Hello, Is there a function to combine two validate...

# arrow

[Lidonis Calhau]

Hello, Is there a function to combine two validated variable to check is they are compatible with each other
Maybe a function like this to allow some check with both values

Validated<ValidationError, Enum1>, Validated<ValidationError, Enum2> -> Validated<Nel<ValidationError>, Pair<Enum1, Enum2>>

[stojan]

I think you are looking for zip

https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/-validated/#improving-the-validation

[Lidonis Calhau]

I tried with zip but the result type is

Validated<Nel<ValidationError>, Validated<Nel<ValidationError>, Pair<Enum1, Enum2>>>

[Lidonis Calhau]

maybe I did something wrong with the type, I will check

[stojan]

``fun <E, A, B, Z> ValidatedNel<E, A>.zip(b: ValidatedNel<E, B>, f: (A, B) -> Z): ValidatedNel<E, Z>``

this signature should work for you 👆 right?

[stojan]

or maybe you need to transform your error to ValidatedNel first

[Lidonis Calhau]

My problem is that errors inside the zip function are not combined with the error outside

[simon.vergauwen]

I think you want a.toValidatedNel().zip(b.toValidatedNel(), ::Pair)

[Lidonis Calhau]

Not really because I need to validate the combination of a and b inside the function. that why I get two validation errors in my return type when I use zip

[simon.vergauwen]

Can you share a full snippet with type signatures

[simon.vergauwen]

I’m not sure what you mean, my implementation matches the desired signature you shared

[Lidonis Calhau]

I made a new project to show what I mean
https://github.com/lidonis/arrow-playground/blob/master/src/main/kotlin/ValidatedCombination.kt
The method checkCombination doesn't compile because it doesn't match the signature I wanted

[stojan]

The sequential validation example should help there

https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/-validated/#sequential-validation