Scala 3.10.0 matches Java records, stabilises SIP 71 and lists eight breaking changes

Serguey Asael Shinder13 October 2026, 06:542 min read

The Scala team published Scala 3.10.0 on 12 October. It is a minor release in the Scala 3 line, but it opens with a section of breaking changes, so it is worth reading before a build bumps the compiler version.

Breaking changes. The release notes list eight. Implicits are no longer inferred from a companion object that is not accessible at the use site. Constant folding during inlining is enhanced. The compiler stops catching StackOverflowError and uses a "fuel" budget instead. this is forbidden in top-level definitions. The runtime.Rich* implicit conversions on primitive types are replaced by direct extension methods, and the -> tuple sugar becomes an inline method. Using with as a type operator is now an error. Finally, bytecode generation uses stock ASM rather than the project's long-standing scala-asm fork.

Highlights. Pattern matching now supports Java records, which matters for codebases that share types with Java modules. String literals gain the \s space escape. The REPL accepts //> using dep directives, so a dependency can be pulled into a REPL session the same way as into a Scala CLI script. The distribution gains .deb and .rpm packages.

Language process. One feature moves to stable: under SIP 71, strictEqualityPatternMatching is enabled by default, together with a deprecation mechanism for -language feature flags. Three SIPs enter preview: SIP 61 (unrolling default arguments for binary compatibility), SIP 75 (relaxed lambda syntax) and SIP 68 (referenceable package objects). Two pre-SIP ideas land as experimental: inline and specialized traits, and "spec strings".

Scala CLI. The bundled Scala CLI moves from 1.16.0 to 1.17.1. Among its changes: JEP 512 flexible main methods on JDK 25 and later (JDK 21 with --enable-preview), individual files as resources, and -d paths ending in .jar producing a library JAR. One detail can surprise build scripts: the lts version tag now resolves to the Scala 3.9 LTS series, and pinning the older line requires 3.3.lts.

Who should act. Libraries that cross-compile, and projects relying on the removed Rich* implicits or on with in type position, should test against 3.10.0 first. Teams on the LTS tag in Scala CLI should check which series their builds now resolve to.

Source: Scala, release notes for 3.10.0 — https://github.com/scala/scala3/releases/tag/3.10.0