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@lrytz lrytz released this May 29, 2019 · 77 commits to 2.13.x since this release

Scala 2.13 is almost here! We present the third 2.13 release candidate. The changes since RC2 are minor.

We hope library maintainers will test and publish their libraries for RC3, to validate the release candidate and enable 2.13.0 to go forward.

About these notes

These are the detailed technical release notes for RC3 only, documenting changes since RC2 only.

We don't yet have a combined, friendlier release note covering 2.13 as a whole yet. That will follow in time for 2.13.0. For now, see also the notes for RC2, RC1, M5, M4, M3, M2, and M1.

Binary compatibility

As usual for Scala pre-releases, RC3 is not binary compatible with any other Scala version, including previous 2.13 milestones and release candidates.

We will not break binary compatibility between RC3 and 2.13.0 unless really necessary.

Libraries for RC3

As libraries are published for RC3, they're added to .

Changes in RC3

We merged 16 pull requests for RC3. The highlights are:

  • Remove unnecessary type parameter on IterableOnce#stepper (#8083)
  • Add default IterableOnce#knownSize impl (#8093)
  • Un-deprecate option2Iterable implicit conversion (#8106)

For further changes, see merged PRs and closed bugs.

See also the notes for the previous release candidates and milestones: RC2, RC1, M5, M4, M3, M2, M1.

Compiler performance in 2.13 is 5-10% better than 2.12. The integration of the new collections library shows up in the performance graph as a nice improvement.

Collections changes

To learn about the collections changes since 2.12 and how to adapt your code, take a look at these documents:

These documents are still being expanded and improved.


A big thank you to everyone who's helped improve Scala by reporting bugs, improving our documentation, spreading kindness in discussions around Scala, and submitting and reviewing pull requests! You are all magnificent.

This release was brought to you by 10 contributors, according to git shortlog -sn --no-merges v2.13.0-RC2..v2.13.0-RC3. Thank you Lukas Rytz, NthPortal, Josh Lemer, Philippus Baalman, Stefan Zeiger, Aaron S. Hawley, mcintdan, Adriaan Moors, Anatolii, Eugene Yokota.

Thanks to Lightbend for their continued sponsorship of the Scala core team’s efforts. Lightbend offers commercial support for Scala.

Obtaining Scala

Scala releases are available through a variety of channels, including (but not limited to):

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