In this episode of The Idealcast, Gene Kim shares and gives commentary on Scott Havens’ talk from the 2019 DevOps Enterprise Summit Las Vegas. Havens is a Director of Engineering at Wayfair, where he leads Engineering for the Wayfair Fulfillment Network. He is a leading proponent of applying functional programming principles to technical and organizational design. Previously, Scott was the architect for Walmart's global omnichannel inventory system, unifying availability and replenishment for the largest company in the world by revenue. In his 2019 DevOps Enterprise Summit talk, Havens highlights functional programming and e-commerce systems work. He also talks about what he did to massively simplify those systems while also making them more testable, reliable, cheaper to operate, and easier to change. Finally, he discusses the implications of using functional programming to change how to design systems and systems of systems on a larger scale.   ABOUT THE GUEST Scott Havens is Director of Engineering at Wayfair, where he leads Engineering for the Wayfair Fulfillment Network. Scott cares deeply about scalable data-intensive software systems. He is a leading proponent of applying functional programming principles to technical and organizational design. Previously, Scott was Director of Engineering at Jet.com and was the architect for Walmart’s global omnichannel inventory system, unifying availability and replenishment for the largest company in the world by revenue. In his home life, Scott enjoys good food, good wine, bad movies, and asking his daughter to stop “redecorating” his Minecraft castles, pretty please.   LinkedIn: https://www.linkedin.com/in/scott-havens/ Twitter: @ScottHavens Email: scott@sphavens.com   YOU’LL LEARN ABOUT Functional programming and what it is. How e-commerce systems work. What Havens did to massively simplify those systems while also making them more testable, reliable, cheaper to operate, and easier to change. The implications of using functional programming to change how to design systems and systems of systems on a larger scale.   RESOURCES Fabulous Fortunes, Fewer Failures, and Faster Fixes from Functional Fundamentals: Scott Havens’ 2019 DevOps Enterprise Summit Talk  Slidedeck for the Havens’ 2019 DOES talk Clojure Pass by reference (C++ only) John Carmack John Carmack Keynote - Quakecon 2013 Panther Systems   TIMESTAMPS [00:24] Intro [02:52] Functional programming [07:59] Gene introduces Scott [09:13] Working at Wal-Mart [11:13] Disaster struck [14:10] One common piece of e-commerce website functionality [17:07] The implications of functional programming for system design [21:05] Changing how to design systems and systems of systems [28:55] Using Panther [33:11] How this affects the hot path and cost [36:43] One bite a time [37:52] Contacting Scott [38:13] Outro