Functional Patterns for Reliable TypeScript

Build reliable systems using Algebraic Data Types (ADTs), discriminated unions, Result/Option types, and branded types. These patterns enable the compiler to prove correctness, prevent runtime errors, and make illegal states unrepresentable.

Why Functional Patterns?

Reliability through types: Use the type system to encode business rules, making invalid states impossible to construct. The compiler becomes your safety net, catching errors at build time rather than runtime.

Key benefits:

• Exhaustiveness checking prevents missing cases
• Impossible states become unrepresentable
• Business logic encoded in types, not runtime checks
• Refactoring becomes safe and mechanical
• Self-documenting code through types

Quick Reference