typed-service-contracts

Type-safe input parsing and exhaustive error handling in TypeScript business logic can be achieved using the Spec-and-Handler pattern, which decouples service contract definitions from impure implementation logic to enforce strict boundary control and compile-time proof of error path coverage.

Replacing runtime exceptions with compile-time error path coverage in Java or Dart is best accomplished by implementing the Result-Type pattern, which substitutes error-throwing with exhaustive error-as-value handling to ensure all failure paths are explicitly managed.

The Spec-and-Handler pattern for building complex service contracts works by decoupling the definition of service specifications from their impure implementation logic, enforcing a strict, language-agnostic contract that satisfies requirements for non-throwing implementations.

Yes, you can use this type-safe service contract pattern for building CLIs, libraries, and complex business logic units, as it standardizes service architecture to ensure type-safe input parsing and exhaustive error handling across multiple dialects.

You should use error-as-value handling instead of throwing exceptions in complex business logic layers because it eliminates unhandled runtime exceptions and inconsistent data handling by enforcing a strict contract that guarantees all potential failure paths are explicitly accounted for at compile-time.