kotlin-sum-types

What problem does it solve?

It solves the problem of scattered validation and unsafe domain logic by forcing external input to be parsed into explicit valid/invalid types at system boundaries.

Core Features & Use Cases

• Sealed valid/invalid modeling: Represents data as Valid* and Invalid* states so domain functions can safely assume correctness.
• Parse, don’t validate: Uses factory create() methods (often with @JsonCreator) to transform untyped data into typed domain objects in one place.
• Error collection with paths: Collects multiple validation errors while preserving original invalid values and composing nested error paths (e.g., email, address.city).
• Controller-style boundary handling: Uses exhaustive when statements to translate validated domain results into OK/error responses.

Quick Start

Ask an AI to explain how to model a JSON payload as a sealed Kotlin type with a create() parser that returns both valid and invalid states while collecting field-specific error messages.