TypeScript, C# and Turbo Pascal with Anders Hejlsberg

Anders Hejlsberg discusses his career designing Turbo Pascal, Delphi, C#, and TypeScript, sharing insights on language design and tooling.

Anders Hejlsberg is a living legend and one of the most influential programming language designers of all time. He created Turbo Pascal, Delphi, C#, and also TypeScript. As well as that, he spent nearly a decade at the pioneering dev tools company, Borland, and is now in his 30th year of working at Microsoft, where he’s a Technical Fellow. In this episode, we discuss what it takes to build programming languages that developers love to use, and trace his career from writing his first compiler to creating Turbo Pascal and Delphi, and helping to pioneer modern software development through C# and TypeScript. Anders details how C# was designed by a small group of experienced language designers who met a few hours each week, and he explains why tooling was just as important as the language for TypeScript’s success, and what he has learned from building languages which stay relevant for decades. We also look into how Anders uses AI today, which language features suit AI-assisted development, and what he thinks is changing in the craft of software engineering as developers move further away from writing code line by line. — *Brought to you by our season partners:* • Antithesis – verify your system’s correctness without human review or traditional integration tests – and avoid bugs or outages. antithesis.com/pragmatic • WorkOS – Everything you need to make your app enterprise ready. workos.com/ • turbopuffer – a vector and full-text search engine built on object storage. It’s fast, cheap, and extremely scalable. turbopuffer.com/pragmatic — *The Pragmatic Engineer deepdives relevant for this episode:* • Microsoft’s developer tools roots newsletter.pragmaticengineer.com/p/microsofts-developer-tool… • 50 Years of Microsoft and developer tools with Scott Guthrie newsletter.pragmaticengineer.com/p/50-years-of-microsoft • How Linux is built with Greg Kroah-Hartman newsletter.pragmaticengineer.com/p/how-linux-is-built-with-g… • How will AI change operating systems? Part 1: Ubuntu and Linux newsletter.pragmaticengineer.com/p/ubuntu-and-ai • How Uber uses AI for development: inside look newsletter.pragmaticengineer.com/p/how-uber-uses-ai-for-deve… — *Where to find Anders Hejlsberg:* • X: x.com/ahejlsberg • LinkedIn: linkedin.com/in/ahejlsberg • GitHub: github.com/ahejlsberg — *In this episode, we cover:* (00:00) Intro (02:48) How Anders got into programming (05:40) Building his first compiler (07:44) Turbo Pascal (12:25) Delphi (14:53) Joining Microsoft (19:41) Building C# (29:11) Async/await (34:01) The rise of JavaScript (37:52) Building TypeScript (42:58) How the TypeScript compiler works (48:30) JavaScript’s strengths and weaknesses (52:18) How Anders uses AI (56:03) What language features work well with AI (1:02:49) How software craftsmanship is changing (1:07:49) Performance and efficiency (1:09:29) Anders’ tool stack (1:11:30) A 3