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EitherTSupport

EitherTSupport

import scalaz._
import Scalaz._

import effectie.scalaz.Effectful._
import effectie.scalaz._
import effectie.scalaz.EitherTSupport._

trait Something[F[_]] {
def foo(a: Int): F[String \/ Int]
def bar(a: String \/ Int): F[String \/ Int]
}

object Something {
def apply[F[_]: Something]: Something[F] =
implicitly[Something[F]]

implicit def something[F[_]: Fx: Monad]: Something[F] =
new SomethingF[F]

final class SomethingF[F[_]: Fx: Monad]
extends Something[F] {

def foo(a: Int): F[String \/ Int] = (for {
x <- a.rightTF[F, String] // == EitherT(Applicative[F].pure(a).map(_.right[String]))
y <- (x + 10).rightTF[F, String] // == EitherT(Applicative[F].pure(x + 10).map(_.right[String]))
y2 <- if (y > 100)
eitherTLeft[Int]("Error - Bigger than 100")
else
eitherTRightPure[String](y)
// โ†‘ if (y > 100)
// EitherT(pureOF("Error - Bigger than 100").map(_.left[Int]))
// else
// EitherT(pureOf(y).map(_.right[String]))
z <- effectOf(y2 + 100).rightT[String] // == EitherT(effectOf(y + 100).map(_.right))
} yield z).run

def bar(a: String \/ Int): F[String \/ Int] = (for {
x <- a.eitherT[F] // == EitherT(pureOf(a: String \/ Int))
y <- effectOf((x + 999).right[String]).eitherT // == EitherT(effectOf((x + 999).right[String]))
} yield y).run
}

}

import scalaz.effect._

Something[IO].foo(1).unsafePerformIO()
// res1: String \/ Int = \/-(b = 111)
Something[IO].foo(10).unsafePerformIO()
// res2: String \/ Int = \/-(b = 120)

Something[IO].bar(1.right[String]).unsafePerformIO()
// res3: String \/ Int = \/-(b = 1000)
Something[IO].bar("No number".left[Int]).unsafePerformIO()
// res4: String \/ Int = -\/(a = "No number")