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Where can I read about the changes to validated in arrow 2.0?

<https://github.com/arrow-kt/arrow/pull/2795>

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&lt;Nel... I see now that there is EitherNel

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

Getting unresolved function on rightNel() though

```     private fun validLength(value: String): EitherNel&lt;SecretError, InternalSecret&gt; =
            if (value.length &gt; 16)  InternalSecret(value).right()
            else SecretError.NotEnoughCharacters.leftNel()```

I'm guessing leftNel() is something like
```fun &lt;E, T&gt; E.leftNel(): EitherNel&lt;E, T&gt; = nonEmptyListOf(this).left()```

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


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

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

`rightNel` or `validNel` theoretically doesn't really make a lot of sense perse because of `Nothing` in the `E` type argument.

Practically many people prefer to use `rightNel` though... this could indeed be completely omitted.

rightNel() could mean Nel&lt;T&gt; though

so Either&lt;Nel&lt;E&gt;, Nel&lt;T&gt;&gt;

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

This would be a good moment to fade `validNel` out using `ReplaceWith` with `@Deprecation`