Scala 2 Files

The Scala team at Akka (formerly Lightbend) is pleased to announce Scala 2.13.16.

The following changes are highlights of this release:

Breaking change

• On the empty string, .tail and .init now throw (instead of returning the empty string) (#10851 by @sh0hei)
  • This is a bugfix, but be aware that existing code might, perhaps inadvertently, be relying on the old behavior

Compatibility

• Support Scala 3.6 in TASTy reader (#10893)
• Support JDK 24 in optimizer (via ASM upgrade) (#10888 by @Philippus)

REPL

• REPL: JLine 3.27.1 (was 3.26.3) and on Windows use JNI not JNA (#10899, #10898, #10882)
  • These upgrades hopefully won't be noticed, but, REPL users on Windows take note
  • JNA is no longer a dependency of scala-compiler.jar

Align with Scala 3

• Under -Xsource:3, deprecate infix named args (#10857 by @som-snytt)

Errors and warnings

• Fix 2.13.15-only false positives with -Wunused:patvars (#10870 by @som-snytt)

Collections

• Do not use rangeHash when rangeDiff is 0 (#10912 by @Friendseeker)
  • This may affect fragile code relying on ordering of hash-based collections
• Deprecate collection.mutable.AnyRefMap (#10862 by @wangyum)
  • Since Scala 2.13.0 it has no performance advantage over collection.mutable.HashMap

More changes

For the complete 2.13.16 change lists, see all merged PRs and all closed bugs.

Compatibility

As usual for our minor releases, Scala 2.13.16 is binary-compatible with the whole Scala 2.13 series.

Upgrading from 2.12? Enable -Xmigration while upgrading to request migration advice from the compiler.

Contributors

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.

We especially acknowledge and thank A. P. Marki, also known as Som Snytt, who is responsible for many of the improvements in this release.

This release was brought to you by 19 contributors, according to git shortlog -sn --no-merges @ ^v2.13.15 ^2.12.x. Thank you A. P. Marki, Seth Tisue, Scala Steward, Lukas Rytz, Friendseeker, Ondra Pelech, Philippus Baalman, Benjamin Maurer, Corey O'Connor, Eric Seidel2, Hamza Remmal, Jamie Thompson, João Costa, Kenji Yoshida, Mathias Kools, Rikito Taniguchi, Yuming Wang, rochala, sh0hei.

Thanks to Akka for their continued sponsorship of the Scala 2 team’s efforts. Akka offers commercial support for Scala.

Scala 2.13 notes

The release notes for Scala 2.13.0 have important information applicable to the whole 2.13 series.

Obtaining Scala

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

• Bump the using scala setting in your Scala-CLI project
• Bump the scalaVersion setting in your sbt or Mill project
• Download a distribution from scala-lang.org
• Obtain JARs via Maven Central