News

A Kotlin-Based Build Language for Gradle

• By John K. Waters
• May 24, 2016

Gradle Inc., chief commercial supporter of the open source Gradle build automation system, is working with software development toolmaker JetBrains to provide a Kotlin-based build programming language for Gradle, the two companies announced. The first milestone release of Gradle Script Kotlin is available now, with another milestone expected with the upcoming release of Gradle 3.0.

Gradle Inc., develops, distributes, and supports the Gradle Platform, which comprises the open source Gradle build tool and a commercial Gradle.com SaaS service. The company had relied on a Groovy-based domain-specific language. Apache Groovy is an optionally typed dynamic language for the Java platform. Kotlin is a statically typed language similar to Scala, Gosu, Ceylon and Fantom. It compiles to both JVM byte code and JavaScript. JetBrains, maker of the code-centric Java IDE, IntelliJ IDEA, began developing the language in 2010, and the company uses Kotlin in production of that IDE and other products.

By supporting Gradle builds in Kotlin, the two companies are "taking the next step in elevating the discipline of build automation," said Miko Matsumura, Gradle Inc.'s chief marketing officer. Until recently, build automation relied on simple shell scripts or inflexible XML files, an approach that no longer works, Matsumura said, because of the complexity introduced to the process by DevOps and Continuous Delivery.

"If you are running builds thousands of times, and these runs are increasingly complex, this transcends the realm of convenience scripting," he said in an e-mail. "There is an increased need to see build code as first-class, performance optimized software -- an enterprise asset as opposed to a collection of scattered, convenience scripts."

Builds now constitute a "full-fledged engineering discipline," he added.

"Today, a product's build is mission-critical; it automates and assembles, connects, tests, packages and -- in many cases -- deploys or ships that product," he said. "The design, implementation, and maintainability of build code demands first-class treatment.

With this partnership, the two companies are providing deep IDE support for Gradle in IntelliJ IDEA and Eclipse, including refactoring, symbol navigation, code completion and content assist.

JetBrains has claimed that Kotlin is more stable at run time than Java, because it can statically check weak points and supports things like variable type interface, closures, extension functions and mix-ins. Prague-based company released Kotlin in July 2011 for distribution under the Apache 2 Open Source License. Kotlin 1.0 went GA in February.

"JetBrains is widely respected for their excellent products," said Hans Docker, CEO and founder of Gradle Inc., in a statement. "This alliance is based on mutual technical admiration and a common goal to place the most effective tools in the hands of developers."

Gradle is among the world's most popular open source build tools. According to Gradle Inc., a wide range of organizations are currently using it to build and deliver mission-critical software written in dozens of programming languages and platforms, including Java, Android, C, C++, Python, Kotlin, Groovy and Scala, among others. The company claims that there were 10.4 million direct downloads of Gradle last year, and that there have been nearly 2 million new direct downloads per month so far in 2016. The Gradle ecosystem currently comprises more than 800 plug-ins that support a wide range of software development and deployment.

Sample Kotlin-based Gradle build scripts are available now on GitHub. Gradle Inc. is expected to announce and provide access to Gradle 3.0 at its Gradle Summit user conference on June 23.