Here’s a short digest for all those who are still unfamiliar with the changes and improvements that are coming in Dotty / Scala 3. I’m not presenting anything that’s not already been presented elsewhere; I’m merely taking a bunch of sources — Dotty documentation, conference talks, blogposts, Google groups, SIPs…

Some of you may have read my article on monads. This time I want to talk about monads from a different, more theoretical point of view. …

In this short article I will demonstrate the generalized type constraints in Scala — what they are, why we need them and how they are used. To start, let me show you two Scala puzzles. Puzzle number one: def pair[S](s1: S, s2: S): (S, S) = (s1, s2) What do you think happens…

In one of my earlier articles I tried to explain monads in an approachable way. Here’s an attempt to do the same for some other members of the same family — functors and applicative functors. …

A few days ago I stumbled upon a StackOverflow question regarding this stuff and while writing my answer I noticed that I wrote a respectable chunk of text. Which is a good indicator for a blog post. …

This article aims to show a couple of techniques to tackle some common problems caused by type erasure in Scala. Introduction Scala has a really strong type system. Existential types, structural types, nested types, path-dependant types, abstract and concrete type members, type bounds (upper, lower, view, context), use-site and declaration-site type…

This article explains what ad-hoc polymorphism is, what kind of problems it solves and how to implement the whole thing using the type class pattern. Types of polymorphism We’ll start from parametric polymorphism. Say we have some list of items; this could be a list of integers, doubles, strings, whatever. Now consider a…

In my previous post I mentioned how I decided to write about variance despite the fact that there are already several dozen articles about the topic. This is a similar situation. I am aware that this is a drop in the sea. I feel the sea is polluted with complex…

This text aims to explain variance in type parameters both in Java and Scala. There is already a lot of material on this subject in various blogs and articles, but to me, they always felt either too complex, diving straight into advanced features and is hard to follow for someone…