Episode Details

This week on the pod, we talk to Dimitri Mitropoulos about building DOOM in the TypeScript type system. We walk through all the nitty gritty and explore this truly amazing engineering feat! We touch on things that Dimitri learned and discovered along the way, and how you might be surprised what you can accomplish by trying! In the news, Zod 4 Beta drops with awesome new features. 

Chapters

• (00:00) - Intro
• (00:37) - SquiggleConf 2025
• (01:00) - Personal News
• (04:28) - Dimitri's Background and Michigan TypeScript
• (08:35) - JSON Parser in TypeScript Types
• (09:08) - Where do you start with DOOM in Types?
• (10:01) - "DOOM" Complete
• (13:57) - How do you run DOOM in TS?
• (17:36) - Debugging an Emulator in TS Types
• (19:22) - How does DOOM work?
• (20:45) - Using Web Assembly
• (22:49) - Understanding WebAssembly and TypeScript Integration
• (24:59) - The Concept of Abstraction in Programming
• (27:02) - Challenges in Implementing WebAssembly from the Spec
• (28:59) - Ambiguities in Specifications and Their Impact
• (30:40) - Debugging Techniques and Error Handling
• (32:24) - Innovative Use of Overflow in Game Development
• (35:40) - Insights Gained from TypeScript During the Project
• (38:24) - The Complexity of TypeScript Types
• (43:08) - Time Travel Debugging and Memory Management
• (45:00) - The Most Challenging Aspects of the Project
• (48:32) - Reactions to DOOM
• (53:10) - The Dawn of TypeScript Go
• (01:02:14) - Lessons Learned and Future Directions
• (01:08:37) - Dimitri Says Goodbye!
• (01:09:50) - News for the Week of April 7th
• (01:14:42) - Community Posts
• (01:17:39) - Secret of the Handbook
• (01:19:07) - Cool Stuff from Erik
• (01:19:51) - Debugging and Performance Optimization Techniques

• SquiggleConf 2025
• Michigan TypeScript
• TypeScript Types Can Run Doom
• Anders TS GO Interview 
• Final Boss Challenge 
• TypeScript Types WASM Runtime

News Links

• Zod 4 Beta
• Matt Pocock's Video
• Dan Abramov - RSCs or Maybe Not
  • https://overreacted.io/react-for-two-computers/ 
  • https://youtu.be/ozI4V_29fj4 
• Axel’s Corner
  • Testing Types 
    • https://2ality.com/2025/04/testing-types-typescript.html 
    • https://bsky.app/profile/dr-axel.de/post/3lmmwp4ovek2q 
  • Deploying TypeScript (timely!)
    • https://2ality.com/2025/04/deploying-typescript-present-future.html
• https://www.pipe0.com/blog/never-in-typescript 
• https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types 
• Kamran
  • https://bun.sh/blog/debugging-memory-leaks