Collect Non-empty options within an Eff-monad

ammonite.repl

Welcome to the Ammonite Repl 0.6.2
(Scala 2.11.8 Java 1.8.0_66)
ben_hutchison-ben_hutchison@ load.ivy("org.typelevel" %% "cats" % "0.7.1")

ben_hutchison-ben_hutchison@ load.plugin.ivy("org.spire-math" %% "kind-projector" % "0.9.0")
ben_hutchison-ben_hutchison@
load.plugin.ivy("com.milessabin" % "si2712fix-plugin_2.11.8" % "1.2.0")

ben_hutchison-ben_hutchison@ load.ivy("org.atnos" %% "eff-cats" % "2.0.0-RC7")

ben_hutchison-ben_hutchison@ import org.atnos.eff._, all._, syntax.all._;
import org.atnos.eff._, all._, syntax.all._;
ben_hutchison-ben_hutchison@  import cats._, data._, implicits._;
import cats._, data._, implicits._;
ben_hutchison-ben_hutchison@ case class Command()
defined class Command
ben_hutchison-ben_hutchison@
def commandFor[E: _Option](strategy: String): Eff[E, Command] = strategy match {
  case "Good" => fromOption(Some(Command()))
  case "Bad" => fromOption(Option.empty[Command])
}
defined function commandFor
ben_hutchison-ben_hutchison@ val strategies = Vector("Good", "Bad")
strategies: Vector[String] = Vector("Good", "Bad")
ben_hutchison-ben_hutchison@ val commandsForStats_OptionInEffect = strategies.traverse(commandFor(_))
commandsForStats_OptionInEffect: Eff[Fx1[Option], Vector[Command]] = Impure(Union1(Some(Command())),Arrs(Vector(<function1>, <function1>)))
ben_hutchison-ben_hutchison@ commandsForStats_OptionInEffect.runOption.run

//compare vs res12
res11: Option[Vector[Command]] = None
ben_hutchison-ben_hutchison@ val commandsForStats_OptionInPayload = strategies.traverse(commandFor(_).runOption).map(_.flatten)
commandsForStats_OptionInPayload: Eff[NoFx, Vector[Command]] = Pure(Vector(Command()))
ben_hutchison-ben_hutchison@ commandsForStats_OptionInPayload.run

//compare vs res11
res12: Vector[Command] = Vector(Command())