Created
July 29, 2019 17:17
-
-
Save alexandredantas/eb5d205fbeb7a6ece837f4f1b9557d21 to your computer and use it in GitHub Desktop.
custom monads for tagless final
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import scalaz.std.list._ | |
| import zio.IO | |
| import scalaz.{ Applicative, Monad } | |
| import scala.util.Try | |
| package object types{ | |
| type ThrowableSafeResult[+T] = IO[Throwable, T] | |
| implicit val ioMonadInstance: Monad[ThrowableSafeResult] = new Monad[ThrowableSafeResult] { | |
| override def point[A](a: => A): ThrowableSafeResult[A] = IO.effectAsync { callback => | |
| Try { | |
| a | |
| } | |
| .map(res => callback(IO.succeed(res))) | |
| .recover { case error => callback(IO.fail(error)) } | |
| } | |
| override def bind[A, B](fa: ThrowableSafeResult[A])(f: A => ThrowableSafeResult[B]): ThrowableSafeResult[B] = | |
| fa.flatMap(f) | |
| } | |
| implicit val ioApplicativeInstance: Applicative[ThrowableSafeResult] = new Applicative[ThrowableSafeResult] { | |
| override def point[A](a: => A): ThrowableSafeResult[A] = IO.effectAsync { callback => | |
| Try { | |
| a | |
| } | |
| .map(res => callback(IO.succeed(res))) | |
| .recover { case error => callback(IO.fail(error)) } | |
| } | |
| override def ap[A, B](fa: => ThrowableSafeResult[A])(f: => ThrowableSafeResult[A => B]): ThrowableSafeResult[B] = | |
| fa.flatMap(a => f.map(_ (a))) | |
| } | |
| implicit class IOMonadInstanceOps[F[_]](monad: Monad[F]) { | |
| def flatLift[A, B](fn: A => F[B]): F[A] => F[B] = { | |
| monad.bind(_)(fn) | |
| } | |
| def sequenceMap[A, B](xs: List[A])(fn: A => F[B]): F[List[B]] = { | |
| monad.sequence(xs.map(fn)) | |
| } | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment