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Every time someone tells me types slow them down, I think about all the production incidents that would have been caught at compile time.

The compiler as a colleague

A good type system isn’t a gatekeeper. It’s a colleague who reviews your code before you even push it. It catches the things you forgot, the edge cases you didn’t consider, the assumptions you didn’t know you were making.

Making impossible states impossible

The real power of types isn’t catching null. It’s making impossible states impossible. When your types are right, entire categories of bugs simply cannot exist.

enum ConnectionState {
    Disconnected,
    Connecting { attempt: u32 },
    Connected { session: Session },
}

There’s no state where you’re “connected” without a session. No state where you’re “connecting” without tracking the attempt. The type is the documentation.

Types as thought tools

Before I write any implementation, I write the types. They force me to think about the domain. What are the states? What are the transitions? What’s the algebra of this problem?

Types aren’t bureaucracy. They’re a conversation with your future self. And your future self will thank you.