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Turbolift: Algebraic Effects for Scala 3


Highlights

 

⭐ Expressive power

Turbolift supports constructs rarely found in other effect systems, or in new programming languages with native support for Algebraic Effects. See Advanced Features.

 

⭐ High performance

Excerpt from Effect Zoo microbenchmark results:

image

image

 

⭐ Lightweight syntax

import turbolift.!!
import turbolift.effects.{Reader, State, Error}

case object MyReader extends Reader[Int]
case object MyState extends State[Int]
case object MyError extends Error[String]

val program =
  for
    a <- MyState.get
    b <- MyReader.ask
    c <- {
      if b != 0
      then !!.pure(a / b)
      else MyError.raise(s"Tried to divide $a by zero")
    }
    _ <- MyState.put(c)
  yield ()
// program: Computation[Unit, MyReader & MyError & MyState] = turbolift.Computation@6de2880e

val result = program
  .handleWith(MyState.handler(100).justState)
  .handleWith(MyReader.handler(3))
  .handleWith(MyError.handler)
  .run
// result: Either[String, Int] = Right(value = 33)

 

Usage

libraryDependencies += "io.github.marcinzh" %% "turbolift-core" % "0.46.0"

 

Credits

  • Turbolift’s syntax and typing of effects and handlers evolved from the predecessor project: Skutek (Eff monad).

  • The monad of delimited continuations is inspired by Scala Effekt.

  • IO related parts (WIP) are inspired by Cats Effect and ZIO.