TypeScript compiler enthusiast and tooling engineer at a Stockholm dev tools company. Wrote the ESLint plugin that enforces exhaustive discriminated union handling, now downloaded 200 K/month.
Client-side form validation catches format errors early and improves user experience, but it cannot enforce business rules, authorization constraints, or uniqueness invariants. Understanding the validation layers and their responsibilities prevents both duplicate effort and dangerous gaps.
19 July 2026
Discriminated unions model state that cannot exist simultaneously — loading and data, success and error, authenticated and anonymous. The pattern eliminates entire classes of impossible state bugs and makes exhaustive handling of variants compiler-enforced.
19 July 2026
Branded types use TypeScript's type system to distinguish values that have the same primitive type but different semantic meanings. Passing a user ID where an order ID is expected becomes a compile-time error instead of a silent runtime bug.
19 July 2026