Kotlin 1.1 release candidate is here

After two beta releases, Kotlin 1.1 is now ready to embrace the release candidate stage.  According to the blog post, this step means that most of the team’s development work is done, they are happy with the results, and they will soon publish them as a final Kotlin 1.1 release.

There’s only one new feature in the RC, namely the takeUnless function – a counterpart of takeIf (added earlier in 1.1) but with an inverted condition. Among other things, they have fixed several performance problems in the IDE – both long-standing sore points and recent regressions.

SEE ALSO: What Kotlin is all about — As explained by Hadi Hariri

Migration

JetBrain’s Mikhail Glukhikh emphasized that all binaries produced by pre-release versions are outlawed by the compiler: you’re now required to recompile everything that was compiled by 1.1‑M0x and Beta’s. All the code from 1.0.x is, of course, perfectly fine without recompilation.

Starting with one of the first 1.1.x updates, the compiler will only run under Java 8 or 9. To prepare you for the migration, the compiler now emits a warning if you run it under Java 6 or 7. However, Glukhikh warned that this only affects the build environment; the compiled code is still compatible with Java 6 by default, and there are no plans to remove the support for that.

The .javaClass extension property is now deprecated, so users are advised to  use ::class.java. The IDE offers a quickfix to update usages, both individually and across the entire project.

What’s more, the team has deprecated a lot of helper functions in the kotlin.dom and kotlin.dom.build packages to make sure the size of the JavaScript standard library is reduced. They will be removed in a future update.

For more details about Kotlin 1.1 RC, check out the changelog.