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4d47's solution

to Hello World in the Kotlin Track

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.

Since this is your first Kotlin exercise, we've included a detailed TUTORIAL.md file that guides you through your solution. Check it out for tips and assistance!


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.


import org.junit.Test
import kotlin.test.assertEquals

class HelloWorldTest {

    fun helloWorldTest() {
        assertEquals("Hello, World!", hello())

fun hello(name: String = "World"): String =
    if (name.isBlank()) hello() else "Hello, $name!"

What can you learn from this solution?

A huge amount can be learnt 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 I could read more about to develop my understanding?