Functional Error Handling with Cats
summary
Option/Try/Either/IO all act as monads so composed parsing stops at the first failure — first-error wins — while Validated (an ApplicativeError, not a Monad) lets independent validations accumulate errors using a Semigroup for the error container — accumulated errors. Wrap per-field errors as Validated[_, F[E]] and combine with mapN to get either a constructed value or a concatenated error collection; prefer NonEmptyList or NonEmptyChain (or Chain for performance) to avoid slow list appends.
AI-written summary · about
chapters (8)
- 0:00Start
- 5:06FOR COMPREHENSION
- 15:15MONAD TYPECLASS
- 18:14MONADS START WITH
- 21:35APPLICATIVEERROR TYPECLASS
- 25:02TUPLE SYNTAX
- 27:10FIRST ERROR WINS
- 31:14SEQUENCES
