How Kotlin Began at JetBrains

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Andrey Breslav is the creator of Kotlin and the founder of CodeSpeak, a new programming language that aims to reduce boilerplate by replacing trivial code with concise, plain-English descriptions. He led Kotlin’s design at JetBrains through its early releases, shaping both the language and its compiler as Kotlin grew into a core part of the Android ecosystem.

In this episode, we talk about what it takes to design and evolve a programming language in production. We discuss the influences behind Kotlin, the tradeoffs that shaped it, and why interoperability with Java became so central to its success. 

Andrey also explains why he is building CodeSpeak as a response to growing code complexity in an era of LLM agents, and why he believes keeping humans in control of the software development lifecycle will matter even more as AI becomes more capable.

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Timestamps

(00:00) Intro

(01:02) Why Kotlin was created

(06:26) Dynamic vs. static languages

(09:27) Andrey joins the Kotlin project

(14:26) Designing a new language 

(19:40) Frontend vs. Backend in language design

(21:05) Why is it named Kotlin?

(24:37) Kotlin vs. Java tradeoffs

(28:32) Null safety 

(31:24) Kotlin’s influences 

(39:12) Smartcasts 

(40:42) Features Kotlin left out

(44:54) Bidirectional Java interoperability

(55:01) The Kotlin timeline 

(58:00) Kotlin’s development process

(1:07:20) From Java to Android developers

(1:12:12) How Android became Kotlin-first 

(1:18:20) CodeSpeak: a language for LLMs

(1:24:07) LLMs and new languages

(1:28:20) How software engineering is changing with AI

(1:36:12) Developer tools of the future 

(1:39:00) Andrey’s advice for junior engineers and students 

(1:42:32) Rapid fire round

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