Avatar of mrolappe

mrolappe's solution

to Hello World in the F# Track

Published at Jul 13 2018 · 1 comment
Test suite

The classical introductory exercise. Just say "Hello, World!".

"Hello, World!" is the traditional first program for beginning programming in a new language or environment.

The objectives are simple:

  • Write a function that returns the string "Hello, World!".
  • Run the test suite and make sure that it succeeds.
  • Submit your solution and check it at the website.

If everything goes well, you will be ready to fetch your first real exercise.

Running the tests

To run the tests, run the command dotnet test from within the exercise directory.

Further information

For more detailed information about the F# track, including how to get help if you're having trouble, please visit the exercism.io F# language page.


This is an exercise to introduce users to using Exercism http://en.wikipedia.org/wiki/%22Hello,_world!%22_program

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.


// This file was auto-generated based on version 1.1.0 of the canonical data.

module HelloWorldTest

open FsUnit.Xunit
open Xunit

open HelloWorld

let ``Say Hi!`` () =
    hello |> should equal "Hello, World!"
module HelloWorld

let hello who =
    match who with
    | None -> "Hello, World!"
    | Some who -> "Hello, " + who + "!"

Community comments

Find this solution interesting? Ask the author a question to learn more.
Avatar of ErikSchierboom

Although string concatenation works, it's a good F# practice to start using sprintf when creating strings. There are multiple benefits of sprintf, of which you can read about here.

What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

  • What compromises have been made?
  • Are there new concepts here that you could read more about to improve your understanding?