Easy and Efficient Data Validation with Cats
summary
Compares Option and Either failure modes and shows Cats’ ValidatedNel as the practical solution for form validation by accumulating errors instead of failing fast; implements email/phone validators, combines them with the mapN/pizza symbol (apply) so all field errors return together, and uses a Semigroup (list/not-empty-list) to merge errors and force at least one message. Provides companion helpers (validateSuccess/Failure, accumulate) and working code on GitHub used successfully on multi-field forms.
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chapters (12)
- 0:00Start
- 2:20DATA VALIDATION
- 6:22CASE STUDY
- 7:23OPTION
- 10:50EITHER (2.11)
- 15:21EITHER (2.12)
- 21:10VALIDATED AND APPLY
- 28:27USE AN EXPRESSIVE ERROR TYPE
- 28:53OUR FINAL SOLUTION
- 31:02STEP 1
- 32:27A CONCRETE EXAMPLE
- 34:27SUMMARY
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