Error handling code samples don't compile about arrow-core HOT 8 CLOSED

Hi @tomvandenberge, looks like that part of documentation is outdated because we are not validating it with Ank. Our mistake. fx was moved to work over the companion object of the type, that is Option.fx {} and Either.fx { }.

This is what would work now:

Option

import arrow.core.None
import arrow.core.Option
import arrow.core.Some
import arrow.core.extensions.fx

object Lettuce
object Knife
object Salad

fun takeFoodFromRefrigerator(): Option<Lettuce> = None
fun getKnife(): Option<Knife> = None
fun prepare(tool: Knife, ingredient: Lettuce): Option<Salad> = Some(Salad)

fun prepareLunchOption(): Option<Salad> =
  Option.fx {
    val lettuce = takeFoodFromRefrigerator().bind()
    val knife = getKnife().bind()
    val salad = prepare(knife, lettuce).bind()
    salad
  }

Either

import arrow.core.Either
import arrow.core.Left
import arrow.core.Right
import arrow.core.extensions.fx

object Lettuce
object Knife
object Salad

typealias NastyLettuce = CookingException.LettuceIsRotten
typealias KnifeIsDull = CookingException.KnifeNeedsSharpening
typealias InsufficientAmountOfLettuce = CookingException.InsufficientAmount

sealed class CookingException {
  object LettuceIsRotten: CookingException()
  object KnifeNeedsSharpening: CookingException()
  data class InsufficientAmount(val quantityInGrams : Int): CookingException()
}

fun takeFoodFromRefrigerator(): Either<NastyLettuce, Lettuce> = Right(Lettuce)
fun getKnife(): Either<KnifeIsDull, Knife> = Right(Knife)
fun lunch(knife: Knife, food: Lettuce): Either<InsufficientAmountOfLettuce, Salad> = Left(InsufficientAmountOfLettuce(5))


fun prepareEither(): Either<CookingException, Salad> =
  Either.fx {
    val lettuce = takeFoodFromRefrigerator().bind()
    val knife = getKnife().bind()
    val salad = lunch(knife, lettuce).bind()
    salad
  }

I've checked and when using it like this, autocomplete works seamlessly. I'm using Arrow 0.10.5.

I you want to help on fixing docs you can find those here. We'd need to adapt those snippets to match my examples here and move all those from to be kotlin:ank blocks instead of simply kotlin, that's what enables our Ank processor to validate doc snippets.

Sorry for the inconvenience, let me know if this is clear enough 👍

from arrow-core.

Thanks for raising this issue, @tomvandenberge. I've seen that the example that is using arrow.core.extensions.option.monad.binding doesn't include the ank rule so it's not being validated when building the documentation.

We're going to fix it and maybe we could create another issue to review the ank rule for all the code snippets because it's missing in other cases 👍

Thanks again!

from arrow-core.

In the meantime, what do I need to change to make it work?

Thanks

from arrow-core.

Hi! It seems there is a reason why it doesn't include the ank rule and there are pending tasks to make it work: arrow-kt/arrow#2097 Let's see if someone else can provide more info about it cc: @pakoito

from arrow-core.

hehehe monad.binding predates fx and the snippets aren't updated nor checked

In the meantime, what do I need to change to make it work?

Load them up in a project with arrow-core, and follow IntelliJ's suggestions about imports for fx. Good chance it'll be just Either.fx because the snippet is for a concrete instance.

Then open a PR to the docs with the fix :D

from arrow-core.

You're making this really hard. As I said in my first message, it doesn't come up with any suggestions. And, yes, my project imports arrow-core (0.10.4). Could you please tell me what to import?

from arrow-core.

Sorry, I missed your edit on your response. Either.fx doesn't work: Function invocation 'fx(...)' expected.

A working code sample, including imports would be great.

from arrow-core.

Created #96 to fix them. Thanks @JorgeCastilloPrz 🙌

from arrow-core.