ZIO is a zero-dependency Scala library for asynchronous and concurrent programming with similar features as Cats IO or Monix.
ZIO — A type-safe, zero-dependency library for asynchronous and concurrent programming in Scala.
Homepage: https://zio.dev/
Questions tagged [zio]
241 questions
2
votes
1 answer
How to narrow down ZIO Schedule environment?
There is an example of a simple API that uses ZIO effect to return None or Option[String]. I use ZIO Schedule to run the effect as long the None is returned, but limited to a certain number of times. The example is based on the code from ZIO…
Valentine
- 147
- 1
- 5
2
votes
1 answer
ScalaJs + ZIO: Program works with sbt 1.2.8 but not >= 1.3
I'm trying out scala.js with zio using the sample app at
https://github.com/wongelz/zio-scalajs-solarsystem
as soon as I update the sbt version from 1.2.8 to 1.3.13 or 1.4.4 I'm getting the following error:
[error] Referring to non-existent method…
Dominik Dorn
- 1,820
- 12
- 18
2
votes
2 answers
Scala - differents between eventually timeout and Thread.sleep()
I have some async (ZIO) code, which I need to test. If I create a testing part using Thread.sleep() it works fine and I always get response:
for {
saved <- database.save(smth)
result <- eventually {
Thread.sleep(20000)
database.search(...)
…
Developus
- 1,400
- 2
- 14
- 50
2
votes
1 answer
Write output of ZIO Stream to file
I am trying to write the results of a ZIO Stream to a file. The following example app takes a sequence of integers, converts them to bytes, compresses them with the gzip transducer, but I cannot figure out how to write them to a file.
I think I need…
RandomBits
- 4,194
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2
votes
1 answer
What is ZIO error channel and how to get a feeling about what to put in it?
ZIO (https://zio.dev/) is a scala framework which has at its core the ZIO[R, E, A] datastructure and its site gives the following information for the three parameters:
ZIO
The ZIO[R, E, A] data type has three type parameters:
R - Environment Type.…
fanf42
- 1,828
- 15
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2
votes
1 answer
Is it possible to do tail-recursion on a method which returns ZIO?
For example:
def foo(bar: String): UIO[String] = {
for {
f <- UIO("baz")
res <- foo(f)
} yield res
}
seems like that it's impossible because the last line is a mapping function
Natan
- 1,944
- 1
- 11
- 16
2
votes
1 answer
Convert ZIO Task to IO
I have the next code:
import zio._
import scala.concurrent.Future
case class AppError(description: String) extends Throwable
// legacy-code imitation
def method(x: Int): Task[Boolean] = {
Task.fromFuture { implicit ec => Future.successful(x ==…
kraik
- 35
- 4
2
votes
0 answers
Scala, ZIO - some strange problem with layers in ZIO
I have created simple own type:
type MyEnv = ZEnv with Clock with MyRepository
and have Main method:
object Main extends App {
lazy val live: ZLayer[Any, Nothing, Has[MyRepository.Service]] = ZLayer.succeed(LiveMyRepository.repository)
val…
Developus
- 1,400
- 2
- 14
- 50
2
votes
2 answers
Composing Multiple Futures and Option in Scala with ZIO
I just started evaluating ZIO to improve the programming model and the performance of my asynchronous Scala code. In my code base I deal with Future[Option[T]] often, and to this point I have dealt with that using Scalaz's OptionT monad transformer.…
Vidya
- 29,932
- 7
- 42
- 70
2
votes
1 answer
Why putStrLn of zio didn't output
Why putStrLn in flatMap followed by a result statement didn't get effectively write to stdout?
object Mgr extends App {
def main1(args: Array[String]) = getStrLn.flatMap { s =>
putStrLn(s) // Why this did not write to console?
…
Michaelzh
- 441
- 5
- 14
2
votes
1 answer
Useful stack traces for futures/parallel code
When running code in threads the stack traces oftentimes do not show the logic flow of the code where it was assembled/defined,
but the execution stack trace. This is oftentimes not the information I need for debugging and context.
ZIO does a great…
Alex
- 8,518
- 4
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2
votes
1 answer
Scala, Circe, Http4s - is it any way to encode Throwable in Circe?
I have created hierarchy of errors:
sealed trait MyError extends Throwable
final case class SecondError(msg: String) extends MyError
Now I could get this kind of error in my http4s routes:
case GET -> Root / "things" => for {
response <-…
Developus
- 1,400
- 2
- 14
- 50
2
votes
2 answers
How does one assert a single field in error type?
Let's assume I have code such as this:
final case class CustomException(errorCode: Int, id: UUID) extends Throwable
val logic: ZIO[Any, Throwable, Unit] = ???
I would like to use ZIO Test to check for a specific error case
val checkForTimeout =…
Tim Steinbach
- 23
- 4
2
votes
1 answer
ZIO: How to dynamic inject a dependency
In ZIO we provide the Environment with initiating Traits:
program.provide(
new Console.Live with MyComponent {}
)
What I wanted to do is to inject MyComponent dynamically from a configuration file - analog Guice Modules.
The whole scenario is…
pme
- 14,156
- 3
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- 95
2
votes
0 answers
ZIO, Release resources after execution
I am playing with ZIO and built a simple application that get content via HTTP :
for {
options <- Options.parse(args)
http = HttpClient(args)
content <- Download.execute(args.resource).provide(http)
} yield ()
It does the job but the…
gervais.b
- 2,294
- 2
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