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Haskell Hello World! 

Haskell Hello World! 



Click on RUN button to see the output

Haskell online compiler

Write, Run & Share Haskell code online using OneCompiler's Haskell online compiler for free. It's one of the robust, feature-rich online compilers for Haskell language, running the latest Haskell version 8.6. Getting started with the OneCompiler's Haskell editor is easy and fast. The editor shows sample boilerplate code when you choose language as Haskell. OneCompiler also has reference programs, where you can look for the sample code and start learning. Happy learning!!

Taking inputs (stdin)

OneCompiler's Haskell online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample Haskell program which takes name as input and prints hello message with your name.

main = do  
    name <- getLine  
    putStrLn ("Hello " ++ name ++ ", Happy learning!") 

About Haskell

Haskell is purely a functional programming language which was introduced in 1990's.

Key Features

  • Haskell is both compiled and interpreted
  • Lazy language as the results are computed only if required
  • Pure functions
  • Pattern matching on data structures
  • Emphasizes on what to do but not on how to do
  • Glasgow Haskell Compiler (GHC), most widely used Haskell compiler also written in Haskell.
  • Data is immutable

Syntax help

Data Types

NumbersHaskell is intelligent to identify numbers without specifying data type
CharactersHaskell is intelligent to identify characters and strings without specifying data type
TupleTo declare multiple values in a single data type. Tuples are represented in single paranthesis. For example (10,20,'apple')
BooleanTo represent boolean values, true or false
ListTo declare same type of values in a single data type. Lists are represented in square braces.For example [1,2,3] or `'a','b','c','d'

Control statements

If-Else / Nested If-Else:

When ever you want to perform a set of operations based on a condition or set of conditions, then If-Else/ Nested-If-Else are used.


main = do   
   let age = 21 
   if age > 18 
      then putStrLn "Adult" 
   else putStrLn "child"


Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Functions play an important role in Haskell, since it is a purely functional language.


multiply :: Integer -> Integer -> Integer   --declaration of a function 
multiply x1 x2 =  x1 * x2                       --definition of a function

main = do 
   putStrLn "Multiplication value is:"  
   print(multiply 10 5)    --calling a function

Help us with your feedback!

Reference Programs:


No tags available for Haskell

How to use?

Choose the language in which you want to run your program, by clicking the button next to Run. And then write your code in the code box, You can use the auto complete snippets and warnings and errors which helps you to write better code faster way.
Once you are done writing your code click the Run button, now the code will be submitted to OneCompiler and you will see the results in a second.

How to contribute?

Please fork OneCompiler repository and contribute us by adding more languages or the features to the existing OneCompiler backend.
You can also contibute to the community by adding more programs which users can search and use as base code for their programs.

API & More

You can embed OneCompiler into your own website. That helps your website users to write and test their programs within your website.
If you want to run and see the results from your backend you can utilize the OneCompiler API by integrating it with your backend.