Scala 3 is here!🎉🎉🎉

Friday 14 May 2021

Anatolii Kmetiuk, LAMP

After 8 years of work, 28,000 commits, 7,400 pull requests, 4,100 closed issues – Scala 3 is finally out. Since the first commit on December 6th 2012, more than a hundred people have contributed to the project. Today, Scala 3 incorporates the latest research in type theory as well as the industry experience of Scala 2. We’ve seen what worked well (or not so well) for the community in Scala 2. Based on this experience we’ve created the third iteration of Scala – easy to use, learn, and scale.

Exciting new features: how to get started?

A lot of new features ended up in Scala 3, and you may wonder where you should start learning about all of it. The go-to place for learning Scala 3 is its documentation.

To get a taste of all the new features that went into Scala 3, you can have a look at the New in Scala 3 article. For a streamlined and more thorough introduction, see the Scala 3 Book. You can try Scala 3 online without installing anything on your machine via Scastie, or you can follow the Getting Started guide to install it on your machine.

One thing has changed completely in Scala 3 compared to Scala 2: it is macros. You can learn more about how they work in Scala 3 in the dedicated documentation.

If you are a seasoned user of Scala 2, chances are you have some projects you’d like to port from Scala 2 to Scala 3. You may find the Migration guide helpful. It outlines the compatibility story between Scala 2 and Scala 3: source compatibility, binary compatibility, changed and dropped features, metaprogramming.

And if you need any help in your Scala journey, you can find various resources to talk to fellow Scala users here.

Ecosystem

Who’s already on Scala 3? Which libraries can you already use? A great place to answer this question is Scaladex. Scaladex is an index of Scala libraries where you can explore the ecosystem by language version, platform or the type of job a library does. At the time of writing this article, there are 308 early adopter libraries on Scala 3, compared to 2597 Scala 2.13 libraries.

Releases and Guarantees in 3.x era

We intend to continue releasing every 6 weeks after 3.0.0, bumping the patch version every time we do so. A stable 3.0.x release will be preceded with 3.0.x-RC1 release candidate 6 weeks prior to such a stable release. Such patch releases will contain bug fixes for bugs affecting the respective minor version. Patch versions will be forward and backward compatible with each other over the source, binary and TASTy compatibilities.

Of course, we intend to continue the development of the language in ways other than bug fixing. New language features and standard library APIs will appear in future minor versions. As any addition in library APIs, these may break backward source compatibility in minor, rare ways. However, minor releases will not break backward binary or TASTy compatibility. Concretely, that means that libraries built with Scala 3.0.0 will keep working with Scala 3.x.y!

Library authors: Join our community build

Scala 3 now has a set of widely-used community libraries that are built against every nightly Scala 3 snapshot. At present, there are 67 projects included, and the number is growing rapidly. Join our community build to make sure that our regression suite includes your library.

Contributors

Thank you to all the contributors who made this release possible 🎉

All-time contributors who made Scala 3 a reality, according to git shortlog -sn --no-merges 2308509d2651ee78e1122b5d61b798c984c96c4d..3.0.0, are: