{"id":9677,"date":"2020-09-15T08:45:36","date_gmt":"2020-09-15T08:45:36","guid":{"rendered":"https:\/\/www.experfy.com\/blog\/?p=9677"},"modified":"2023-11-07T06:46:04","modified_gmt":"2023-11-07T06:46:04","slug":"an-introduction-to-functional-programming-in-haskell","status":"publish","type":"post","link":"https:\/\/www.experfy.com\/blog\/software-ux-ui\/an-introduction-to-functional-programming-in-haskell\/","title":{"rendered":"An Introduction to Functional Programming in Haskell"},"content":{"rendered":"\t\t
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Haskell is a functional programming language that has been specially designed to handle symbolic computation and list processing applications<\/p>\n\n\n\n

This is a beginner’s tutorial to let them understand the fundamentals of Haskell.<\/p>\n\n\n

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What Is Haskell?<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Haskell is a widely used purely functional language.<\/p>\n\n\n\n

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Functional programs are more concurrent, and they follow parallelism in execution to provide more accurate and better performance. In typical programming languages, we instruct a compiler to do something and how to do it. \u2014\u00a0https:\/\/www.tutorialspoint.com\/haskell\/haskell_overview.htm<\/a><\/p>\n<\/blockquote>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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That\u2019s not so in Haskell, where we ask what it is we do. Also, Haskell is a sluggish programming language, so the program doesn\u2019t execute code that it thinks is not necessary.<\/p>\n\n\n\n

A Haskell program is nothing more than a series of functions that execute.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Haskell is a strictly typed language. By the term\u00a0strictly typed language<\/em>, we mean the Haskell compiler is intelligent enough to figure out the type of the variable declared. Hence we need not explicitly mention the style of the variable used.\u2013\u00a0https:\/\/www.tutorialspoint.com\/haskell\/haskell_overview.htm<\/a><\/p>\n<\/blockquote>\n

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\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Getting Started<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To set up a Haskell environment on your Windows computer, go to their official website\u00a0https:\/\/www.haskell.org\/platform\/windows.html<\/a>\u00a0and download the installer.<\/p>\n\n\n\n

To set up a Haskell environment on your MAC system, go to their official website\u00a0https:\/\/www.haskell.org\/platform\/mac.html<\/a>\u00a0and download the Mac installer.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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For Linux, the installation process is as follows:<\/p>\n\n\n\n

$ sudo apt-get install haskell-platform<\/pre>\n\n\n
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Starting Haskell<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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It\u2019s effortless to start the Haskell programming language, and you enter the following command in the terminal:<\/p>\n\n\n\n
$ ghci
GHCi, version 7.6.3: http:\/\/www.haskell.org\/ghc\/<\/a>  :? for help 
Loading package ghc-prim ... linking ... done. 
Loading package integer-gmp ... linking ... done. 
Loading package base ... linking ... done.
Prelude><\/pre>\n\n\n\n
Now, you can enter your Haskell code, for example:<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Example program<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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It is a simple example to demonstrate the dynamism of Haskell. Take a look at the following code:<\/p>\n\n\n\n
Prelude> main = putStrLn \"Hello Medium\"<\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
Hello Medium<\/pre>\n\n\n
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Basic Operations<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Haskell is intelligent enough to decode some number as a number. Therefore, you need not mention its type externally as we usually do in other programming languages.<\/p>\n\n\n\n
An example:<\/p>\n\n\n\n
Prelude> 4*4<\/pre>\n\n\n\n
You will receive the output:<\/p>\n\n\n\n
Prelude> 16<\/pre>\n\n\n
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Characters<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Like numbers, Haskell can intelligently identify a character given as an input to it.<\/p>\n\n\n\n
To display the type of a variable, you can enter the following line of code:<\/p>\n\n\n\n
Prelude> :t \"a\"<\/pre>\n\n\n\n
This will display:<\/p>\n\n\n\n
\"a\" :: [Char]<\/pre>\n\n\n
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Strings<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A string is nothing but a collection of characters. We can create the following string:<\/p>\n\n\n\n
Prelude> \"Hello Medium\"<\/pre>\n\n\n\n
It will display:<\/p>\n\n\n\n
\"Hello Medium\"<\/pre>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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If want to know the type of this string, we can use\u00a0:t<\/code>\u00a0again:<\/p>\n\n\n\n
Prelude> :t \"Hello Medium\"<\/pre>\n\n\n\n
The output will be:<\/p>\n\n\n\n
\"Hello Medium\" :: [Char]<\/pre>\n\n\n\n
As I already said, a string is just a collection of characters, so this will be returned as a\u00a0Char<\/code>\u00a0data type.<\/p>\n\n\n
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Booleans<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The boolean data type is pretty much as straightforward as other data types. In the example below, you see some booleans.<\/p>\n\n\n\n
Prelude> True && True<\/pre>\n\n\n\n
Or<\/p>\n\n\n\n
Prelude> True && False<\/pre>\n\n\n
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Lists<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Like other data types,\u00a0List<\/code>\u00a0is also a beneficial data type used in Haskell. As per example, [a,b,c] is a list of characters. Hence, by definition,\u00a0List<\/code>\u00a0is a collection of items of the same data type, separated by a comma.<\/p>\n\n\n\n
Let\u2019s create a list:<\/p>\n\n\n\n
Prelude> x = [1,2,3,4,5]<\/pre>\n\n\n\n
Outputs:<\/p>\n\n\n\n
[1,2,3,4,5]<\/pre>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Length<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Lists also have a couple of methods. Given list x, you can use the following method to get the length:<\/p>\n\n\n\n
Prelude> length x<\/pre>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Reverse<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Or to reverse a list, you can use:<\/p>\n\n\n\n
Prelude> reverse x<\/pre>\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Add<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To add an element to a list, you use the\u00a0++<\/code>\u00a0operator;<\/p>\n\n\n\n
Prelude> x ++ y<\/pre>\n\n\n\n
The code above combines list x with list y.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Delete<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To delete one single element from a list, you use\u00a0drop<\/code>:<\/p>\n\n\n\n
Prelude>`drop n xs<\/pre>\n\n\n
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Tuple<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Haskell provides another way to declare multiple values in a single data type. It is known as a\u00a0tuple<\/em>. A tuple can be considered as a list. However, there are some technical differences between a tuple and a tist.<\/p>\n\n\n\n
A tuple has a fixed amount of elements inside it. Tuples are immutable. A Tuple is created as follows:<\/p>\n\n\n\n
Prelude> (8,16,'b')<\/pre>\n\n\n\n
Outputs:<\/p>\n\n\n\n
(8,16,'b')<\/pre>\n\n\n\n
This tuple contains three elements, two numbers, and a character.<\/p>\n\n\n\n
Like lists, tuples contain methods with them to determine things like the first or last element in the tuple.<\/p>\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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First element<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To retrieve the first element of a tuple, use the following method:<\/p>\n\n\n\n
Prelude> fst (16, 8)<\/pre>\n\n\n\n
This will output:<\/p>\n\n\n\n
16<\/pre>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Head and tail<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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When using the\u00a0head<\/code>\u00a0method, you also retrieve the first element of a tuple:<\/p>\n\n\n\n
Prelude> head (16, 8, 24, 32)<\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
16<\/pre>\n\n\n\n
But when using the\u00a0tail<\/code>\u00a0method, you don\u2019t just take the last or second element of a tuple but all the elements except the first one:<\/p>\n\n\n\n
Prelude> tail(16, 8, 24, 32)<\/pre>\n\n\n\n
Outputs:<\/p>\n\n\n\n
[8, 24, 32]<\/pre>\n\n\n
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Conditional Statements<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Conditional statements are a feature that allows programmers to apply a condition in the code flow. The programmer can execute a set of instructions depending on a predefined condition.<\/p>\n\n\n\n
Haskell has the following conditional statements:<\/p>\n\n\n\n