Matt stumbled across a famous John Carmack email from 2007 — the one where he asks his team to start thinking about inlining their functions — and couldn’t stop thinking about it. So this week we sat down to pull it apart.
On the surface it reads like a hot take on code style: stop breaking everything into small functions, inline the logic, use big comment blocks instead. Easy to dismiss, easy to misread. Matt read it, formed a confident take, went back and re-read it, and discovered his first take was wrong. That gap, between what the email seems to say and what it’s actually getting at, is where the whole conversation lives.
Because the real message isn’t “inline everything.” It’s think about it. And once you take that seriously, one short email starts asking uncomfortable questions about state, consistency, and why we trust the advice we trust. What does it mean to write code with no surprises? When is running code you don’t need the safer choice? And why does a technique that’s obviously right for a game’s core loop feel obviously wrong for the software the two of us actually build?
That last question turns out to be the point. Carmack isn’t handing down a rule; he’s showing his working for a specific set of constraints, and trusting his readers to notice their own constraints are different. Which is exactly the part our industry is worst at: we take “here’s how I do it” and turn it into “here’s how it’s done,” pattern by pattern, until blind adherence becomes its own anti-pattern.
And then there’s the human sting in the tail. Carmack signs off the whole thing with a single word — “Discussion?” — inviting his team to push back. It’s a lovely gesture. It’s also, we suspect, a little naive about what happens when someone that senior “invites discussion.” Sometimes the most powerful person in the room can’t make a suggestion at all, no matter how they phrase it.
No grand thesis, no neat landing. Just two mates thinking out loud about a genuinely great piece of writing; which, fittingly, is all Carmack was ever asking for. We barely scratched the surface, and we’d genuinely love to hear what it stirs up for you.
🍻 Tonight’s Drinks
Liam – Neither beer nor scotch this week (the garage beckoned, the scotch cupboard was bare). Just a driven dev. Matt – Not Coffee, but the placebo effect helped
🔗 Links from the episode
- The famous John Carmack 2007 email on inlining functions (also contains the 2014 follow-up)
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