Kotlin programming language: Here's what's inside the first big release of this year

Kotlin, the top app programming language for building Android apps, gains a bunch of new features.
Written by Liam Tung, Contributing Writer

Developer tools maker JetBrains has released Kotlin 1.5.0, its "first big release of 2021", which includes the stable release of its new Java virtual machine (JVM) internal representation (IR) compiler. 

Java-compatible Kotlin is endorsed by Google as the official programming language for developing Android applications. 

Kotlin is developed in the open on GitHub primarily by JetBrains — the maker of the popular IDE IntelliJ IDEA — but with contributions from Google. IntelliJ IDEA is the basis of Google's Android Studio IDE for building Android apps. 

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The new JVM IR compiler gives JetBrains the capacity to build new language features at a faster clip for its various implementations, including Kotlin native (Kotlin/Native) for building apps for iOS and Windows, Kotlin for JavaScript (Kotlin/JS) for building web applications, and Kotlin for JVM (Kotlin/JVM) for the Java platform. 

"The new compiler shares a unified pipeline and business logic with Kotlin/Native and Kotlin/JS IR compilers, which will allow us to implement most features, optimizations, and bug fixes for all platforms simultaneously," JetBrains' Ekaterina Volodko said in a blogpost.  

"It will also allow you to add custom processing and transformations that will automatically work on all platforms." 

More than 25,000 developers have already tried the new JVM IR compiler in IntelliJ IDEA, JetBrains said.

Kotlin 1.5.0 also brings support for JVM records to ensure interoperability with the Java features called record classes that act as transparent carriers for immutable data. Record classes was finalized in JDK 16, which reached general availability in March.  

There are also improvements to the standard library and test library. 

The standard library brings new "stable APIs for unsigned integer types as well as for ranges, progressions, and functions for them". 

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Developers using IntelliJ IDEA and Android Studio should see a notification alerting them to update Kotlin to 1.5.0 automatically. Users can also update it manually.  

Kotlin/Native gains support for compiler caches in debug mode for linuxX64 and iosArm64 targets. It also deactivates the build-in memory leak checker to help avoid issues that might cause application crashes.

"With compiler caches enabled, most debug compilations complete much faster, except for the first one. Measurements showed about a 200% speed increase on our test projects," JetBrains said. 

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