SKB – Scala operators


This article is part of the Scala knowledge bits Series.

Periodically, I will publish new exercises so you can slowly build up knowledge about Scala.

It is designed to be done in a very short amount of time and learn a little bit each day, just to create a routine.

This episode will teach you about Scala operators.

Hope you are going to enjoy it! It is designed for anyone to learn Scala from scratch and slowly learn, one Bit at a time.

After this Bit, I would love to hear your feedback in the comments down below.

Feel free to join the Discord server as well if you would like some help and support from the rest of our community.

What are we learning today?

Today we are going to learn about Scala operators !

Have you ever wondered how ! and + operator works ?

Let’s make your own !

Time to try on the exercise on your own and scroll down for more information when you are done or if you are stuck.


Here is an exercise to complete today.

If I did my job well, you should be able to guess by yourself the solution based on what you previously learned and based on the clues.

But if you get stuck, scroll down to get more information.

The goal of the exercise is to replace the ??? by a piece of code so that the exercise compiles and that’s how you win! Good luck!

You can fill the exercise right in here:

Or, if it does not load, go on to Scastie (i2ZSLmI0R7egM6vkvJqKug).

More information about Scala operators

In this exercise you will learn (or have learned, if you have already solved the puzzle) about Scala operators.

Long exercise but I wanted to make sure to see several examples to get a good knowledge about Operators for you !

The first section ({...}) is about traditional, easy operator such as + and *. In Scala, you can use pretty much any characters to create a method name so it is not too hard at this point. Sorry for the math about complex numbers !

Next we see weirder ones with backslash \ and one famous one, the combine operator : |+|, present in many libraries such as Cats.

And finally even weirder ones. Operator that goes before the caller ! Those are called unary and the syntax is :

class MyClass(...) {
   // ... other fields and methods ...
    def unary_[prefix_name] = ???

   // ... more things ...

val a : MyClass = ???

[prefix_name] a

It is worth noting that only a selected list of characters and names are authorized for unary methods. For example, +, *, ~, and ! are allowed. You can find a lot of example of people using unary on GitHub.

Feel free to go back to the exercise, modify the code to try out new things and get a better intuition for Scala operators.


I hope you have learned something new or had fun during this Scala Knowledge Bit.

Please ask questions or post feedback in the comments below.

Feel free to try on the next Scala Knowledege Bit.

If you are curious about the previous Scala knowledge Bits, go check it out! 🙂

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