m05-type-driven

You can enforce compile-time invariants by encoding invalid states as impossible using type-driven design. This approach leverages type-level patterns like type state and marker traits to catch errors during compilation rather than at runtime.

The typestate pattern encodes state transitions directly into the type system, ensuring safer APIs by making invalid API usage a compile-time error. It restricts operations to valid states, preventing unauthorized transitions before execution.

Use phantom types and newtypes to represent domain concepts safely when you need to distinguish data at the type level without runtime overhead. They provide zero-cost type safety by tagging data with compile-time distinctions.

The best way to progressively construct complex objects is by using builder patterns alongside validated constructors. This ensures invariants are sealed during construction, preventing the creation of partially valid or invalid objects.

Validate data at construction to guarantee an object is never instantiated in an invalid state, and validate during state transitions to enforce lifecycle rules. Type-driven design helps determine the optimal checkpoint for compile-time checks.

Yes, type-driven design patterns apply across languages that support generics and type systems. While Rust excels at zero-cost abstractions, you can implement newtypes, phantom types, and builders in any statically typed language for safer APIs.