Cats ValidatedNec mapN with Case Class Error Types

Question

I'd like to use the Cats ValidatedNec data type similarly to the example in the Cats documentation for Validated in the section Meeting applicative -- in my case, I'm parsing String s from a file, validating against an appropriate regex for the field, and then (for several fields) converting to a different data type (assuming the regex matched). However, instead of using case object s which extend a common trait for the invalid results (as in the example), I'd like to use case class es (which extend a common trait) so I can include contextual information in the case of failure. Can this be done as simply as calling all the validation methods (putting the results in a tuple), as in the validateForm example, and calling mapN ? I'm getting conflicting errors from Intellij (from IntelliJ, it's telling me the expected and actual parameters to mapN are the same (though it is still marking it as an error); when running sbt on the command line, it doesn't resolve the mapN method. I'm using Scala 2.12.8 and cats 2.0.0-M1. Any help would be appreciated!

Answer 1

https://gist.github.com/DmytroMitin/6cf51c3563dba62307a2a256eeb4ebb5

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"IntelliJ errors" are irrelevant.

Regarding "sbt errors", in order to make mapN work, check that you have

import cats.syntax.apply._

If this still doesn't work for you provide your MCVE .