Kleisli demonstration

conf.sc

interp.configureCompiler(_.settings.YpartialUnification.value = true)

kleisli.sc

import $file.`conf`
import $ivy.`org.typelevel::cats-core:1.1.0`
import cats.data.Kleisli
import cats.instances.future._
import cats.syntax.compose._
import cats.syntax.traverse._

import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future

val f1 = (i: Int) => Future(i + 2)
val f2 = (i: Int) => Future(i * 3)
val f3 = (i: Int) => Future(i - 1)

val f = Kleisli(f1) >>> Kleisli(f2) >>> Kleisli(f3)

println(f(2))

val r = Future.successful(42)
val sf = (i: Int) => (s: String) => Future.successful(s"$i$s")

val ksf = sf.andThen(Kleisli(_))

val rx = Kleisli.liftF(r).flatMap(ksf).run