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Version: v1

Fx

Fx​

If you use Cats Effect and write tagless final code, and look for a generic way to construct F[A], Fx can help you.

import effectie.cats._

trait Something[F[_]] {
  def get[A](a: => A): F[A]
}

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

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

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

    def get[A](a: => A): F[A] =
      Fx[F].effectOf(a)
  }
}

import cats.effect._

val get1 = Something[IO].get(1)
// get1: IO[Int] = Delay(thunk = <function0>)

get1.unsafeRunSync()
// res1: Int = 1

If you feel it's too cumbersome to repeat Fx[F].effectOf(), consider using Effectful

Effectful​

If you're sick of repeating Fx[F].effectOf() and looking for more convenient ways?, use Effectful instead.

import effectie.cats.Effectful._
import effectie.cats._

trait Something[F[_]] {
  def get[A](a: => A): F[A]
}

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

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

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

    def get[A](a: => A): F[A] =
      effectOf(a)
      // No more Fx[F].effectOf(a)
  }
}

import cats.effect._

val get1 = Something[IO].get(1)
// get1: IO[Int] = Delay(thunk = <function0>)

get1.unsafeRunSync()
// res3: Int = 1