Where can I read about the changes to validated in arrow 2 0 kotlinlang #arrow

rightNel() replaces validNel() then? and leftNel() replaces invalidNel(). Are these extensions implemented in arrow 2.0? I can see them in the new docs in the PR, but they don't seem to be implemented?

Ah, nevermind I misunderstood it as ValidatedNel being deprecated for Either<Nel... I see now that there is EitherNel

simon.vergauwen

01/16/2023, 1:50 PM

Yes, in practice not much changes. All the idioms and APIs remain the same.

Kristian Nedrevold

01/16/2023, 2:02 PM

Getting unresolved function on rightNel() though

and leftNel()

simon.vergauwen

01/16/2023, 2:02 PM

What version are you trying?

Kristian Nedrevold

01/16/2023, 2:04 PM

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private fun validLength(value: String): EitherNel<SecretError, InternalSecret> =
            if (value.length > 16)  InternalSecret(value).right()
            else SecretError.NotEnoughCharacters.leftNel()

I'm guessing leftNel() is something like

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fun <E, T> E.leftNel(): EitherNel<E, T> = nonEmptyListOf(this).left()

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implementation(platform("io.arrow-kt:arrow-stack:2.0.0-SNAPSHOT"))

simon.vergauwen

01/16/2023, 2:07 PM

Yes, if that is not available then it should be added to 2.0.0

Kristian Nedrevold

01/16/2023, 2:10 PM

as a side note. The old validNel() is kind of strange right?

because invalidNel = leftNel != left and that sounds good but also vanlidNel = right = rightNel

simon.vergauwen

01/16/2023, 2:18 PM

rightNel

validNel

theoretically doesn't really make a lot of sense perse because of

Nothing

in the

type argument. Practically many people prefer to use

rightNel

though... this could indeed be completely omitted.

Kristian Nedrevold

01/16/2023, 2:27 PM

rightNel() could mean Nel<T> though

so Either<Nel<E>, Nel<T>>

Obviously rightNel won't be there for that type signature so It's not a real problem

I personally just think that rightNel seems unnecessary

simon.vergauwen

01/16/2023, 2:36 PM

Right, I agree.

This would be a good moment to fade

validNel

out using

ReplaceWith

with

@Deprecation

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