Where communities thrive


  • Join over 1.5M+ people
  • Join over 100K+ communities
  • Free without limits
  • Create your own community
People
Repo info
Activity
Ivano Pagano
@ivanopagano
this is some form of CanBuildFrom, semantically, yet I would rather avoid doing it procedurally
but I guess I need to be able to "unfold" rather than "fold" as in traverse
owww, sorry, I meant Traverse[T] of course
Gavin Bisesi
@Daenyth
I'm not sure there's a typeclass describing unfold
Ivano Pagano
@ivanopagano
I guess not, indeed
I guess this means that I may stop searching
Rob Norris
@tpolecat
List is already traversable … what is your intent?
Gavin Bisesi
@Daenyth
@tpolecat I think he wants def unfoldWhatever[F[_]: Foldable, G[_]: ?Unfoldable?, A](as: F[A]): G[A] ( @ivanopagano is that right)
something something recursion schemes?
Greg Pfeil
@sellout
đź‘€
Rob Norris
@tpolecat
Haha
We don’t have such a thing but you can do it with Foldable and MonoidK
JsonFn
@JsonFn
When trying Applicative example e.g. Applicative[List].product(List(3), List(4)).flatten It throws No implicit view available from (Int, Int) => scala.collection.GenTraversableOnce[B]. How can I create GenTraversableOnce? The only way is to create a new such instance? for instance new GenTraversableOnce { ... }
Fabio Labella
@SystemFw
that's a red herring
Rob Norris
@tpolecat
What is your intent? The product is a List of pairs of Int.
Fabio Labella
@SystemFw
there no implicit views needed in cats, you must be getting flatten from collections
Rob Norris
@tpolecat
If you want a list of Int you can flatMap the pairs to lists.
Fabio Labella
@SystemFw
random info: Applicative cannot flatten, you need monad. you can use syntax and do (List(3), List(4)).product
or mapN and many other things
JsonFn
@JsonFn
@SystemFw no wonder. my fault. thanks for the advice.
Soren
@srnb_gitlab

wonder why you'd want F[A] => F[Boolean] instead of A => F[Boolean] tho

@oleg-py I'm checking the state of whether creating a Resource[F, ?] failed or not

So I want to use dropWhileF(_.attemptT.isLeft)
then take the head on it
Jakub Kozłowski
@kubukoz

We don’t have such a thing but you can do it with Foldable and MonoidK

MonoidK or Alternative?

Soren
@srnb_gitlab
@Daenyth On the usage of fs2, how should I get the head from the stream? Is calling compile in the middle of my program ok?
Jakub Kozłowski
@kubukoz
it's fine (stream.head.compile.lastOrError should do it)
Gavin Bisesi
@Daenyth
Sure. You can .head.compile.last and get F[Option[A]]
Jakub Kozłowski
@kubukoz
or that yeah
Gavin Bisesi
@Daenyth
But if your F[A] is a resource you don't want this
because you've lost release
Jakub Kozłowski
@kubukoz
I think he doesn't have a resource since there's a List[A] mentioned forget it, I can't read again today
Soren
@srnb_gitlab
Yeah, I need the first Resource[F, Connection[F]] that doesn't encounter an error
Gavin Bisesi
@Daenyth
that's a bit trickier
and when I say a bit... massively
uh
how about
Jakub Kozłowski
@kubukoz
hmm
Soren
@srnb_gitlab
It's a List[ServerEndpoint] that I'm trying to find the first valid one
Jakub Kozłowski
@kubukoz
stream.head.compile.resource.last.flatMap(_.sequence)
not sure but according to my knowledge resource might help there
Gavin Bisesi
@Daenyth
val operation = connRes.use(stuff)
Stream.retry(connRes, ...)
oh I see, you don't have Resource, you have List[A] and A => Resource ?
that seems easier
Soren
@srnb_gitlab
Yes
Gavin Bisesi
@Daenyth
Hmm, the failure handling is a little trickier though
like
you can't just return a Resource
Soren
@srnb_gitlab
I have List[ServerEndpoint], ServerEndpoint => Resource[F, Connection[F]], and I want the first Resource[F, Connection[F]] that doesn't fail to connect
Gavin Bisesi
@Daenyth
because in order to make sure you didn't fail you need to run acquire
so since you need to run acquire you should take your use as an input