Scala core articles


Sealed keyword in Scala

When we come to Scala and see the sealed keyword, we often wonder "why". After all, having all subclasses defined in one or more files shouldn't be a big deal. For us, programmers, it's not but for the compiler, it has an importance. In this post, I will try to show the sealed class use cases. Continue Reading →

Annotations in Scala

When I was working with Java and Spring framework, the annotations were my daily friend. When I have started to work with Scala, I haven't seen them a lot. It was quite surprising at the beginning. But with every new written line of code, I have started to see them more and more. After that time it's a good moment to summarize the experience and focus on the Scala annotations. Continue Reading →

Java, SAM and Scala

During the years Java was much more verbose than its JVM-based colleagues (Clojure, Groovy, Scala, ...). But it changed with Java 8 and its Lambda expressions. However the years of the verbosity brought some patterns into Java-based applications. One of them is known as SAM and fortunately it can be easily used with Scala. Continue Reading →

Enums in Scala

Some people coming from Java are often confused about enumerations. In Java, they're often used not only to enumerate things as in dictionaries but also to create singletons. In Scala, the latter use case is much more reserved to objects and apparently, only the former one remains. We'll see through this post whether it's true or not. Continue Reading →

Regular expressions in Scala

Even though the regular expressions look similarly in a lot of languages, each of them brings some own constructs. Scala is not an exception for this rule and we'll try to see it in this post. Continue Reading →

String interpolators in Scala

I've always found concatenating Strings with "+" a laborious task. Hence when I've discovered Scala and its text construction methods I was immediately convinced. And as you can imagine, this topic merits its own short post in the Scala category. Continue Reading →

Companion objects

Scala doesn't come with static keyword as Java does. However, with object singleton type it allows to define static properties and methods. It goes even further and thanks to object "class" lets us to build an instruction called companion objects. Continue Reading →

Handling exceptions in Scala

At first glance, the try-catch block seems to be the preferred approach to deal with exceptions for the people coming to Scala from Java. However, in reality, this approach is not a single one available in Scala. Continue Reading →

Package objects

Who didn't encounter a question about helper classes ? For ones, creating them isn't legitimate since everything we can link to an object. For the others they're fully legal because they help to keep code base understandable. Scala comes with an idea that can make both sides agree - package objects. Continue Reading →

Quasiquotes in Scala

Apache Spark inspired not only the last week's post about closures but also the one you're reading about quasiquotes - a mysterious Scala experimental feature those existence we can difficulty suspect in the first months of work with the language. Continue Reading →

Lazy operator in Scala

Scala's lazy instances generation can be helpful in a lot of places. It simplifies writing since we can declare an instance at right and common place and delay its physical creation up to its first use. In Java we've this possibility too, though, it's much more verbose than in Scala. Continue Reading →

Scala and for loop

For loop was maybe the most used iterative structure in Java before the introduction of lambda expressions. With this loop we're able to write everything - starting with a simple mapping and terminating with a more complex "find-first element in the collection" feature. In Scala we can made these operations with monads and despite that, for loop is a feature offering a lot of possibilities. Continue Reading →

Scala and pattern matching

At first glance Scala's pattern matching looks similar to Java's switch statement. But it's only the first impression because after analyzing the differences we end up with some smarter idea. Continue Reading →

Scala extractors

Scala's apply method is a convenient way to create objects without the use of new operator and thus, to reduce the verbosity just a little. Often, as for instance in the case of case classes, apply is accompanied by its opposite, unapply, used in its turn to build extractors. Continue Reading →

Scala implicits

Scala implicits have many drawbacks but in some cases their use is justified. They remain though one of the advanced concepts for a lot of newcomers and it's worth explaining them a little bit more in details. Continue Reading →

Mixins in Scala

Multiple inheritance can lead to a lot of issues and one of the most known is the diamond problem where the compiler doesn't know which of inherited methods use. However in Scala we can use another structure to compose a class with several different classes, keeping us far away of the diamond problem. This structure is called mixin. Continue Reading →