Haskell Hello World Example: How To Write, Compile and Execute Haskell Program on Linux OS

Question: I would like to understand the basics of how to write and execute Haskell program on Linux OS. Can you explain it with a simple example?

Answer: In this article, let us review very quickly how to write a basic Hello World Haskell program and execute haskell program on Linux or Unix OS.

Also, refer to Haskell article on wikipedia to learn about this programming language.

1. Write a Hello World Haskell Program

Create the helloworld program using the Vim editor as shown below.

$ vim helloworld.hs

-- hello world example
main = putStrLn "Hello, World!"

Note: Comment in Haskell starts with –.

2. Make sure Haskell Compiler is installed on your system

Make sure Haskell compiler is installed on your system as shown below.

$ whereis ghc
ghc: /usr/bin/ghc /usr/share/man/man1/ghc.1.gz

Installing haskell ( ghc ) compiler

If you don’t have haskell compiler, install it as shown below.

$ sudo apt-get install ghc6

3. Compile the haskell program

Compile the HelloWorld which will create the HelloWorld executable.

Compile and get a.out.

$ ghc helloworld.hs

Compile and get executable in desired name with -o option.

$ ghc -o helloworld helloworld.hs

4. Execute the haskell Program

Execute by mentioning the program name.

$./a.out
Hello, World!

$./helloworld
Hello, World!