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libraryDependencies+="dev.zio"%%"zio-interop-cats"%"<latest-version>"

ZIO integrates with Typelevel libraries by providing an instance ofConcurrent,Temporal andAsync forTaskas required, for instance, byfs2,doobie andhttp4s.

For convenience, the ZIO library defines an alias as follows:

typeTask[A]=ZIO[Any,Throwable,A]

Therefore, we provide Cats Effect instances based on this specific datatype.

In order to get aConcurrent[Task] orConcurrent[RIO[R, *]] (note* is kind-projector notation) we need to importzio.interop.catz._:

importcats.effect._importzio._importzio.interop.catz._defceConcurrentForTaskExample= {valF: cats.effect.Concurrent[Task]= implicitlyF.racePair(F.unit,F.unit)}

importcats.effect._importzio._importzio.interop.catz._defceTemporal= {valF: cats.effect.Temporal[Task]= implicitlyF.sleep(1.second)*>F.unit}

importcats.effect._importzio._importzio.interop.catz._defceAsync= {valF: cats.effect.Async[Task]= implicitlyF.racePair(F.unit,F.sleep(1.second)*>F.unit)}

There are many other typeclasses and useful conversions that this library provides implementations for:

• Seezio/interop/cats.scala file to see all available typeclass implementations for the Cats Effect 3 typeclasses
• Seezio/stream/interop/cats.scala for ZStream typeclass implementations
• Seezio/stream/interop/FS2StreamSyntax.scala for FS2 <-> ZStream conversions

If you only need instances forcats-core typeclasses, notcats-effect importzio.interop.catz.core._:

importzio.interop.catz.core._

Note that this library only has anOptional dependency on cats-effect – if you or your libraries don't depend on it, this library will not add it to the classpath.

The following example shows how to use ZIO with Doobie (a library for JDBC access) and FS2 (a streaming library), which both rely on Cats Effect instances (cats.effect.Async andcats.effect.Temporal):

importzio.{durationIntas_,*}importzio.interop.catz.*importdoobie.*importdoobie.implicits.*importscala.concurrent.duration.*objectExampleextendsZIOAppDefault:valrun= {valxa:Transactor[Task]=Transactor.fromDriverManager[Task]("org.h2.Driver","jdbc:h2:mem:test;DB_CLOSE_DELAY=-1","user","",None)sql"SELECT 42"      .query[Int]      .stream      .transact(xa)      .delayBy(1.second)      .evalTap(i=>Console.printLine(i))      .compile      .drain      .exitCode  }

Learn more on theZIO Interop Cats homepage!

For the general guidelines, see ZIOcontributor's guide.

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