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kotlinlang

Hi, what happen if one these option is None  :
```Option.applicative().tupled(coursOpt, eleveOpt).fix().map { tuple -&gt; // doing stuff }.```
Is there a possibility to know which one has failed ?

options `applicative` instance should always short-circuit and return `None` when it finds a `None`.
Generally speaking the order in which this happens is undefined as `applicative` makes no assumptions about it, however I believe we have a convention that unless explicitly noted the order is always left to right. This is somewhat important for things like `traverse`.
Knowing which failed is not possible with `Option` because `None` carries no information with it, consider using a type that has a custom error like `Either` or similar.
Figuring out where something went short-circuit in an `Applicative` combinator is usually the wrong approach (because the order is just by convention), do you want to recover in those cases or just for the error message?

In my case  I just want to throw an error message. The 2 optionals come from  requests from the database and I do some verifications with these 2 values. If one them is None, I want to throw the appropriate error message.

Is there any alternative to handle this ?

you could to something like `Either.applicative().tupled(a.toEither { "MyErr1" }, b.toEither { "MyErr2" })`
This will return a `Either&lt;String, Tuple2&lt;...&gt;&gt;` which you can then fold to get the error or the value.
Note this will not combine errors if both fail, if you want that you'd need `Validated` instead of error, but the idea is the same

Can definitely recommend using Validated for this pattern.  <https://arrow-kt.io/docs/0.10/apidocs/arrow-core-data/arrow.core/-validated/>