fibers's Introduction

Fibers for Scala

This library implements fibers (or coroutines) on top of delimited continuations as provided by the Scala CPS compiler plugin.

Usage

In your build.sbt file:

// Enable CPS plugin
addCompilerPlugin("org.scala-lang.plugins" % "scala-continuations-plugin_2.12.2" % "1.0.3"),
libraryDependencies += "org.scala-lang.plugins" %% "scala-continuations-library" % "1.0.3",
scalacOptions += "-P:continuations:enable",

// Depend on fibers-core
resolvers += Resolver.bintrayRepo("mulk", "maven")
libraryDependencies ++= Seq(
  "eu.mulk" %% "fibers-core" % "0.1.0",
)

Examples

Awaiting futures and tasks and emitting values:

import monix.eval.Task
import monix.execution.Scheduler.Implicits.global
import monix.reactive.Observable

import eu.mulk.fibers.Fiber._

import scala.util.Success

val slowBackgroundTask = Task.delay(100)

def produceNumbers: Unit @fiber[Int] = {
  val Success(x) = await(slowBackgroundTask)
  emit(x)
  emit(x*2)
  emit(x*3)
}

val observable: Observable[Int] = run(produceNumbers)
observable.foreachL(println).runAsync  // => 100, 200, 300

Using fiber-local state:

import monix.eval.Task
import monix.execution.Scheduler.Implicits.global
import monix.reactive.Observable

import eu.mulk.fibers.Fiber._

def emitFiberVar: Unit @fiber[Int] = {
  emit(getFiberVar)
}

def produceNumbers: Unit @fiber[Int] = {
  putFiberVar[Int](100)
  emitFiberVar
}

val observable: Observable[Int] = run(produceNumbers)
observable.foreachL(println).runAsync  // => 100