functional-ts

Model domain state transitions in TypeScript by using discriminated unions with a kind property for state and pure functions for deterministic transitions. This functional approach replaces brittle class-based state management with safer, more maintainable domain logic.

Handle errors functionally in TypeScript domain modeling using Railway Oriented Programming with Result types. This enforces exhaustive error typing and safe state transitions without relying on exceptions for control flow.

Discriminated union domain modeling in server-side TypeScript works by defining states with a discriminant property like kind. Pure functions then handle transitions between states such as Waiting and EnRoute, ensuring deterministic and type-safe workflows.

Protect PII data types in TypeScript domain models using a Sensitive type at validation boundaries. This ensures personally identifiable information is explicitly marked and safeguarded during functional domain state transitions and use case processing.

Functional domain modeling works for complex workflows like order processing and taxi dispatch. By applying pure functions, Result types, and boundary validation, use cases and domain events remain safe, readable, and maintainable across server-side operations.

Use pure functions instead of classes for TypeScript domain logic to ensure deterministic state transitions and avoid brittle class hierarchies. Functional domain modeling with Result types and discriminated unions improves safety and readability.