To not leave you without an episode for August, Pascal brings you an episode from the Archive. Back in August 2023 for Episode 55, Pascal spoke with Katherine and returning guest Dustin, two software engineers at Meta about how to ship code at Meta. Why do we have a monorepo? Why and how do we do pre-commit code review? What does our CI infrastructure look like? Get the answers to these questions and many more in this episode of the Meta Tech Podcast. Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Instagram (https://instagram.com/metatechpod) and don’t forget to follow our host Pascal (https://mastodon.social/@passy, https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/. Links The evolution of Facebook’s iOS app architecture - Engineering At Meta: https://engineering.fb.com/2023/02/06/ios/facebook-ios-app-architecture/ Episode 47: Source control at Meta - https://pca.st/episode/429e9f38-6537-43e3-b929-fbeeda326ed5 Timestamps Intro 0:06 Intro Katherine 1:55 Dustin's Origin Story 4:38 Topic Intro 6:28 Why Monorepo(s) 7:18 What Makes Monorepos Hard? 12:15 Why do we Have so Many Files? 17:31 Who Owns Stuff? 25:29 Life of a Diff 28:58 Writing Bots Writing Code Writing Bots 34:16 Finding Reviewers 38:46 Why Are Things Not Constantly on Fire? 41:43 Outro 47:47 Outtakes 48:46
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77: How to build a generic neuromotor interface
Join Pascal as he explores the groundbreaking world of generic neuromotor interfaces with Jesse, Lauren, and Sean. Discover how these technologies enable control of devices with just a flick of the wrist or even a simple intention to move. We'll discuss the role of AI in eliminating the need for personalised training, the differences between non-invasive interfaces and their predecessors, and the exciting implications for accessibility. Don't miss this deep dive into the future of human-computer interaction. Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Instagram (https://instagram.com/metatechpod) and don’t forget to follow our host Pascal (https://mastodon.social/@passy, https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/. Timestamps Intro 0:06 Jesse introduction 1:29 Lauren introduction 2:42 Sean introduction 3:29 Team's mission statement 3:49 What's a neuromotor interface? 4:24 Paper overview 5:29 Non-invasive interfaces 7:50 How to make it generic 9:42 Design tradeoffs 11:29 Real-world model performance 14:21 Feedback cycle 16:22 LLMs and EMG 17:22 Handwriting vision 18:39 Working with product 20:55 EMG for accessibility 22:25 How Meta helps 25:53 Open-source repos 28:02 What's next? 28:45 Outro 30:51 Links A generic non-invasive neuromotor interface for human-computer interaction - Nature - https://www.nature.com/articles/s41586-025-09255-w How the low-vision community embraced AI smart glasses - The Verge - https://www.theverge.com/the-vergecast/701018/ray-ban-meta-smart-glasses-be-my-eyes-ceo-accessibility-tech MKBHD on Orion - https://www.youtube.com/watch?v=G0eKzU_fV00
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76: From C to Rust on Mobile
What happens when decades-old C code, powering billions of daily messages, starts to slow down innovation? In this episode, we talk to Meta engineers Elaine and Buping, who are in the midst of a bold, incremental rewrite of one of our core messaging libraries—in Rust. Neither came into the project as Rust experts, but both saw a chance to improve not just performance, but developer experience across the board. We dig into the technical and human sides of the project: why they took it on, how they’re approaching it without a guaranteed finish line, and what it means to optimise for something as intangible (yet vital) as developer happiness. If you’ve ever wrestled with legacy code or wondered what it takes to modernise systems at massive scale, this one’s for you. Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Instagram (https://instagram.com/metatechpod) and don’t forget to follow our host Pascal (https://mastodon.social/@passy, https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/. Timestamps Intro 0:06 Introduction Elaine 1:54 Introduction Buping 2:49 Team mission 3:15 Scale of messaging at Meta 3:40 State of native code on Mobile 4:40 Why C, not C++? 7:13 Challenges of working with C 10:09 State of Rust on Mobile 18:10 Why choose Rust? 23:36 Prior Rust experience 28:55 Learning Rust at Meta 34:14 Challenges of the migration 37:47 Measuring success 42:09 Hobbies 45:15 Outro 46:41
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75: Open-sourcing Pyrefly - A faster Python type checker written in Rust
Pyrefly is a faster, open-source Python type checker written in Rust, succeeding Pyre. But what prompted the rewrite and what besides the language choice ended up making it faster? Host Pascal talks to Maggie, Rebecca and returning guest Neil about the unexpected complexities of building an incremental type checker that scales to mono repositories in episode 75. Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Instagram (https://instagram.com/metatechpod) and don’t forget to follow our host Pascal (https://mastodon.social/@passy, https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/. Links Pyrefly: https://pyrefly.org/ Pyre: https://pyre-check.org/ Ruff: https://github.com/astral-sh/ruff PEP 484: https://peps.python.org/pep-0484/ Timestamps Intro 0:06 Rebecca Introduction 1:45 Maggie Introduction 2:45 Neil (Re-)Introduction 3:12 Team Mission 3:56 History of Typing in Python 4:29 The State of Typed Python at Meta 5:32 fbcode 6:02 Original Motivation for building Pyre 6:19 Justifying the Rewrite 7:48 Pyrefly vs the Rest 9:41 Why Rust? 10:45 Fearless Concurrency 12:02 Why is it faster? 12:37 Python community and Rust 14:57 Pyrefly wasm crate 15:46 Upgrade experience 17:34 Type checking differences 19:12 IDE experience 21:31 State of Pyrefly at Meta 22:27 Being open-source-first 23:36 Open-source challenges 25:06 Unexpected challenges 26:39 Outro 31:05
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74: Taking the plunge - The engineering journey of building a Subsea Cable
To ensure that everyone has access to resilient, high-speed and low-latency connections to Meta services, no matter where in the world they are, Meta makes large-scale investments into subsea cable infrastructure. The recently announced Project Water worth will, Once complete, reach five major continents and span over 50,000 km (longer than the Earth’s circumference), making it the world’s longest subsea cable project using the highest-capacity technology available. In this episode, host Pascal talks with another Pascal and his colleague Andy who are involved at every stage of these projects and share the surprising challenges one has to deal with when working on the largest subsea cable project in the world. Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Instagram (https://instagram.com/metatechpod) and don’t forget to follow our host Pascal (https://mastodon.social/@passy, https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/. Links Project Waterworth: https://engineering.fb.com/2025/02/14/connectivity/project-waterworth-ai-subsea-infrastructure/ Timestamps Intro 0:06 Introduction Andy 2:14 Introduction Pascal 3:21 Why do we build our own subsea cable infrastructure? 4:15 Current state of Meta-owned subsea cables 6:20 Project Waterworth 7:40 Why invest in more subsea cables? 9:00 What does a cable look like? 11:14 The process of laying subsea cable 16:39 Unexpected findings on the ocean floor 19:25 Shallow vs deep ocean 21:12 Merging different cable types 24:00 What happens when a cable breaks? 25:04 Memorable challenges 27:42 Cable capacity 29:51 The long history of subsea cables 33:07 What's next? 36:27 Outro 39:02
Brought to you by Meta. In addition to remaining active in the open source community and conference circuit, this podcast offers another channel that allows us to highlight the technical work of our engineers who will discuss everything from low-level frameworks to end-user features. Throughout the podcast, Meta engineer Pascal Hartig (@passy) will interview developers in the company.
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