No Snakes on My Ladder: Winning at Software with Types

Do you know how to play Snakes and Ladders? Great, you already know enough to enjoy this talk. I want to show you one of my favourite ideas in software design: using a type system to make whole categories of bugs impossible. Not "unlikely if you write enough tests," but actually impossible. Whatever language you write in, I think it'll change how you look at your code. We'll use everyone's favourite board game as our playground. Because without the right types, square 247 exists. A snake and a ladder can both be true at once. A winner keeps rolling the dice. And nobody notices until it's 2am and production is on fire. Using Rust as our guide, we'll see how a board position that can never exceed 100 is more honest than a plain number and a hopeful prayer, and how a Winner with no methods is just the compiler's way of saying "you're done, go home, you've earned it." No Rust experience needed. No type theory, no jargon, no monads, no PhD. Just Snakes and Ladders, a friendly compiler, and ideas you can use in whatever language you're working in tomorrow morning. Because somewhere out there, a player is sitting on square 247, somehow on a snake and a ladder at the same time, who won the game ages ago but is still taking turns. Let's fix that together.