell environment, go to:

Https:www.haskell.org/platform/windows.html

You can then download the installer following the onscreen directions and use your own customizable architecture to do so. In some situations, you may need to update your CABAl configuration if it is out of date.

You can follow similar steps for Mac at: Check here

If you want to use Linux, you can, though it is a bit more challenging. Go here to get the process set up:

Let’s Get Programming with Haskell: What Makes It Work

Now that you are ready to start adopting this language, it’s critical to see what really makes Haskell so sought after (by those who have given it a try). First, is that it is easy to read Haskell code, much like any type of mathematical expression would be read. Once you know the details and individual features, you can then apply it and read the code quickly.

Also note that with Haskell code, you can specify the probable output for a program and then rely on the language to do the rest of the work.

Another area to consider is the GHCi compiler. It’s hard not to see the value in this particular component. Here’s why.

With the GHCi compiler, you can interactively use the compiler. That’s different from other languages. More so, you can use multi-line coding. That is typically not available in other compilers but it is in GHCi. If you have used Python IDLE, for example, you know that to write a full script, you must write every line, one after the other, step by step, and every line has to be complete. Haskell does not require this for multi-line coding.

Programming in Haskell: Basic Data Models

Now that you have access, it is time to start learning some skills to help you. The following Haskell program example can help you get started, but you may need to learn a bit more to perfect your skills. This is a great place to start!

Remember, Haskell is a purely functional programming language. This means it is more interactive and intelligent than some of the other programming languages you may be using now. There are some excellent advantages to this, which you will notice as you work through the next steps.

Haskell numbers

Haskell can decode some numbers as a number. This means that you do not have to type externally that it is a number like in other languages.

Haskell characters

Haskell can identify a character given in as an input to it. You can try this out by going to the command prompt and typing in any character with double or single quotation. Here is an example:

Prelude> :t”a”

Will lead to:

“c” :: [Char}

With Haskell characters, you need to use :t when providing the input.

Also, note that Haskell follows the conventional ASCII encoding style.

Haskell string

A string is a collection of characters. Haskell follows the conventional style in the way it represents a string with double quotation. There is no specific syntax when using a string, though.

Here is an example to consider:

Prelude> :t “Abc.com”

This will produce the output:

“Abc.com” :: [Char]

In this example, you can see how the string has been decoded as an array of Char.

Haskell Boolean

Like other data type, Boolean is not challenging with Haskell.

Here is an example of how simple it can be using different Boolean operations. This uses some Boolean inputs as “true” or “false.”

Prelude> True && True

True

Prelude> True && False

False

Prelude> True || True

True

Prelude> True || False

True

Haskell can decode that “true” and “false” are Boolean values. You do not have to tell it to do this. Consider this modification:

Prelude> true

This will produce the following instead:

<interactive>:9:1: Not in scope: ‘true’

In this situation, Haskell did not have the information it needed to be able to tell the difference between “true” and a number value. As the result of that, “true” is not a number. This leads to an error message because that input isn’t in the scope.

Haskell list and list comprehension

List is an important data type that is commonly used in Haskell. A list of characters is a list, of course! List is a collection of the same data type separated by a comma between each. With Haskell, you do not have to declare a List as a List – much like other date types with this tool. It will decode your input by utilizing the syntax in the expression.

Here is another example:

Prelude> [6,7,8,9]

In this situation, it would produce:

[6,7,8,9]

Key in this List data type is that Haskell does not allow you to declare a list when the data type is different. If, for example, we throw a bunch of letters into the above line, it would create an error because those letters are not in the scope.

As for list comprehension, which is the process of creating a list using a mathematical expression, Haskell offers this method of creating on List using mathematical expression.

Tuple

Tuple is another data type. It is used to declare multiple values in a single data type. It is much like a List, but there are a few differences between the two. Tuple is a type of immutable data type. That means that you cannot modify the number of elements at runtime. That differs from a List which is a mutable data type.

Tuple is heterogenous in nature. That means that it can include different types of data within it (those letters in the above example would have been understood here, for example). Tuples are expressed as a single parenthesis. It looks like this:

Prelude> (1,1,’a’)

In this situation, the end result would look like:

(1,1,’a’)

Haskell Is Hard: Haskell Programming Jobs Seem So Much Harder Than Python – Why Bother?

As you work through this information about the Haskell programming language, you’ll find a lot of comparisons between other languages, especially Python. Python is perhaps the easiest of all computer languages to learn. It also is the most versatile and, as a result, the most useful. Sounds good, right?

By contrast, Haskell is more challenging to both learn and to perfect your skills at. It seems like – a completely different way of doing something that is easier to do in Python.

If you are very used to Python, consider a bit of a better explanation of Haskell using Python language features.

First, Haskell is a functional language, and Python is a mix of functional programming with both procedural and object-oriented styles. Second, both systems have a strong type system. As a result of this, explicit conversations are necessary. PHython is dynamically typed, and by comparison, Haskell is statically typed.

One of the big differences is that Haskell is faster than Python, by a lot. While the learning curve for Haskell is harder, especially if you do not have any background in functional programming to rely on, it can be worthwhile.

Haskell Program Example Uses: When to Use Haskell and Why

One of the best ways to see the value of Haskell is to see the multitude of ways that it can be used. There is no limit to the applications for computer languages today, but Haskell does a few key things better than others.

Web development with Haskell

If you are working on web development, use Haskell. It works well for this application. Wai is the package from Haskell for managing HTTP requests and responses.

If you are using Python with Flask and Django, and others, then align that same functionality with Haskell’s versions in Scotty, Servant, and Yesod. These are all built with Wai. Yesod is the most complete of all be framework options.

Cardano blockchain development with Haskell

Cardano is a blockchain platform that uses the Proof-of-Stake consensus algorithm. When launched, it was the first to enable peer-review research. It was based to tackle the more complex and “flaws” that are found in Ethereum and Bitcoin.

To write the Cardano blockchain system, you will use Haskell-based Plutus. It is a Turing-complete programming language.

Academic research with Haskell

Another use for Haskell is in academic research, specifically in programming languages and functional programming. It has a mathematical principle that makes it ideal for those who are learning and exploring new ideas and concepts.

Compiler construction with Haskell

You can also use Haskell to construct interpreters and compilers. Because of the expressive type system and its abstractions, Haskell is a strong option for the implementation of language processors.

Financial modeling with Haskell

Financial industry applications for Haskell are numerous. It can be used in modeling, risk analysis, as well as algorithmic trading.

Data analysis and visualization

Haskell is a solid choice for data analysis and visualization tasks. This is due to the available Data Analysis Library (Haskell-data-analysis). It also has diagrams that make processing and visualizing data effective.

Domain-specific languages

For those who are building domain-specific languages (DSLs), Haskell is beneficial as well because of its expressive syntax and abstractions. Most of the time, DSLs in Haskell will be concise and expressive. This makes them ideal for even some problem domains.

Concurrent and parallel programming

Use Haskell for its functional and pure nature to create concurrent and parallel programming. It avoids many of the most common pain points of the shared mutable state.

There are numerous other ways to use Haskell, including for game development, bioinformatics, education and teaching, and artificial intelligence, among other areas.

Learning Haskell Programming Language? Let Our Team Help You

The Haskell programming language can be an exciting new adventure to take on, and we recommend picking up the Programming in  Haskell book that is out there (one of many).

At Rayobyte, our team works to provide our clients with access to the knowledge and tools they need to advance their presence online and build incredible tools. Reach out to our team now to learn more about how we can help you. We also encourage you to learn more about how Rayobyte proxies change the game.

The information contained within this article, including information posted by official staff, guest-submitted material, message board postings, or other third-party material is presented solely for the purposes of education and furtherance of the knowledge of the reader. All trademarks used in this publication are hereby acknowledged as the property of their respective owners.