Overview

Andre Breslav, creator of Kotlin, discusses how he built one of the world’s most influential programming languages by deliberately borrowing proven ideas from Scala, C#, and Groovy rather than inventing new concepts. The language now runs on billions of Android devices and transformed mobile development when Google made it official in 2017, catching even the Kotlin team by surprise.

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Key Takeaways

  • Build on proven ideas rather than inventing from scratch - Kotlin succeeded by taking the best features from existing languages like Scala’s data classes, C#’s extensions, and Groovy’s builders, then adapting them for practical use
  • Seamless interoperability with existing ecosystems is crucial but extremely complex - Making Kotlin work transparently with Java required years of engineering effort, including custom compilation tricks and type system workarounds that weren’t visible to developers
  • Target growing platforms for language adoption - Kotlin found massive success on Android because mobile developers were stuck with outdated Java versions while iOS had Swift, creating pent-up demand for modern language features
  • Backwards compatibility requires extensive tooling and planning - The team spent a full year before 1.0 release prohibiting features that might conflict with future additions, plus building automated migration tools and experimental feature flags
  • AI coding agents create a new problem: intent gets lost - When you prompt an agent in English but commit machine code, your teammates only see the implementation, not the reasoning behind it

Topics Covered