Higher-kinded composition makes objects compose through higher-level interfaces, much as functions compose by passing outputs into inputs. Algebraic data types (ADTs) provide this object-level composability. section 5.0
Function composition works cleanly when inputs are valid and operations cannot fail. Validation, null values, and exceptions complicate that model, so ADTs represent one concept—such as validation or error handling—behind a concise composable interface. section 5.0
The pattern shifts branching and failure handling into composable operations:
- Model a single concern with an ADT rather than a broad class. section 5.0
- Expose an interface that lets similar abstractions chain together. section 5.0
Composable validation
A validation pipeline can chain length, tampering, difficulty, linkage, and timestamp checks with successive flatMap calls instead of embedding guards before every function.
