9 - Haoyi Li on Mill, Scala at Scale, Conference Touring and Moving Up the Stack

Haoyi Li is a software engineer and a core contributor to the Scala ecosystem. He's built a whole suite of Scala libraries under the com.lihaoyi banner, focusing on simplicity and productivity, as well as the Mill build tool, which he has since expanded beyond Scala to support other JVM tools like Java and Kotlin and experimental support for other things like TypeScript and Android, and promises better performance and user friendliness than Gradle and Maven can ever match. He's also the author of the book Hands-on Scala Programming, which focuses on getting things done with Scala.

You can find Mill at https://mill-build.org/

My own course, Scala Projects, uses Haoyi's book examples as starting points for full-fledged, shippable projects that you can use for yourself or turn into products: https://rockthejvm.com/courses/scala-projects

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0:00 Intro 1:14 The 45-conference sabbatical tour 4:55 In-person feedback vs. shouting into the void 8:38 Mill's current development process 11:00 Mill beyond Scala: targeting Java and Kotlin 14:05 Why build tools terrify developers 17:07 Mill's YAML config format 22:24 Scala at Databricks: using one language everywhere 26:17 Fast Scala onboarding: no Akka, no CATS, no ZIO 29:04 Scala vs Kotlin, TypeScript, and Go today 30:12 What Scala actually needs: IDE support and a simpler stack 35:56 The async obsession Scala needs to drop 43:10 IC to manager and back: the cost of remote leadership 50:26 From EverQuest XML mods to Scala 1:02:24 Maintaining a library ecosystem without burning out 1:03:30 Open-sourcing Hands-on Scala Programming 1:07:45 Self-publishing the book: pipeline, printing, and margins 1:13:09 Rewriting the book: dropping Quill, evolving Ammonite 1:15:33 Vibe-coding contributions to the Scala compiler 1:22:17 Moving up the stack: engineers in the AI era 1:27:12 The fun of wrangling half-baked code 1:31:38 Haoyi's message to Scala developers